Introduction: Anterior knee pain is a very common presenting symptom. Fat pad syndrome is an uncommon and a difficult condition to manage. The diagnosis is usually reached after a period of physiotherapy and investigation to rule out the more common aetiologies of anterior knee pain.

Patients & Methods: All patients who underwent excision of the infrapatellar fat pad following a diagnosis of Fat pad syndrome are included. Each patient was evaluated to exclude patellofemoral problems and intraarticular pathologies as the cause of anterior knee pain. Each patient underwent MR imaging and all the excised specimens were sent for histological analysis.

Results: The MR imaging provided with the provisional diagnosis in all patients. All the specimens were examined by a single senior histopathologist to correlate with the provisional diagnosis. The histology confirmed Hoffa’s syndrome in 5 patients and in the remaining 15 patients a spectrum of rare diagnoses as suspected by Magnetic Resonance imaging.

The more notable conditions were two synovial sarcomas, three haemangiomas and a Giant cell tumour of the tendon sheath. All patients were treated successfully with complete excision. No recurrences were recorded at the end of 3 year follow-up and all patients were symptom free.

Conclusion: The work up of a patient with suspected infrapatellar fat pad syndrome must include MR imaging and the exact underlying pathology should be confirmed with histological analysis of the excised fat pad as the rare causes include soft tissue malignancy.

Introduction: PVNS is a benign proliferative disorder of the synovium presenting as local or diffuse variants. The condition commonly involves the knee with a slow and indolent progress.

Case series:

Presented with anterior knee pain. Examination revealed supra-patellar fullness and tenderness. MRI scan showed a suspicious soft tissue tumour. Histology confirmed PVNS after excision biopsy.

Conclusion: This case series aims to highlight the complexities in diagnosing PVNS. It should be a differential diagnosis of any kind of soft tissue problem especially around the knee. Immunohistochemistry may be useful. Multiple recurrences is a problem; adjuvant therapy may be indicated in resistant cases.

Hip resurfacing arthroplasty has become a popular treatment option for younger active patients. The early published results from designing surgeons/centers have been favourable. We undertook a prospective multi-center trial to determine the outcome of hip resurfacing arthroplasty at independent centers. The clinical, radiographic and functional results were assessed.

A prospective IRB approved study was initiated in July 2003 to assess the outcome of hip resurfacing arthroplasty using a contemporary design implant. (Conserve Plus - Wright Medical Technology) Disease specific (Harris Hip Score/WOMAC) and global (Rand self assessment index) outcome measures were used. Radiographs were reviewed for component position and migration as well as any signs of lysis or loosening. Complications and re-operations were recorded.

A total of one hundred and eighty-eight patients have been enrolled in the study to date. One hundred and four patients have a minimum one year follow-up and forty-six patients have a minimum two year follow-up. Mean Harris Hip Scores (pre-op, one year, two years) were fifty-five, eighty-nine and ninety-one. Mean WOMAC pain scores were forty-seven, ninety and ninety. Mean WOMAC stiffness scores were forty, seventy-eight and eighty-two. Mean WOMAC function scores were forty-six, eighty-seven and eighty. RAND physical function mean scores were thirty-three, seventy-six and seventy-six and the RAND physical limitations mean scores were nineteen, sixty-seven and seventy-five. Radiographic analysis showed average cup abduction to be forty-six degrees (range twenty-six to sixty-three). Average femoral stem position was one hundred and thiry-eight degrees (range one hundred and eighteen to one hundred and fifty-seven). Nine patients have been revised to date (4.8%). Four for acetabular loosening, two for neck fracture, one for femoral loosening, one for impingement and one for persistent pain. There have been eight other patients requiring re-operation without revision. Medical complications occurred in fifteen patients.

Early results have demonstrated a good return of function in patients with hip resurfacing arthroplasty. A high early revision rate (4.8%) was seen in our study. Technical factors appear to be the main contributor to the high early complication rate. Hip resurfacing is associated with a steep learning curve. We continue to utilise hip resurfacing in select patients but recommend caution for those who are new to the technique.

The traditionally accepted etiology of Scapholunate Advanced Collapse (SLAC) requires traumatic rupture of the scapholunate (SL) ligament which leads to abnormal wrist kinematics and thereafter severe localised degenerative arthritis of the wrist. The purpose of this prospective blinded kinematic analysis was to demonstrate that SLAC wrist also exists in the absence of trauma, and that abnormal carpal bone kinematics (specifically, decreased lunate flexion) is the initiating factor.

Patients with SLAC and no history of upper extremity trauma were compared with an age matched control group. All patients completed a questionnaire, personal interview, and a physical examination. A specialised flexion / extension radiographic jig was designed to control for the magnitude of force and position of the wrist in all planes.

A total of thirty-five subjects (sixty-nine wrists) were retained for the study, including thirty-three non-traumatic SLAC wrists and thirty-six control wrists. The non-traumatic SLAC group had significantly different radiographic kinematic analysis compared to the control group: increased Watson Stage (2 v 0), SL gap (3.4 v 1.8mm), revised carpal height ratio (rCHR) (77 v 68), SL angle in flexion (forty-one v twenty-eight degrees), and decreased radiolunate (RL) joint flexion (nine v twenty-seven degrees). Most importantly flexion of the asymptomatic non-degenerative wrist of the non-traumatic SLAC group was distributed 70% through the lunocapitate (LC) joint and only 30% through the RL joint (p< 0.05). Conversely, flexion was more evenly distributed in the control group (48% LC and 52% RL). Non-traumatic or developmental SLAC does exist. SLAC can thus be classified into non-traumatic (developmental) and traumatic types.

Non-traumatic SLAC begins with abnormal wrist kinematics. Over time restricted lunate flexion and normal scaphoid flexion leads to increased SL angles and eventual attrition of the SL ligament and predisposes patients to SLAC despite having no history of trauma.

The purpose of the present study is to report the failure rate after total knee replacements performed with poly-ethylene inserts that had been sterilized with gamma irradiation in air and implanted after a prolonged shelf life. 395 PFC total knees were performed using polyethylene that had been sterilized by gamma irradiation in air. Shelf life of all polyethylene inserts was determined from manufacturer data. A Chi-square test revealed that the proportion of implants that required a revision for polyethylene failure was related to the number of years that the implant had been stored on the shelf.

Report failure rate of PFC total knee replacements performed with polyethylene sterilized by gamma irradiation in air and implanted after a prolonged shelf life.

There was an increased revision rate in total knees with polyethylene sterilized by gamma irradiation in air and implanted after a shelf life greater than two years.

Polyethylene sterilized by gamma irradiation in air should not be implanted after a shelf life of greater than two years.

Ten of twelve revisions had polyethylene inserts with a shelf life greater than two years. A Chi-square test revealed that the proportion of implants that required a revision was related to the number of years that the implant had been on the shelf, particularly if greater than two years χ² (1)=7.427, p=.006

395 PFC total knees were performed using polyethylene sterilized by gamma irradiation in air. Shelf life of all polyethylene inserts was determined from manufacturer data. A retrospective review was undertaken to determine which patients underwent revision surgery as a result of aseptic loosening secondary to polyethylene failure. The data was then used to determine the relationship between shelf life and revision status.

The mechanical toughness of polyethylene that has been sterilized by gamma irradiation in air decreases with a prolonged shelf life. This results in an unacceptably high revision rate. We therefore recommend against the use of polyethylene that has been gamma irradiated in air and stored for greater than two years on the shelf.

Funding: This study has been sponsored in part by Johnson& Johnson/Depuy Orthopedics.

We reviewed forty-three patients who had humeral head replacement for proximal humeral fractures between 1992–2000, with a minimum of two years of follow-up. The patients were evaluated for range of motion, post-operative pain, and the overall activities using the American Shoulder and Elbow Surgeons Evaluation form (ASESE) and the Western Ontario Rotator Cuff Index (WORC). Patients with delayed surgery had more pain than those with primary hemiarthroplasty, all of which were treated with the Global type prosthesis. Postoperative pain was significantly associated with the presence of intra-operative cuff tear.

The purpose of this study was to evaluate the functional outcome after hemiarthroplasty for proximal humeral fractures and whether the prosthesis type, intra-operative technique, or the presence of previous surgery would affect the outcome.

The Medical records and radiographs of patients who had hemiarthroplasty for proximal humeral fractures between 1992–2000 were reviewed. Forty-three patients were identified, thirty-seven with acute fractures and six with fracture related complications. One surgeon performed fifteen cases (35%), while the rest divided among eleven others. The patients were evaluated for pain, range of motion, strength, stability, and function using the American Shoulder and Elbow Surgeons Evaluation form (ASESE) and Western Ontario Rotator Cuff Index. The radiographs were reviewed by the senior authors.

The mean age of the patients at presentation was sixty-nine year (range forty-six to ninety-five year). The mean duration of follow-up was 4.6 years. The mean active forward elevation was ninety-six, active external rotation twenty-two, and the mean active internal rotation was eight. Fifteen percent of the patients reported severe pain and twenty-five percent were unable to sleep on the affected side. The patients with previous surgeries and those with intra-operative cuff tear were found to have more post-operative pain (p=0.027 and 0.022 respectively). The Global type prosthesis was used in all the cases of secondary hemiarthroplasty (p=0.031) and all the Neer prostheses were cemented (0.001).

We concluded that integrity of rotator cuff and primary surgery were more inclined to better results. There does remain significant stiffness and pain in most patients however.

Purpose: Resurgence in mobile bearing unicompartmental arthroplasty o the knee has come to Canada in last 3 years. This has been attributed to the popularity of minimally invasive surgery, improved instrumentation, and encouraging outcome results from the developers and others. A prospective study was undertaken at an academic institution to evaluate the initial experience with the first 400 Oxford knees.

Methods: Oxford unicompartmental knees have been implanted since Feb 2001 at our institution. A majority of these were entered into the Ontario Joint Registry. All others were retrieved from hospital records to capture 100% of all cases done form our institution. All surgeons attended an Oxford training course. The main outcome of interest was repeat surgery revision for any cause, including revision.

Results: Three hundred and fifty Oxford knees with minimum 1 year follow up were available for study. Three surgeons have implanted 90 % of the implants. Fourteen patients have come to revision surgery as of October 1, 2005 for an incidence of 3,7 %. Causes include rapid lateral compartment deterioration (6), persisting medial pain (6), and medial collateral ligament disruption (1). Ten were revised to ttoal knee arthroplasty (8 cruciate retaining and 2 posterior stabilized), except the ligament disruption, which was reconstructed with Achilles allograft. Two others had open debridement for medial pain. This rate of revision is higher than reported in literature. Severe obesity (BMI > 35) was a factor in 4 failures.

Conclusions: Our experience was not as successful as reported in the literature from the prosthesis designers. Causes include poor technique and inappropriate indications when scrutinized closely. The temptation to stretch indications must be tempered by acceptance of higher revision rate than reported in literature and should be part of informed consent. Survivorship should be institution specific and not that of original published data from the developers.

Purpose: A multicenter prospective evaluation of the Conserve Plus resurfacing implant (Wright Medical Technology) was undertaken to assess clinical and radiographic outcomes as well as ion levels. This study focuses on the serum, erythrocyte and urinary levels of cobalt and chromium in those patients undergoing hip resurfacing arthroplasty.

Methods: A subset of patients enrolled in a multicenter trial to assess hip resurfacing arthroplasty had serum, erythrocyte and urinary cobalt and chromium levels measured. Levels were assessed preoperatively, then at three months, six months then yearly thereafter. Clinical outcome measurements were performed with WOMAC and Rand questionnaires.

Results: Fifty-four out of 124 patients enrolled in the overall study had cobalt and chromium ion assessments performed. During the first year there was an increase in serum cobalt levels from 1.4 ug/l at 3 months to 2.4 ug/l at one year. Serum chromium levels increased from 1.4 ug/l at 3 months to 3.5 ug/l at one year. Erythrocyte cobalt levels increased from 0.8 ug/l at 3 months to 1.4 ug/l at one year. Erythrocyte chromium levels decreased from 1.5 ug/l at 3 months to 1.4 ug/l at one year. Urinary levels for cobalt increased from 12.7 ug/l at 3 months to 13.8 ug/l at one year. Urinary chromium levels rose from 4.0 ug/l at 3 months to 5.1 ug/l at one year.

Conclusions: Increasing ion levels were seen during the first year post hip resurfacing arthroplasty. Clinical outcomes demonstrate predictable improvements in pain and function consistent with hip replacement surgery. Resurfacing arthroplasty is a viable option to total hip arthroplasty for younger active patients. The clinical significance of increased cobalt and chromium ions remains unknown. Funding: Commerical funding Funding Parties: Wright Medical Technology Inc.

This study evaluates metal ion levels in patients enrolled in a prospective evaluation of hip resurfacing arthroplasty utilizing the Conserve Plus implant (Wright Medical Technology). Serum, urine and erythrocyte metal ion levels were assessed preoperatively and postoperatively. Average levels at three months were 24 nmol/l for cobalt and 40 nmol/l for chromium. These increased to 40 nmol/l for cobalt and 80 nmol/l for chromium at the six-month mark. The clinical significance of increased metal ion levels is yet to be determined.

To evaluate the clinical, functional and radiographic outcome of hip resurfacing arthroplasty utilizing the Conserve Plus implant (Wright Medical Technology). Serum, urine and erythrocyte metal ion levels were evaluated both pre and postoperatively.

Ion levels for both cobalt and chromium increased from the three-month to the six-month mark postoperatively and were significantly elevated relative to preoperative values.

This study helps to establish a baseline for metal ion levels following hip resurfacing arthroplasty.

Serum, urine and erythrocyte metal ion levels were assessed preoperatively and postoperatively. All levels were within normal range preoperatively. Average serum levels at three months were 24 nmol/l for cobalt and 40 nmol/l for chromium. These increased to 40 nmol/l for cobalt and 80 nmol/l for chromium at the six-month mark. Average erythrocyte metal ion levels at three months were 0.92 ug/l for cobalt and 1.8 ug/l for chromium. The average erythrocyte levels at six months were 1.3 ug/l for cobalt and 2.0 ug/l for chromium.

A prospective multi-center study to evaluate the outcome of hip resurfacing arthroplasty was initiated in July 2003. Each patient was evaluated preoperatively and postoperatively with outcome scores, radiographs as well as serum, urine and erythrocyte metal ion levels.

The results of this prospective evaluation show a rise in ion levels from three to six months postoperatively. Further follow-up is necessary to assess future trends with respect to the ion levels as well as the clinical significance.

Funding: This study has been sponsored in part by Wright Medical Technology.