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: 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.