Introduction

Flexor sheath infections require prompt diagnosis, and management with intravenous antibiotics and/or surgical washout followed by physiotherapy. Complication rates as high as 38% have been reported.

Aims

The purpose of this study was to assess the success rate and functional outcomes of bone grafting for periprosthetic bone cysts following total ankle arthroplasty (TAA). Additionally, we evaluated the rate of graft incorporation and identified associated predisposing factors using CT scan.

With an aging population and increase in total knee arthroplasty, periprosthetic distal femur fractures (PDFFs) have increased. The differences between these fractures and native distal femur fractures (NDFF) have not been comprehensively investigated. The purpose of this study was to compare the demographic, fracture, and treatment details of PDFFs compared to NDFFs.

A retrospective study of patients ≥ 18 years old who underwent surgical treatment for either a NDFF or a PDFF from 2010 to 2020 at a level 1 trauma center was performed. Demographics, AO/OTA fracture classification, quality of reduction, fixation constructs, and unplanned revision reoperation were compared between PDFF patients and NDFF patients using t-test and Fisher's exact test. 209 patients were identified with 70 patients having a PDFF and 139 patients having a NDFF. Of note, 48% of NDFF had a concomitant fracture of the ipsilateral knee (14%) or tibial plateau (15%). The most common AO/OTA classification for PDFFs was 33A3.3 (71%). NDFFs had two main AO/OTA classifications of 33C2.2 (28%) or 33A3.2. (25%). When controlling for patient age, bone quality, fracture classification, and fixation, the PDFF group had increased revision reoperation rate compared to NDFF (P < 0.05).

PDFFs tend to occur in elderly patients with low bone quality, have complete metaphyseal comminution, and be isolated; whereas, NDFF tend to occur in younger patients, have less metaphyseal comminution, and be associated with other fractures. When controlling for variables, PDFF are at increased risk of unplanned revision reoperation. Surgeons should be aware of these increased risks in PDFFs and future research should focus on these unique fracture characteristics to improve outcomes.

Determine the prevalence, etiologies, and risk factors of unplanned return to the OR (UROR) in adult orthopaedic trauma patients.

Retrospective review of a trauma prospective registry from 2014 – 2019 at a Level 1 academic hospital. An UROR was defined as a patient returning to OR unexpectedly following a planned definitive surgery to either readdress the presenting diagnosis or address a complication arising from the index procedure. Univariate and multivariate logistic regression was performed comparing those patients with an UROR versus those without.

A total of 1568 patients were reviewed. The rate of UROR was 9.8% (153 patients). Symptomatic implant was the leading cause of UROR (60%). Other significant UROR causes were infection (15%) and implant failure (9%). The median time between index procedure and UROR was 301 days.

For the univariate and multivariate analysis, open fracture (p< 0.05), fracture complexity (p<0.01), and weekend procedure (p< 0.01) were all associated with increased risk of UROR. All other variables were not statistically significant for any associations.

Those patients with an UROR for reasons other than symptomatic implants were more likely to have polyorthopaedic injuries (p < 0.05), ISS > 15 (p < 0.05), osteoporosis (p < 0.01), ICU status (p < 0.05), psychiatric history (p < 0.05), compartment syndrome (p < 0.05), neurovascular injury (p < 0.01), open fracture (p < 0.05), and fracture complexity (p < 0.05).

The rate of UROR in the orthopaedic trauma patient population is 10%. Most of these cases are due to implant-related issues. UROR for reasons other than symptomatic implants tend to be polytraumatized patients with higher-energy injuries, multiple complex fractures, and associated soft tissue injuries. Future focus on improved implant development and treatments for polytraumatized patients with complex fractures is warranted to decrease a relatively high UROR rate in orthopaedic trauma.

Aims

To test the hypothesis that reseeded anterior cruciate ligament (ACL)-derived cells have a better ability to survive and integrate into tendon extracellular matrix (ECM) and accelerate the ligamentization process, compared to adipose-derived mesenchymal stem cells (ADMSCs).

The use of routine sampling for histological analysis during revision hip replacement has been standard practice in our unit for many years. It is used to identify the presence of inflammatory processes that may represent peri-prosthetic infection.

This study follows up on a smaller study in the same unit in 2019 where an initial 152 cases were scrutinised. In this follow up study we examined 1,361 consecutive patients over a 16-year period whom had undergone revision hip replacement in a tertiary orthopaedic centre for any reason excluding primary bone tumour or malignant metastasis. All patients had tissue sampling for histopathological analysis performed by consultant histopathologists with a specialist interest in musculoskeletal pathology. The presence of bacteria in greater than 50% of samples sent for microbiological analysis in each patient was used as the gold standard diagnostic comparator for infection. This was then compared with the histology report for each patient.

After excluding 219 patients with incomplete data and 1 sample rejection, 1,141 cases were examined. Microbiology confirmed infection in 132 cases (prevalence of infection 11.04%) and histopathology analysis suggested infection in 171 cases. Only 64 cases with confirmed infection in more than 50% of microbiology samples had concurrent diagnosis of infection on histological analysis (5.60% of total; PPV 51.20%). Furthermore, microbiology analysis confirmed infection in 62 cases where histological analysis failed to identify infection (5.43% of total; False negative rate 49.21%). Overall, histopathology analysis was seen to have a good specificity of 93.99% but poor sensitivity of 50.79%.

We believe that this is the largest series in the literature and is somewhat unique in that all histology analysis was performed by consultant histopathologists with specialist interest in musculoskeletal pathology. Based on the costs incurred by this additional investigation our experience does not support routine sampling for histological analysis in revision hip arthroplasty. This is a substantial paradigm shift from current practice among revision arthroplasty surgeons in the United Kingdom but would equate to a substantial cost saving.

Aims

This study aimed to identify the tibial component and femoral component coronal angles (TCCAs and FCCAs), which concomitantly are associated with the best outcomes and survivorship in a cohort of fixed-bearing, cemented, medial unicompartmental knee arthroplasties (UKAs). We also investigated the potential two-way interactions between the TCCA and FCCA.

Purpose

Management and outcomes of fungal periprosthetic joint infection (PJI) remain unclear due to its rarity. Although two-stage exchange arthroplasty is considered a treatment of choice for its chronic features, there is no consensus for local use of antifungal agent at the 1st stage surgery. The purpose of this study was to evaluate the efficacy of antifungal-impregnated cement spacer in two-stage exchange arthroplasty against chronic fungal PJIs after total knee arthroplasty (TKA).

Introduction

The use of open wedge high tibial osteotomy (OWHTO) to reduce knee pain by transferring weight-bearing loads to the relatively unaffected lateral compartment in varus knees and to delay the need for a knee replacement by slowing or stopping destruction of the medial joint compartment. To maintain the stability of OWHTO, the most common type of plate was T-Plate as the locking compression plate (LCP) concept. Anterior portion of T-Plate infringe patient's soft tissue resulted in some complications, whereas anatomical L-plate does not. To evaluate the structural stability of the anatomically contoured L-plate in the present study, the effect of weight bearing after osteotomy should be reviewed in the point of the stress of the plate and screws. We hypothesize that its stress path diverge through collateral portion of tibia and the stress level in screws lowered comparing to the result of T-plate presented in existing literature.

Background

Open-wedge high tibial osteotomy (OWHTO) is an operation involving proper load re-distribution in the treatment for medial uni-compartmental arthritis of the knee joint. Therefore, stable fixation is mandatory for safe healing of this additive type of osteotomy to minimize the risk of non-union and loss of correction. For stability, screws provide optimal support and anchorage of the fixator in the condylar area without risking penetration of either the articulating surface. The purpose of the study was to evaluate the screw insertion angle and orientation with an anatomical plate that is post-contoured to the surface geometry of the proximal tibia after OWHTO.

Introduction

The Rotational alignment is an important factor for survival total knee Arthroplasty. Rotational malalignment causes knee pain, global instability, and wear of the polyethylene inlay. Also, the anterior cortex line was reported that more reliable and more easily identifiable landmark for correct tibial component alignment. The aims of the current study is to identify effect of inserting the tibial baseplate of using anterior cortex line landmark of TKA on stress/strain distributions within cortical bone and bone cement. Through the current study, final aim is to suggest an alternative position of tibia baseplate for reduction of TKA failures with surgical convenience.

Background

Rotational alignment is important for the long-term success and good functional outcome of total knee arthroplasty (TKA). While the surgical transepicondylar axis (sTEA) is the generally accepted landmark on the distal femur, a precise and easily identifiable anatomical landmark on the tibia has yet to be established. Our aim was to compare five axes on the proximal tibia in normal and osteoarthritic (OA) knees to determine the best landmark for determining rotational alignment during TKA.

Buechel and Pappas invented a modified version of LCS RP system (Co-Cr) with light material (Titanium), axial rotation limiting bar and improved conformity. The purpose of this prospective randomized study was to compare the minimum 3-year clinical outcomes including lightness, preference, and instability between the Co-Cr implant system and the Titanium implant system in bilateral total knee arthroplasty.

We prospectively enrolled 108 patients and 20 patients were lost to follow-up. Therefore, 88 patients (176 knees; mean age, 69.9±6.0years) were included in the study. The range of motion and clinical scores such as Knee Society score (KSS), Hospital for Special Surgery score (HSS) and Western Ontario and McMaster University (WOMAC) scores were measured preoperatively and postoperatively. At each follow-up, patients also complete a Likert scale questionnaire regarding subjective pain, lightness, left-right side preference (naturalness and satisfaction) and subjective instability.

There were no significant differences in all preoperative variables between two groups (p>.05). Mean follow-up period was 46.3±8.8 (36 to 72) months. The mean weight of Titanium implants was three times lighter than that of Co-Cr implants (133.9g versus 390.1g, p<.01). At the minimum of 3-year follow-up, there were no significant differences in pain, range of motion (ROM), clinical scores including KSS, HSS, and WOMAC between both groups. Also, the study showed no significant differences with subjective pain, lightness, preference (convenience, naturalness, and satisfaction), and subjective instability between the Co-Cr protheses and the Titanium protheses (p>.05).

No differences in clinical outcomes as well as subjective side-to-side differences between the Co-Cr prostheses and the Titanium prostheses were observed in the minimum 3-year follow-up. This implies that patients do not feel differently with two different weighted implants in mid-term follow-up.

Introduction

Revision total knee arthroplasy (TKA) has been often used with a metal block augmentation for patients with poor bone quality. However, bone resorption beneath metal block augmentation has been still reported and little information about the reasons of the occurrence of bone resorption is available. The aim of the current study is to identify a possibility of the potential occurrence of bone resorption beneath metal block augmentation, through evaluation of strain distribution beneath metal block augmentation in revision TKA with metal block augmentation, during high deep flexion.

Introduction

Open wedge high tibial osteotomy (OWHTO) is an operation by the proper load re-distribution in the treatment for medial uni-compartmental arthritis of the knee joint. However, for the proper load re-distribution, stable fixation is mandatory. For the stable fixation, plate should be contoured to the bony surface and screws should be inserted from the central area of the medial side to the hinge area of the lateral side in the proximal fragment because most failures occur at the relatively lesser supported lateral hinge area. Therefore, the purpose of this study was to evaluate the screw insertion angle and orientation that is inserted to the direction of the lateral hinge with an anatomical plate that is post-contoured with a surface geometry of the proximal tibia after the OWHTO. The hypothesis of this study was that the position and orientation would be different according to the correction degree (median value 10 mm) and surgical technique (uni-planar vs bi-planar).

Introduction

Revision total knee arthroplasty (TKA) has been often used with a metal block augmentation for patients with poor bone quality. However, bone defects are frequently detected in revision TKA used with metal block augmentation. This study focused on identification of a potential possibility of the bone defect occurrence through the evaluation of the strain distribution on the cortical bone of the tibia implanted revision TKA with metal block augmentation, during high deep flexion.

We compared the clinical and radiographic results of total ankle replacement (TAR) performed in non-diabetic and diabetic patients. We identified 173 patients who underwent unilateral TAR between 2004 and 2011 with a minimum of two years’ follow-up. There were 88 male (50.9%) and 85 female (49.1%) patients with a mean age of 66 years (sd 7.9, 43 to 84). There were 43 diabetic patients, including 25 with controlled diabetes and 18 with uncontrolled diabetes, and 130 non-diabetic patients. The clinical data which were analysed included the Ankle Osteoarthritis Scale (AOS) and the American Orthopaedic Foot and Ankle Society (AOFAS) scores, as well the incidence of peri-operative complications.

The mean AOS and AOFAS scores were significantly better in the non-diabetic group (p = 0.018 and p = 0.038, respectively). In all, nine TARs (21%) in the diabetic group had clinical failure at a mean follow-up of five years (24 to 109), which was significantly higher than the rate of failure of 15 (11.6%) in the non-diabetic group (p = 0.004). The uncontrolled diabetic subgroup had a significantly poorer outcome than the non-diabetic group (p = 0.02), and a higher rate of delayed wound healing.

The incidence of early-onset osteolysis was higher in the diabetic group than in the non-diabetic group (p = 0.02). These results suggest that diabetes mellitus, especially with poor glycaemic control, negatively affects the short- to mid-term outcome after TAR.

Cite this article: Bone Joint J 2014;96-B:1674–80.

Purpose

To determine the effect of leg dominance on trunk muscle activity during bridging exercises on the floor and a gym ball.

To develop a useful surgical navigation system, accurate determination of bone coordinates and thorough understanding of the knee kinematics are important. In this study, we have verified our algorithm for determination of bone coordinates in a cadaver study using skeletal markers, and at the same time, we also attempted to obtain a better understanding of the knee kinematics.

The research was performed at the Medical Simulation Center of Tzu Chi University. Optical measurement system (Polaris® Vicra®, Northern Digital Inc.) was used, and reflective skeletal markers were placed over the iliac crest, femur shaft, and tibia shaft of the same limb. Two methods were used to determine the hip center; one is by circumduction of the femur, assuming it pivoted at the hip center. The other method was to partially expose the head of femur through anterior hip arthrotomy, and to calculate the centre of head from the surface coordinates obtained with a probe. The coordinate system of femur was established by direct probing the bony landmarks of distal femur through arthrotomy of knee joint, including the medial and lateral epicondyle, and the Whiteside line. The tibial axis was determined by the centre of tibia plateau localised via direct probing, and the centre of ankle joint calculated by the midpoint between bilateral malleoli. Repeated passive flexion and extension of knee joint was performed, and the mechanical axis as well as the rotation axis were calculated during knee motion.

A very small amount of motion was detected from the iliac crest, and all the data were adjusted at first. There was a discrepancy of about 16.7mm between the two methods in finding the hip centre, and the position found by the first method was located more proximally. When comparing the epicondylar axis to the rotation axis of the tibia around knee joint, there was a difference of 2.46 degrees. The total range of motion for the knee joint measured in this study was 0∼144 degrees. The mechanical axis was found changing in an exponential pattern from 0 degrees to undetermined at 90 degrees of flexion, and then returned to zero again. Taking the value of 5 degrees as an acceptable range of error, the calculated mechanical axis exceeded this value when knee flexion angle was between 60∼120 degrees.

The discrepancy between the hip centres calculated from the two methods suggested that the pivoting point of the femur head during hip motion might not be at the center of femur head, and the former location seemed closer to the surface of head at the weight bearing site. Under such circumstances, the mechanical axis obtained through circumduction of the thigh might be 1∼2 degrees different from that obtained through the actual center of femur head. During knee flexion, the mechanical axis also changed gradually, and this could be due to laxity of knee joint, or due to intrinsic valgus/varus alignment. However, the value became unreliable when the knee was at a flexion angle of 60∼120 degrees, and this should be taken into account during navigation surgery.

Clinical assessment of elbow deformity in children at present is mainly based on physical examination and plain X-ray images, which may be inaccurate if the elbow is not in fully supination; furthermore, the rotational deformity is even harder to be determined by such methods. Morrey suggested that the axis of rotation of the elbow joint can be simplified to a single axis. Based on such assumption, we are proposing a method to assess elbow deformity using rotational axis of the joint, and an optimized calculation algorithm is presented.

The rotation axis of elbow in respective to the upper arm can be obtained from the motion tract of markers placed at the forearm. Cadaver study was done, in which three skeletal motion trackers were placed over both the anterior aspect of humerus, as well as distal ulna. Osteotomy was created at the supracondylar region of humerus through lateral approach, and the bone fragments were stabilized with a set of external skeletal fixator, leaving the soft tissue intact. The amount of deformity was created manually by adjusting the position of the distal fragment via skeletal fixator. Ultrasound 3D motion tracking system from Zebris® was used in this study, and the program was developed under the Matlab environment. Cycles of passive elbow flexion/extension motion were carried out for each set of deformity. The data were initially transformed to humerus coordinate, and since the upper arm was not absolutely stationary, its influence on the measured position of ulna was adjusted. With this adjusted data, a best fit plane that would include most of the ulna positions (M_U) within a minimal distance was obtained. The rotation axis was calculated as the normal vector to this plane, and the carrying angle could subsequently be assessed according to the relationship between this axis and the x-axis on the xy-plane as well as on the xz-plane.

Fresh frozen cadaver study was conducted in the Medical Simulation Center at Tzu-Chi University. After adjustment of the raw data to eliminate the influence of humerus motion, the ulna motion could be narrowed down from a band of 10mm to 3mm, with a significant smaller standard deviation. The rotation axis was obtained by the normal vector to the best fit plane. Two different approaches were attempted to find the plane. In the first method, the plane was obtained via least square method from the adjusted ulna positions, and the second method found the plane via RANSAC method. Calculations were repeated several times for each method, and the results showed a variation of 5 degrees in the first method and about 2 degrees in the second method.

Rotational axis can be used to define the 3-dimensional deformity of elbow joint; however, it is difficult to obtain such axis accurately due to hypermobility and multi-directional motion of the shoulder joint. In this study, we have developed another method to assess the elbow deformity using motion analysis system instead of the conventional image studies, and this may be applicable clinically if the facility becomes more accessible in the future. (This research was supported by the project TCRD-TPE-99-30 granted by the Buddhist Tzu-Chi General Hospital, Taipei Branch).

To determine presenting features, treatment modalities and associated outcome following treatment of spinal dural arteriovenous fistulas in a tertiary centre.

Retrospective cohort study of patients with SDAVF assessed at a single tertiary referral centre, between 1999 and 2009. Medical records were used to identify intervention type, pre- and post-intervention Aminoff-Logue disability score (ALDS), recurrence rate, follow-up time and discharge status. Statistical analysis was performed using Wilcoxon signed rank.

26 patients were identified with 23 receiving intervention. Two were unavailable for follow up. Endovascular embolization was performed successfully in 13 patients, recurrence occurred in 6 of these, 3 of which were subsequently treated surgically. Surgery was the initial treatment for 10 patients due to either unsuccessful embolization attempt or proximity of the fistula to spinal artery feeders; only 1 of these recurred. ALDS-gait reduced (improved) by a mean of 0.33 points following intervention but this was not statistically significant (P=0.0645). There was negligible change in micturition and bowel ALDS. Improvement in ALDS was greater in patients treated with surgery first and also in patients whose fistula did not recur. Mean follow-up was 38 months with 56% of working age patients returning to work.

Both embolisation and surgery achieved the primary aim of reducing disease progression, leading to an improved ALDS. Outcome was superior if initially treated surgically and recurrence occurred more frequently in patients treated endovascularly. The small number of patients in our cohort emphasise the need for further studies into this group of patients.

It has been shown that a cognitive function (CF) loss can occur after hip or knee arthroplasty procedures, with an incidence of 40 to 70%. The pathogenesis remains unclear but studies suggest some form of brain emboli; although both trans-cranial doppler and trans-oesophageal doppler have both shown emboli per-operatively a correlation has never been shown with CF loss post-operatively. In contrast, in the cardiothoracic literature an embolic cause is widely accepted for detectable post-operative CF drop. The purpose of this study was to ascertain whether MRI could show evidence of embolic phenomena in patients undergoing hip or knee arthroplasty.

Twenty-five patients presenting for hip or knee arthroplasty procedures were consented for this study. Brain MRI scans and MR angiograms were performed 1 week pre-operatively and within 1 week post-operatively using a Phillips 1.5Tesla MRI unit. All scans recorded were independently reviewed by 2 radiologists. A series of tests to examine several modes of cognitive function were carried out by a clinical psychologist pre-operatively, and at 1 week post-operatively. The CF tests showed a clinically significant drop following surgery in 64% of cases – this is in keeping with other recently published data.

None of the post-operative scans or angiograms showed overt evidence of new lesions. Three Scans had equivocal tiny brainstem hypodensities on a single slice with no correlating abnormality on diffusion images to support the presence of new ischaemia.

We conclude that either the aetiology of post-operative CF drop following arthroplasty is not embolic in nature, or that with current technology MRI brain scans even with angiograms are not sensitive enough to show the corresponding abnormality. With currently available equipment there appears to be no benefit from using MRI as a tool to evaluate post-operative CF loss in this group of patients.

Hyaluronic acid (Hyalunan, HA), β-1,4-linked D-glucuronic acid and β-1,3 N-acetyl-D-glucosamine polysaccharide, is a nonsulfated glycosaminoglycan(GAG) conserved in the extracellular matrix (ECM). Due to its biocompatibility, biodegradable properties, HA is widely applied for tissue engineering. However, HA also has defects for tissue engineering such as mechanical properties, difficulty of handling. Thus, it is various modified by chemical reaction to produce HA derivative. HA plays an important role in tissue morphogenesis, proliferation and cell differentiation. Ascorbic acid (AA) has an effect on collagen synthesis and bone mineralization. Ascorbate levels also have a significant effect on osteoblast proliferation and alkaline phosphatase (ALP) expression. However AA is weak to heat and light, thus it is easily degradable. Consequently, we conjugated HA with AA in order to make it more stable and effective. In this study, we prepared HA-AA conjugate and evaluated activity of products in pre-osteoblast.

To produce more effective conjugation, we synthesised HA derivative, HA-N-hydroxysuccinimide, an activated ester of the glucuronic acid moiety. This HA-active ester intermediate is a precursor for drug-polymer conjugates. The degree of substitution was calculated by NMR analysis. The modified HA was dialysed and lyophilised. The yield of conjugation is calculated by Gel Permeation Chromatography (GPC). After the process, HA was conjugated with AA once again as previously mentioned. In this study, the resultant HA-AA conjugate was tested on MC3T3-E1, murine pre-osteoblast cells. We examined cellular viability (cytotoxicity), proliferation and gene expression. The expression of Type 1 collagen was examined by RT-PCR and western blot. Osteocalcin (OCN), osteopontin (OPN) and bone sialoprotein (BSP), bone proliferation and differentiation marker were detected by RT-PCR. Alkaline phosphatase assay was also performed. For confirmation on bone mineralization, alizarin red staining and von Kossa staining was performed.

In conclusion, the in vitro data demonstrate that HA-AA conjugate has an important role in bone formation, as it can increase proliferation and osteogenic differentiation of MC3T3-E1 cells. These observations further support the use of in vivo system for tissue engineering applications.

Constrained condylar knee (CCK) prosthesis offers an implant option for complex revision total knee arthroplasties in which stable varus-valgus constraint as well as rotational control is needed for severe bone defect and ligament insufficiency. The aim of this study was to evaluate the clinical and radiological outcome of CCK prosthesis in revision TKA.

Fify-one revision TKAs performed using CCK prosthesis between Jan. 1998 and Feb. 2006 were performed. The mean follow-up period was 5 years and 3 months (2 to 9 years) and the interval between initial and revision TKA was 8 years (4 months to 21 years). The mean age was 67 years. Range of motion (ROM), knee society (KS) score, hospital for special surgery (HSS) score, complication rate and failure rate was evaluated. The tibiofemoral angle and radiolucent line was also evaluated on plain radiograph.

The mean ROM improved from 81.9° to 102°. The mean KS score improved from 49.3° to 79.7°, and KS function score from 50.3 to 71.0 (P< .001). The mean HSS score improved from 50.7 to 78.7 (P< .001). Tibiofemoral angle improved from valgus 3.1° to valgus 5.6° (P< .001). Radiolucent line more than 2mm was observed around 4 femoral and 4 tibial components. Complications including 1 skin necrosis, 1 tibial tubercle nonunion, 2 infections, 3 periprosthetic fractures and 5 arthrofibrosis were observed. Overall rating was excellent or good in 88% at the last follow up.

Revision TKA using CCK prosthesis showed comparable results with other reports in average 5 years follow-up.

The aim of this study was to evaluate the rotational axis of the tibia and the association of its axis to tibial coronal alignment after TKR.

TKRs were performed using navigated mobile bearing system (40 knees), conventional mobile bearing (48 knees) and conventional fixed bearing (40 knees) and preoperative and postoperative CT scans were assessed using 3D image reconstruction-analysis program. The tibial AP axis which was defined as the line connecting the middle of the PCL and the medial edge of the patellar tendon attachment was measured relative to the AP axis of distal femur preoperatively and postoperatively, as well as the coronal angle of the tibia and posterior slope. The tibial coronal alignments in navigation, postoperative plain radiograph and CT were compared.

The AP axis of the tibia was in 2.10° internally rotated position relative to the AP axis of the femur preoperatively and 3.54° postoperatively (range, 19.5° internal rotation to 16.8° external rotation). The coronal angle of the tibia was 0.46° varus on plain radiograph, 0.72° varus on CT, 0.37° valgus in navigation (p=0.005). Posterior slope was 2.53° on plain radiograph and 0.67° in navigation (p< 0.001). There was no correlation between postoperative rotational position of the tibia relative to the femur and the difference in the tibial coronal angle between navigation data and CT.

The proposed anteroposterior axis of the tibia centered between 0 to 5 degrees internally rotated position relative to the femur but showed wide range of deviation. The rotation angle of the tibial cutting in navigated TKR did not influence on the postoperative measurement discrepancy between navigation and CT.

The aim of this study was to evaluate passive kinematics of a mobile-bearing, ultracongruent (UC) total knee design compared with a mobile-bearing, posterior stabilised (PS) design intraoperatively using navigation system.

Thirty-four knees of 24 patients which had undergone total knee arthroplasty with UC prosthesis (E-motion^®, Aesculap, Tuttlingen, Germany) for primary osteoarthritis and fifteen knees of 14 patients with PS prosthesis (E-motion^®) were included in this study. Thirty-one female and seven male patients were included and the mean age was 70.4 years. Patients were followed up for 7.26 months (6 to 12 months). Intraoperative kinematics including valgus/varus rotation, internal/external rotation, and anterior/posterior translation was assessed from 10° to 120° of passive flexion before and after total knee replacement using a surgical navigation system (Orthopilot^®, Aesculap). The range of motion (ROM) was measured preoperatively and at the final follow up.

The tibiofemoral alignment in 10° flexion changed from varus 5.85° to valgus 0.38° in UC group and changed from varus 7.45° to valgus 1.08° in PS group (p> 0.05), the magnitude of varus rotation during flexion was 0.01° in UC group and 4.08° in PS group (p< 0.05). PS knee showed the tendency to slight varus alignment during flexion but UC knee showed the tendency toward valgus alignment fter midflexion. The mean internal rotation during flexion was 10.3° in UC group and 13.2° in PS group (p> 0.05). The translation of the femur was 4.99mm posteriorly in UC group and 3.24mm posteriorly in PS group at 120° flexion (p> 0.05). The maximum flexion angle at the final follow up was 123° in UC group and 118° in PS group (p> 0.05). Total knee arthroplasty with high flexion PS prosthesis showed good ROM and satisfactory early clinical results.

UC total knee design showed less varus rotation during flexion, more valgus pattern in higher flexion angle than PS design, similar internal rotation angle and pattern, and similar posterior translation at 120° flexion with PS design.

Clinical experience has shown the needs for high flexion. The aim of this study was to evaluate the clinical and radiological results of a fixed bearing high flexion posterior stabilized (PS) total knee arthroplasty (TKA).

Between July 2001 and December 2005, 422 TKAs in 288 patients were performed with high flexion PS prosthesis and 378 knees of 258 patients had been followed up for 2 to 6.5 years (mean: 3 years 11 months). We evaluated range of motion (ROM), Knee rating system of the Hospital for Special Surgery (HSS) and Knee Society (KS) score, and radiological results.

The mean flexion improved from 110.1 degrees to 126.7 degrees at the latest follow-up. 333 knees (88 %) showed more than 120 degrees of flexion, 105 knees (28 %) more than 140 degrees of flexion. The mean KS clinical score improved from 39 to 93 points (p< 0.01) and KS function score, from 40 to 85.4 points (p< 0.01). The mean HSS score improved from 41.2 to 86.3 points (p< 0.01). In 28 knees, radiolucent line of 1–2 mm in width was observed at zone 1 without symptoms. Aseptic loosening in 4 knees, Mid-flexion instability in 2 knees, superficial infection in 3 knees and deep infection in 3 knees were observed.

Total knee arthroplasty with high flexion PS prosthesis showed good ROM and satisfactory early clinical results. Complication rate was similar to those of other series. Close observation and serial radiological evaluation are needed for long term results.

Background : A composite femoral stem was introduced with a structural stiffness similar to that of the native femur to promote proximal load transfer. This consisted of a cobalt-chromium alloy core surrounded by an injection-moulded layer of polyaryletherketone covered with a porous titanium mesh.

Material and Methods: 31 consecutive primary total hip replacement stems were implanted in 26 patients with an average age of 37 years (range 17–57) using the Epoch stem (Zimmer, Warsaw, IN) as part of a prospective multi-centre trial. A cementless Harris-Galante I acetabular component with a 28mm polyethylene insert (Zimmer) was used in 29 cases, a Plasmacup with 28mm polyethylene insert (Aesculap, Tuttlingen, Germany) in 1 case and a bipolar head in 1 case. Annual follow-up with Harris Hip Scores and radiographic evaluation was performed for a mean of 10.1 years.

Results : Harris Hip Scores improved from a mean of 52 points preoperatively to 90 at the time of last follow-up. Radiographs showed no stem migration or loosening. 4 cases with polyethylene wear showed trochanteric osteolysis. Specific radiographic features noted were a sclerotic halo in Gruen zones 1 in 8 cases, calcar rounding in 10 cases and improvement in calcar appearance with squaring of the calcar in 4 cases. Calcar resorption was seen in 1 case associated with polyethylene wear. There have been 8 instances of revision of the head or acetabular component- 3 liner exchanges for polyethylene wear, 3 acetabular component revisions for liner dissociation with associated cup damage, 1 acetabular component revision for infection and 1 bipolar head revised to unipolar head with cementless acetabular component for pain. No stem has required or requires revision.

Conclusion : The Epoch stem resulted in an excellent clinical outcome with evidence of radiographic stability and proximal bone preservation, and no cases of stem revision in a cohort of young patients with long-term follow-up.

Introduction: A composite femoral stem was introduced with a structural stiffness similar to that of the native femur to promote proximal load transfer. This consisted of a cobalt-chromium alloy core surrounded by an injection-moulded layer of polyaryletherketone covered with a porous titanium mesh.

Materials and Method : 31 primary total hip replacement stems were implanted in 26 patients with an average age of 37 years (range 17–57) using the Epoch Stem (Zimmer, Warsaw, IN) as part of a prospective multicentre trial. A cementless Harris-Galante I acetabular component with a 28mm polyethylene insert was used in 28 cases, a Plasma cup (Aesculap) in 1 case and a bipolar head in 2 cases. Annual follow-up using Harris Hip Scores and radiographic evaluation was performed for a mean of 10.1 years.

Results: Harris Hip Scores improved from a mean of 56 points preoperatively to 90 at the time of last follow-up. Radiographs showed no stem migration or loosening. 4 cases with polyethylene wear showed trochanteric osteolysis. Specific radiographic features noted were calcar rounding in 10 cases and improvement in calcar appearance with squaring in 4 cases. Calcar resorption was seen in 1 case associated with polyethylene wear. There have been 9 instances of revision of the head or acetabular component – 3 liner exchanges for polyethylene wear, 3 liner exchanges for dissociation, 1 acetabular component revision for infection and 2 bipolar heads revised to unipolar heads with cementless acetabular component for pain. No stem has required or requires revision.

Discussion: The Epoch stem resulted in an excellent clinical outcome, with evidence of radiographic stability and proximal bone preservation, and no cases of stem revision in a small cohort of young patients at 10-year follow-up. The limitation of reconstruction in this cohort of young patients has been the acetabular component.

Purpose: To establish and validate animal model for Achilles tendon disease with subsequent examination of histology, biochemistry and biomechanics

Methods: Experimental rats were subjected to an over-exercise running regime. Achilles tendons were analyzed for histology, glycosaminoglycan content, collagen content, collagen subtype, collagen cross-linking (hydrothermal isometric tension testing), and mechanical properties.

Results: Experimental rat Achilles tendons demonstrated: decreased semi-quantitative grade for collagen organization (2.9 vs. 3.7, p < 0.05), decreased semi-quantitative grade for collagen staining (1.9 vs 3.5, p < 0.05) and increased nuclear numbers per high-power field (527 vs. 392, p < 0.05). Immunohistochemical analysis revealed a predominance of by fibroblasts or endothelial cells. The total collagen content remained unchanged (84.3 vs. 89.0% p=0.38), while the glycosaminoglycan content was increased (17.5 vs. 9.0% p=0.02). Differences in collagen cross-linking were characterized by a greater proportion of reducible intrahelical crosslinks. These differences did not translate into a decrease in ultimate tensile failure during mechanical testing (UTS of 77.8 vs. 88.8 N, p=0.26).

Conclusions: Over-exercise model produced Achilles tendons with histology and biochemistry consistent with the animal and human tendon disease and characteristic of a remodeling response not an inflammatory response.

Introduction Historically, lumbar discography has been one of the most controversial subjects in the management of discogenic low back pain. The diagnostic value of normal psychometric specific pain provocation by disc pressurization has emerged. The sensitivity, specificity and accuracy of discography as a diagnostic test are not in doubt. In clinical discography pain reproduction and location are essential elements. There is an accepted rate of 0–10% false positives. This rate is influenced by occupational disability and abnormal psychometric profiles. By contrast, little attention has been given to false negative results and their outcomes if surgically treated. Traditionally, whether or not the test is considered to be positive or negative is determined immediately after completion of the diagnostic procedure. This study shows that patient’s pain reproduction may occur up to 24 hours after the discogram which often initially interpreted as a true negative when it is actually a false negative result. This study verifies the existence and significance of a false negative through the patients’ treatment and outcomes.

Methods In this study, 150 patients underwent discography for investigation of chronic persistent low back pain (CPLBP). All patients had a control (morphologically normal) discogram at the level above the degenerative segment. No patients with abnormal psychometric profiles or compensation were included. All patients were followed up 24 hours post discogram by the radiologist to further assess their clinical status. Ten of the patients (7.5%) were considered to have a false negative discogram, as per the Dallas Discogram Scale. The surgeon correlated the delayed response on the subsequent follow-up. These ten patients were diagnosed as having a positive response and were treated surgically for their discogenic pain. VAS-B, VAS-L, ODI, RMD were collected prospectively. Preoperative and 6 month results were reviewed.

Results Seven of the 10 patients (70%) reported severe increase CPLBP and reproduction of pain within 8 hours of the discogram, while 3 patients (30%) did so in the ensuing 24 hours after the discogram. Surgical treatment was either by total disc replacement or anterior lumbar interbody fusion. All patients reported greater than 50% reduction in VAS-B and VAS-L and with improvements of greater than 50% in their ODI and RMD scores.

Discussion The clinical reliability of discography hinges on the subjective assessment of pain concordance as the discriminating factor in determining false positives from false negatives. Given the limitations of discography, all information about the patient should be considered prior to diagnosis, including clinical, radiological, historical, and psychometric factors. The delayed positive discography response is an important consideration for the patient, the radiologist, and the treating surgeon to be aware of. The results of this study verify the existence of this subgroup and justify their surgical treatment.

Introduction The CPS-Plus stem (Endoplus UK) is a polished double-taper with rectangular cross section maintained throughout for rotational stability. There are 5 stem sizes with proportionate offset, and 5 neck length options. A unique proximal stem centraliser has been shown to increase proximal cement pressurisation during insertion in-vitro, also assists with alignment of the stem and helps create an even cement mantle. RSA analysis has demonstrated linear subsidence in a vertical plane, without posterior head migration and valgus tilt.

We report a multi-centre prospective clinical trial. 231 hips in 223 patients have been entered into the study. 151 of these have reached 3 years follow-up.

Method Patients were recruited by surgeons working at three centres in the UK, and two in Norway. Merle d Aubigne and Postel, Harris, and Oxford hip scores were recorded pre-operatively and at follow-up (3, 6, 12, 24, 36, 60 months). Radiographic assessment included evaluation of subsidence and the presence of any radiolucencies.

Results Hip scores have been very satisfactory. Radiological subsidence is less than 1.5mm in over 95% of cases and only one stem has subsided more than 3mm. There has been one revision for deep sepsis, 7 dislocations and one femoral fracture, but none of these complications were related to the choice of femoral component. There have been no revisions for aseptic loosening. Kaplan Meier survivorship analysis at 36 months for aseptic stem loosening is 0.997 (95% CI 0.977 – 1) and for all-cause revision is 0.981 (95% CI 0.958 – 1). 53 hips had reached 5-year follow-up at 30/9/04.

Discussion The tradition of polished tapered stems arose from serendipity and most results have been excellent. The CPS-Plus stem represents an attempt to re-examine the issues relating to rotational stability, subsidence, cement pressurisation and offset. Earlier laboratory studies have now been supplemented by this clinical evaluation, performed in a number of different centres by several surgeons, and the evidence is encouraging.

In particular, the RSA subsidence characteristics, cement pressurisation and rotational stability already associated with this implant in-vitro have been supported by excellent survivorship analysis, and the authors believe that increasing familiarity with the concepts raised by this implant will result in clinical benefits in relation to polished taper cemented stem longevity.

Dissociation of the polyethylene liner of modular acetabular components is a rare occurrence, and previous reports have commented on the difficulty in diagnosis from plain radiographs. The radiograph is often incorrectly reported by radiologists as showing advanced polyethylene wear, causing delay in referral and increasing the complexity of treatment required.

We report 9 cases of late polyethylene liner dissociation of the cementless Harris-Galante II porous-coated acetabular component (Zimmer Inc, Warsaw, IN) which occurred without trauma or injury. This is the largest reported series to date.

In all cases, there was a common pattern of clinical symptoms and signs which is described.

Radiographs showed a distinct appearance with a radiolucency medial to the femoral neck in association with an eccentrically placed femoral head lying in contact with the acetabular metal shell. We have termed this the ‘crescent sign’.

We believe that the diagnosis can be made from a single antero-posterior pelvic radiograph without the need for previous films for comparison, or the need for arthrography. Clinicians should look specifically for the crescent sign when an eccentrically placed femoral head has been noted, in order to differentiate the more unusual diagnosis of dissociation from that of polyethylene wear. Early diagnosis and prompt referral prevents further damage to the femoral head and metal acetabular shell, thus reducing the complexity of revision surgery.

Introduction Primary and revision total hip surgery in the face of poor neuromuscular function, cognitive impairment or recurrent dislocation are fraught with complications. A useful option for such cases is the constrained acetabular component, or “captive cup”. We present the largest series reported to date, and use radiostereometric analysis (RSA) to assess cup migration.

Method Between February 1999 and September 2003 133 patients (141 hips) were identified as high risk of dislocation and were treated with a constrained acetabular component. One hundred and twenty cases were revision arthroplasties and 21 were primary replacements. Patients were assessed pre-operatively (WOMAC, Harris Hip Scores and SF-36). Defects were reconstructed with allograft (massive, morsellised or strut) where required. Most components were inserted into uncemented metal cups. Radiostereometric beads were inserted. Post-operatively patients were followed up regularly and clinical scores repeated. Radiostereometric analysis (RSA) was performed at 6 months, and then annually to assess prosthesis migration.

Results Mean follow-up was 3.1 years (range 1 – 5.6 years). At last review 26 patients had died, and 7 were lost to follow-up. There were 8 revisions for cup loosening. There were 5 dislocations and 2 dissociations in 6 patients. There was a statistically significant improvement in WOMAC and Harris Hip scores. RSA confirmed cup migration was greater than for non-captive cups, but was nevertheless minimal. Interestingly there was no statistically significant difference at 6, 12 and 24 months suggesting most migration occurs early on.

Conclusion Our results suggest the “captive cup” is an effective and safe option for the treatment of primary and revision arthroplasty in those at high risk of dislocation.

Introduction: Primary and revision total hip surgery in the face of poor neuromuscular function, cognitive impairment or recurrent dislocation are fraught with complications. A useful option for such cases is the constrained acetabular component, or “captive cup”. We present the largest series reported to date, and use radiostereometric analysis (RSA) to assess cup migration.

Method: Between February 1999 and September 2003 126 patients were identified as high risk of dislocation and were treated with a constrained acetabular component. One hundred and sixteen cases were revision arthroplasties and 10 were primary replacements. Patients were assessed pre-operatively (WOMAC, Harris Hip Scores and SF-36). Defects were reconstructed with allograft (massive, morsellised or strut) where required. All components were inserted into uncemented metal cups. Radiostereometric beads were inserted. Post-operatively patients were followed up regularly and clinical scores repeated. Radiostereometric analysis (RSA) was performed at 6 months, and then annually to assess prosthesis migration.

Results: Mean follow-up was 3.1 years (range 1 – 5.6 years). At last review 8 patients had died, and 2 were lost to follow-up. There were 7 revisions: 3 for infection, 2 for periprosthetic fractures, and 2 for aseptic loosening. There was one case of cup disassociation successfully treated with open reduction. There have been no further dislocations. There was a statistically significant improvement in WOMAC and Harris Hip scores. RSA confirmed cup migration was greater than for non-captive cups, but was nevertheless acceptable: 0.16mm medially, 0.47mm proximally, 0.16mm posteriorly. Interestingly there was no statistically significant difference at 6, 12 and 24 months suggesting most migration occurs early on.

Conclusion: Our results suggest the “captive cup” is an effective and safe option for the treatment of primary and revision arthroplasty in those at high risk of dislocation. RSA analysis confirms minimal prosthesis migration.

Introduction and Aims: Accumulating evidence suggests that bacterially derived endotoxins may contribute to aseptic loosening. This study determined whether lipopolysaccharide (LPS), the classical endotoxin from Gram-negative bacteria, can be detected in periprosthetic tissue from patients with aseptic loosening. We utilised an assay that detects all forms of LPS and is unaffected by beta-glucan-like molecules.

Method: Periprosthetic tissue from revision total hip arthroplasty and synovia from primary total joint arthroplasty were homogenised in PBS in endotoxin-free conditions. Non-specific amidases in the homogenates were inactivated at 100 degrees C. LPS was measured using the Endospecy assay (Associate of Cap Cod). Multiple dilutions of the homogenates were assayed to maximise sensitivity, while avoiding assay inhibition assessed by spike recovery determinations. Results were corrected for colour and spike recovery. Assay results were considered positive if the absorbances were higher than the lowest standard and the LPS level was significantly greater (p< 0.05) than the PBS control. Statistical analysis was by ANOVA with Bonferroni-Dunn (Control) post-hoc tests.

Results: Samples from 13 patients have been studied to date. Multiple assays of four of these samples showed no detectable LPS while nine of these samples resulted in both positive and negative assays. This inter-assay variability prevents measurement of the concentration of LPS in the samples. Nonetheless, many of the samples contain detectable amount of LPS. Thus, six out of eight samples from revision THA patients with aseptic loosening had positive assays, as did two of four primary TJA patients. LPS was also detected in a sample from a revision control. These results demonstrate that samples from THA patients with aseptic loosening and from primary TJA contain detectable amounts of LPS derived from Gram-negative bacteria.

Conclusion: This conclusion is consistent with numerous studies, showing that human serum contains LPS derived from minor infections, gut flora, or dental procedures. It is likely that many of these samples also contain molecules derived from Gram-positive bacteria that have very similar biological effects as LPS. However, detection of these Gram-positive molecules await further improvements in assay specificity and sensitivity.

Introduction: The treatment with epidural steroids and local anaesthetic for radicular pain arising from nerve root compression is a commonly utilised and recognised treatment. The aim of this study is to determine the efficacy of CT-guided injection of epidural steroids without anaesthetic for radicular pain but without clinical neurology in the presence of a degenerative of lytic spondylolisthesis and concomitant foraminal narrowing.

Method: The study subjects, 21 in total, were selected over a 1-year period by the surgeon. All patients had either degenerative or lytic spondylolisthesis as determined by CT, MRI and plain film and were suffering from radicular pain – sharp, shooting and burning in the L5 or S1 dermatome. For inclusion, there had to be no associated evidence of nerve root compression. All patients completed, prior to epidural therapy, a pain diagram, visual analogue scale (VAS) of pain severity on a scale of 1 to 10 and Oswestry Disability Index (ODI). The MRI and clinical pain picture were correlated. The level of the spondylolithesis was determined.

Highly selective CT-guided epidural steroid injection was then carried out at the level of spondylolithesis by an experienced interventional radiologist. The pain diagram, VAS of pain severity and ODI were all completed again by the subjects themselves or by telephone at 1 and 3 months after injection in the presence of an independent assessor (nurse) and then reviewed and discussed with the treating doctor. All subjects were also asked to complete a functional questionnaire.

Results: One month after injection 86% of those treated had greater than 50% radicular pain relief and from this group 72% had radicular pain reduction of greater than 80%. All had improvement in function. All of the above, confirmed that their quality of life had certainly improved. Three months after injection 76% of those treated still had a reduction in their radicular pain of greater than 50% (92% of these still had pain reduction of over 80%). Again all reported continued functional improvement.

Discussion: Despite the small sample size, this study highlights the short-term Benefit of CT-guided steroid epidural injections with symptomatic lumbosacral spondylolisthesis and spondylolysis with radicular pain. Pain can be relieved without anaesthesia. The mechanisms of pain relief are speculative.

We retrospectively reviewed 45 hip arthroplasties which were performed over a period of 20 years in 38 patients with cirrhosis of the liver. There was a high perioperative 30-day complication rate (26.7%). Advanced cirrhosis was associated with a higher risk of complications (p = 0.004) as also was increased age, a high level of creatinine, a low level of albumin, a low platelet count, ascites, encephalopathy and an increased operative blood loss. The survival of the prosthesis at five years was 77.8% and infection was a major cause of failure.

In view of the high rate of early complications and the limited longevity of the prosthesis, surgeons who perform hip arthroplasty on such patients should counsel them appropriately preoperatively.

We report the results of seventy-six Harris Galante Porous Cups (HGP 1) in sixty-three patients treated by Total Hip Arthroplasty (THA) with a diagnosis of avascular necrosis (AVN) of the femur (grade III and IV). The cups were inserted between 1986 and 1994 and followed prospectively. Seventy hips with a follow up of more than five years (mean 7.6 years) were reviewed.

At last review the mean Harris Hip Score was 94 (standard deviation (& dcl001;) .8), preoperatively the mean had been 29 (& dcl001;14.7). Radiographically there was no evidence of acetabular migration. The revision rate of the femoral prosthesis was 8.6%, however only three stems (4.3%) were revised for loosening the rest being revised to allow down sizing of the femoral head. The revision rate for the acetabular prosthesis was 7.1%, (five cups). At the time of revision none of the cups were clinically loose and only required the liner to be changed. The complication rate was low with no deep infections or dislocations and only nine hips, (11.8%) with grade III heterotopic ossification. Survival analysis for both stem and cup at 8 years is 96.3% (confidence interval 91 – 100%), with a worst-case survival of 93.6%, (C.I 87.4 – 99.9%)

Previous studies of patients undergoing cemented THA for the treatment of advanced AVN have reported a high incidence of component loosening. This study shows good medium term results using the Harris Galante Porous cup for acetabular reconstruction with cemented femoral components for the treatment of this difficult problem.

There are several techniques for the accurate measurement of the migration of components after arthroplasty some of which require the operative placement of tantalum balls. We have reviewed the position and migration of these markers in 64 patients after total hip arthroplasty.

In 40% of cases, one or more balls was seen to be outside the proximal femur on the postoperative radiograph, although all were considered to be within the bone at operation. In two hips, one ball appeared to have migrated towards the joint, although none was seen within the joint. Misplacement was not related to the experience of the surgeon or the operative approach.

Migration analysis which necessitates the insertion of tantalum balls requires careful technique to avoid a potential source of third-body wear. It should probably be used only for research in small series of patients.

A technique of examining the infant hip joint with real-time ultrasound is described. Since the cartilaginous femoral head is clearly imaged by ultrasound, anatomical structures and their relationships can be accurately determined. Dislocated hips are easily detected and subluxations also can be visualized. We report our experience with 131 examinations in 104 patients, comprising 259 single hip studies. Of 83 patients who were previously untreated, there were 178 hip studies with three false-negative and four false-positive ultrasound results. No dislocations were missed. Twenty-seven patients who were already being treated were examined to assess hip location, comprising a total of 81 hip studies. In some cases the patients were examined while in an abduction device, cast, or Pavlik harness. In one case a dislocation was not detected. The method of examination using real-time ultrasound is considered to be reliable, accurate, and a useful adjunct to radiography. The advantages are that it is non-invasive, portable, and involves no exposure to radiation.