Introduction

Major trauma during military conflicts involve heavily contaminated open fractures. Staphylococcus aureus (S. aureus) commonly causes infection within a protective biofilm. Lactoferrin (Lf), a natural milk glycoprotein, chelates iron and releases bacteria from biofilms, complimenting antibiotics. This research developed a periprosthetic biofilm infection model in rodents to test an Lf based lavage/sustained local release formulation embedded in Stimulin beads.

Abstract

Abstract

Abstract

Biplane video X-ray (BVX) – with models segmented from magnetic resonance imaging (MRI) – is used to directly track bones during dynamic activities. Investigating tibiofemoral kinematics helps to understand effects of disease, injury, and possible interventions.

Develop a protocol and compare in-vivo kinematics during loaded dynamic activities using BVX and MRI.

BVX (60 FPS) was captured whilst three healthy volunteers performed three repeats of lunge, stair ascent and gait. MRI scans were performed (Magnetom 3T Prisma, Siemens). 3D bone models of the tibia and femur were segmented (Simpleware Scan IP, Synopsis). Bone poses were obtained by manually matching bone models to X-rays (DSX Suite, C-Motion Inc.). Mean range of motion (ROM) of the contact points on the medial and lateral tibial plateau were calculated using custom MATLAB code (MathWorks). Results were filtered using an adaptive low pass Butterworth filter (Frequency range: 5-29Hz).

Gait and Stair ascent activities from one participant's data showed increased ROM for medial-lateral (ML) translation in the medial compartment but decreased ROM in anterior-posterior (AP) translation when comparing against the same translations on the lateral compartment of the tibial plateau. Lunge activity showed increased ROM for both ML and AP translation in the medial compartment when compared with the lateral compartment.

These results highlight the variability in condylar translations between different activities. Understanding healthy in-vivo kinematics across different activities allows the determination of suitable activities to best investigate the kinematic changes due to disease or injury and assess the efficacy of different interventions.

Acknowledgements: This research was supported by the Engineering and Physical Sciences Research Council (EPSRC) doctoral training grant (EP/T517951/1).

To be able to assess the biomechanical and functional effects of ankle injury and disease it is necessary to characterise healthy ankle kinematics. Due to the anatomical complexity of the ankle, it is difficult to accurately measure the Tibiotalar and Subtalar joint angles using traditional marker-based motion capture techniques. Biplane Video X-ray (BVX) is an imaging technique that allows direct measurement of individual bones using high-speed, dynamic X-rays.

The objective is to develop an in-vivo protocol for the hindfoot looking at the tibiotalar and subtalar joint during different activities of living.

A bespoke raised walkway was manufactured to position the foot and ankle inside the field of view of the BVX system. Three healthy volunteers performed three gait and step-down trials while capturing Biplane Video X-Ray (125Hz, 1.25ms, 80kVp and 160 mA) and underwent MR imaging (Magnetom 3T Prisma, Siemens) which were manually segmented into 3D bone models (Simpleware Scan IP, Synopsis). Bone position and orientation for the Talus, Calcaneus and Tibia were calculated by manual matching of 3D Bone models to X-Rays (DSX Suite, C-Motion, Inc.). Kinematics were calculated using MATLAB (MathWorks, Inc. USA).

Pilot results showed that for the subtalar joint there was greater range of motion (ROM) for Inversion and Dorsiflexion angles during stance phase of gait and reduced ROM for Internal Rotation compared with step down. For the tibiotalar joint, Gait had greater inversion and internal rotation ROM and reduced dorsiflexion ROM when compared with step down.

The developed protocol successfully calculated the in-vivo kinematics of the tibiotalar and subtalar joints for different dynamic activities of daily living. These pilot results show the different kinematic profiles between two different activities of daily living. Future work will investigate translation kinematics of the two joints to fully characterise healthy kinematics.

Abstract

Abstract

Abstract

Optical motion capture (OMC) is the current gold standard for motion analysis, however measuring patellofemoral kinematics is not possible using the technique. One approach to measuring in-vivo kinematics is to use biplane video X-ray (BVX) and 3D models generated from MRI to track the movement of the patellar. Understanding how the patellar is moving during different loaded dynamic activities can help with understanding the effects of different interventions when treating disease or injury.

Abstract

Skeletal kinematics are traditionally measured by motion analysis methods such as optical motion capture (OMC). While easy to carry out and clinically relevant for certain applications, it is not suitable for analysing the ankle joint due to its anatomical complexity. A greater understanding of the function of healthy ankle joints could lead to an improvement in the success of ankle-replacement surgeries. Biplane video X-ray (BVX) is a technique that allows direct measurement of individual bones using highspeed, dynamic X-Rays.

Three-dimensional (3D) printing has become more frequently used in surgical specialties in recent years. Orthopaedic surgery is particularly well-suited to 3D printing applications, and thus has seen a variety of uses for this technology. These uses include pre-operative planning, patient-specific instrumentation (PSI), and patient-specific implant production. As with any new technology, it is important to assess the clinical impact, if any, of three-dimensional printing.

The purpose of this review was to answer the following questions:

What are the current clinical uses of 3D printing in orthopaedic surgery?

Four electronic databases (Embase, MEDLINE, PubMed, Web of Science) were searched for Articles discussing clinical applications of 3D printing in orthopaedics up to November 13, 2018. Titles, abstracts, and full texts were screened in duplicate and data was abstracted. Descriptive analysis was performed for all studies. A meta-analysis was performed among eligible studies to compare estimated blood loss (EBL), operative time, and fluoroscopy use between 3D printing cases and controls. Study quality was assessed using the Methodological Index for Non-Randomized Studies (MINORS) criteria for non-randomized studies and the Cochrane Risk of Bias Tool for randomized controlled trials (RCTs). This review was prospectively registered on PROSPERO (Registration ID: CRD42018099144).

One-hundred and eight studies were included, published between 2012 and 2018. A total of 2328 patients were included in these studies, and 1558 patients were treated using 3D printing technology. The mean age of patients, where reported, was 47 years old (range 3 to 90). Three-dimensional printing was most commonly reported in trauma (N = 41) and oncology (N = 22). Pre-operative planning was the most common use of 3D printing (N = 63), followed by final implants (N = 32) and PSI (N = 22). Titanium was the most commonly used 3D printing material (16 studies, 27.1%). A wide range of costs were reported for 3D printing applications, ranging from “less than $10” to $20,000. The mean MINORS score for non-randomized studies was 8.3/16 for non-comparative studies (N = 78), and 17.7/24 for non-randomized comparative studies (N = 19). Among RCTs, the most commonly identified sources of bias were for performance and detection biases. Three-dimensional printing resulted in a statistically significant decrease in mean operative time (−15.6 mins, p < .00001), mean EBL (−35.9 mL, p<.00001), and mean fluoroscopy shots (−3.5 shots, p < .00001) in 3D printing patients compared to controls.

The uses of 3D printing in orthopaedic surgery are growing rapidly, with its use being most common in trauma and oncology. Pre-operative planning is the most common use of 3D printing in orthopaedics. The use of 3D printing significantly reduces EBL, operative time, and fluoroscopy use compared to controls. Future research is needed to confirm and clarify the magnitude of these effects.

Distracted driving is now the number one cause of death among teenagers in the United States of America according to the National Highway Traffic Safety Administration. However, the risks and consequences of driving while distracted spans all ages, gender, and ethnicity. The Distractions on the Road: Injury eValuation in Surgery And FracturE Clinics (DRIVSAFE) Study aimed to examine the prevalence of distracted driving among patients attending hospital-based orthopaedic surgery fracture clinics. We further aimed to explore factors associated with distracted driving.

In a large, multi-center prospective observational study, we recruited 1378 adult patients with injuries treated across four clinics (Hamilton, Ontario, Toronto, Ontario, Calgary, Alberta, Halifax, Nova Scotia) across Canada. Eligible patients included those who held a valid driver's license and were able to communicate and understand written english. Patients were administered questions about distracted driving. Data were analyzed with descriptive statistics.

Patients average age was 45.8 years old (range 16 – 87), 54.3% male, and 44.6% female (1.1% not disclosed). Of 1361 patients, 1358 self-reported distracted driving (99.8%). Common sources of distractions included talking to passengers (98.7%), outer-vehicle distractions (95.5%), eating/drinking (90.4%), music listening/adjusting the radio (97.6%/93.8%), singing (83.2%), accepting phone calls (65.6%) and daydreaming (61.2%). Seventy-nine patients (6.3%), reported having been stopped by police for using a handheld device in the past. Among 113 drivers who disclosed the cause of their injury as a motor vehicle crash (MVC), 20 of them (17%) acknowledged being distracted at the time of the crash. Of the participants surveyed, 729 reported that during their lifetime they had been the driver in a MVC, with 226 (31.1%) acknowledging they were distracted at the time of the crash.

Approximately, 1 in 6 participants in this study had a MVC where they reported to be distracted. Despite the overwhelming knowledge that distracted driving is dangerous and the recognition by participants that it can be dangerous, a staggering amount of drivers engage in distracted driving on a fairly routine basis. This study demonstrates an ongoing need for research and driver education to reduce distracted driving and its devastating consequences.

One of the main surgical goals when performing a total knee replacement (TKR) is to ensure the implants are properly aligned and correctly sized; however, understanding the effect of alignment and rotation on the biomechanics of the knee during functional activities is limited. Cardiff University has unique access to a group of local patients who have relatively high frequency of poor alignment, and early failure. This provides a rare insight into how malalignment of TKR's can affect patients from a clinical and biomechanical point of view to determine how to best align a TKR. This study aims to explore relationship clinical surgical measurements of Implant alignment with in-vivo joint kinematics.

28 patient volunteers (with 32 Kinemax (Stryker) TKR's were recruited. Patients undertook single plane video fluoroscopy of the knee during a step-up and step-down task to determine TKR in-vivo kinematics and centre of rotation (COR). Joint Track image registration software (University of Florida, USA) was used to match CAD models of the implant to the x-ray images. Hip-Knee-Ankle (HKA) was measured using long-leg radiographs to determine frontal plane alignment.

Posterior tibial slope angle was calculated using radiographs. An independent sample t-test was used to explore differences between neutral (HKA:-2° to 2°), varus (≥2°) and valgus alignment (≤-2°) groups. Other measures were explored across the whole cohort using Pearson's correlations (SPSS V23).

There was found to be no statistical difference between groups or correlations for HKA. The exploratory analysis found that tibial slope correlated with Superior/Inferior translation ROM during step up (r=−0.601, p<0.001) and step down (r=−.512, p=0.03) the position of the COR heading towards the lateral (r=−.479, p=0.006) during step down.

Initial results suggest no relationship between frontal plane alignment and in-vivo. Exploratory analyses have found other relationships that are worthy of further research and may be important in optimizing function.

Whilst home-based exercise rehabilitation plays a key role in determining patient outcomes following orthopaedic intervention (e.g. total knee replacement), it is very challenging for clinicians to objectively monitor patient progress, attribute functional improvement (or lack of) to adherence/non-adherence and ultimately prescribe personalised interventions. This research aimed to identify whether 4 knee rehabilitation exercises could be objectively distinguished from each other using lower body inertial measurement units (IMUs) and principle components analysis (PCA) in the hope to facilitate objective home monitoring of exercise rehabilitation.

5 healthy participants performed 4 repetitions of 4 exercises (knee flexion in sitting, knee extension, single leg step down and sit to stand) whilst wearing lower body IMU sensors (Xsens, Holland; sampling at 60 Hz). Anthropometric measurements and a static calibration were combined to create the biomechanical model, with 3D hip, knee and ankle angles computed using the Euler sequence ZXY. PCA was performed on time normalised (101 points) 3D joint angle data which reduced all joint angle waveforms into new uncorrelated PCs via an orthogonal transformation. Scatterplots of PC1 versus PC2 were used to visually inspect for clustering between the PC values for the 4 exercises. A one-way ANOVA was performed on the first 3 PC values for the 9 variables under analysis. Games-Howell post hoc tests identified variables that were significantly different between exercises.

All exercises were clearly distinguishable using the PC scatterplot representing hip flexion-extension waveforms. ANOVA results revealed that PC1 for the knee flexion angle waveform was the only PC value statistically different across all exercises.

Findings demonstrate clear potential to objectively distinguish between different knee rehabilitation exercises using IMU sensors and PCA. Flexion-extension angles at the hip and knee appear most suited for accurate separation, which will be further investigated on patient data and additional exercises.

Electronic PROMs have many potential uses in orthopaedic practice. The primary objective of this three-phase pilot study was to measure uptake using a web-based ePROM system following the introduction of two separate process improvements.

80 consecutive new elective orthopaedic patients in a single surgeon's practice were recruited. Group 1 (n=26) received a reminder letter, Group 2 (n=31) also received a SMS message via mobile or home telephone and Group 3 (n=23) also had access to Tablet Computer in clinic.

Overall 79% of patients had Internet access. 35% of Group 1, 55% of Group 2 and 74% of Group 3 recorded an ePROM score (p=0.02). There was no significant age difference between groups. In Group 3, 94% of patients listed for an operation completed an ePROM score (p=0.006).

Collecting PROM data effectively in everyday clinical practice is challenging. Electronic collection should improve healthcare delivery, but is in its infancy. This pilot study shows that the combination of SMS reminder and access to Tablet Computer within clinic setting enabled 94% of patients listed for an operation to complete a score on a clinical outcomes web-based system. Further process improvements, such as additional staff training and telephone call reminders, may further improve uptake.

Introduction:

Periprosthetic infections that accompany the use of total joint replacement devices cause unwanted and catastrophic outcomes for patients and clinicians. These infections become particularly problematic in the event that bacterial biofilms form on an implant surface. Previous reports have suggested that the addition of Vitamin E to ultra-high-molecular-weight polyethylene (UHMWPE) may prevent the adhesion of bacteria to its surface and thus reduce the risk of biofilm formation and subsequent infection.^1–3 In this study, Vitamin E was blended with two types of UHMWPE material. It was hypothesized that the Vitamin E blended UHMWPE would resist the adhesion and formation of clinically relevant methicillin-resistant Staphylococcus aureus (MRSA) biofilms.

Treatment of trochanteric fractures is associated a high complication rate. This prospective multicenter study evaluates the new Zimmer Cephalomedullary Nail (CMN).

Patients over 50 years sustaining a pertrochanteric or subtrochanteric femoral fracture were prospectively enrolled and patients with multiple injuries, pathological fractures or severe dementia were excluded.

101 patients (70% female, 30% male) from 5 different hospitals were prospectively recruited between January 2011 and August 2012. Mean age was 78 (51–98) years and mean Charlson Score was 2.6 (1–6). 65% of the trochanteric fractures were unstable, 35% were stable. There were 4 (5%) minor (3 superficial infections and 1 pain over distal locking screw) and 3 (4%) major (2 lag screw cut out, 1 nail breakage) complications Fracture healing was completed in 27 of 31 patients (87%) after 12 month (3 month: 14/42 (33%); 6 month: 27/39(69%)). The Barthel Index (85, SD 19) and EQ-5-D (0.61, SD 0.30) values reached prefracture level after 6 month.

The study population and fracture type were comparable to other studies and complication and early union rates were also comparable. Technical complications were low and early functional results encouraging. Final results of this trial at one year follow up are awaited.

Introduction

Osteoporotic vertebral fractures can cause severe vertebral wedging and kyphotic deformity. This study tested the hypothesis that kyphoplasty restores vertebral height, shape and mechanical function to a greater extent than vertebroplasty following severe wedge fractures.

Objectives

This study examines variations in knee arthroplasty patient reported outcome measures according to patient age.

Introduction

Vertebroplasty helps to restore mechanical function to a fractured vertebra. We investigated how the distribution of injected cement benefits both fractured and neighbouring vertebrae.

Aims

The BOA/BAPRAS guidelines for the management of open tibial fractures (2009) recommend early senior combined orthoplastics input and appropriate facilities to manage a high caseload. St Georges Hospital is one of four London Trauma Centres fulfilling these criteria. Our aim is to determine whether becoming a trauma centre has affected the management of patients with open tibial fractures.

Background

Fracture of an osteoporotic vertebral body reduces vertebral stiffness and decompresses the nucleus in the adjacent intervertebral disc. This leads to high compressive stresses acting on the annulus and neural arch. Altered load-sharing at the fractured level may influence loading of neighbouring vertebrae, increasing the risk of a fracture ‘cascade’. Vertebroplasty has been shown to normalise load-bearing by fractured vertebrae but it may increase the risk of adjacent level fracture. The aim of this study was to determine the effects of fracture and subsequent vertebroplasty on the loading of neighbouring (non-augmented) vertebrae.

Introduction

Vertebral osteoporotic fracture increases both elastic and time-dependent ('creep') deformations of the fractured vertebral body during subsequent loading. The accelerated rate of creep deformation is especially marked in central and anterior regions of the vertebral body where bone mineral density is lowest. In life, subsequent loading of damaged vertebrae may cause anterior wedging of the vertebral body which could contribute to the development of kyphotic deformity. The aim of this study was to determine whether gradual creep deformations of damaged vertebrae can be reduced by vertebroplasty.

Purpose

To examine the clinical characteristics of patients undergoing knee arthroplasty with a pre-operative Oxford Knee Score >34 (‘good’/‘excellent’), and assess the appropriateness of surgical intervention for this group.

Periarticular metastasis may be treated with endoprosthetic reconstruction. The extensive surgery required may not, however, be appropriate for all patients. Our aim was to establish if the outcome of locking plate fixation in selected patients with periarticular metastases.

Prospective data collection was performed. Twenty one patients underwent surgery for periarticular metastatic tumours. The median duration of follow-up for surviving patients was one year. There have been no cases of implant failure and no requirement for revision surgery. Pain relief was excellent or good in the majority of patients. Patients who had sustained a fracture prior to fixation had restoration of their WHO performance status. All patients had a dramatic improvement in their MSTS scores. The median pre-operative score was 15% (0%-37%) improving to a median score of 80% (75% -96%) post operatively.

Locking plates provide reliable fixation and excellent functional restoration in selected patients suffering from periarticular metastatic bone disease.

Favourable long-term results have been reported with the standard Exeter cemented stem. We report our experience with a version for use in smaller femora, the Exeter 35.5 mm stem. Although, also a collarless polished taper, the stem is slimmer and 25 mm shorter than a standard stem.

Between August 1988 and August 2003, 192 primary hip arthroplasties were performed in 165 patients using the Exeter 35.5 mm stem. Clinical and operative data were collected prospectively. Clinical evaluation was by the Charnley, Harris and Oxford hip scores and radiographs were analysed post-operatively and at latest follow up.

The mean age at time of operation was 53 years (18 to 86), with 73 patients under the age of 50 years. The diagnosis was osteoarthritis in 91, hip dysplasia in 77, inflammatory arthritis in 18, septic arthritis of the hip in three, secondary to Perthes disease in two and avascular necrosis of the hip in one patient. The fate of every implant is known.

At a median follow-up of 8 years (5 to 19), survivorship with revision of the femoral stem for aseptic loosening as the endpoint was 100%. Fifteen cases (7.8%) underwent further surgery 11 for acetabular revision, one for stem fracture and three others.

Although, smaller than a standard Exeter Universal polished tapered cemented stem—with a shorter, slimmer taper—the performance of the Exeter 35.5 mm stem was equally good even in this young, diverse group of patients.

The cement in cement technique for revision total hip arthroplasty (THA) has shown good results in selected cases. However, results of its use in the revision of hemiarthroplasty to THA has not been previously reported.

Between May 1994 and May 2007 28 (20 Thompson's and 8 Exeter bipolar) hip hemiarthroplasties were revised to THA in 28 patients using the cement in cement technique. All had an Exeter stem inserted at the time of revision. Clinical and operative data were collected prospectively. Clinical evaluation was by the Charnley, Harris and Oxford. Hip scores and radiographs were analysed post-operatively and at latest follow up.

The mean age at time of hemiarthroplasty revision was 80 (35 to 93) years. The reason for revision was acetabular erosion in 12 (43%), recurrent dislocation in eight (29%), aseptic stem loosening in four (14%), periprosthetic fracture in two (7%) and infection in a further two (7%) patients. No patient has been lost to follow up. Three patients died within three months of surgery. The mean follow up of the remainder was 50 (16 to 119) months. Survivorship with revision of the femoral stem for aseptic loosening as the endpoint was 100%. Three cases (11%) have since undergone further revision, one for recurrent dislocation, one for infection, and one for periprosthetic fracture.

The cement in cement technique can be successfully applied to revision of hip hemiarthroplasty to THA. It has a number of advantages in this elderly population including minimising bone loss, blood loss and operative time.

CT guided percutaneous radiofrequency thermocoagulation is the treatment of choice for osteoid osteomas. Good results with a low complication rate have been shown for spinal lesions. When lesions are within close proximity to neurological structures or if patients have radicular symptoms surgery rather than radiofrequency ablation has been advocated. We present our experience of radiofrequency ablation of spinal osteoid osteomas which are less than 5mm from neurological structures, including those causing radicular symptoms.

Data was collected prospectively on all patients with a spinal osteoid osteoma within 5mm of nerve roots or the spinal cord as measured on CT scanning.

There were nine patients, five female and four male with a mean age of 15 years. Four tumours were located in the thoracic spine, three in the lumbar spine and two in the cervical spine. The mean distance to the nearest neurological structure was 3mm. Radicular symptoms were present in two patients. The mean number of probe positions used was two. Lesions were heated to 90 degrees for 5 minutes for each probe position. There were two cases of recurrence, both treated successfully with one further procedure each. There were no cases of neurological injury. The two patients with radicular symptoms had full resolution of their symptoms. At a mean follow up of 2 years following treatment all patients are asymptomatic.

Radiofrequency ablation can be safely performed to treat osteoid osteomas located within 5mm of neurological structures and has a low rate of recurrence.

To investigate whether restoration of mechanical function and spinal load-sharing following vertebroplasty depends upon cement distribution.

Fifteen pairs of cadaver motion segments (51-91 yr) were loaded to induce fracture. One from each pair underwent vertebroplasty with PMMA, the other with a resin (Cortoss). Various mechanical parameters were measured before and after vertebroplasty. Micro-CT was used to determine volumetric cement fill, and plane radiographs (sagittal, frontal, and axial) to determine areal fill, for the whole vertebral body and for several specific regions. Correlations between volumetric fill and areal fill for the whole vertebral body, and between regional volumetric fill and changes in mechanical parameters following vertebroplasty, were assessed using linear regression.

For Cortoss, areal and volumetric fills were significantly correlated (R=0.58-0.84) but cement distribution had no significant effect on any mechanical parameters following vertebroplasty. For PMMA, areal fills showed no correlation with volumetric fill, suggesting a non-uniform distribution of cement that influenced mechanical outcome. Increased filling of the vertebral body adjacent to the disc was associated with increased intradiscal pressure (R=0.56, p<0.05) in flexed posture, and reduced neural arch load bearing (F_N) in extended posture (R=0.76, p<0.01). Increased filling of the anterior vertebral body was associated with increased bending stiffness (R=0.55, p<0.05).

Cortoss tends to spread evenly within the vertebral body, and its distribution has little influence on the mechanical outcome of vertebroplasty. PMMA spreads less evenly, and its mechanical benefits are increased when cement is concentrated in the anterior vertebral body and adjacent to the intervertebral disc.

The time at which patients should drive following total hip replacement (THR) is dependant upon recovery and the advice they are given. The Driver Vehicle and Licensing Agency (DVLA) in the United Kingdom does not publish recommendations following THR and insurance companies usually rely on medical instruction. Few studies have been performed previously and have reached different conclusions.

Brake reaction times for patients undergoing primary THR were measured pre-operatively and at four, six and eight weeks after surgery using a vehicle driving simulator at a dedicated testing centre. Patients were prospectively recruited. Ethical approval was granted. Participants included eleven males and nine females, mean age 69 years. Side of surgery, frequency of driving and type of car (automatic or manual) were documented. Patients with postoperative complications were excluded. No adverse events occurred during the study.

Statistical analysis using Friedman's test demonstrated a statistically significant difference (P=0.015) in reaction times across the four time periods. Wilcoxon test demonstrated a highly significant difference between initial and six week mean results (P=0.003), and between four and six week results (P=0.001). No significant difference was found between six and eight weeks.

Our data suggests reaction times improve until week six and significantly between week four to six. Patients making an uncomplicated recovery following primary THR may be considered safe to return to driving from week six onwards. We recommend this is clearly documented in the medical notes, and patients should check with their insurance company prior to recommencement.

Knee dislocation is a rare injury in high energy trauma, but it is even rarer in low energy injuries. We present, to our knowledge, the only case in the world literature of knee dislocation following a cricketing injury. The patient was a 46 year old recreational fast bowler who, whilst bowling, slipped on the pitch on the follow through. He sustained an anteromedial knee dislocation which was reduced under intravenous sedation. He also sustained a neuropraxia of the common peroneal nerve with grade 2 weakness of ankle and toe dorsiflexion. Magnetic Resonance Imaging (MRI) confirmed a complete rupture of anterior cruciate ligament (ACL), lateral collateral ligament (LCL) and postero-lateral corner (PLC). Patient underwent surgical reconstruction and repair of his PLC along with repair of LCL with combination of anchor sutures and metal staple within 72 hours of the injury. He was treated in a cast brace. The ACL insufficiency was treated conservatively. Patient made an uneventful recovery and follow up at 3 months revealed a full range of knee movements with asymptomatic ACL laxity

We aimed (1) to determine the factors which influence outcome after surgery for CES and (2) to study CES MRI measurements. 56 patients with evidence of a sphincteric disturbance who underwent urgent surgery (1994-2002) were identified and invited to clinic. 31 MRIs were available for analysis and randomised with 19 MRIs of patients undergoing discectomy for persistent radiculopathy. Observers estimated the percentage of spinal canal compromise and indicated whether they thought the scan findings could produce CES and whether the discs looked degenerate. Measurements were repeated after two weeks.

(1) 42 patients attended (mean follow up 60 months; range 25–114). Mean age at onset was 41 years (range 24–67). 26 patients were operated on within 48 hours of onset. Acute onset of sphincteric symptoms and the time to operation did not influence the outcomes. Leg weakness at onset persisted in a significant number at follow-up (p<0.005). Bowel disturbance at presentation was associated with sexual problems (<0.005) at follow-up. Urinary disturbance at presentation did not affect the outcomes. The 13 patients who failed their post-operative trial without catheter had worse outcomes. The SF36 scores at follow-up were reduced compared to age-matched norms in the population. The mean ODI was 29, LBOS 42 and VAS 4.5.

(2) No significant correlations were found between MRI canal compromise and clinical outcome. There was moderate to substantial agreement for intra- and inter-observer reproducibility.

Introduction

Osteoporotic fracture reduces vertebral stiffness, and alters spinal load-sharing. Vertebroplasty partially reverses these changes at the fractured level, but is suspected to increase deformations and stress at adjacent levels. We examined this possibility.

Introduction

Vertebral osteoporotic fracture increases both elastic and time-dependent (‘creep’) deformations of the fractured vertebral body during subsequent loading. This is especially marked in central and anterior regions of the vertebral body, and could explain the development of kyphotic deformity in life. We hypothesise that vertebroplasty can reduce these creep deformations.

Purpose: To determine how cement volume during vertebroplasty influences:

stress distributions on fractured and adjacent vertebral bodies,

Methods: Nineteen thoracolumbar motion segments from 13 cadavers (42–91 yrs) were loaded to induce fracture. Fractured vertebrae received two sequential injections (VP1 and VP2) of 3.5cm3 of polymethylmethacrylate cement. Before and after each injection, motion segment stiffness was measured in compression and in bending, and the distribution of compressive “stress” in the intervertebral disc was measured in flexed and extended postures. Stress profiles yielded the intradiscal pressure (IDP), stress peaks in the posterior (SPP) annulus, and the % of the applied compressive force resisted by the neural arch (FN). Cement leakage and vertebral body volume were quantified by water-immersion, and % cement fill was estimated.

Results: Bending and compressive stiffness fell by 37% and 50% respectively following fracture, and were restored only after VP2. Depending on posture, IDP fell by 59%–85% after fracture whereas SPP increased by 107%–362%. VP1 restored IDP and SPP to prefracture values, and VP2 produced no further changes. Fracture increased FN from 11% to 39% in flexion, and from 33% to 59% in extension. FN was restored towards pre-fracture values only after VP2. Cement leakage, IDP and compressive stiffness all increased with %fill.

Conclusions: 3.5cm3 of cement largely restored normal stress distributions to fractured and adjacent vertebral bodies, but 7cm3 were required to restore load-sharing between the vertebral bodies and neural arch. Risks of cement leakage increased with %fill.

Conflicts of Interest: None

Source of Funding: This work was funded by Action Medical Research and The Hospital Saving Association Charitable Trust. Vertebroplasty materials were provided by Stryker.

Purpose: Removal of all foreign material is the normal practice at the time of revision arthroplasty for sepsis. However, removal of well-fixed bone cement is time consuming, can result in significant bone stock loss and increases the risk of femoral shaft perforation or fracture. We have performed two-stage revision for infection in a series of cases in which we have left oseeointegrated femoral cement at the first stage and we present the results of this technique.

Method: All patients underwent two-stage revision for infection. At the first stage the prostheses and acetabu-lar cement were removed but when the femoral cement mantle demonstrated good osseo-integration it was left in-situ. Following Girdlestone excision arthroplasty (GEA), patients received local antibiotics delivered by cement spacers, as well as systemic antibiotics. At the second stage the existing cement mantle was reamed, washed and dried and then a femoral component was cemented into the old mantle.

Results: Sixteen patients (M:F 5:11) had at least three years follow up (mean 80 months, range 43 to 91). One patient died of an unrelated cause at 53 months. Recurrence of infection was not suspected in this case. The mean time to first stage revision was 57 months (3 to 155). The mean time between first and second stages was 9 months (1 to 35). Organisms were identified in 14 (87.5%) cases (5 Staphylococcus Aureas, 4 Group B Streptococcus, 2 Coagulase negative Staphylococcus, 2 Enterococcus Faecalis, 1 Escheria Coli). At second stage, five (31.2%) acetabuli were uncemented and 11 (68.8%) were cemented. There were two complications; one patient dislocated 41 days post-operatively and a second patient required an acetabular revision at 44 days for sudden loss of fixation. No evidence of infection was found at re-revision. One patient has been revised for recurrent infection. Currently no patients are suspected of having a recurrence of infection.

Conclusion: Retention of a well-fixed femoral cement mantle during two-stage revision for infection and subsequent in-cement reconstruction is safe with a cure rate of 93%. Advantages include a shorter operating time, reduced loss of bone stock, improved component fixation and a technically easier second stage procedure.

The cement in cement technique for revision total hip arthroplasty (THA) has shown good results in selected cases. However results of its use in the revision of hemiarthroplasty to THA has not been previously reported.

Between May 1994 and May 2007 28 (20 Thompson’s and 8 Exeter bipolar) hip hemiarthroplasties were revised to THA in 28 patients using the cement in cement technique. All had an Exeter stem inserted at the time of revision. Clinical and operative data were collected prospectively. Clinical evaluation was by the Charnley, Harris and Oxford hip scores and radiographs were analysed post-operatively and at latest follow up.

Survivorship of the standard Exeter Universal cemented stem with revision of the femoral component for aseptic loosening as the endpoint has been reported as 100% at 12 years. A version for use in smaller femora, the Exeter 35.5 mm stem, was introduced in 1988. Although also a collarless polished taper, the stem is slimmer and 25 mm shorter than a standard stem.

Between August 1988 and August 2003 192 primary hip arthroplasties were performed in 165 patients using the Exeter 35.5 mm stem. Clinical and operative data were collected prospectively. Clinical evaluation was by the Charnley, Harris and Oxford hip scores and radiographs were analysed post-operatively and at latest follow up.

The time at which patients should drive following total hip replacement (THR) is dependant upon recovery and the advice they are given. The Driver Vehicle and Licensing Agency (DVLA) do not publish recommendations following THR and insurance companies usually rely on medical instruction.

Brake reaction times for patients undergoing THR were measured before and four, six and eight weeks after surgery using a vehicle-driving simulator. Patients were prospectively recruited. Ethical approval was granted.

Participants included eleven males and nine females, mean age 69 years. Side of surgery, frequency of driving and type of car (automatic or manual) were documented. Patients with postoperative complications were excluded. No adverse events occurred during the study.

Statistical analysis using Friedman’s test demonstrated a statistically significant difference (P=0.015) in reaction times across the four time periods. Wilcoxon test demonstrated a highly significant difference between initial and six week mean results (P=0.003), and between four and six week results (P=0.001). No significant difference was found between six and eight weeks.

Our data suggests reaction times improve until week six and significantly between week four to six. Patients making an uncomplicated recovery should be considered safe to drive by week six.

Purpose: The aim of this research was to characterize the correlation of magnetic resonance image (MRI) measurements of femoral anteversion and tibial torsion with transverse plane kinematics from the gait analysis of ten healthy and nine cerebral palsy (CP) children.

Methods: The bone morphologies of nine spastic diplegic CP and ten healthy children were obtained by analysis of 3D MRIs. Location of anatomical landmarks along the femur and tibia were detected using medical imaging software. Each point was then defined with respect to bone-embedded femoral and tibial Cartesian coordinates, allowing 3D reorientation of the bone independent of the patient position within the scanner. Femoral anteversion was defined as the angle between the femoral neck and the transcondylar plane. Tibial torsion was defined as the angle between the transcondylar axis of the proximal tibia and the bi-malleolar axis.

Three-dimensional motion of the lower limbs was measured using gait analysis. Transverse plane kinematics, including hip rotation and foot progression angles were recorded.

Results: A moderate correlation was found between femoral anteversion, and maximum and average hip rotation in CP children (0.64 and 0.65). A high correlation was also seen between tibial torsion and maximum and average values of hip rotation for CP children (0.71 and 0.74). In healthy children, the only correlation observed was between femoral anteversion and average foot progression in stance (0.75).

Discussion: In healthy children, femoral anteversion appears to influence foot progression angle, implying that this can lead to an internally rotated gait. In CP children, the correlation between femoral anteversion and hip rotation is only moderate. The interaction between different joints is more complex and the rotation of joints is determined by multiple factors. This study showed that tibial torsion also plays a role in determining hip rotation during gait.

Purpose: Medical research has classically been based on the male model, this is no different in the design of arthroplasty implants. Focus has recently shifted to gender-specific implant design but evidence is just developing in the literature as to gender specific outcomes. We hypothesised that outcomes in arthroplasty patients are affected by gender.

Methods: Patients were retrospectively identified from a prospectively collected database of total joint arthroplasties performed at one center. Six surgeons performed 1123 primary unilateral cemented TKA’s, and 989 primary unilateral cementless THA’s over a period of seven years. General demographic data was collected along with preoperative and 1-year clinical outcomes including the Harris Hip/Knee Society Score and Oxford Hip/Knee scores. These were compared to determine differences, if any, between males and females using independent samples t-test.

Results: The TKA sample was comprised of 540 (55%) females and 449 (45%) males. The THA sample included 744 (66%) females and 379 (34%) males.

In the TKA group, females were significantly younger, had higher BMI and had differing rates of comorbidities and complications. Female KSS, Oxford and ROM outcomes were significantly inferior to male scores preoperatively and at 1 year follow up. Significantly more females reported higher pain scores than males from pre-op to 1 year. Interestingly, females showed significantly more improvement from pre-op to 1 year in both scores.

In the THR group there were varying rates of complications and comorbidities by gender. Females did significantly worse in the HHS and Oxford hip score from pre-op until one year when results equalized. Similarly pain scores were higher for females preop and at 6 weeks but became equivalent thereafter. Females showed significantly greater improvements from pre-op to 1 year in both outcome scores.

Conclusion: As reported in the literature, results of this study indicate that women choose TJR at a later stage of disease than men do, presenting with inferior functional status. The effect of waiting seems most marked in the knee arthroplasty population with inferior outcomes and pain relief persisting out to 1 year. Surgeons must counsel females differently about expectations and recovery in joint arthroplasty.

Introduction: Vertebroplasty increases stiffness and partly restores normal load-sharing in the human spine following vertebral fracture. The present study investigated whether the mechanical effects of vertebroplasty are influenced by the distribution of injected cement.

Methods: Ten pairs of cadaver motion segments (58–88 yr) were loaded to induce fracture, after which one from each pair underwent vertebroplasty with polymethyl-methacrylate cement, the other with a resin (Cortoss). Various mechanical parameters were measured before fracture, after fracture and following subsequent vertebroplasty. Micro-computed tomography scans and plane radiographs (sagittal, frontal, and axial) obtained from each augmented vertebral body were analysed to determine percentage cement fill in the whole vertebral body and in selected regions. The relationship between volumetric fill obtained by micro-CT and areal fill obtained by radiography was investigated using linear regression analysis. Regression analysis also indicated whether changes in mechanical parameters following vertebroplasty were dependent upon cement distribution.

Results: Cement type had no significant influence upon regional fill patterns, so data from both cements were pooled for all subsequent analyses. Volumetric fill of the whole vertebral body was predicted best by areal fill in the sagittal plane (R2=0.366, P=0.0047). Restoration of intradiscal pressure and compressive stiffness following vertebroplasty were dependent upon volumetric cement fill both in the whole vertebral body (R2=0.304, P=0.0118 and R2=0.197, P=0.0499 respectively), and in the anterior half (R2=0.293, P=0.0137 and R2=0.358, P=0.0053).

Conclusion: Cement fill patterns can best be assessed radiographically from sagittal plane views. Placement of cement in the anterior vertebral body may help to improve mechanical outcome following vertebroplasty.

Total hip arthroplasty (THA) allows patients to return to an active lifestyle. Unfortunately one of the more common complications of cementless THA is a fracture of the greater trochanter (GT) or the calcar. These may compromise the outcomes of THA, but there are no large studies looking into this hypothesis.

Between September 1998 and August 2005 the Hamilton Arthroplasty group performed 2282 THA operations. Demographic and outcome data on these patients was collected and tabulated in a prospective database. Radiographs were available on a picture archiving system for 1075 of the patients, 85% of which were primary THAs. GT and calcar fractures were identified. Statistical comparisons on the normal distributed outcome data were made using the Student’s T-test comparing repaired and missed fractures.

A total of 60 GT fractures were found in the review of 1075 radiographs, giving an incidence of 5.6%. This included 19 isolated GT fractures and 10 GT fractures with associated calcar fractures that were found in primary hip arthroplasties, 48% of the total. Revision hip surgeries had 14 isolated GT fractures and 17 GT fractures with associated calcar fracture. We found that 23 (40%) of all GT fractures were missed intra-operatively and did not receive any fixation. All calcar fractures were noted and repaired, even if the associated GT fracture was not.

106 isolated calcar fractures were noted, 10% of all arthroplasties, only one of which did not receive fixation. Of this, 85 (80%) were from primary total hip arthroplasty and 21 (20%) from revision hip arthroplasty.

Evaluation of the outcome data showed no significant difference between repaired and missed GT fractures. Reported outcomes compared favourably with the average for all THA in that time period.

Adoption of cementless total hip arthroplasty in North America undoubtedly increases the rate of GT and calcar fractures. Most calcar fractures were noted and fixed but only 50% of GT fractures were discovered intraoperatively, an area of potential improvement. Greater trochanter and recognized calcar fractures may not have long-term detrimental effects.

Introduction: Unilateral posterior Pelvic Ring injuries but especially bilateral sacral fractures or bilateral sacroiliac joint (SI) ruptures as well as lumbosacral dislocations and fracture dislocations remains a significant surgical challenge.^1,2,3 despite advances in surgical techniques. Although the true incidence of these fractures are unknown, 30% are identified late.⁴

The treatment of those fractures varies from conservative treatment, posterior plate fixation, anterior plating as well as percutaneous and open Sacroiliac (SI) joint screws.

However, screw pull-outs and loss of fixation in those methods are well described In the Alfred Hospital, Melbourne (Australia) a Level 1 Trauma Center a series of 14 patients were treated from 10/2006 to date with a multiaxial spinal system.

Methods: Patients with posterior pelvic injuries separation were identified prospectively since October 2006. Data was extracted from the trauma registry database and medical record and diagnostic imaging. Since Ocober 2006, 10 patients with bilateral posterior pelvic ring injuries and 4 with unilateral injuries were identified for fixation.

Technique: The patients were put supine and a incision medial/distalto the posterior iliac spine was made. The placement for the incision gives the surgeon the opportunity to estend the approach to an open reduction of the sacral fracture or SI Joint disruption if a closed reduction cannot be achieved.

A pedicel screw from a multiaxial spinal system (Xia, Stryker or Pangea, Synthes) is placed percutaneously in the posterior iliac crest on both sides and the reduction is performed with the screws attached to the screw handles and with Image Intensifier.

After the reduction the multiaxial screwheads are bent and transfixed with a bar which is tunneled epifacial.

All patients underwent a multislice pelvic and lumbar spine CT and these patients were assessed clinically for neurovascular symptoms and stability. The follow-up included clinical assessment and CT imaging.

Results: Since October 2006 14 patients (10 male, 4 female) with an average age of 32.4 years (range: 20–44 years, median 33 years) and an average ISS (Injury Severity Score) of 37 (range: 14–66, median 34). The mechanism of injury for these patients included: pedestrians versus car; motorcylce; paragliding and motor car collision. All patients had associated anterior pelvic ring injuries which were internally fixed in all but one case.

The follow up time was one to 18 month. The patients were assessed clinically and with CT imaging. No complications or loss of fixation have been observed in this patient group in this short follow up time.

Discussion: The fixation system is highly versaitle and the whole posterior iliac crest can be used for fixation. The posterior instrumentation provides also a good control of the reduction of anterior pelvic ring fractures which should be fixed when associated. In all cases but 3 the nature of the comminuted sacral fractures did not allow the use of SI-Joint screws or anterior SI-Joint plating.

The construct provides initial stability and allows mobilization of the patient. It can be used in cases with sacral comminution and may offer advantages over posterior plate fixation, by reducing complications with prominent metalware.

Pelvic fractures in multi-trauma patients are an indicator of severe trauma and often require advanced wound management of pelvic, abdominal or extremity injuries. Poor wound management may result infected pelvic hardware, necessitating revision surgery. We propose that TNP is a safe method of wound management and report our experience.

In 2006 91 multi-trauma patients required pelvic/ace-tabular fixation at The Alfred, either internal or external. Of those, 23 needed TNP for wound care of pelvic, abdominal or extremity injuries. Indications for TNP included Morel-Lavelle lesions, concomitant bladder disruption with anterior wounds, severe edema preventing any wound closure, extremity open fractures/degloving/fasciotomies and post-op infections.

The average age of the group was 33, the average injury severity score was 36, 5 were female, 18 were male. There was one pelvic wound infection that resolved with TNP and local wound care. Two unsalvageable limbs (one transhumeral, one transfemoral) required amputation after TNP, all others were either closed primarily or with a flap and skin graft. There was one death in the group from unrelated causes. Pelvic scores, SF-12, visual analog pain scores and sexual dysfunction rates are being gathered and will be reported.

Topical negative pressure is a safe and effective method of managing complex wounds in multi-trauma patients with pelvic injuries.

Endoprosthetic replacement is often the preferred treatment for neoplastic lesions as internal fixation has been shown to have a high failure rate. Due to anatomical location, disease factors and patient factors internal fixation may be the treatment of choice. No reports exist in the literature regarding the use of locking plates in the management of neoplastic long bone lesions.

Data was collected prospectively on the first 10 patients who underwent locking plate fixation of neoplastic long bone lesions. Data was collected on the nature of the lesion, surgery performed, complications and outcome.

The patients mean age was 56.6 (15–88). Six lesions were metastatic, one haematological (myeloma) and 3 were primary bone lesions (lymphoma, Giant cell tumour, simple bone cyst). In nine cases a fracture through the lesion had occurred. Anatomical locations of the lesions were; proximal humerus (four), proximal tibia (three), distal femur (two) and distal tibia (one). Cement augmentation of significant bone defects was necessary in seven cases.

The mean hospital stay was 8 days (3–20). There were no inpatient complications. Five patients received adjuvant radiotherapy and one patient received neo-adjuvant radiotherapy to the lesion. There have been 3 deaths. All were due to metastatic disease and occurred between 6 and 12 months after surgery. The mean follow up in the surviving patients is currently 9 months (5–16). There have been no fixation related complications. Patients who had suffered a fracture had restoration of their WHO performance status. At last follow up the mean MSTS was 78% (57–90) for lower limb surgery and 70% (63–76) for upper limb surgery. These figures compare favourably with the results of endoprosthetic replacement.

The early results of locking plate fixation for neoplastic long bone lesions are excellent. Follow up continues to observe how these devices perform in the long term.

Purpose: To determine if administration of recombinant bFGF in an alginate gel would increase early healing mechanical parameters in acutely injured rat rotator cuff tendon at specific time points.

Method: Sprague Dawley rats were randomly divided into 2 groups and had surgically created 1mm (half tendon width) full thickness injuries at exactly 2mm from insertion site of Infraspinatus on the humerus. 200ng of bFGF or vehicle control was administered to randomly chosen rats. Tendons were harvested at 1 week, 2 weeks and 4 weeks. In both groups, the Infraspinatus tendon was dissected, and left attached to the humerus. At the time of testing, the intact portion of the injured tendon was divided sharply across tendon fibers at the level of the injury leaving only the healing tissue callus in continuity with the remaining proximal and distal portions of the tendon and loaded to failure.

Results: At 1 week the injury group’s average load to failure was 0.60N versus 0.61N in the bFGF injury group P = 1.000. At 2 weeks the injury group’s average load to failure increased to 1.03N versus 2.08N in the bFGF injury group P = 0.440 At 4 weeks the injury group’s average load to failure increased to 3.93N versus 5.56N in the bFGF injury group P = 0.008 representing a 41% increase in ultimate load. At 4 weeks, callus size of the injury group was 0.4mm2 versus 2.7mm2 in the bFGF injury group P < 0.001. Stiffness at 4 weeks for the injury tendons was 2.15 N/mm versus 3.54 N/mm in the bFGF group P = 0.008.

Conclusion: At 4 weeks healing tissue of acutely injured rotator cuff exposed to bFGF has an increase in ultimate load to failure (41% compared to control), increase in tendon callus size and stiffness. Our findings suggest a role of bFGF or similar growth factors in accelerating the healing of injured rotator cuff tendon.

Purpose: Medical research has classically been based on the male model, this is no different in the design of arthroplasty implants. Focus has recently shifted to gender-specific implant design but little evidence exists in the literature as to gender specific outcomes. We hypothesized that outcomes in arthroplasty patients are affected by gender.

Method: Patients were retrospectively identified from a prospectively collected database of total joint arthroplasties performed at one center. Six surgeons performed 1123 primary unilateral cemented TKA’s, and 989 primary unilateral cementless THA’s over a period of seven years. General demographic data was collected along with preoperative and 1-year clinical outcomes including the Knee Society (KSS)/Harris Hip Scores (HHS) and Oxford Knee/Hip scores. These were compared to determine differences, if any, between genders using independent samples t-test and chi-square test for proportions.

Results: The TKA sample was comprised of 540 (55%) females and 449 (45%) males. The THA sample included 744 (66%) females and 379 (34%) males. In the TKA group, females were significantly younger, had higher BMI and differing rates of comorbidities and complications. Female KSS, Oxford and flexion outcomes were significantly inferior to male scores pre-operatively and at 1-year follow-up. Significantly more females reported higher pain scores than males from pre-op to one year. Interestingly, females showed significantly more improvement from pre-op to one year in both scores. In the THR group there were varying rates of complications and comorbidities by gender. Females did significantly worse in the HHS and Oxford hip score from pre-op until one year when results equalized. Similarly pain scores were higher for females preop and at 6 weeks but became equivalent thereafter. Females showed significantly greater improvement from pre-op to 1 year for both outcome scores.

Conclusion: As reported in the literature, results of this study indicate that women choose arthroplasty at a later stage of disease than men do, presenting with inferior functional status. The effect of waiting seems most marked in the knee arthroplasty population with inferior outcomes and pain relief persisting out to one year. Surgeons must counsel females differently about expectations and recovery in joint arthroplasty.

Introduction: The aim of this cadaver study was to examine how cement volume used in vertebroplasty influences the restoration of normal load-sharing and stiffness to fractured vertebrae.

Methods: Nineteen thoracolumbar motion segments obtained from 13 spines (42–91 yrs) were compressed to failure in moderate flexion to induce vertebral fracture. Fractured vertebrae underwent two sequential vertebroplasty treatments (VP1 and VP2) each of which involved unipedicular injection of 3.5ml of polymethyl-methacrylate cement. During each injection, the volume of any cement leakage was recorded. At each stage of the experiment (pre-fracture, post-fracture, post-VP1 and post-VP2) measurements were made of motion segment stiffness, in bending and compression, and the distribution of compressive stress across the disc. The latter was measured in flexed and extended postures by pulling a pressure transducer through the mid-sagittal diameter of the disc whilst under 1.5kN load. Stress profiles indicated the intradiscal pressure (IDP), stress peaks in the posterior annulus (SPP), and neural arch compressive load-bearing (FN). Measurements obtained after VP1 and VP2 were compared with pre-fracture and post-fracture values using repeated measures ANOVA to examine the effect of cement volume (3.5 ml vs. 7 ml) on the restoration of mechanical function.

Results: Fracture reduced compressive and bending stiffness by 50% and 37% respectively (p< 0.001) and IDP by 59%–85%, depending on posture (p< 0.001). SPP increased from 0.53 to 2.46 MPa in flexion, and from 1.37 to 2.83 MPa in extension (p< 0.01). FN increased from 11% to 39% of the applied load in flexion, and from 33% to 59% in extension (p< 0.001). VP1 partially reversed the changes in IDP and SPP towards pre-fracture values but no further restoration of these parameters was found after VP2. Bending and compressive stiffness and FN showed no significant change after VP1, but were restored towards pre-fracture values by VP2. Cement leakage occurred in 3 specimens during VP1, and in 7 specimens during VP2. Leakage volumes ranged from 0.5–3.0 ml, and were larger during VP2 than VP1.

Conclusions: Unipedicular injection of 3.5 ml of cement reversed fractured induced changes in IDP and SPP, but did not affect stiffness and neural arch load-bearing. Larger injection volumes may provide some extra mechanical benefit in terms of restoring stiffness and reducing neural arch loading, but these extra mechanical benefits can be at the cost of increased risk of cement leakage.

Thinning of the femoral neck occurs in 77% of patients undergoing hybrid Birmingham hip resurfacing using a posterior approach (Shimmin 2007). Villar recently reported lower neck thinning rates in uncemented Cormet resurfacings (11.7%) compared with hybrid Birmingham resurfacing (13.4%), both via a posterior approach.

We have evaluated implant position and femoral neck thinning in a cohort of 273 uncemented HA coated Cormet 2000 hip resurfacings using ‘B’-series (Titanium/HA coated) cups in 269 patients (mean age 54 years, 39% female) with a mean follow-up of 3 years (range 1–4 years).

Mean cup inclination was 45° (30°–63°), mean SSA 138° (120°–178°). No lucent or sclerotic zones have been identified around the stem of the component. Only one femoral neck fracture has occurred (incidence 0.36%)

We have identified only one case of femoral neck thinning in our series (0.36%).

Whilst Villar has demonstrated a slight reduction in neck thinning rates using the same implants compared to a hybrid fixation Birmingham resurfacing, his neck thinning rates are almost 40 times higher than in our series. Shimmins ‘severe neck thinning (> 10%) rates (27%) are approximately 120 times higher than our series. In addition, we have been unable to confirm the relationship between implant position and neck thinning described by Shimmin in our series using the combined Ganz/uncemented resurfacings compared with Birmingham resurfacings.

Implant design and surgical approach have an impact on ‘neck thinning after resurfacing; we should be wary of treating all resurfacing implants and techniques as a uniform cohort.