Background

The procedures of total elbow and shoulder replacements increased 6% to 13% annually from 1993 to 2007 with revision-related burden increasing from 4.5% to 7%. The revisions of the shoulder and elbow prostheses due to aseptic loosening, periprosthetic fractures, infections have led to the use of standard or custom-made implants due to significant bone loss. This study reports our experience in the management of complicated primary and revisions of total shoulder and elbow replacements with significant humeral bone loss and in metabolic diseases of the elbow and shoulder treated with bone resection using The Mosaic Humeral Replacement System.

Patients and Materials

A total of 20 patients underwent total elbow or shoulder arthroplasty using the Mosaic Humeral Replacement System (Biomet, UK). The Mosaic system was used in 8 shoulder arthroplasties (Group A) and in 12 elbow arthroplasties (Group B). The underlying pathologis in Group A included 2 malunited proximal humerus fracture, 1 humeral osteomyelitis, 1 shoulder chondrosarcoma, 1 aggressive Gigantic Cell Tumor with prosthetic fracture, 2 metastatic lytic lesion, and 1 failed fixation of non-union proximal humerus. Figure 1 shows Mosaic implant after complex fracture of proximal humerus. Reasons for Mosaic arthroplasty in Group B included 3 humeral component revisions due to periprosthetic fracture, 1 prosthesis breaking-up with fractures, 1 revision of loose Souter Strathclyde prosthesis, 1 loose prosthesis due to infection, 1 highly comminuted elbow fracture, 1 aseptic loosening of humeral component of total elbow replacement, 3 revision of total elbow replacement due loosening and 1 pathological distal humerus fracture due to metastasis. Figure 2&3 shows pre- and post-operative Mosaic implant following complex periprosthetic fracture of distal humerus.

Background

The quest for the perfectly designed elbow prosthesis continues as instability and loosening remain the foremost reasons for the failure of total elbow replacement (TER). The Discovery® Elbow System (Biomet, UK) (Figure 1), which has been used in UK since 2003, is one of the latest generations of linked prosthesis. This system was designed to decrease polyethylene-bushing wear, improve anatomic stem design, restore elbow joint biomechanics, and produce a hinge that could be easily revised. This report describes the short term outcome of TER using the Discovery® Elbow System.

Patients and Methods

A total of 60 TERs including 48 primary and 12 revisions were performed between 2003 and 2008. Patients included 21 males (37%) and 36 females (63%) with a mean age of 63 years. The indications for primary TER were advanced rheumatoid arthritis (n=19), osteoarthritis (n=16), post traumatic osteoarthritis (n=9), acute fractures (n=3), and haemophilic arthropathy (n=1). The outcome was assessed using pain score, Liverpool Elbow Score (LES), and range of movement during a mean follow-up of 26 months. Associated complications were documented. Radiological assessment included evaluation for loosening, instability and periprosthetic fractures.

BACKGROUND

Reverse total shoulder arthroplasty (RTSA) provides an alternative to standard total shoulder arthroplasty in the treatment of selected complex shoulder problems including failed shoulder replacements. The purpose of this report is to present outcome of RTSA using Comprehensive Reverse System (CRS) as either primary or revision treatment choice.

PATIENTS AND MATERIALS

Between September 2010 and April 2012, 54 patients (36 females, 18 males) with the mean age of 68.4 (±10) underwent RTSA-CRS. In 27 patients RTSA-CRS was performed as a revision due to failed previous arthroplasty. Primary underlying conditions included AVN (2), massive irreparable rotator cuff tear (2), primary osteoarthritis (7), post-traumatic osteoarthritis (2), rheumatoid arthritis (6), and rotator cuff arthropathy (8). It was not possible to complete the operation in 6 patients (4 revisions group 2 AVN cases) due to substantial glenoid erosion. Preoperative CT scan was performed in 50% of patients to assess the bony stock of the glenoid. In some patients ultrasound and MRI were performed to acquire additional information. A total of 46 patients were followed-up by means of antroposterior and axial plain X-rays, pain and satisfaction level (VAS/0–10), stiffness, Constant Score, Oxford Shoulder Score, SF-12 (Physical and mental Subscales), and range of movement for a mean duration of 6.5 months (±4.2).

INTRODUCTION

Poor acetabular cup orientation in total hip arthroplasty (THA) can cause dislocation and impingement, and lead to osteolysis (Little et al., 2009) and inflammatory soft tissue reactions (Haan et al., 2008). While the intrinsic accuracy of cup positioning in navigation is reported as low as 1° (Parratte et al., 2009), a large anterior pelvic tilt may lead to an offset of the same magnitude in the final cup anteversion (Wolf et al., 2005). The objectives of this study are to demonstrate feasibility of a new, non-invasive radiographic tool for accurate preoperative determination of a patient's specific pelvis angle, and intraoperative and postoperative assessment of the acetabular cup orientation with respect to boney landmarks.

METHODS

The methodology stitches multiple radiographic views around the pelvis using a multi-planar radiography setup (Amiri et al., 2011) and reconstructs the reference boney landmarks and the acetabular cup in three dimensions using previously developed algorithms and software (Amiri et al., 2012). To validate the methodology, a Sawbone model of the pelvis and femur was implanted with a standard cementless metal-on-polyethylene THA, and was tracked and digitized by an Optotrak motion tracking system. Five radiographic views were acquired at the pubic tubercle (PT) and anterior-superior iliac spine (ASIS) levels (Views 1 to 5 in Fig 1). Imaging and analysis were repeated 10 times. Custom software (Joint 3D) was used to reconstruct the right and left PT and ASIS by fitting spheres to the corresponding pairs of images (Fig 1). The three-dimensional pose of the acetabular cup was reconstructed in the software by solving a back-projection equation of the elliptical shadow of the cup opening. Accuracies were measured as mean differences from the digitized references. A sample of the reconstructed graphical output for the anterior pelvic plane (APP) and the cup, in comparison to the digitized reference, is shown in Fig 2. Repeatability was estimated as standard deviation of the measures for the reconstructed locations of the boney landmarks and the APP (known as a standard reference plane for cup placement).

Introduction

The aim of this study was to quantitatively analyze the amount coronal plane laxity in mid-flexion that occurs with a loose extension gap in TKA. In the setting of a loose extension gap, we hypothesized that although full extension is achieved, a loose extension gap will ultimately lead to increased varus and/or valgus laxity throughout mid flexion.

Methods

After obtaining IRB approval, six fresh-frozen cadaver legs from hip-to-toe underwent TKA with a posterior stabilized implant (APEX PS OMNIlife Science, Inc.) using a computer navigation system equipped with a robotic cutting-guide, in this controlled laboratory cadaveric study. After the initial tibial and femoral resections were performed, and the flexion and extension gaps were balanced using navigation, a 4 mm distal recut was made in the distal femur to create a loose extension gap (using the same thickness of polyethylene as the well-balanced case). Real implants were used in the study to eliminate error in any laxity inherent to the trials. The navigation system was used to measure overall coronal plane laxity by measuring the mechanical alignment angle at maximum extension, 30, 45, 60 and 90 degrees of flexion, when applying a standardized varus/valgus load of 9.8 [Nm] across the knee using a 4 kg spring-load located at 25 cm distal to the knee joint line. (Figure 1). Coronal plane laxity was defined as the absolute difference (in degrees) between the mean mechanical alignment angle obtained from applying a standardized varus and valgus stress at 0, 30, 45, 60 and 90 degrees. Each measurement was performed three separate times.

Two tailed student t-tests were performed to analyze whether there was difference in the mean mechanical alignment angle at 0°, 30°, 45°, 60°, and 90° between the well balanced scenario and following a 4 mm recut in the distal femur creating a loose extension gap.

Introduction

Total ankle arthroplasty is increasingly used as an alternative to arthrodesis to treat advanced ankle arthritis. In an attempt to assess the survivorship and patient outcome as well as peri- and postoperative complications and possible risk factors, we retrospectively analyzed the demographics, clinical outcome and radiographic characteristics of 100 ankle prostheses (97 patients).

Patients and methods

Between 3/2005 and 5/2010 114 S.T.A.R. Prostheses were implanted by one surgeon at our institution. Indication for TAA was primary and secondary osteoarthritis, 81 cases were posttraumatic. From the 53 female and 44 male patients the mean age was 63 and the mean BMI was 28,4.

11 patients had been smoking for longer than 12 years, 29 patients either had a history of diabetes, peripheral vascular or cardiovascular disease or varicosis.

All operations were performed with a tourniquet, using a standard anterior midline incision. All patients received the same postoperative rehabilitation and follow up program. Postoperative evaluation included the AOFA Score and clinical radiographic follow ups 6 weeks after surgery and yearly thereafter. Additional procedures during surgery included lengthening of the Achilles tendon for 12 patients and fusion of the subtalar ankle for 5 patients.

Introduction

Computer aided surgery aims to improve surgical outcomes with image-based guidance. Navigated Freehand bone Cutting (NFC) takes this further by eliminating the need for cumbersome mechanical jigs. Multiple previous experiments on plastic and porcine bones, performed by surgeons with different level of expertise, suggested that the NFC technique was feasible. This study pushes NFC further by using the technique to perform complete total knee replacement (TKR) surgeries on cadavers (including implant cementing of tibia and femur).

Materials and Methods

A single surgeon performed a series of TKR surgeries on full cadaveric legs. Cruciate sacrificing implants were selected because these were considered more challenging for a freehand cutting approach due to the extra number and complexity of the cuts needed around a posterior stabilizing post recess when present.

A proprietary NFC prototype system was used, with real time graphics to indicate where/how to cut the bone without jigs. The system comprised a navigated smart oscillating saw, reciprocating saw and drill without any of the conventional jigs typically used in TKR.

The tasks performed included (and were grouped) to include pre-surgical planning, incision, placement of navigation pins & markers on tibia and femur, bone registration, marking and cutting, cut surface digitization (for quality assessment), implant placement and cementing, assessment of implant fit and location, and pin removal and wound closing.

Introduction

The introduction of the Stanmore Implants Savile Row mobile-bearing UKA procedure in July 2011 marked a world first – the use of a patient-specific knee implanted with robotic technology – the Sculptor Robotic Guidance Arm (RGA). This union gives a truly personalised solution by designing an implant for each patient based upon preoperative CT data and using Sculptor RGA to prepare the bone accurately so that the implant is correctly positioned as planned. The purpose of this study is to evaluate the accuracy of Sculptor RGA both in-vitro and in-vivo. We report on the accuracy of our first clinical procedures.

Methods

In-vitro:

CTs of plastic-bones were used to create plans for Sculptor RGA, establishing a relationship between the implant position and plastic-bone (planned-transform). Sculptor RGA was then used to prepare bones for 16 UKA implants mimicking the clinical set-up. The implants were placed in the prepared bones without cement. A coordinate-measuring-arm was used to register a)the bone, and b)the implant in relation to the bone (achieved-transform). The difference between planned-and-achieved transforms gives the error in implant position.

In-vivo:

Preoperative CTs of 8 OA patients, acquired using the low-dose Imperial Knee CT protocol, were used to plan the position and the shape of the patient-specific implants. Intra-operatively, Sculptor RGA was used to register and prepare the bone and the implants were cemented in place. Post-operative CTs were also acquired. Two techniques were used to measure planned-to-achieved positions of the implants: 1). Preoperative-to-postoperative CT image registration followed by extraction of the achieved implant position and comparison with the plan, 2). Surface-to-surface registration of bone-models segmented from the preoperative and postoperative CTs followed by extraction of the achieved implant position and comparison with the plan.

Introduction

The purpose of this study was to evaluate the functional outcome in the medium and long-term of hip resurfacing in comparison with cementless hip replacement in patients under the age of 55.

Methods

Eighty patients were enrolled between 1999 and 2002. Twenty-four were randomised (11 hip re-surfacing, 13 total hip replacement), 18 refused hip resurfacing and chose cementless total hip replacement with a 32 mm bearing, 38 insisted on re-surfacing. All the patients have been reviewed at a minimum follow-up of 8 years and a mean of 10.1 years. Patients were assessed clinically and radiographically at one year, five years, eight years and ten years. Outcome measures included EQ 5, SF 36, Oxford, Harris hip, UCLA and UCH scores.

Methods

A prospective review of 19 patients managed at two tertiary referral units between 2000 and 2011. Each patient was diagnosed and managed according to similar institutional protocols. Investigation through aspiration and biopsy of periprosthetic tissue supplemented haematological tests to confirm infection. The Cannulock uncoated stem was used in 14 cases, and the Kent hip prosthesis in 5 cases. Allograft struts were used in patients with deficient bone stock.

Results

The mean follow-up for the series was a 53 months (range, 24–99 months). 13 patients underwent definitive revision within 7.9 months (range, 6–10 months; SD, 2.2 months). In 6 cases we implanted an extensively porous-coated stem, in 4 cases a tapered distally fixed cementless stem was used, and in 3 cases a proximal femoral replacement was used. There were no reinfections after the second stage revisions in these patients. 2 patients were offered further staged surgery due to persistently raised inflammatory markers but being mobile and relatively painfree declined. They are being managed in the community on oral antibiotics. Satisfactory outcome was noted in all cases, and in 13 cases, revision to a definitive stem was undertaken after successful control of infection and fracture union. The average postoperative Harris Hip score was 83 (range 79–89). All patients returned to their low to moderate premorbid functional state after discharge.

Introduction

Realistic knee contact forces and moments are needed for testing implant wear, fatigue and static strength, for analysing strains and remodelling at interfaces, as ‘gold standard’ for analytical musculo-skeletal models, or as input for finite element models. ISO 14243 defines the loading conditions for wear tests, but the defined loads from walking are based on very old data.

Methods

Therefore we compared the ISO loads with data obtained from instrumented tibial components with telemetric data transmission. Cruciate ligaments sacrificing total knee implants (Innex FIXUC, Zimmer) were equipped with inductively powered electronics and strain gauges to measure 6 force and moment components acting on the tibial component [1]. The coordinate system is fixed at the tibial component. -Fz acts inferiorly, +Fy anteriorly, and +Mz if the tibia is rotated outwards with the femur being fixed.

Loads were measured in 8 subjects (70 years Ø) during 10–20 repeated cycles of free walking at about 4 km/h. For each subject the load components were normalized to 75 kg body weight (BW) and averaged [2] (‘Aver75_1Subj’). These individual results were averaged again and delivered the ‘standard’ load components ‘Aver75’. From all 8 ‘Aver75_1Subj’ patterns of the resultant force Fres the highest peak value was taken and divided by the peak value of Fres in ‘Aver75’. The obtained factor was then multiplied with all ‘Aver75’ components and the BW increased to 100 kg. The final ‘standard’ components (‘High 100’) describe the highest average loads to be expected in a heavy-weight subject. This worst case but still realistic conditions should be used for wear and fatigue tests.

Introduction

The marriage of rapid prototyping technologies with Arthroplasty has resulted in the fabrication and use of cutting jigs and guides which are tailored to a patients' individual anatomy. These disposable cutting blocks are designed based on input parameters obtained from pre-operative CT and MRI scans and manufactured using 3-D printers. Indirect benefits include a reduction in inventory and a decrease in the burden for central sterilising units. This approach is advantageous for the surgeon in the attainment of ideal mechanical alignment, which is known to be associated with an improved clinical outcome and implant longevity. This study evaluated the postoperative alignment parameters from a single surgeon series of patients following TKA with the Signature (Biomet) system.

Methods and Materials

The postoperative alignment of a single surgeon series of 60 consecutive patients receiving a Vanguard cruciate retaining TKR (Biomet) using the Signature patient-specific surgical positioning guides was performed. Postoperative CT and preoperative templating MRI scans were imported into Mimics 14.0 (Materialise, Belgium) where specific bony landmarks were identified in both data sets. A subset of these points was used to transform the MRI data into the CT coordinate frame to enable the computation of femoral mechanical alignment in the absence of a full-length lower limb CT scan. CT and transformed MRI landmarks were then imported into ProEngineer (PTC, MA) where angular measurements were made by projecting axes onto anotomical planes. Flexion, rotation, valgus/varus of the femoral component and posterior slope, rotation and valgus/varus of the tibial component were computed. Femoral rotation was referenced to the trans-epicondylar axis as opposed to Whiteside's line. Overall limb alignment was determined based on individual component position.

Method

3 groups of retrieval tapers were analysed (Group 1: 28 mm CoCr heads from well functioning MOMTHRs (n=5); Group 2: Large diameter CoCr heads from LHMOMTHRs revised for failure secondary to adverse reaction to metal debris (n=5); Gp 3 (control): 28 mm heads from well functioning metal on Polyethylene (MOP) THRs; n=3). Clinical data on the retrievals was collated. The Redlux profiling of modular head tapers involves a non direct method whereby an imprint of the inside surface of a modular head is taken, and this is subsequently scanned by an optical non contact sensor using dedicated equipment [1]. The wear was also measured on the bearing surface [1]. RedLux profiling of the tapers produced a taper angle and 3D surface maps. The taper angles obtained with the Redlux method were compared to those obtained using CMM measurement on 3 parts. The Redlux profiling, including imprints, was also repeated 3 times to gauge potential errors.

Results

There was no difference in mean 12/14 taper angles between groups. There was no difference in volumetric and linear wear at the bearing surface between groups. Only the LHMOMs showed transfer of pattern from the stem to the internal head taper, with clear demarcation of the contact and damaged area between head taper and stem trunnion (see figure 1 – interpretation of head taper surface features demonstrated using Redlux optical imaging). 3D surface mapping demonstrated wear patterns compatible with motion or deformations between taper and trunnion in the LHMOM group. These appearances were not seen in tapers from small diameter MOM and MOP THRs (see Figure 2).

Case

A 69 year old woman had a THR in 2008. A year later she started to complain of lateral based hip pain. Clinical examination and initial imaging indicated trochanteric bursitis and heterotopic bone formation. The symptoms became worse over the next 3 years and the patient was listed for exploration and excision of heterotopic bone.

Surgical findings

Extensive pseudotumour was encountered deep to bursa and adherent to capsule. Abductors, external rotators and vastus lateralis were spared. There was minimal calcar osteolysis and marginal erosion in superior acetabulum. There was no obvious wear on the articulating surfaces of the femoral head and polyethylene inlay of the socket nor was there any evidence of neck-to-rim impingement or edge loading. There was visible blackening of both the taper and trunnion after femoral head removal.

Introduction

Proper femoral stem and acetabular implant orientation is critical to the initial and long-term success of THA. Post-operative determination of cup and stem anteversion is important in cases of hip instability and planning isolated component revisions. At ISTA 2010 Dubai, we introduced a novel, simple stem modification that can be added to any stem design to help assess stem, and possibly cup anteversion with plain post-operative radiographs throughout the lifespan of the implant. [Figure 1] As the stem is rotated, the visible hole pattern changes. [Figure 2] This study was performed to further validate the accuracy and potential usefulness of this design.

Methods

We prospectively reviewed 100 consecutive THA cases using the stem reference hole modification on rectangular tapered Zweymuller-type stems implanted from September 2010 to May 2012. Post-operative hip/femur CT scans were obtained to determine the true cup and stem orientation to validate and quanitify the precision of the reference holes. Intra-operative estimates of stem anteversion and combined anteversion (Ranawat Sign) were recorded. Post-operative radiograph measurement of stem anteversion (AP hip x-ray with leg in neutral rotation) was obtained and compared to the CT scan measurement referencing stem rotation relative to the knee epicondylar axis. [Figure 3] In addition, we compared the modified reference hole anteversion assessment to a control group of original unmodified stems assessed using the same methods.

Introduction

Proper total knee arthroplasty balancing relies on accurate component positioning and alignment as well as soft tissue tensioning. Technology for cutting guide alignment has evolved from the “free hand” technique in the 1970's, to traditional intra/extra medullary rods in the 1980's and 1990's, to computer navigated surgery in the 2000's, and finally to patient specific custom cutting blocks in the 2010's. The latest technique is a modification to conventional computer navigation assisted surgery using Brainlab's Dash™ TKA/THA software platform that runs as an application on an Apple IPod held by the surgeon in a sterile pouch in the operative field. The handheld IPod touch screen allows the surgeon to control all aspects of the navigation interface without needing the assistance of an observer to manually run the software. In addition, the surgeon is able to always focus on the operative field while ‘navigating’ without looking up at a remote image monitor. This study represents a prospective analysis of the first 30 U.S. TKA cases performed using the newly commercially released Dash™ software using an IPod during surgery.

Methods

Thirty consecutive primary total knee arthroplasty procedures were performed using the Dash™ software (Brainlab) and an IPod touch (Apple). A cemented Genesis II (Smith Nephew) posterior stabilized implant was used in all cases. Femoral and tibial sensor arrays were placed in meta-diaphyseal regions for bone registration. We recorded the time spent to set up the arrays, time for bony registration, time to navigate the cutting guides, and the tourniquet time. After all bone cuts were completed, the tibial cut was manually measured with an intramedullary angle check instrument to assess the planned zero degree posterior slope and neutral varus/valgus coronal alignment. Final femoral and tibial component alignment and orientation was measured on standing long axis AP and lateral radiographs. Measurements from the Dash™ alignment group were compared to 30 consecutive surgeries using the author's traditional technique of intramedullary cutting block alignment (control group).

INTRODUCTION

Conventional surgical exposures are usually inadequate for 2-stage revision knee replacement ofinfected implants. Reduced range of motion, extensor mechanism stiffness, peripatellar contracture and soft tissue scarring make patellar eversion difficult and forced eversion places the integrity of the extensor mechanism at risk. On the contrary, a wide exposure is fundamental to allow complete cement spacer removal, soft tissue balancing, management of bone loss and reimplantation without damaging periarticular soft tissues.

OBJECTIVES

To compare the long-term clinical, functional and radiographic results and the reinfection rate of the quadriceps snip approach and the tibial tubercle osteotomy in 2-stage revision knee replacement performed for septic loosening of the primary implant.

INTRODUCTION

The purpose of our work was to evaluate changes in clinical scores, passive knee kinematics and stability after mobile bearing TKA surgery.

MATERIAL AND METHODS

60 patients were treated with a mobile bearing prosthesis (Gemini, Waldemar Link, Hamburg, Germany). PCL was always resected. Inclusion criteria were BMI >30, age range 60–80 yrs. Preoperative KSS, KOOS and SF36 scores were recorded. Surgeries were performed with a navigation system (BLU-IGS, Orthokey Italia, Firenze, Italy) to verify bone cuts, ligament balancing and implant positioning. Kinematic tests were executed to determine: tibial rotation and femoral translation through flexion range. Stability tests were performed using varus-valgus stress in extension and at 30° of flexion and drawer test. Acquisition were perfomed with menisci and cruciate ligaments intact, and repeated after final implant fixation. Clinical scores were recorded at 6 months follow-up.

Introduction

Unicompartmental knee arthroplasty (UKA) is a successful procedure for medial compartment osteoarthritis (OA). Recent studies using the same implant report a revision rate of 2.9%. Other centers have reported revision rates as high as 10.3%. The purpose of this study was to retrospectively review the clinical results of Oxford Phase 3 UKA's performed in the setting of isolated medial compartment OA and to compare our results to the previous mid-term studies. Our secondary goal was to determine reasons for revision and evaluate selected independent predictors of failure.

Methods

A retrospective review of 465 Oxford Phase 3 medial UKA's performed on 386 patients (222 female; 164 male) with isolated medial compartment OA. The average age at surgery was 69.5 years (40–88). Outcome measures included: Knee Society Scores(KSS), Oxford Knee Scores(OKS), SF-12, WOMAC, revision rates, and patient satisfaction. We evaluated independently predictors of failure including: gender, body mass index(BMI), number of previous surgeries, implant sizes, cement technique (simultaneous vs staged), cement type. Revision rates based upon the polyethylene thickness (defined as thin 3–4 mm; medium 5–6 mm; thick 7–9 mm). The need for stems and augments and the degree of constraint required at revision to a total knee arthroplasty (TKA) were evaluated.

Background

The constraint of total knee replacement (TKR) implants is not simply defined and many of the factors that influence it are not well understood. Variability in the constraint of different TKR implants designed for the same indication (e.g. cruciate-retaining, or posterior-stabilized) have been previously demonstrated, but these differences among implants have yet to be simply quantified. Furthermore, the relative importance of several variables on the implant constraint remains unknown. The purpose of this study was to quantify the differences in constraint that exist between different implant designs, and to examine the effects of axial load and flexion angle on the constraint of current cruciate-retaining (CR) TKR components.

Methods

Four contemporary CR TKR designs underwent laxity testing using a multi-axis mechanical test machine. Implants were tested at flexion angles of 0°, 20°, 90° and maximum flexion and axial loads of 712 N (1 BW) and 1424 N (2 BW). Friction-free motion in all secondary degrees of freedom was allowed. Force-displacement curves were generated for each testing condition in both anterior-posterior (AP) and rotational tests. AP constraint (N/mm) and rotational constraint (Nm/deg) were then calculated.

Purpose

Bilateral simultaneous and staged total hip arthroplasty has been issues in terms of safety and costs with development of surgical technique, postoperative medical care. The purpose of this prospective study is to compare the outcomes of simultaneous and staged bilateral operations, in terms of outcome, safety, and socioeconomic-effectiveness.

Patients and Methods

All patients(470 cases) that underwent simultaneous or staged bilateral THA using modified minimally invasive two-incision technique between January 2004 and November 2009 were registered, and after exclusion divided into two groups; simultaneous bilateral THA group (Group A: 171 patients) and staged bilateral THA group (Group B: 64 patients) by patient's condition and preference. Staged operations were performed at the time when patients want to get surgery due to undurable pain. For clinical evaluations, amounts of blood loss, blood transfusion, postoperative morbidity and mortality were compared. And for socioeconomic-effectiveness, costs for hospitalization and time for returning to previous job were investigated.

Introduction

In recent years, there has been a growing interest in bioresorbable metals. Orthopaedic components made from these materials do not require removal by secondary surgery, and offer superior load bearing capability compared to the existing biodegradable polymers.

Research on bioresorbable metals have largely focused on alloys based on a subset of the Mg-Zn-Ca ternary system [1, 2], which are pre-existing elements inside the human body. Cytocompatibility assessments of these alloys have reported no signs of inflammation or adverse cellular reactions [2-4]. Rather than designing for longevity, bioresorbable metals rely on their tendency to corrode in a controlled manner. Hence, controlling their corrosion rates is of utmost importance. In the present work, we have explored the effect of compositional variation on the properties of the Mg-Zn-Ca amorphous metals. Subsequent characterisations are performed to assess their suitability as a bioresorbable material.

Materials and Methods

A mixture of pure elements and master alloys, namely magnesium, zinc, calcium, and Mg-Ca master alloy, were melted in an induction furnace, followed by injection casting to produce the amorphous metallic samples. Pure magnesium (crystalline) was also used in the subsequent characterisation tests for comparison. The thermophysical properties of the as-cast amorphous metals were characterized using x-ray diffraction (XRD) and differential scanning calorimetry (DSC). The biocorrosion performance was assessed by a combination of immersion, potentiodynamic polarisation (PDP) and hydrogen evolution studies. These tests were conducted in cell media, with a sodium bicarbonate buffer, at 37°C and pH 7.4 in a humidified CO₂ atmosphere.

Introduction

Total knee arthroplasty (TKA) has proven to be cost-effective and efficative in the treatment of osteoarthritic knees. Although traditional computer navigation systems improve implant placement, they require fixation of the femoral and tibial reference arrays for software recognition using anchoring pins. This increases the risk of bony fracture, pin sites infection and osteomyelitis. Our study aims to investigate the accuracy of a new inless navigation system (Brainlab VectorVision Knee 2.5 Navigation System) that would avoid these complications.

Methods

119 patients were prospectively recruited over a year. These patients all underwent a primary TKA by a senior surgeon who performs more than 200 TKAs per annum. They were divided into two surgical technique arms. In Group 1, 74 patients underwent TKA using conventional techniques. In Group 2, 45 patients underwent TKA using a pinless navigation system.

Post-operative films were taken and three radiographic measurements were measured: 1) Hip-Knee-Ankle Angle (HKA); 2) Coronal Femoral-Component Angle (CFA); 3) Coronal Tibia-Component Angle (CTA) (Figure 1). Two reviewers blinded to the surgical method performed the measurements on the radiographic films on two separate occasions.

Introduction & Aims

Intravenous administration of tranexamic acid (TXA) has been shown to be effective in reducing blood loss and transfusion requirements in total knee arthroplasty (TKA). However, concern exists that I.V. TXA may heighten the risk of venous thrombo-embolism. The intra-articular administration of TXA is an attractive and simple option to deliver this agent locally with minimal systemic effects on inducing hypercoagubale states. In this study, we analysed the effect of varying dosages of intra-articular tranexamic acid on blood loss in TKA.

Methods

176 patients who underwent a unilateral TKA for osteoarthritis were retrospectively analysed. Patients were excluded if they underwent a revision knee arthroplasty, concurrent removal of hardware, extensive synovectomy, or lateral patellar retinacular release. All patients underwent a primary cemented posterior stabilised TKA by 2 surgeons using a medial parapatellar approach. Tourniquet was only inflated for initial exposure and intra-articular drains were not used. Patients were separated into three groups; a control group (n=56) who did not receive TXA, and 2 treatment groups who received intra-articular TXA with doses of 1500 mg (n=60) or 3000 mg (n=60). Once the wound was closed, tranexamic acid was injected intra-articularly via an epidural pain catheter. Haemoglobin (Hb) levels were taken pre-operatively and on post-operative days 1 and 2. The primary outcome measure was mean difference in Hb drop between the three groups.

Purpose

There are some concerns about doing hip resurfacing arthroplasty in ONFH due to bone defect which can cause mechanical weakness of femoral component and highly active young age of patients which can cause high wear rate and failure rate. The purpose of this study is to verify the HRA is safe procedure in ONFH in the aspect of mechanical and biological issue.

Materials and Methods

Between December 1998 and May 2005, 185 hips of 169 patients underwent MoM HRA using Birmingham Hip Resurfacing System® at single center. 166 hips (26 hips of female, 140 hips of male) of 144 patients have been reviewed for at least 7 years after MoM HRA. Mean follow-up period was 101.8 (84–178) months. Their mean age at the time of operation was 37.7(16–67) years old. Clinically, Harris hip scores (HHS), UCLA activity scores and range of motion were evaluated. Radiologically, the extent of necrotic area in preoperative MRI and radiolucency around implants, narrowing of retained neck, impingement, stress shielding, and heterotopic ossification were evaluated in the serial anteroposterior and groin lateral radiographs of hip. Complications were defined as joint dislocation, infection, implant loosening, femoral neck fracture and pseudotumor. Failure was defined as revision arthroplasty due to the complications.

Introduction

Periprosthetic osteolysis following total hip arthroplasty is caused mainly by polyethylene wear particles and necessitates revision surgery at some stage even in the presence of well-fixed implants. Therefore, methods to estimate the polyethylene wear become important, with manual wear measurement methods as the main outcome measurement even in the presence of computer-assisted measurement methods on account of easy availability and simplicity in their use with reasonable accuracy. The purposes of this study were to quantify the accuracy and reproducibility of the slide presentation software method on clinical radiographs and to compare it with that of the previously described Livermore's method, and to determine the usefulness of the slide presentation software methods for highly cross linked polyethylene wear measurement.

Materials and Methods

81 hips out of 61 patients who underwent primary total hip arthroplasty between October 2000 and January 2006 were retrospectively evaluated for polyethylene wear by two independent observers using the Livermore's and the slide presentation software methods. All the hips were implanted with highly cross linked polyethylene acetabular liners with cementless acetabular components. The 28 mm sized cobalt chrome alloy femoral heads were used in all cases. The mean age of the patients was 50.8 years(range, 27–73 years), and the mean follow-up period was 6.6 years (range, 2–11 years). Paired radiographs were analyzed using the Livermore's and the slide presentation software method. For the Livermore's methods, radiographs were magnified to 200%, printed, and readings taken with digital calipers with an accuracy of 0.01 mm(Figure 1). For the slide presentation software method, we used Microsoft Office PowerPoint software(Microsoft Corp., Redmond, WA, USA) as described in a previous our study(Figure 2).

Introduction

Patellar resurfacing during Total Knee Arthroplasty (TKA) is controversial. Problems unique to patellar resurfacing may be influenced by available patellar component design. These issues include; over-stuffing (the creation of a composite patellar-prosthesis thickness greater than the native patella) that may contribute to reduced range of motion; and over-resection of the native patellar bone that may contribute to post-operative fracture. Prosthesis design may play a role in contributing to these problems. Component diameter and thickness are quite variable from one manufacturer to another and little information has been previously published about optimal component dimensions. This anatomic study was performed to define the native patellar anatomy of patients undergoing TKA, in order to guide future component design.

Methods

This retrospective, IRB approved study reviewed 797 Caucasian knees that underwent primary TKA by a single surgeon. Data recorded for each patient included: gender; patellar thickness before and after resurfacing, and the size of the component that provided the greatest patellar coverage without any overhang. The residual patellar bone thickness after resection was also calculated.

Methods

A retrospective review of one hundred and ninety one Rejuvenate Stems that were implanted between January 2010 and January of 2012. However, after March 2011, this stem was only used on those patients who had a rejuvenate stem on the contralateral side. They were all implanted through a mini posterior incision with the first 82 patients receiving a Tritanium cluster hole cup (Stryker Orthopedics) with between two and three screws. The remaining 109 patients had an ADM (Anatomic Dual Mobility, Stryker Orthopedics). All patients were allowed to bear weight as tolerated and were followed up with Xrays at six weeks and one year. Clinical visits were recorded at 2 weeks and 6 months postop. Additional follow up was scheduled every two years following the first annual visit.

Results

One hundred and seventy four of the 191 hips were available for review at the one-year follow-up. Fourteen patients have undergone revision of the hip due to increased pain and formation of an avascular pseudo capsule due to corrosion at the neck stem junction. All patients have demonstrated a black flaky residue at the taper junction and all have had a large, tense effusion with a milky colored fluid. A neo caspsule has formed in all patients that appeared avascular and thickened. Seven of the eight tritanium cups in the revision cases were loose and required revision, while none of the ADM cups were loose. One patient has undergone two revisions since the initial cause of failure was not recognized and she subsequently developed pain within three months following placement of a new modular neck at the initial revision. One patient who underwent revision developed a deep infection and is currently on antibiotics but has not cleared the infection as of this writing.

INTRODUCTION

Immediate post-operative stability of a cementless hip design is one of the key factors for osseointegration and therefore long-term success [1]. This study compared the initial stability of a novel, shortened, hip stem to a predicate standard tapered wedge stem design with good, long-term, clinical history. The novel stem is a shortened, flat tapered wedge stem design with a shape that was based on a bone morphology study of 556 CT scans to better fit a wide array of bone types [2].

METHODS

Test methods were based on a previous study [3]. Five stems of the standard tapered wedge design (Accolade, Stryker Orthopaedics, Mahwah, NJ) and the novel stem (Accolade II, Stryker Orthopaedics, Mahwah, NJ) were implanted into a homogenous set of 10 synthetic femora (Figure 1) utilizing large left fourth generation

composite femurs (Sawbones, Pacific Labs, Seattle, WA). The six degrees-of-freedom (6 DoF) motions of the implanted stems were recorded under short-cycle stair-climbing loads. Minimum head load was 0.15 kN and the maximum load varied between 3x Body Weights (BW) and 6 BW. Loading began with 100-cycles of “normal” 3 BW and was stepped up to 4 BW, 5 BW & 6 BW for 50-cycles each. Prior to each load increase, 50 cycles of 3 BW loading was applied. This strategy allowed a repeatable measure of cyclic stability after each higher load was applied.

The 6 DoF micromotion data, acquired during the repeated 3 BW loading segments, were reduced to four outcome measures: two stem migrations (retroversion and subsidence at minimum load) and two cyclic motions (cyclic retroversion and cyclic subsidence). Data were analyzed using repeated measures ANOVA with a single between-subjects factor (stem type) and repeated measures defined by load-step (3 BW, 4 BW, 5 BW 6 BW).

Objectives

To examine patient mortality, implant survivorship, and complication profiles of proximal femoral replacement (PFR) as compared to revision total hip arthroplasty (REV) or open reduction internal fixation (ORIF) in the treatment of acute periprosthetic fractures of the proximal femur.

Methods

We performed a retrospective controlled chart review at our tertiary center from from 2000–2010, identifying 97 consecutive acute periprosthetic proximal femoral fractures. Patients were stratified into three treatment groups: PFR (n=21), REV (n=19), and ORIF (n=57). Primary outcome measures included death, implant failure, and reoperation. We also recorded patient demographics, medical comorbidities, fracture type, treatment duration, time to treatment, and complication profiles. Statistical analyis included competing risks survival, which allows independent survival analysis of competing failure mechanisms such as death and implant failure.

INTRODUCTION

Adult reconstructive orthopedic surgery in the United States is facing an imminent logjam due to the increasing divergence of the demand for services and the ability for the community to supply those services. In combination with several other factors, a perfect storm is brewing that may leave the system overtaxed and the patient population suffering from either a lack of treatment, or treatment by less qualified providers. A key component to improving the overall efficiency of surgical care is to introduce enabling technologies that can effectively increase the throughput while simultaneously improving the quality of care. One such enabling technology that has proven itself in many industries is robotics, which has recently been introduced in surgery with even more recent applications in orthopedic surgery. A surgeon interactive robotic arm has been developed for partial knee arthroplasty (PKA) and total hip arthroplasty (THA). This study aims to analyse the efficiency of a new robotic technology for use in orthopaedic surgery.

METHODS

18 robotic arm assisted PKA's across 10 sites were recorded to accurately capture the timeline elemental tasks throughout the procedure. Two camera angles were set up to capture both surgical staff group dynamics and individual procedural steps. 17 tasks were identified and measured from video data. (Fig 1) The robotic arm specific tasks were analyzed for correlation to total surgical time (measured as first incision to last suture). The tasks for the surgeons with the shortest and longest total times were compared directly to determine areas of opportunity.

Introduction

Improper acetabular component orientation has been shown to negatively affect the outcome of total hip arthroplasty through increasing dislocation rates, component impingement, bearing surface wear, and the rate of revision surgeries. The “Safe Zone” was defined by Lewinnek et al. in 1978 as 5 to 25 degrees of cup version and 30 to 50 degrees of cup inclination. Later, the inclination “Safe Zone” values were modified to 30 to 45 degrees.

Objectives

The primary purpose of this study was to assess whether the use of Mako robotic hip system improves cup positioning when compared to traditional THR.

Introduction

Large diameter metal-on-metal hip arthroplasty (LDMMTHA) provides benefits of reduced dislocation rates and low wear. The use of modular systems allows better restoration of hip biomechanics. There have been reports of modular LDMMTHAs with tapered sleeves generating excessively high metal ions, due to possible mismatch between the titanium stem and the cobalt-chrome sleeve and the dual Morse tapers involved. We evaluated metal ion levels in LDMMTHA patients with and without a cobalt-chrome (CoCr) tapered sleeve.

Methods

A cross-sectional series of 91 patients with proximal porous titanium alloy stem LDMMTHA with identical design CoCr bearings, attending a 1 to 2-year review were assessed with routine clinical and radiographic examinations, hip scores and metal ion analysis. Of these 65 had a single Morse taper between monoblock CoCr heads and the stems. Twentysix had a tapered cobalt-chrome sleeve in addition, with the resultant dual taper. Mean bearing diameter was 46 mm in both groups and mean age was 58 years in the monoblocks and 66 years in the tapered sleeve group.

Introduction

High early failure rates have been reported with certain metal-metal surface arthroplasties and good results have been reported with others. This is a minimum 10-year review of the first 1000 consecutive resurfacings including all ages and diagnoses from one centre.

Methods

The first 1000 surface arthroplasties (892 patients) were followed-up with postal questionnaires. Of these the first 402 hips (350 patients) were also invited for a clinico-radiological review. 54 patients (63 hips) died 6.7 years (0.7–12.6) later due to unrelated causes. Mean follow-up is 12.2 years (range 10.8–13.7). Radiographs were assessed independently by a senior musculoskeletal radiologist.

Introduction

This is a retrospective review of the incidence of deep venous thrombosis (DVT) in 679 consecutive unilateral primary hip arthroplasty procedures performed between January 2007 and December 2010 managed with no anticoagulants. Mean age at operation was 58 years. Mean BMI was 26. The prophylaxis regimen included hypotensive epidural anesthesia, compression stockings, intermittent calf compression, early mobilization and an antiplatelet agent.

Methods

562 hybrid hip resurfacing procedures and 117 uncemented THRs, all performed through a posterior incision were included. Doppler ultrasound screening for DVT was performed in all patients between the fourth and sixth post-operative days. Patients were reviewed clinicoradiologically 6 to 10 weeks after operation and with a postal questionnaire at the end of 12 weeks to detect symptomatic VTE incidence following discharge. 14 patients with pre-existent VTE, coagulation disorders or cardiac problems requiring anticoagulant usage were excluded.

Introduction

the aim of the study is to evaluate the clinical results of the shoulder prosthesis revision procedure to reverse implant without removing the humeral stem using a modular system (Lima LTD) and determine if this procedure is beneficial for the patients.

Methods

e selected only the patients where a revision to reverse (RSA) of hemiarthroplasty (Hemi) originally implanted for fracture (Group I) and revision to reverse (RSA) of anatomical total prosthesis (TSA) were performed. From 2004 to 2009 26 cases responding to these parameters were identified: 18 cases in Group I (failed hemiarthroplasty for tuberosities resorptions or rotator cuff failure) and 8 in Group II (failed TSA for rotator cuff omplication).

The mean follow-up was 32 months (min 18–max 76) and the mean age was 72 (min 65–max 80)

Clinical assessment was performed with preoperative and postoperative Constant score rating scale (CS) and range of motion evaluation (ROM)

Radiological assessment was performer by AP and Axial X-ray views. Operative time was calculated.

Introduction

The low-cost, no-harm conditions associated with vibroarthography, the study of listening to the vibrations and sound patterns of interaction at the human joints, has made this method a promising tool for diagnosing joint pathologies. This current study focuses on the knee joint and aims to synchronize computational models with vibroarthographic signals via a comprehensive graphical user interface (GUI) to find correlations between kinematics, vibration signals, and joint pathologies. This GUI is the first of its kind to synchronize computational models with vibroarthographic signals and gives researchers a new advantage of analyzing kinematics, vibration signals, and pathologies simultaneously in an easy-to-use software environment.

Methods

The GUI (Figure 1) has the option to view live or previously captured fluoroscopic videos, the corresponding computational model, and/or the pre- or post-processed vibration signals. Having more than one signal axes available allows for comparison of different filtering techniques to the same signal, or comparison of signals coming from different sensor placements (ex: medial vs. lateral femoral condyle). Using computational models derived using fluoroscopic data synchronized with the vibration signals, the areas of contact between articulating surfaces can be mapped for the in vivo signal (figure 2). This new method gives the opportunity to find correlations between the different sensor signals and contact maps with the diagnosis and cartilage degeneration map, provided by a surgeon, during arthroscopy or TKA implantation (figure 3).

Introduction

Previous fluoroscopy studies have been conducted on numerous primary-type TKA, but minimal in vivo data has been documented for subjects implanted with revision TKA. If a subject requires a revision TKA, most often the ligament structures at the knee are compromised and stability of the joint is of great concern. In this present study, subjects implanted with a fixed or mobile bearing TC3 TKA are analyzed to determine if either provides the patient with a significant kinematic advantage.

Methods

Ten subjects are analyzed implanted with fixed bearing PFC TC3 TKA and 10 subjects with a mobile bearing PFC TC3 TKA. Each subject underwent a fluoroscopic analysis during four weight bearing activities: deep knee bend (DKB), chair rise, gait, and stair descent. Fluoroscopic images were taken in the sagittal plane at 10 degree increments for the DKB, 30 degree increments for chair rise, and at heel strike, toe off, 33% and 66% cycle gait and stair descent.

Background

These days, total hip arthroplasties (THA) are more implanted in young patients. Due to the expected lifespan of a THA and the life expectancy of young patients, a future revision is inevitable. Indirectly increasing the number of revisions in these patients. Therefore we evaluated the results of revision THA in patients under the age of 60 years. However, we used a unique protocol in which we used in all cases of acetabular and/or femoral bone deficiencies reconstruction with bone impaction grafting.

Methods

To determine the mid- to longterm results of cemented revision total hip arthroplasties in patients under the age of 60, all clinical data and radiographs were analyzed of patients operated between 1992 and 2005. Patients with multiple previous revisions were also included. Only cemented components were used. During this period 146 consecutive revision total hip arthroplasties were implanted in 129 patients. This included 124 cup and 106 stem revisions. The average age at index surgery was 47 years. No case was lost. Mean follow-up was 7.6 (range, 2.0–16.7) years.

Conclusion

Larger incisions and surgical approaches have been associated with larger blood loss, greater need for perioperative transfusion, use of more postoperative analgesics, a longer hospital stay, and a slower recovery. In this modified approach, the gluteus medius is left intact. The postoperative strength of the abductors of the operated side was the same as that on the non-operated side and functionally, the direct lateral approach was a safe alternative to other approaches in decreasing the trendelenburg gait and incidence of heterotrophic ossification.

Introduction

The following study start from an idea of the evaluation of the osteointegration in the bone cage of the Equinoxe Reverse shoulder prosthesis.

The aim of the study is to assess the values of Bone Mineral Density (BMD) in periprosthetic areas, in patients undergoing shoulder arthroplasty with implants of the Equinoxe system by Excatech, Inc.

To better understand the steps of osteointegration time of the bone cage with the glenoid

The objectives of the work are not only expanded to the value of osteointegration, but could also be useful for the evaluation of both mechanical and septic loosening of the stem of the glenoid.

Materials and Methods

In the period from November 2011 to May 2012, 15 patients were evaluated.

All patients were subjected to bone densitometry type of DXA within the first 15 days after surgery and at 3 months after surgery.

The patients are all part of a homogeneous group for anatomical glenoid

Were excluded from the study all patients who were no significant alterations of the head and the glenoid.

The acquisitions were performed with the patient in an oblique position, with limb in a neutral position, in order to obtain images in the coronal plane “true” of the joint.

Were subsequently calculated values of BMD is around the stem with the 7 areas used by Gruen for the hip prosthesis and peripherally to the central peg using 3 areas, superiorly, medially and inferiorly to the same.

INTRODUCTION

Wear and polyethylene damage have been implicated in up to 22% of revision surgeries after unicompartmental knee replacement. Two major design rationales to reduce this rate involve either geometry and/or material strategies. Geometric options involve highly congruent mobile bearings with large contact areas; or moderately conforming fixed bearings to prevent bearing dislocation and reduce back-side wear, while material changes involve use of highly crosslinked polyethylene. This study was designed to determine if a highly crosslinked fixed-bearing design would increase wear resistance.

METHODS

Gravimetric wear rates were measured for two unicompartmental implant designs: Oxford unicompartmental (Biomet) and Triathlon X3 PKR (Stryker) on a knee wear simulator (AMTI) using the ISO-recommended standard. The Oxford design had a highly conforming mobile bearing of compression molded Polyethylene (Arcom). The Triathlon PKR had a moderately conforming fixed bearing of sequentially crosslinked Polyethylene (X3).

A finite element model of the AMTI wear simulation was constructed to replicate experimental conditions and to compute wear. This approach was validated using experimental results from previous studies.

The wear coefficient obtained previously for radiation-sterilized low crosslinked polyethylene was used to predict wear in Oxford components. The wear coefficient obtained for highly crosslinked polyethylene was used to predict wear in Triathlon X3 PKR components. To study the effect design and polyethylene crosslinking, wear rates were computed for each design using both wear coefficients.

Introduction

We acquired an optical tracking navigation system for Total Hip Arthroplasty. We compare cup positioning and other operative factors along with clinical results using navigated and non-navigated techniques in a series of 341 Total Hip Arthroplasties.

Method

This is a retrospective review of consecutive patients from November 2005 through December 2010, including 126 cases of imageless computer assisted total hip replacement and 215 cases of standard total hip replacement. We analyzed operative time, blood loss, leg length discrepancy, acetabular component inclination, complications, Harris Hip scores and performed a cost analysis. Follow-up was from 3–64 months. All cases were performed by or under the supervision of a single surgeon. Digital AP pelvic radiographs centered on hips were used for measurements. Radiographic results were averaged based on three individual measurements. Statistics required the student t-Test.

Hypothesis

Custom cutting blocks can produce similar alignment compared to computer navigated and conventional total knee arthroplasty (TKA) techniques.

Method

We conducted a retrospective review of 37 patients who underwent TKA by a single surgeon in a teaching hospital setting. Groups were conventional method (10), computer assisted navigation (10), and custom blocks (18). The custom group was further subdivided to CT and MRI based blocks. Post-operative alignment was measured (blinded) using full length weight bearing radiographs at 18 weeks on average. Hospital records were reviewed to determine operative time, transfusion requirements, length of hospital stay, complications and cost.

Introduction

Edge loading commonly occurs in all bearings in hip arthroplasty. Edge loading wear can occur in these bearings when the biomechanical loading axis reaches the edge and the femoral head loads the edge of the cup producing wear damage on both the head and cup edge. When the biomechanical loading axis passes through the polished articulating surface of the acetabular component and does not reach the edge, the center of the head and the center of the cup are concentric. The resulting wear known as concentric wear is low in metal-on-metal (MOM) bearings, and is negligible in ceramic-on-ceramic (COC) bearings. Edge loading is well defined in COC hip bearings. However, edge loading is difficult to identify in MOM bearings, since the metal bearing surfaces do not show wear patterns macroscopically. The aims of this study are to compare edge loading wear rates in COC and MOM bearings, and to relate edge loading to clinical complications.

Materials and Methods

Twenty-nine failed large diameter metal-on-metal hip bearings (17 total hips, 12 resurfacings) were compared to 54 failed alumina-on-alumina bearings collected from 1998 to 2011. Most COC bearings were revised for aseptic loosening or periprosthetic bone fracture, while most MOM bearings were revised for pain, soft tissue reactions or impingement. The median time to revision was 3.2 years for the metal hip bearings and 3.5 years for alumina hip bearings. The surface topography of the femoral heads was measured using a RedLux AHP (Artificial Hip Profiler, RedLux Ltd, Southampton, UK).

Introduction & Aims

Mild to moderate CD after TKA is a common side-effect of an otherwise successful procedure. Despite improvement in the majority of the cases within weeks to a few months, this is a source of concern and disappointment. This analysis presents a possible mechanism for post-TKA cognitive changes.

Method

We reviewed the literature on the hemodynamic events around limb exsanguination, tourniquet placement and release during TKA. The majority of this literature is in anesthesia journals, with only a few in orthopedic journals (e.g., Berman, JBJS, 1998, 389–96). Once the data was collected, we scrutinized it for validity and in order to identify a plausible etiology that links between the TKA operating procedure and CD.

Introduction

Traditional methods of component positioning in total hip replacement (THR) utilize mechanical alignment guides which estimate position relative to the plane of the operating room table. However, variations in pelvic tilt alter the relationship between the anatomic plane of the pelvis and that of the table such that components placed in optimal position relative the table may not land within the classic anatomic “safe zone” described by Lewinnek. It has been suggested that navigation software should incorporate adjustments for the degree of pelvic tilt. Current imageless navigation software has this capability, however there is a paucity of data regarding the accuracy of this technology.

Purpose

We aimed to assess the accuracy of intra-operative pelvic tilt adjusted anteversion measurements as compared to unadjusted measurements.

Introduction

Acute infection following Total Hip Arthroplasty (THA) is a serious complication. It is commonly treated by irrigation and debridement (I&D) with component retention (exchange only the mobile parts of the joint - head and liner). However, the reported re-infection rate with the use of this approach remains high. We are reporting our experience in using single - stage revision arthroplasty in treating acute infection of THA. We hypothesized that the infection control rate after immediate early revision for acute infection of cementless implants is better than has been reported for I&D with exchange of mobile parts.

Methods

From our infection arthroplasty database, we reviewed the outcome of 19 patients who had an acute infection (within 6 weeks) of cementless THA. Our management strategy includes I&D and single-stage (direct-exchange) revision arthroplasty followed by 6 weeks course of culture specific oral antibiotics.

Introduction

Technology in Orthopaedic surgery has become more widespread in the past 20 years, with emerging evidence of its benefits in arthroplasty. Although patients are aware of benefits of conventional joint replacement, little is known on patients' knowledge of the prevalence, benefits or drawbacks of surgery involving navigation or robotic systems.

Materials & Methods

In an outpatient arthroplasty clinic, 100 consecutive patients were approached and given questionnaires to assess their knowledge of Navigation and Robotics in Orthopaedic surgery. Participation in the survey was voluntary.

Introduction

To evaluate the clinical success and hip pain and function of patients with infected hip replacement treated by two-stage exchange using a temporary implant with high dose vancomycin added to the antibiotic cement at the first stage revision.

Method

Thirty-three hips in 32 patients (median 67 yrs) underwent first stage revision using the PROSTALAC™ system (n=27) or a self-made system using an Elite long stem (n=6). Infection was diagnosed after 19 primary, 11 revision and 3 hemiarthroplasty hip replacements. Patients were reviewed regularly clinically and by questionnaire. The median follow-up was 3 years.

Introduction

There has been almost universal adoption of highly cross-linked polyethylene as the polyethylene of choice in metal-on-polyethylene articulations in total hip replacement (THR). Although wear of conventional polyethylene has been shown to be related to periprosthetic osteolysis, the relationship between wear of highly cross-linked polyethylene and osteolysis remains uncertain. Our aim was to determine the incidence and volume of periacetabular osteolysis at a minimum of seven years following primary THR with metal on highly cross-linked polyethylene articulations.

Methods

644 patients were enrolled into a randomised controlled trial which examined the effect of articulation size (28 vs 36 mm) on the incidence of dislocation one year following THR. To date, 62 patients (34 patients – 28 mm articulation; 28 patients – 36 mm articulation) have undergone a quantitative computed tomography (CT) scan, with metal artefact reduction protocol, to detect and measure osteolysis at a minimum of seven years following THR. Osteolysis was defined as a localised area of bone loss of at least 1 cm³ that is expansile, with a well-defined sclerotic border, a clear communication between the defect and the joint space and the absence of acetabular cysts. Pre-operative and post-operative plain radiographs were examined to identify the existence of acetabular cysts. Polyethylene wear from one to seven years following THR was also measured, using a computerised edge detection technique (PolyWare Rev 5, Draftware) of analysing standard radiographs.

Introduction

Acetabular dysplasia is a common cause of osteoarthritis of the hip. Chiari pelvic osteotomy enables medialization of the center of the femoral head and improvement of coverage over the femoral head for hip dysplasia and prevents or delays progression of degenerative arthritis. We reviewed 104 patients after this augmentation procedure.

Patients and methods

Between 1989 and 2000, 167 patients with developmental dysplasia of the hip had undergone the surgery at university hospital. Among them, 104 patients were able to be traced after surgery for more than 10 years. The mean follow-up period was 15.5 years. There were 96 women and 8 men with an average age of 34.3 years at surgery. The average angle of osteotomy was 6.6 degree craniad to the horizontal plane. Ratio of migration of the distal pelvis was 42%.

Case presentation

A 62-year-old woman consulted our clinic with bilateral knee pain and walking distability. She was diagnosed rickets and had bilateral severe varus bowing deformity of femurs from an infant. Her height was 133 cm and body weight was 51 kg. Bilateral femur demonstrated severe bowing and her knee joint demonstrated varus deformity with medial joint line tenderness, no local heat, and no joint effusion. Bilateral knee ROM was 90 degrees with motion crepitus. Bilateral lower leg demonstrated mild internal rotation deformity. Bilateral JOA knee score was 40 Roentgenogram demonstrated knee osteoarthritis with incomplete development of femoral condyle. Mechanical FTA angles were 206 degree on the right and 201 on the left. She was received right simultaneous femoral supra-condyle valgus osteotomy with TKA was performed at age 63. Key points of surgical techniques were to use the intramedullary guide for valgus osteotomy as temporary reduction and fixation then performed mono-cortical locking plate fixation. Several mono cortical screws were exchanged to bi-cortical screws after implantation of the femoral component with long stem. Cast fixation performed during two weeks and full weight bearing permitted at 7 weeks after surgery. Her JOA score was slightly improved 50 due to other knee problems at 9 months after surgery, her right mechanical FTA was decreased to 173, and she received left simultaneous femoral supra-condyle valgus osteotomy with TKA as the same technique at April of this year. She has been receiving rehabilitation at now.

Conclusions

Most causes of varus knee deformity are defect or deformity of medial tibial condyle and TKA for theses cases are not difficult to use tibial augment devices. However the cases like our presentation need supra-femoral condyle osteotomy before TKA. It was easy and useful to use intramedullary guide for valgus osteotomy as temporary reduction and fixation then performed mono-cortical locking plate fixation before TKA.

Introduction

Navigation system has been used for very accurate surgery. It can also be useful for preoperative planning. A surgeon can understand whole surgery, plan the surgery and perform the surgery three dimensionally and accurately. But the planning procedures should be installed before everything is started. When the surgery will be done in an ordinary method, the surgeon would not find particular difficulties. But in sometimes the surgeon can have unordinary situation such as massive defect that should be treated with acetabular enforcement device and bone grafted. Using postoperative DICOM data which is predicted by preoperative planning using 3D CAD software, we will be able to use the navigation system for those cases with difficulties that is not supported.

Objectives

To establish a method to use a navigation system using preoperative planning data that is processed by our 3D CAD software which is not supported by the navigation system itself, including device preparation using plastic models.

Introduction

Accurate alignment and sizing of the femoral component in total knee arthroplasty (TKA) is important for stability and functional outcomes. In relation to the shape of the distal femur, it has been reported that the medial-lateral (ML) femur width in women is narrower than that in men for the same antero-posterior (AP) length. In addition, it has been noted that the elevation of the anterior condyle in women is lower than that in men. Therefore, in TKA for women, it is suggested that a medial or lateral overhanging femoral component can cause pain or limit the range of motion (ROM). As a result, a gender-specific implant for women has been developed. However, there are few studies addressing the morphological dimensions of the distal shape of the femur in the Japanese population. The objective of this study was to reveal the appropriateness of using gender-specific implant for Japanese women.

Methods

This study was based on 40 women (40 knees) and 40 men (40 knees) who had primary preoperative osteoarthritis of the knee. The average height was 161.2 cm for men and 149.4 cm for women. The average weight was 68.0 kg for men and 58.5 kg for women. These are significantly different. Resection of the distal femur for TKA was simulated with preoperative computed tomography (CT) data. The ML width on the anterior and distal cut surface, the ML width at the surgical epicondylar axis (SEA) level, the maximum AP length at the medial and lateral condyle, and the AP length after resection were measured. These values were compared between men and women, and compatibility with NexGen LPS-Flex and Gender Solution Femur (GSF) (Zimmer, Warsow, Ind) was evaluated.

Background

dl-α-Tocopherol (vitamin E) blended ultra-high molecular weight Polyethylene (UHMWPE) was originally developed as a bearing material for use in knee prostheses ⁽¹⁾. The reduced biological response observed for vitamin E (VE) blended UHMWPE wear particles in in vitro experimentation ⁽²⁾ has also demonstrated the materials potential for use in other orthopedic applications, especially total hip arthroplasty (THR). However, due to the excellent results achieved by highly crosslinked UHMWPE in hip simulator testing ⁽³⁾, the use of VE blended UHMWPE in THR would similarly require crosslinking. It was previously reported that VE radicals are formed during radiation crosslinking of VE blended UHMWPE ⁽⁴⁾, and it is hypothesized that these VE radicals may negatively impact the materials biological activity. In this study, ascorbic acid 6-palmitate (lipophilic vitamin C) was applied to electron-beam-irradiated VE blended UHMWPE in an attempt to oxidatively reduce the VE radicals. Electron Spin Resonance (ESR) was used to measure the number of VE radicals within the material and evaluate the regenerating effect of ascorbic acid 6-palmitate.

Materials & Methods

UHMWPE resin powder (GUR 1050, Ticona, USA) was mixed with dl-a-Tocopherol (vitamin E) at 0.3 wt% and molded under direct compression at 25 MPa and 220°C. Virgin samples were produced by the same process, but without the addition of vitamin E (VE). Cylindrical pins (length: 40 mm, diameter: 3.5 mm) were then machined from these samples, packaged in a vacuum, and irradiated by electron-beam at 300 kGy. Samples were subsequently doped with either ascorbic acid 6-palmitate (Sigma, Japan) or ethanol (Ethanol 99.5%, Kishida, Japan) and subjected to a hydrostatic pressure of 100 MPa for 7, 14, and 21 days at room temperature. Radical measurements were made using ESR at 9.44 GHz and room temperature. All ESR spectra were recorded at 0.1 mW microwave power and 0.1 mT modulation amplitude.

INTRODUCTION

Cup orientation of total hip arthroplasty (THA) is critical for dislocation, range of motion, polyethylene wear, pelvic osteolysis, and component migration. But, substantial error under manual technique has been reported specially in revision THA due to a bone loss and poor anatomical landmark. We have used three kinds of navigation systems for cup positioning in primary and revision THA.

OBJECTIVES

The purpose of this study is to evaluate the accuracy of navigation in revision THAs.

Background

Various postoperative evaluations using fluoroscopy have reported in vivo knee flexion kinematics under weight bearing conditions. This method has been used to investigate which design features are more important for restoring normal knee function. The objective of this study is to evaluate the kinematics of a Low Contact Stress total knee arthroplasty (LCS TKA) in weight bearing deep knee flexion using 2D/3D registration technique.

Patients and methods

We investigated the in vivo knee kinematics of 6 knees (4 patients) implanted with the LCS meniscal bearing TKA (LCS Mobile-Bearing Knee System, Depuy, Warsaw, IN). Mean period between operation and surveillance was 170.7±14.2 months. Under fluoroscopic surveillance, each patient did a deep knee flexion under weight-bearing condition. Femorotibial motion was analyzed using 2D/3D registration technique, which uses computer-assisted design (CAD) models to reproduce the spatial position of the femoral, tibial components from single-view fluoroscopic images. We evaluated the knee flexion angle, femoral axial rotation, and antero-posterior translation of contact positions.

Introduction

Segmental defects of the femur present a major problem during revision hip arthroplasty. In particular, calcar segmental defects may compromise initial and long-tem femoral stem stability.

Objective

The objective of the present study is to assess mid-term clinical and radiographic follow-up results at least two years after femoral revision comprising reconstruction for calcar segmental defect using metal wire mesh and impacted morcellised allograft.

Introduction

The Delta Motion device (developed by Finsbury Orthopaedics, Leatherhead, United Kingdom, now manufactured by DePuy, Leeds, United Kingdom) is a pre-assembled factory fitted cup. It has been introduced to overcome some of the concerns relating to intra-operative assembly with improper seating of the liner and chipping. This device has a thinner shell and liner in comparison with other cups, allowing the use of larger sized heads which should help reduce the risk of impingement and dislocation. A drawback of the pre-assembled design is the inability to use supplementary screws to achieve stability and the difficulty in obtaining primary stability compared with a thin titanium shell. To date we are not aware of any publications reviewing the outcomes of these devices.

Methods

206 DeltaMotion cups were implanted in 195 patients, between Dec 2008 to Dec 2009 by the three senior authors. All the hips had the same stem (Osteonics) and a ceramic head was used. Data was prospectively collected and we reflect on our two year results.

INTRODUCTION

Polyethylene wear is one of the reasons for failure of total knee replacement (TKR). There are several reasons for wear, and the femoro-tibial contact area is an important factor. Mobile bearing, highly congruent prostheses might be more resistant to polyethylene wear than fixed bearing, incongruent prostheses. We evaluated the 5- to 8-year experience of three university departments by using an original system with following highlights: implantation with a navigation system, extended congruency up to 90° of flexion, floating polyethylene component with non-limited movements of rotation, antero-posterior translation and medio-lateral translation.

MATERIAL

347 patients have been operated on in the three participating departments with this new prosthesis system between 2001 and 2004, and have been prospectively followed with clinical and radiologic examination with a minimal follow-up time of 5 years. There were 246 women and 101 men, with a mean age of 67 years.

Introduction

Unicompartmental knee arthroplasty (UKA) has seen renewed interest in recent years and is a viable option for patients with limited degenerative disease of the knee as an alternative to total knee arthroplasty. However, the minimally invasive UKA procedure is challenging and accurate component alignment is vital to long-term survival. Robotic-assisted UKA allows for greater accuracy of component placement and dynamic intraoperative ligament balancing which may improve clinical patient outcomes. The purpose of this study was to examine the clinical outcomes in a large, consecutive cohort of patients that underwent robotic-assisted UKA.

Materials and Methods

A search of the institutional joint arthroplasty registry identified 507 patients with a mean age of 63 years (range, 28 to 88 years) who underwent robotic-assisted UKA between July 2008 and June 2010. Clinical outcomes were evaluated using the Oxford Knee Score and patients without recent follow-up were contacted by telephone. The revision rate and time to revision were also examined.

Introduction

Hip resurfacing arthroplasty has been surgical options in younger and more active patients with osteoarthritis (OA) and osteonecrosis (ON) of the femoral head. Although excellent midterm results of this procedure have been reported, there is a concern about postoperative impingement between the preserved femoral neck and the acetabular component. There were few reports about kinematics after hip resurfacing. Therefore, the purpose of this study was to investigate the postoperative motion analysis after hip resurfacing using a noble dynamic flat-panel detector (FPD) system by which clear sequential images were obtained with low dose radiation exposure.

Materials and methods

11 patients (mean age: 47.8 ± 7.4), 15 hips were included in this study. There were ten men and one woman. The preoperative diagnoses were ON of the femoral head in 10 hips, OA in 3 hips, and others in 2 hips. Mean postoperative follow-up period was 25.1 ± 21.6 months. Femoral anteversion, cup inclination and cup anteversion were measured on computed tomography and plain radiograph. Impingement signs such as the reactive osteophyte formation and divot around the femoral neck were also investigated on the anteroposterior (AP) and lateral radiographs. Sequential images of active and passive flexion motion in 45-degrees semilateral position, and active abduction motion in a supine position were obtained using a noble dynamic FPD system.

Introduction

Since2007, we have used CT-based fluoroscopy-matching navigation system (Vector Vision Hip Ver.3.5.2, BrainLAB, Germany) in Total hip arthroplasty. This system completes the registration procedure semi-automatically by matching the contours of fluoroscopic images and touching 3 adequate points to the contours of 3D bone model created in the computer. Registration procedure using fluoroscopic figures has finished before making surgical incision. It needs no elongation time during the operation. The accuracy of navigation system depends on the techniques of registration used for the navigation and secure fixation of the dynamic reference markers. These could be affected by the different type of approaches. The objective of this study was to evaluate the accuracy of CT-based fluoroscopy-matching navigation system in THA and compare the cup position by anterolateral and posteolateral approaches.

Material and method

We analysed the acetabular cup in consecutive 132 hips with both intra-operative and post-operative alignment data (based on navigation system and CT evaluation), including 65 cases with anterolateral approach(Modified Watson Jones) (Group AL) and 67 cases with posterolateral approach(Group PL). We aimed the cup angle for THA as following, the inclination: 40 degrees, the anteversion: 20 degrees. Anteversion on the navigation system must be adjusted by the pelvic tilt.

Introduction

In TKA, it is important to make the equal extension and flexion gap (EG and FG) of the knee. Although, this principal concept applies to all knees, flexion contracture is known to have difficulties to achieve the equal EG and FG because of its smaller EG than usual. Whereas, it is also well known that PCL resection makes FG wider than EG, however, many surgeons recommend PCL resection in case of flection contracture because it is easy to manage during surgery, nevertheless the risk of further gap unbalance. Although, flexion contracture is not rare in TKA, the controversial problem of the PCL resection for the flexion contracture still remains even in today.

Materials and methods

To investigate this contradiction, we measured intra-operative EG and FG of the knee with 20 degree or more pre-operative flexion contracture. The gaps were measured by 3 different ways; a tension device system with 30 and 40 pound tension (group 1 and 2) and a spacer block system which had 1 mm increment thickness variation (group 3). The cases were 41, 46 and 51 knees in group 1, 2 and 3 respectively. Group 1 and 2 have overlapping in 27 knees.

Purpose

The purpose of this study is to inspect balance of the pelvis in the acetabular operation of total hip arthroplasty (THA) using direct anterior approach (DAA), and it is to examine precision of the acetabular socket setting.

Materials and Methods

We performed THA using DAA to 104 patients (114 hips) joints from August 2006 to April 2009 and identified for seventy five patients (eighty four hips) that imaging of the postoperative CT was possible. The orientation of acetabular sockets were performed using an alignment guide which assumed an operating table an axis from August 2006 to September 2008 (A group), and using an alignment guide which assumed a pelvis an axis from October 2008 to May 2009(B group). A group were thirty eight patients (forty four hips), and B group were twenty eight (thirty). There were two men and thirty six women in A group, and one man and twenty seven women in B group. The average age of both groups was 66 years old. The objective angle of the acetabular socket was performed as angle guide of abduction of 45° and anteversion of 20°. The orientation of the acetabular socket converted the angle of postoperative CT into radiographic angle, and measured it. For sixteen hips in B group, both angle guide was used, and there were measured a difference of two angle guide in the acetabular operation as movement of the pelvis. The examination item assumed it the mean values of angle for the acetabular socket in both groups, precision to set up the acetabular socket to planned orientation within ±5 °and a mean difference of two angle guides of sixteen hips in B group.

Introduction

Metal on metal (MoM) bearings have been dealt a severe blow in the past few years. The release of metal ions may have arisen from corrosion, wear, or a combination of the two. Edge loading due to implant malposition is thought to cause a failure of lubrication and to contribute to excessive wear and increased metal ion release [1]. Literature reports aseptic lymphocytic vasculitis-associated lesions (ALVAL) are associated with a variety of failures which occur to some degree in all implanted metal femoral components [2, 3]. Moreover, Willert et al [4] has described ALVAL in non-MoM bearing designs too. This paper has investigated the metal ion release due to total hip replacement (THR), Hip Resurfacing (HR) and total knee replacement (TKR).

Methods

Following human ethics approval 200 patients were enrolled in this single surgeon randomised controlled study. The treatment groups were total knee replacement (TKR) (n=100), HR (n=50) and THR (n=50). Serum cobalt (Co) and chromium (Cr) ion levels were taken preoperatively for baseline measurement then at 6 month, 1 year and 2 years postoperatively.

Introduction

47 yrs male patient had a prior history

2005 Fx. proximal tibia (open Fx.)

2007 Metal removal

2008 Arthroscopic debridement (2 times)

He visited out hospital with severe pain and tenderness X-ray (Fig 1) and MRI (Fig 2) findings as follows.

Conclusively, He had a chorinic osteomylitis of proximal tibia with soft tissue absess.

1st Surgery

I did arthroscopic debridement Arthroscopic finding shows synovitis, meniscus tear and chondromalacia. I did meticulous debridement (irrigation & curettage)

2^nd Surgery

He did primary total knee arthro-plasty instead of two-stage exchange arthroplasty in may, 2010 at the another hospital

3^rd Surgery

After 7 months since he had did total knee arthroplasty, he visited to my hospital again with sudden onset of painful swelling & heating sensation

4^th Surgery

I did second stage reimplantation for infected total Knee arthroplasty after 7 weeks. Now he got a pain relief & ROM restroration.

Results

Follow up 12 months X-ray showing all implants to be well-positioned and stable. Clinically, there was no implant considered to be loose

In this study, the knee society and functional scores at final follow up were 82 and 68.

Purpose

Complete wear-out of Polyethylene (PE) liner results in severe metallosis following articulation of the artificial head with the acetabular metal shell. We postulated that an adverse response can be led to surrounding bone tissue and new implant after revision surgery because the amount of PE wear particle is substantial and the metal particles are infiltrated in this catastrophic condition. We evaluated clinical characteristics and the survival rate of revision total hip arthroplasty (THA) performed in patients with severe metallosis following failure of PE liner.

Materials and Methods

Between January 1996 and August 2004, severe metallosis following complete wear-out of PE liner were identified during revision THA in 28 hips of 28 patients. One patient had died at 7 days after surgery and 3 patients could not be reached at 5 year follow-up. Twenty-four hips of 24 patients (average age, 47.5 years) were followed for at least 6.5 years (average, 11.3 years; range, 6.5–15.9 years) and were evaluated. The mean time interval between prior surgery and the index revision surgery was 9.6 years (range, 4.0–14.3 years). The indications for revision surgery were osteolysis around well-fixed cup and stem in 22 hips and osteolysis with aseptic loosening of the cup in 2 hips. Bubble sign was observed on preoperative radiograph in 10 hips. Total revision, cup revision, and solitary bearing change were performed in 13, 10, and one hip respectively. A cementless implant was used in 23 hips and acetabular reinforcement ring was used in one. Clinical evaluation was performed using Harris hip scores and Kaplan-Meier survival analysis was performed. Multivariate analysis was performed with age, gender, BMI, bone defect type, existence of bubble sign and type of revision surgery as variables to evaluate the association with osteolysis or loosening.

Introduction

Regarding TKA, patient specific cutting guides (PSCG), which have the same fitting surface with patient's bones or cartilages and uniquely specify the resection plane by fitting guides with bones, have been developed to assist easy, low cost and accurate surgery. They have already been used clinically in Europe and the USA. However little has been reported on clinical positioning accuracy of PSCG. Generally, the methods of making PSCG can be divided into 3 methods; construct 3D bone models with Magnetic Resonance (MR) images, construct 3D bone models with Computed Tomography (CT) images, and the last is to construct 3D bone models with both MR and CT images. In the present study, PSCG were made based on 3D bone models with CT images, examined the positioning accuracy with fresh-frozen cadavers.

Materials and Methods

Two fresh-frozen cadavers with four knees were scanned by CT. Image processing software for 3D design (Mimics Ver. 14, Marialise Inc.) was used to construct 3D bone model by image thresholding. We designed femoral cutting guides and tibial cutting guides by CAD software (NX 5.0, Siemens PLM Software Co.). CT free navigation system (VectorVision Knee, BrainLab, Inc.) was used to measure positioning error. Average absolute value of positioning error for each PSCG was derived.

Background

Two-stage revision is considered the gold standard for treatment of knee prosthetic joint infections. Current guidelines for selecting the most appropriate procedure to eradicate knee prosthetic joint infections are based upon the duration of symptoms, the condition of the implant and soft tissue evaluated during surgery and the infecting organism. A more robust tool to identify candidates for two-stage revision and who are at high risk for treatment failure might improve preoperative risk assessment and increase a surgeon's index of suspicion, resulting in closer monitoring, optimization of risk factors for failure and more aggressive management of those patients who are predicted to fail.

Methods

Charts from 3,809 revision total joint arthroplasties were reviewed. Demographic data, clinical data and disease follow-up on 314 patients with infected total knee arthroplasty treated with two-stage revision were collected. Univariate analyses were performed to determine which variables were independently associated with failure of the procedure to eradicate the prosthetic joint infections. Cox regression was used to construct a model predicting the probability of treatment failure and the results were used to generate a nomogram which was internally validated using bootstrapping.

Introduction

Traditional Total Knee Arthpolasty (TKA) replaces all 3 compartments of the knee for patients diagnosed with OA. There might be functional benefit to replacing only damaged compartments, and retaining the normal ligamentous structures. There is a long history of performing multi-compartment arthroplasty with discrete components. Laskin reported in 1976 that good pain relief and acceptable clinical results were achieved at two years in patients with bi-unicondylar knee replacement [Laskin 1976]. Other authors also have reported on bi-unicompartmental knee arthroplasty achieving successful clinical outcomes [Stockley 1990; Confalonieri 2005]. Banks et al. reported that kinematics of bi-unicompartmental arthroplasties during gait demonstrated some of the basic features of normal knee kinematics [Banks 2005]. These reports suggest that a modular approach to resurfacing the knee can be successful and achieve satisfactory clinical and functional results.

Objective

The primary objective of this study is to compare the functional outcomes of three patient groups treated for osteoarthritis.

Aim

The purpose of the study was to analyse short- and medium-term results of a modern cementless short stem design hip joint endoprosthesis together with different parameters (offset, CCD, leg length), radiological findings and scores.

Material and Methods

186 cases using a metaphyseal fixed short stem prosthesis (MiniHip, Corin) at two hospitals were included for clinical follow-up. 180 patients were available for clinical follow-up with standardized scores: Oxford-Hip Score (OHS), Hip Dysfunction an Osteoarthritis Outcome Score (HOOS) and EQ-5D – Score. The scores were caught preoperatively and postoperatively every year.

Further on we could do a prospective radiological study of 250 consecutive hips with degenerative hip osteoarthritis were included (246 patients). These patients were operated by five different surgeons at 4 different hospitals. Standardized X-rays were performed with the same technique pre- and postoperatively in all patients. Different anatomical parameters of the hip were documented by using the pre- and postoperative x-rays (Offset, CCD angle, length of leg).

The 250 patients included 129 female and 117 male. The average age of the patients was 59.7 years (range: 27–82 years).

The whole follow-up and all measurements were performed by an independent examiner.

INTRODUCTION

There is historical evidence of increased incidence of transitional cell tumours of the renal tract in workers exposed to high levels of metal ions. This study was designed to establish any correlation between Metal on metal bearing hip arthroplasty and TCC.

METHODS

A prospective North-East database of 2900 Urology/Oncology cases was compared with the Freeman Joint Registry, which is a prospective database of all Arthroplasty performed since 2001 to establish any correlation with TCC. After comparing the Urology database with the Freeman Joint Registry from 2001 to 2011, a group of patients was identified who underwent hip replacement and had TCC of bladder. The incidence of TCC was calculated in patients who had metal on metal hip replacement and those who had metal on poly hip replacement. On comparing both the groups no significant difference in incidence of TCC of bladder was recorded.

Introduction

The purpose of this multicenter study was to assess the oxidative stability, mechanical behavior, wear and reasons for revision of 2nd generation sequentially annealed HXLPE, X3, and compare it to 1^st generation XLPE, Crossfire. We hypothesized that X3 would exhibit similar wear rates but lower oxidation than Crossfire.

Methods

182 hip liners were consecutively retrieved during revision surgeries at 7 surgical centers and continuously analyzed over the past 12 years in a prospective, multicenter study. 90 were highly crosslinked and annealed (Crossfire; Implanted 4.2±3.4 years, max: 11 years), and 92 were highly crosslinked and annealed in 3 sequential steps (X3; Implanted 1.2±1.5 years; max: 5 years). Oxidation was characterized in accordance with ASTM 2102 using transmission FTIR performed on thin sections (∼200μm) from the superior/inferior axis. Mechanical behavior was assessed via the small punch test (ASTM 2183).

Introduction

Wear debris generation in metal-on-metal (MOM) total hip arthroplasty (THA) has emerged as a compelling issue. In the UK, clinically significant fretting corrosion was reported at head-taper junctions of MOM hip prostheses from a single manufacturer (Langton 2011). This study characterizes the prevalence of fretting and corrosion at various modular interfaces in retrieved MOM THA systems used in the United States.

Methods and Materials

106 MOM bearing systems were collected between 2003 and 2012 in an NIH-supported, multi-institutional retrieval program. From this collection, 88 modular MOM THA devices were identified, yielding 76 heads and 31 stems (22 modular necks) of 7 different bearing designs (5 manufacturers) for analysis. 10 modular CoCr acetabular liners and 5 corresponding acetabular shells were also examined. Mean age at implantation was 58 years (range, 30–85 years) and implantation time averaged 2.2 ± 1.8 years (range, 0–11.0 years). The predominant revision reason was loosening (n=52). Explants were cleaned and scored at the head taper, stem taper, proximal and distal neck tapers (for modular necks), liner, and shell interfaces in accordance with the semi-quantitative method of Goldberg et al. (2002).

Introduction

Accurate prosthetic cup placement is very important in total hip arthroplasty (THA). When the surgeon is impacting the acetabular cup, it is assumed that the patient's pelvis is perpendicular to the operating table. In reality the pelvis may not be truly lateral, and error in patient positioning may influence the resultant cup orientation.

Objectives

The primary aim of this study was to examine the accuracy of patient positioning prior to THA. A secondary aim was to see if patient BMI influenced the accuracy of positioning.

Introduction

Leg length and offset are important considerations in total hip arthroplasty (THA). Navigation systems are capable of providing intra-operative measurements, which help guide the surgeon in leg length and offset adjustment.

Objective

This controlled study investigates whether the use of computer navigation leads to more accurate achievement of pre-operative leg length and offset targets in THA.

Introduction

Leg length and offset are important considerations in total hip arthroplasty (THA). Navigation systems are capable of providing intra-operative measurements of leg length and offset, and high accuracy has been shown in experimental studies.

Objective

This in-vivo study assesses the accuracy of an imageless navigation system, with a pin-less femoral array, in measuring offset and leg length changes.

Purpose

To evaluate the radiological changes after metal on metal resurfacing arthroplasty.

Materials and Methods

Between December 1998 and August 2004, 166 hips in 150 patients who underwent metal resurfacing arthroplasty and followed up more than 4 years. Their mean age at the time of operation was 37.3 years(range, 15–68 years) and mean period of follow-up was 6.1 years(range, 48–95 months). The cause of arthroplasty included 115 avascular necrosis, 43 osteoarthritis, 7 ankylosing spondylitis, 1 haemophilic arthropathy. All patients had anteroposterior, translateral radiographs of the hip made preoperatively and each follow-up visit, and we analyzed radiographic findings such as radiolucencies or impingement signs around implant, neck narrowing and heterotopic ossification.

Introduction

While shoulder elevation can be reliably restored following reverse total shoulder arthroplasty (RTSA), patients may experience a loss of internal and external rotation. Several recent studies have investigated scapular notching and have made suggestions regarding glenosphere placement in order to minimize its occurrence. However, very few studies have looked at how changes in glenosphere placement in RTSA affect internal and external rotation. The purpose of this study was to determine the effect of glenosphere position on internal and external rotation range of motion at various degrees of scaption following RTSA. We hypothesized that alteration in glenosphere position will affect the amount of impingement-free internal and external rotation.

Methods

CT scans of the scapula and humerus were obtained from seven cadaver specimens and 3-Dimensional (3D) reconstructions were created. A corresponding 3D RTSA model was created by laser scanning the baseplate, glenosphere, humeral stem and bearing. The RTSA models were then virtually implanted into each specimen. The glenosphere position was determined in relation to the neutral position in 6 different settings: Medialization (5 mm), lateralization (10 mm), superior translation (6mm), inferior translation (6 mm), superior tilt (20°), and inferior tilt (15° and 30°). The humerus in each virtual model was allowed to freely rotate at a fixed scaption angle until encountering bone-bone or bone-implant impingement (180 degrees of limitation). Each model was tested at 0, 20, 40, and 60 degrees of scaption and the impingement-free internal and external rotation range of motion for each scaption angle was recorded.

Introduction

It is widely accepted that computer navigation more reliably restores neutral mechanical alignment than conventional instrumentation in total knee arthroplasty (TKA) surgery. Recently, magnetic resonance (MR) based instrumentation has been introduced to the market with a rapid growth in usage. However, a paucity of comparative data still exists on the precision of magnetic resonance (MR) based instruments in achieving acceptable lower limb alignment when compared to other validated techniques. In this analysis, we compare the radiographic outcomes of 3 techniques to achieve satisfactory prosthetic alignment by 2 surgeons using the same prosthesis and surgical technique.

Methods

A series of 180 patients who had undergone TKA surgery were included in this study. Two fellowship-trained knee surgeons performed all surgeries using the same cemented, posterior stabilized implants (NexGen, Zimmer, Warsaw, In). Patients were stratified in to 3 groups according to the technique used to align the knee; 1. Conventional Intra-medullary Instrumentation, 2. Computer Navigation (Orthosoft), and 3. MR-based guides (Zimmer PSI). All patients underwent a post-operative CT Perth Protocol to assess coronal, sagittal and rotational alignment of the femoral and tibial implants. A radiographer who was blinded to the alignment technique used performed all radiographic measurements. Outliers were defined at a deviation of more than 3 degrees from the mechanical axis in all planes of motion.

Introduction

Total knee arthroplasty is a painful operation. Peri-articular local anesthetic injections reduce post-operative pain and assist recovery. It is inconclusive whether intra-operative injections of peri-articular corticosteroids are of benefit. Clinical Question: In patients with osteoarthritis who are undergoing TKA, does the addition of high or low dose corticosteroid to peri-articular injections of local anesthetic and adrenaline improve post-operative pain and range of motion?

Methods

A prospective, randomized, double-blinded study was undertaken to assess the efficacy of adding peri-articular corticosteroids to intra-operative, peri-articular high volume local anaesthetic in post-operative pain management following TKA. 127 patients were randomised into three groups receiving local anaesthetic alone (control) or either low dose (40 mg) or high dose (80 mg) peri-articular corticosteroid plus local anaesthetic. Primary outcomes included ROM and visual analog pain scores (VAS). Pain was defined as the worst pain lasting for more than 20 minutes, measured at both rest (RVAS) and during activity (AVAS).

Methods

25 consecutive knees of 21 patients, with medial osteoarthritis undergone TKR have been nominated in this study. All were done by a single surgeon, via mid vastus approach, using cemented PS implant with patellar resurfacing. Patients were arrowed to start full weight bearing from the next day.

Assessing walking ability, gait speed and width of a step were measured. As for balancing, “Functional Reach (FR)” which was the difference between arm's length and maximal forward reach (Duncan PW et al), “Timed Up and Go Test (TUG)” which was time while a patient rose from an arm chair, walked 3 meters, turned, walked back (Podsiadlo D et al), and sat down again, and possible period standing on one leg (one leg standing) were used. Every measurement was performed prior to the operation, and every 1-week after operation until 4-weeks postoperatively. Data were analyzed by one-way ANOVA, and then differences among means were analyzed using Bonferroni procedures. Also, the relation of improvements between ROM and each data were investigated by Pearson's correlation coefficient test.

Result

Every result showed the worst during the first week, followed by better results over time (p<0.05) (Fig. 1–3). The time point when better result than that of pre-operation could be achieved was 2 weeks in FR and one leg standing, 3 weeks in gait speed and width of a step, and 4 weeks in TUG, though statistically not significant. Each of the result was not correlated with its recovery rate of the ROM when compared at 4 weeks of time (r = 0.2–0.3). Interestingly, postoperative one leg standing period of contra-lateral leg showed improvement with similar tendency.

Objective

A study was performed in a tertiary health care centre to evaluate outcomes of arthroplasty in Indian Population. Various factors which may affect knee flexion after surgery were also evaluated.

Methods

82 patients with 60 unilateral & 22 bilateral total knee arthroplasties were included in the study. Assessment was done as per knee society knee score and function score. A simple functional questionaire including ability to squat, ability to sit cross leg, kneel while prayers, ability to use Indian toilet was filled and patients were rated accordingly as fair, good and excellent.

Backgrounds

In order to permit soft tissue balancing under more physiological conditions during total knee arthroplasties (TKAs), we developed an offset type tensor to obtain soft tissue balancing throughout the range of motion with reduced patella-femoral (PF) and aligned tibiofemoral joints and reported the intra-operative soft tissue balance assessment in cruciate-retaining (CR) and posterior-stabilized (PS) TKA [1, 2]. However, the soft tissue balance in unicompartmental knee arthroplasty (UKA) is unclear. Therefore, we recently developed a new tensor for UKAs that is designed to assist with soft tissue balancing throughout the full range of motion. The first purpose of the present study is to assess joint gap kinematics in UKA. Secondly, we attempted to compare the pattern in UKA with those in CR and PS TKA with the reduced PF joint and femoral component placement, which more closely reproduces post-operative joint alignment.

Methods

Using this tensor, we assessed the intra-operative joint gap measurements of UKAs performed at 0, 10, 30, 45, 60, 90, 120 and 135° of flexion in 20 osteoarthritic patients. In addition, the kinematic pattern of UKA was compared with those of CR and PS TKA that were calculated as medial compartment gap from the previous series of this study.

Background

The Copeland shoulder resurfacing arthroplasty (CSRA) (Figure1) is a cementless, pegged humeral head surface replacement which has been in clinical use since 1986. The indications for CSRA are more or less the same as conventional stemmed arthroplasty. This procedure can be considered for all patients who require shoulder replacement due to GHJ arthritis resulted from primary or secondary OA, RA, and other variations of inflammatory arthritis. It is also suggested as the first choice option for relatively young patients with post-traumatic arthritis, avascular necrosis (AVN), and instability arthropathy. This observational study reports functional and radiological outcome in CSRA during 4 years follow-up.

Methods

109 consecutive patients with primary osteoarthritis (45.9%), rheumatoid arthritis (39.4%), rotator cuff arthropathy (9.2%), and avascular necrosis (5.5%) underwent CSRA. Patients including 68 females (63%) and 41 males (37%) underwent this procedure (63 right-sided and 46 left-sided including 9 bilateral shoulders). The outcome assessment included pain and satisfaction, Oxford Shoulder Score (OSS), Constant Score (CS), and SF-12. Imaging was reviewed for glenoid morphology (Walch classification) (Figure2) and humeral head migration. The average follow-up period was 4 years, (range: 1 to 10 years).

INTRODUCTION

Rotational malalignment of the components in total knee arthroplasty has been linked to patellar maltracking, improper soft tissue balance, abnormal kinematics, premature wear of the polyethylene inlay, and subsequent clinical complications such as anterior knee pain (Barrack et al., 2001; Zihlmann et al., 2005; Lakstein at al., 2010). This study investigates an innovative image-based device that is designed to be used along with an intraoperative Isocentric (ISO-C) 3D imaging C-arm, and the conventional surgical instruments for positioning the femoral component at accurate rotational alignment angles.

METHODS

The new device was tested on 5 replica models of the femur (Sawbones). Zimmer NexGen total knee replacement instruments were used to prepare the bones. After making the distal transverse cut on the femurs, the trans-epicondylar-axis (TEA) were defined by a line connecting the medial and lateral epicondyles which were marked by holes on the bone models. The 4-in-1 cutting jig was placed and pinned to the bones with respect to the TEA considering 5 different planned rotational alignments: −10°, −5°, 0°, +5°, and +10° (minus sign indicating external and plus sign internal rotation). At this point, the jig was replaced by the alignment device using the head-less pins as the reference, and subsequently an Iso-c 3D image of the bone was acquired using Siemens ARCADIS Orbic C-arm. The image was automatically analyzed using custom software that determined the angle between the TEA and the reference pins (Fig 1). The difference between the angle read from the device and the planned angle was then used to correct the locations of the reference pins through a custom protractor device. Preparation of the bone was continued by placing the 4-in-1 jigs on the newly placed pins. Three-dimensional images of the bones after completion of the cuts were acquired, and the angle between the final cut surface and the TEA was determined.

Purpose

Arthritis is the most common chronic illness in the United States. TKR provides reliable pain relief and improved function for patients with advanced knee arthritis. Total joint replacement now represents the greatest expense in the national healthcare budget. Surgical costs are driven by two key components: fixed and variable costs. Patient Specific Instruments™ (PSI, Zimmer, Warsaw, IN, USA) has the potential to reduce both fixed and variable costs by shortening operative time and reducing surgical instrumentation. However, PSI requires the added costs of pre-operative MRI scanning and fabrication of custom pin guides. Previous studies have shown reduction in operating room times and required instrumentation, but question the cost-effectiveness of the technology. Also, these studies failed to show improvement in coronal alignment, but call for additional studies to determine any improvement in clinical function and patient satisfaction. Our pilot study aims to compare the incremental PSI costs to fixed and variable OR cost savings, and compare meaningful patient and clinical outcomes between PSI and standard TKR surgeries.

Methods

This IRB approved, prospective, randomized pilot trial involves 20 TKR patients. Inclusion criteria includes: diagnosis of osteoarthritis, ability to undergo MRI, and consent for primary TKR. Following informed consent, patients are randomized to PSI or standard TKR. Patients randomized to PSI undergo pre-operative non-contrast MRI of the affected knee at least 4 weeks prior to surgery. Custom pin guides are prototyped from 3D pre-operative planning software customizable to individual surgeon and patient. All surgeries will be completed by a single surgeon (DA), using a medial parapatellar arthrotomy and Zimmer Nexgen™ implants. Surgical technique for PSI patients utilizes custom pin guides to determine placement of the femoral and tibial cutting guides, whereas an intramedullary femoral rod and extramedullary tibial guide are used in standard TKR patients.

Our pilot study will compare numerous intra-operative and post-operative variables between the two patient cohorts. Intra-operative variables include: bony cutting time, tourniquet time, total OR time, surgical instrumentation, and bony resection height. Post-operative variables include: instrument processing and sterilization, blood transfusion, pain medication usage, length of stay, complications (including hospital readmission), and patient reported outcomes (SF-36, WOMAC, and satisfaction) at 4 weeks, 6 months, and 1 year. Additional economic sensitivity analyses using hospital and national cost-to-charge figures will quantify the potential added revenue or costs of implementing the PSI system.

Introduction

Modularity is being increasingly used throughout the world for both primary and revision total hip arthroplasty. Recently there have been concerns of increased corrosion and fretting at the modular junctions. In the SROM® modular hip system, two modular junctions are the head-neck taper junction and the stem-sleeve taper junction. The aim of this study was to investigate corrosion at these junctions with the use of different bearing materials.

Methods

Between 1994 and 2012, fourty-two patients were revised with SROM® stems. Reasons for revision included aseptic loosening of the cup or stem (11), periprosthetic fracture (2), osteolysis (8), dislocation (13) and other reasons (7). One was revised for stem breakage, and this was excluded from this study. We examined 41 retrieved S-ROM® comprised of 6 metal-on-metal (MOM), 12 metal-on-polyethylene (MOP), 7 ceramic-on-polyethylene (COP) and 16 ceramic-on-ceramic (COC). The orientation for all components was marked at the time of revision surgery. Both the proximal sleeve/stem and the femoral head-neck modular junctions were examined under 10X magnification, and graded by two independent observers. The head tapers were divided into 4 regions, and graded using a previously published 3 point scoring system for fretting and corrosion damage (Goldberg et al, Kop et al), for a total corrosion damage score of 12. The SROM stems were also assessed at the sleeve/stem taper junction. Each stem was divided into 8 quadrants, and graded for corrosion and fretting using the same system as the taper. In addition to severity, we also quantified area of corrosion damage of the stem at the sleeve-stem junction from 0–3, which was multiplied by the severity of damage, to give a score out of 9 for each quadrant (maximum total score of 72 for the stem). The bearing type was unknown to the investigators, so the grading was done in a blinded fashion. Corrosion scores were divided by time to account for differences in time to revision.

Introduction

The aim of this study was to quantitatively analyze the amount coronal plane laxity in mid-flexion that occurs in a well-balanced knee with an elevated joint line of 4 mm. In the setting an elevated joint line, we hypothesized that we would observe an increased varus and/or valgus laxity throughout mid flexion.

Methods

After obtaining IRB approval, nine fresh-frozen cadaver legs from hip-to-toe underwent TKA with a posterior stabilized implant (APEX PS, OMNIlife Science, Inc.) using a computer navigation system equipped with a robotic cutting-guide, in this controlled laboratory cadaveric study. After the initial tibial and femoral resections were performed, the flexion and extension gaps were balanced using navigation, and a 4 mm recut was made in the distal femur. The remaining femoral cuts were made, the femoral component was downsized by resecting an additional 4 mm of bone off the posterior condyles, and the polyethylene was increased by 4 mm to create a situation of a well-balanced knee with an elevated joint line. Real implants were used in the study to eliminate any inherent error or laxity in the trials. The navigation system was used to measure overall coronal plane laxity by measuring the mechanical alignment angle at maximum extension, 30, 45, 60 and 90 degrees of flexion, when applying a standardized varus/valgus load of 9.8 [Nm] across the knee using a 4 kg spring-load located at 25 cm distal to the knee joint line (Figure 1). Coronal plane laxity was defined as the absolute difference (in degrees) between the mean mechanical alignment angle obtained from applying a standardized varus and valgus stress at 0, 30, 45, 60 and 90 degrees. Each measurement was performed three separate times.

Two tailed student t-tests were performed to analyze whether there was difference in the mean mechanical alignment angle at 0°, 30°, 45°, 60°, and 90° between the well balanced scenario and following a 4 mm joint line elevation with an otherwise well balanced knee.

Objective

Superior bone ingrowth and resistance to bacterial infection are ideal for orthopaedic implants. We compared new bone formation, strength of bone bonding, and infection rates between silicon nitride ceramic (Si3N4; abbreviated SiN), medical-grade PEEK (PEEK), and titanium (Ti) in rat calvariae. PEEK and Ti are used in spinal and arthroplasty implants respectively, while SiN is a non-oxide ceramic used in spinal implants for the past 4 years.

Methods

Specimens of 10 mm × 10 mm by 1.75 mm size were implanted into experimental calvarial defects in 2-year old Wistar rats using standard surgical techniques (n's: SiN=48; PEEK=24; Ti=24). One group of animals was immediately inoculated with 1 × 104 Staphylococcus epidermidis; control animals received saline only. After sacrifice at 3 days, 7 days, 14 days, and 3 months post-inoculation (n=4 rats per time period), one calvarial sample each for PEEK and Ti, and two samples for SiN (per bacterial condition and time point) were retrieved for histology; remaining samples were used for sample push-out testing with a Micro Tester 5848 (Instron) with a 1-kN load cell, using published techniques. New bone formation was measured with tetracycline double-labeling at 11 and 4 days before the 14-day and 3-month time periods.

Background

The acetabular labrum is an essential stabilizer of the hip joint, imparting its greatest effect in extreme joint positions where the femoral head is disposed to subluxation and dislocation. However, its stabilizing value has proved difficult to quantify. The objective of the present study was to assess the contribution of the entire acetabular labrum to mechanical joint stability. We introduce a novel “dislocation potential test” that utilizes a dynamic, cadaveric, robotic model that functions in real-time under load-control parameters to map the joint space for low-displacement determination of stability, and quantify using the “stability index”.

Methods

Five fresh-frozen human cadaveric hips without labral tears were mounted to a six-degree-of-freedom robotic manipulator and studied in 2 distinct joint positions provocative for either anterior or posterior dislocation. Dislocation potential tests were run in 15° intervals, or sweep planes, about the face of the acetabulum. For each interval, a 100 N force vector was applied medially and swept laterally until dislocation occurred. Three-dimensional kinematic data from conditions with and without labrum were quantified using the stability index, which is the percentage of all directions a constant force can be applied within a given sweep plane while maintaining a stable joint.

Background

With the projected 673% increase in total knee arthroplasties (TKA) through the year 2030 in the United States alone, arthrofibrosis will become one of the more commonly encountered challenges in orthopaedic surgery.

Methods

After obtaining Institutional Review Board approval we retrospectively reviewed the results of 19 patients with a mean age at the time of surgery of 55.4 years (41–83) who underwent arthroscopic lysis of adhesions (ALOA) for arthrofibrosis at a minimum of 3 months after primary total knee arthroplasty by a single surgeon (SJC) at a single institution. All patients underwent a standardized adhesiolysis in the operating room. All patients had a minimum of 6 months follow up. All patients underwent arthroscopic lysis of adhersions for restricted range of motion (ROM) after failing aggressive physical therapy. We defined restriction in ROM as any extension lag >5°, and flexion ≤90°. Eight patients underwent manipulation under anesthesia for ROM less than 90° after ALOA.

Introduction

Extensive bone loss and poor residual bone quality can make implant fixation difficult to achieve in revision of failed megaprostheses. While newer porous components are available to address various periarticular cavitary and segmental defects, diaphyseal fixation remains challenging without resorting to cemented techniques, or cementless fully-coated stems that achieve fixation over long segments of bone. In cases of previous infection, it may be advantageous to avoid the use of such devices as they can be difficult to remove and may result in even greater bone loss if the infection were to persist. Compressive osseointegration technology has been become a valuable device in the management of these challenging situations.

Objectives

We aimed to evaluate the short-term results of compressive osseointegration when used for reconstruction of massive diaphyseal and segmental bone defects. We believe that compressive osseointegration provides predictable, strong endoprosthesis fixation in the short-term and that osseointegration can be evaluated radiogrphically.

Introduction

Surgical drill-bits are used in a raft of procedures, from trauma, joint reconstruction to Arthroplasty. Drilling of bone is associated with the conversion of mechanical work energy into shear failure of bone and heat generation, causing a transient rise in temperature of hard and soft tissues. Thermal insults above 47°C sustained for one minute or more may cause osteonecrosis, reduced osteogenic potential, compromise fixation and influence tolerances with cutting blocks. Drill design parameters and operational variables have marked effects on cutting performance and heat generation during drilling. Dulling and wear of the cutting surfaces sustained through repeated usage can significantly reduce drill bit performance. Deterioration of cutting performance substantially increases the axial thrust force required to propel the cutting face through bone, compromising surgeon control during drilling and increasing the likelihood of uncontrolled plunging, cortical breakthrough and improper placement of holes as well as other jigs.

Methods

The drilling accuracy and skiving of 2.8 mm 3-fluted SurgiBit (Orthopedic Innovation (OI), Sydney, Australia) (Figure 1) was compared with a standard 2-fluted drill (Synthes) at 15, 30 and 45 degrees using a 4^th generation Sawbone as well as bovine cortical bone. A surgical handpiece was mounted in a servo-hydraulic testing machine and the motion of the drill-bit confined to 2 degrees of freedom. The lateral force and skiving distance was measured (n=6 per drill per angle per testing medium). A new drill was used for each test. Wear performance over multiple drilling episodes (1, 10 and 100) was performed in bovine cortical bone. The surface characteristics of the cutting faces of the drills were assessed optically at 10x magnification and at higher magnifications (50, 100 and 500x) using an environmental electron microscope.

Introduction

Humeral head subluxation in patients with cuff tear arthropathy (CTA) and in patients with primary arthrosis has been classified by Hamada and by Walch (type B). These classifications are based on 2D evaluation techniques (AP X-ray view, axial CT images). To our knowledge no 3D evaluation of the direction of humeral head subluxation has been described

Aim

To describe a reproducible 3D measuring technique to evaluate the direction of the humeral head subluxation in shoulder arthropathy

RESULTS

1

Basal IOP has a pulse wave and an underlying respiratory wave (RW).

CONCLUSIONS

IOP measurement in isolation is meaningless. With arterial and venous occlusion, perfusion at the needle tip can be studied.

Compartment syndrome testing should be similar.

Subchondral bone is a compressible perfused sponge with a ‘pumped’ microcirculation.

Very high pressures arise in subchondral bone during activity.

There are protective modifications of the microcirculation.

Failure of subchondral circulation causes arthritis. Arthritis is mainly a ‘vasculo-mechanical’ disease. This work explains the spectrum of arthritis and osteonecrosis, and Perthes, caisson and sickle cell disease patterns. It explains why osteoporosis might protect against arthritis.

Introduction

Wear of polyethylene continues to be a significant factor in the longevity of total knee replacement (TKR). Moderately cross-linked polyethylene has been employed to reduce the wear of knee prostheses, and more recently anti-oxidants have been introduced to improve the long-term stability of the polyethylene material. This is the initial study of the wear of a new anti-oxidant polyethylene and a new TKR design, which has modified femoral condylar geometry.

Materials and Methods

The wear of a new TKR the Attune knee was investigated using a physiological six station Prosim knee wear simulator (Simulator Solutions, UK). Six mid-size Attune fixed bearing cruciate retaining TKRs (DePuy Inc, Warsaw, USA) were tested for a period of 6 million cycles. The inserts were manufactured from AOX™, a compression moulded GUR1020 polyethylene incorporating Covernox™ solid anti-oxidant. The AOX polymer was irradiated to 8M Rad, to give a moderately cross-linked material.

High and intermediate kinematics, under anterior-posterior displacement control were used for this study (McEwen et al 2005). The maximum femoral axial loading was 2600N, with flexion-extension of 0 to 58°, an anterior-posterior displacement of 0–10 mm for high kinematics and 0–5 mm for intermediate, and an internal-external rotation of ±5°. The lubricant was 25% (v/v) calf serum supplemented with 0.03% (v/v) sodium azide solution in deionised water, as an antibacterial agent, and was changed approximately every 0.33 Mc. Wear was assessed gravimetrically and moisture uptake was assessed using unloaded soak controls. Volumetric wear was calculated using a density of 0.94 mg/mm³, and compared with a previous study examining the Sigma XLK TKR design which uses moderately crosslinked polyethylene which is in current clinical use (Brockett et al 2012).

INTRODUCTION

The literature suggests a survivorship of unicompartmental knee arthroplasties (UKA) for spontaneous osteonecrosisof the knee range from 93% to 96.7% at 10 to 12 years. However, these data arise from series reporting 23 to 33 patients, jeopardizing meaningful conclusions.

OBJECTIVES

Our purpose is to examine a long term survivorship of UKA's in a larger group of patients with SPONK, along with their subjective, symptomatic and functional outcome; to determine the percentage of failures and the reasons for the same in an attempt to identify relevant indications, contraindications, and technical parameters in treating SPONK with a modern implant design.

Introduction

To minimize leg length discrepancies (LLD), preoperative measures are taken using the PACS; the head center to the proximal end of the lesser trochanter distance (HLD) of the opposite side of the operating limb are calculated, while during operation, the modular neck selection is adapted to equal the opposing limb's length.

The purpose of this study was to see whether the HLD method would show far less occurrences of LLD, in comparison to the conventional method(preoperative templating and shuck test).

Method

349 (412 hips) patients who had undergone THRA were divided into two groups based upon which methods they had used to equalize limb length during operation: (1) HLD method, and (2) conventional methods. Six months after surgery, using the PACS system, LLD's of the two groups were compared.

Introduction

Metal-on-metal (MOM) hip joints have regained a favor in arthroplasty since they own excellent wear resistance. In this study, wear tests by using a hip joint simulator were conducted with MOM bearings of specified 40 mm femoral heads. The influence of clearance on the wear behavior was investigated. Furthermore, an optimized radial clearance was estimated by lubricant film thickness and contact pressure analysis.

Materials and methods

Co-27Cr-5Mo-0.13N-0.05C (hereafter CCMN) alloy (mass %) was used. The ingots were vacuum induction melted, homogenized and hot forged successively. The microstructure shows equiaxed crystal grains with abundant annealing twins but no carbides.

Two groups of bearings, indicated as c_r 1 and c_r 2, were designed. The radial clearances for c_r 1 and c_r 2 were 37.9 and 148.7 μm, respectively. Wear tests were conducted in a hip joint simulator (INSTRON 8870) in Hanks' solution at 37±2°f. The force and 3-axile angle of movement were applied on the articulation according to ISO 14242-1 for 1.5 million cycles (Mc).

The contact pressures on the hip joints were also analyzed by using ABAQUS. The femoral heads were set 40 mm with radial clearances of 0–200 μm. Half models were set up and only the maximum force of 3 kN converted as pressure was applied as boundary condition.

Aim

Cementless prosthesis is one of the major bone-implant interface fixation methods in total joint replacement. Grit blasted surface, hydroxyapatite coated surface and plasma sprayed metallic porous coating have been popularly used. The latter has demonstrated higher bone implant mechanical stability in previous laboratory study in early and middle stages. However, question remains what the mechanism is to make it performing better and how to improve them further. This study is designed to examine the mode of failure in bone-implant interface in a sheep model.

Method

Plasma sprayed porous coated (TiPL); hydroxyapatite (HA) coated and and grit blasted (TiGB) titanium implants were examined in the study. Each type has 36 specimens. Implants were inserted into cortical bones in a press-fit fashion in a total of 22 sheep bilateral hind limbs. Specimens were retrieved at 4 weeks and 12 weeks. Push- out testing was performed to just reach ultimate failure. Failed bone-implant interface were investigated by histology and BSEM. The percentage of failure at bone-coating interface, bone itself fracture, coating itself failure, and coating-substrate dissociation were measured by BSEM.

AIM

Tibial component design has be been scrutinized in a number of studies in an attempt to improve tibial coverage in total knee arthroplasty. However, very few have controlled for both component rotation and resultant changes to posterolateral tibial tray overhang and posteromedial underhang. We hypothesize that asymmetrical tibial components can provide greater coverage than symmetrical trays without increasing overhang.

METHODS

The 6 most commonly used tibial trays on the Australian Joint Registry (2009) were superimposed on MRI slices of normal knees to assess tibial component overhang, underhang and percent coverage. Rotational alignment in this analysis was based upon the line joining the junciton of the medial and middle 1/3 of the patellar tendon and the PCL insertion.

Purpose

In general, the amount and rate of linear wear are associated with femoral head size in the conventional UHMWPE acetabular liner. The smaller the femoral head, the higher the linear wear rate. The aim of this study is to verify the relationship between wear rate and femoral head size and the polyethylene cup thickness.

Materials and Methods

We conducted a retrospective review of all patients who had undergone primary cementless total hip arthroplasty using the conventional UHMWPE (HGP2) acetabular liner between July 1992 and December 2002. 128 hips (34 hips of female, 94 hips of male) of 64 patients who had 28 mm femoral head with different polyethylene acetabular linear thickness and 102 hips (41 hips of female, 61 hips of male) of 81 patients with 22 mm femoral head were included. Patients were assessed clinically and radiographically at postop 6 weeks, 3 months, 6 months and annually thereafter. Clinical assessment was performed using Harris Hip Score. Radiographic analysis included measurement of acetabular component position, polyethylene wear using a validated radiographic technique (Dorr method). Their mean age at the time of operation was 45.3 (24–81) years old and mean follow-up period was 10.8 (96–144 months) years.

Purpose

To report clinical results and demonstrate any posterior femoral translation (PFT) in medial rotation total knee arthroplasty (TKA) of posterior cruciate ligament (PCL) retaining type.

Materials and Methods

A prospective study was performed upon thirty consecutive subjects who were operated on with medial rotation TKA of PCL retaining type (Advance® Medial Pivot prosthesis with ‘Double High’ insert; Wright Medical Technology, Arlington, TN, USA) (Fig. 1). between March 2009 and March 2010 and had been followed up for a least 2 years. Inclusion criteria were age between 60 and 75 years and primary degenerative joint disease of knee graded as Kellgren Lawrence grade III or higher. Exclusion criteria were age under 60 years, any inflammatory joint disease including rheumatoid arthritis, early stage of primary degenerative joint disease of knee or any history of previous osteotomy around knee. Clinically, the knee society knee score and function score were used to evaluate pain and function. At last follow-up, all subjects performed full extension, thirty degree flexion and full active flexion sequentially under fluoroscopic surveillance. In each of these lateral radiographs, anteroposterior(AP) condylar position was pinpointed and the magnitude of PFT was determined by degree of transition of AP condylar position from full extension to full active flexion radiograph (Fig. 2 A–B). Statistical methods used were paired t-test, Pearson correlation, Steadman rank correlation and regression analysis. Component migration and radiolucent line were also observed.

Introduction

CT based systems that are used to create custom components and custom cutting guides in total knee arthroplasty (TKA) have variable methods for accounting for the thickness of remaining cartilage that may influence component sizing and bone resection. Little information has been published about the thickness of this cartilage, especially on the posterior femoral condyles. Failure to account for this cartilage may lead to under-sizing of the femoral component, or a reduction in the posterior condylar offset that may adversely affect flexion after TKA.

Methods

This IRB approved, retrospective study included 140 consecutive patients who underwent primary TKA. The medial and lateral posterior condylar bone cuts were performed in the usual manner with mechanical instruments. The resected specimen was sectioned in the sagital plane and the cartilage thickness was measured at the mid portion to the nearest millimeter.

Introduction

While prosthesis survival in Total Knee Arthroplasty (TKA) exceeds 90% at 10 year, failures do occur. One area of concern has been the potential for metal allergy or metal sensitivity causing persistent pain, swelling or early failure of the implant in some patients. Definitive tests for diagnosing metal allergy and metal sensitivity have not been developed and this field remains controversial. In most cases where metal sensitivity is a concern, metals such as Chromium and Nickel are implicated. Despite the lack of good diagnostic tests for identifying these patients, several orthopedic prosthesis manufacturers have developed implants made of Titanium or ceramic designed for use in patients where concerns exist regarding metal allergy. In the absence of good diagnostic tests, use of these devices in patients that self identify is one option. To date, little information has been presented about the incidence of self reported metal sensitivity in patients undergoing joint replacement. This study was undertaken to determine the incidence of self reported metal allergy or sensitivity in patients undergoing total knee arthroplasty.

Methods

An IRB approved, retrospective chart review was performed in a consecutive series of 194 patients who had undergone TKA at one institution, with one surgeon. Self reported metal sensitivity and allergy had been routinely elicited from each individual who had not undergone implantation of a previous metallic device, during pre-operative consultation.

Introduction

Wear and corrosion of metal-on-metal (MM) bearings releases (a) soluble metal ions which collect locally and pass into the systemic circulation and (b) insoluble particles which undergo local deposition and lymphoreticular dissemination. Debris-related failures from osteolysis, metallosis and pseudotumours warrants revision of these MM bearing devices to non-MM bearing arthroplasties with the expectation that both the systemic and local effects will be reversed with time since the source of metal ion release is removed.

The purpose of the present study is to determine (a) whether metal ion levels in blood and urine decrease after revision of a MM bearing arthroplasty to a non-MM bearing device and (b) the rate at which this decrease is effected.

Methods

Blood and urine levels of cobalt and chromium ions are studied prospectively over two years in 15 patients whose MM resurfacings were revised to cross-linked polyethylene containing total hip replacements (THRs). Specimen collection was started before and periodically after the revision at 2, 4 and 6 days and 2 months, 6, 12 and 24 months after operation. None of the patients had other MM devices or compromised renal function.

Introduction

Hip simulator studies show that metal-on-metal bearing wear can be reduced by reducing the diametral clearance of the bearing. We present the six-year follow-up results of a prospective clinico-radiological and metal ion study in patients with a low clearance metal-metal surface arthroplasty. The results are compared to published results of similar design bearings with conventional clearance.

Methods

Twentysix male patients (mean age 55 years, mean BMI 26) who received a 50 mm bearing resurfacing (radial clearance 50μm) were included in an ongoing clinico-radiological and metal ion study. Urine/blood specimens were obtained before and periodically after hip resurfacing. Patients were also assessed with Oxford Hip Scores and Harris Hip Score questionnaires. Two hips were excluded during follow-up, one for revision and another for contralateral hip arthroplasty.

Introduction

Modern metal-on-metal bearing resurfacings have been in use for nearly two decades. Local and systemic metal ion exposure continues to cause concern. We could not find a prospective metal ion study in such patients with a 10-year follow-up. This is the first ten year prospective study of metal ion levels in blood and their release in urine following hybrid fixed metal-on-metal surface arthroplasty.

Methods

Twenty six patients were included in an ongoing longitudinal metal ion study of patients with unilateral metal-on-metal hip resurfacings. Three of them were excluded due to subsequent contralateral resurfacing and one has relocated abroad. Cobalt and chromium levels were assessed in 12 hour urine collections before and periodically after operation (5 days to 10 years) using high resolution plasma mass spectrometry. Mean age at operation was 53 years and mean BMI 27.9.

Introduction

Metal-metal surface replacement (MoMSRA) continues to be used in young women. Systemic metal ion release and its effects cause concern. Do metal ions crossing the placenta in pregnant women have potential mutagenic effects? The hypothesis is that metal ions pass freely through the placenta and there is no difference in maternal and cord metal levels.

Methods

This is a controlled cross-sectional study of women with MoMSRA. (n = 25, 3 bilateral, mean age 32 years, time from implantation to delivery 60 months). The control group consisted of 24 subjects, mean age 31 years, with no metallic implant and not receiving cobalt/chromium supplements. No patient was known to have renal failure. Whole blood specimens were obtained before delivery and before any infusion or transfusion, and cord blood specimens immediately after delivery.

INTRODUCTION

The aim of this retrospective study is to evaluate clinically and radiographically the effectiveness of implanting an eccentric glenosphere and if a correct glenosphere positioning would avoid the occurrence of notching.

METHODS

since 2006 40 patients with shoulder eccentric osteoarthritis were treated with reverse shoulder arthroplasty with a 36 mm eccentric glenosphere. We have selected 25 patients, with a minimum follow up of 24 months. The patients were clinically evaluated with the Constant score and SST and with X-ray, MRI and/or CT before and after surgery. At the follow up we evaluated the presence or absence of notch, and we measured the PSNA (prosthesis-scapular neck angle), the DBSNG (distance between the scapular neck angle and glenosphere), the PGRD distance (peg glenoid distance). Stastistical analysis was performed with a paired t test.

Purpose

Reverse shoulder prosthesis may lead to scapular notching, caused by attrition of the upper humeral component with scapular neck. We compared the clinical and radiographic results obtained with a SMR prosthesis, which allows a concentric or an eccentric glenosphere to be applied.

Patients and methods

67 patients, mean age 73 years, were treated with reverse prosthesis using concentric and eccentric glenosphere. In patients with concentric glenosphere, the glenosphere extended about 4 mm below the glenoid. The eccentric glenosphere protected the upper glenoid neck by its inferior prolongment. Patients were followed for a mean of 33 months. At final F-U the Constant Score (C.S.) and the score with the Simple Shoulder test (S.S.T.) were calculated. Radiographs were obtained to evaluate the presence of scapular notching, psna (prosthesis-scapular neck angle), pgrd (peg- glenoid rim distance) and DBSNG (distance between scapular neck and glenosfere). Included in this study were patients, as much homogeneous as possible by age and pathology, 25 with concentric (Group I) and 30 with eccentric (Group II) glenosphere, who had a minimum F-U of 24 months. Statistical analysis was performed with a paired test.

Introduction

Total hip arthroplasties in younger patients often requires revision because these patients frequently have acetabular deficiencies, which hamper proper implantation of the cup essential for good long-term prosthesis survival. For 30 years, we have used a biological acetabular-reconstruction technique with bone-impaction grafting in all patients <50 years with an acetabular deficiency at surgery, always in combination with a cemented total hip implant.

Methods

We evaluated all 150 consecutive patients (177 hips) < 50 years with an acetabular reconstruction by bone-impaction grafting surgically-treated from 1978–2004 at our clinic. Mean follow-up was 10.3 (range, 2.0–28.3) years with no patient lost to follow-up. Mean index surgery age was 38.1 (range, 16–49) years. Clinical, radiological, and statistical analysis of all patients was performed.

Background

Surgeons always must take into account that a primary total hip arthroplasty (THA) in a young patient will be revised in the future, this because of the long life expectancy of young THA patients and the limited durability of prosthetic implants in these patients. Therefore we would like to accentuate the revisability of a primary THA in this specific and high demanding patient population.

Methods

343 consecutive THA in 267 patients under the age of 50 years were evaluated. We also assessed the results of the revised THA (n=53) within the same population. Clinical, radiographical and survival of primary and revision THA were evaluated.

INTRODUCTION

Osteoarthritis (OA) of the hip and the knee has been found to affect sexual activity. Few retrospective studies have investigated the role of total hip replacement on sexual function. We designed a prospective study to evaluate the influence of total hip arthroplasty (THA) and total knee arthroplasty (TKA) on the physical and psychological aspects of sexuality of patients.

METHODS

Between April 2009 and April 2011, patients under 70 years of age scheduled for primary THA or TKA for OA were invited to anonymously participate in this study. All patients were recruited from the practices of 2 arthroplasty surgeons (at the same institution) by mailing the 2 questionnaires, 2 pre-paid self-addressed envelopes and a cover letter. Patients were instructed to mail back the pre-operative questionnaire prior to surgery and the post- operative questionnaire 6 months after surgery. Enrolled patients were also contacted after 1 year of surgery to fill a similar questionnaire. Responses were identified only by a unique code number on the questionnaire.

Introduction

Core decompression is used in precollapse lesions to forestall disease progression in avascular necrosis (AVN) of femoral head (FH). The author reports a new technique using reverse bone graft technique to effectuate core decompression.

Aim

To prevent precollapse in Ficat Type 1&2 and revascularization using synthetic bone graft material.

Methods

FE model geometry was based on standard femur from the international Society of Biomechanics Mesh Repository. Loading simulated for one- legged stance with body weight of 826 N. 2 regions were defined, R1 (40 mm from tip of head) and R2 41 mm–150 mm) of the intramedullary part of the stemmed model's interface with bone. 2 different loading conditions bending and torsion were compared for stress and strain. The FE model was solved with ANSYS version 6.1 on a single processor NT station.

Results

With conventional implants, stem shields cortical bone from being loaded. In nonstemmed implants, Von Misses stress contours show a similar distribution as intact bone, transferring loads to the cortical shell but with higher stresses and a maximum displacement of 17.39% higher than that of intact bone. 15–23 mm proximal to R2 and around 110 mm, region of the stem tip, there were higher stress and strain concentrations.

Introduction

Component and limb alignment (especially varus >3°) have been associated with soft-tissue imbalance, increased polyethylene wear, and tibial tray subsidence. However, not all clinical outcome studies have found significant correlation between tibial varus and revision surgery. While the link between limb alignment and failure has been attributed to increased medial compartmental loading and generation of shear stress, quantitative biomechanical evidence to directly support this mechanism is incomplete. In this study, we analyzed the effect of limb alignment and tibial tray alignment on the risk for bone damage and subsequent risk for tray loosening.

Methods

A finite element model of knee arthroplasty previously validated with in vitro cadaver testing was used. Models of four subjects were constructed with tibial resections simulating a 0°, 3°, 5°, and 7° varus alignment with respect to the mechanical axis of the tibia and the tray implanted at the corresponding angles. Tibial tray orientation was simulated without change in limb alignment (i.e. maintaining the mechanical axis of the knee at 0°) and with limb alignment ranging from 3° valgus to 7° varus (Fig 1).

A static load equivalent to three times the bodyweight of the subject was applied in line with the mechanical knee axis. Relative motion between the tibial tray and tibial bone was calculated. Elements with an equivalent von Mises strain >0.4% were selected and assigned an elastic modulus of 5 MPa to reflect damaged bone. Simulation was repeated and after-damage micromotion recorded.

Introduction

Hip Arthrodesis had been considered as a useful surgical option in young adult patient with high activity demands suffering from osteoarthritis of the hip. Although the procedure surely eliminates pain of the hip joint, it can also cause disorders of the adjacent joints in addition to the complete loss of motion, might consequently deteriorate the activity of daily living. The purpose of this retrospective study was to investigate the efficacy and drawback of hip arthrodesis, focusing on the effect of this procedure on the adjacent joints.

Materials and Methods

From 1976 to 1989, 29 hip arthrodesis were performed and 22 hips were followed up (1 died, 6 lost). Disorders led to arthrodesis were septic arthritis (1 hip), post-traumatic (1), osteonecrosis (1), primary osteoarthritis (3), and secondary osteoarthritis due to DDH (16). The average age at surgery was 38 years (range, 19–53 years, 6 men and 16 women). Hip arthrodesis was indicated for young active adults with end stage osteoarthritis, who had normal or mild osteoarthritis in contralateral hip and needed physical labor. The hip was positioned in 30 degrees of flexion, 0 to 5 degree of external rotation, and 0 to 5 degree of abduction. Clinical and radiographic assessment was done for these patients. The clinical follow-up consisted of questionnaire which assessed ability of typical Japanese daily living movement and patient's satisfaction. The condition of the adjacent joints was evaluated clinically and radiographically.

Introduction

Two types of ceramic materials currently used in total hip replacements are third generation hot isostatic pressed (HIPed) alumina ceramic (commercially known as BIOLOX®forte, CeramTec) and fourth generation alumina matrix composite ceramic consisting of 75% alumina, 24% zirconia, and 1% mixed oxides (BIOLOX®delta, CeramTec). Delta ceramic hip components are being used worldwide, but very few studies have analyzed retrieved delta bearings. The aim of this study is to compare edge loading ‘stripe’ wear on retrieved femoral heads from delta-on-delta, delta-on-forte and forte-on-forte ceramic bearings revised within 2 years in vivo.

Material and Methods

Ceramic bearings revised at one center from 1998 to 2010 were collected (61 bearings). Eleven delta heads revised between 1–33 months were compared to 24 forte femoral heads with less than 24 months in vivo (Figure 1). The surface topography of the femoral heads was measured using a RedLux AHP (Artificial Hip Profiler, RedLux Ltd, Southampton, UK). Three representative samples were examined with a FEI Quanta 200 Scanning Electron Microscope (SEM).