Retrieval of a well-functioning extensor mechanism allograft from a total knee arthroplasty. Clinical and histological findings.

We present the histological findings of an extensor mechanism allograft which was used in a total knee arthroplasty two years after implantation. Analysis of the graft was undertaken at four distinct anatomical levels and it was found to be incorporated into host tissue at each level. A wedge of fibrinoid necrosis, probably related to impingement of the graft on the tibial polyethylene insert, was seen. Impingement may play a role in the injury and necrosis of an allograft and may be one mode of failure in an extensor mechanism allograft.

Does the new generation of high-flex knee prostheses improve the post-operative range of movement?: a meta-analysis.

A new generation of knee prostheses has been introduced with the intention of improving post-operative knee flexion. In order to evaluate whether this goal has been achieved we performed a systematic review and meta-analysis. Systematic literature searches were conducted on MEDLINE and EMBASE from their inception to December 2007, and proceedings of scientific meetings were also searched. Only randomised, clinical trials were included in the meta-analysis. The mean difference in the maximum post-operative flexion between the 'high-flex' and conventional types of prosthesis was defined as the primary outcome measure. A total of five relevant articles was identified. Analysis of these trials suggested that no clinically relevant or statistically significant improvement was obtained in flexion with the 'high-flex' prostheses. The weighted mean difference was 2.1° (95% confidence interval -0.2 to +4.3; p = 0.07).

A prospective randomized clinical trial of patellar resurfacing and nonresurfacing in bilateral TKA.

UNLABELLED: We conducted a randomized clinical trial to determine long-term outcome differences of patella resurfacing versus nonresurfacing in patients undergoing bilateral total knee arthroplasty. We questioned whether there were differences with respect to the operative procedure, anterior knee pain, Knee Society scores, patellofemoral-related revision rates, patient satisfaction and preference, and patellofemoral functional activities. Thirty-two patients (64 knees) underwent primary bilateral single-stage total knee arthroplasty for osteoarthritis. All patients received the same cruciate-retaining total knee arthroplasty. Patients were randomized to resurfacing or nonresurfacing of the patella for the first total knee arthroplasty, and the second knee received the opposite treatment. All living patients were followed to a minimum of 10 years. We found no differences with regard to range of motion, Knee Society Clinical Rating Score, satisfaction, revision rates, or anterior knee pain. Thirty-seven percent of patients preferred the resurfaced knee, 22% the nonresurfaced knee, and 41% had no preference. Two patients (7.4%) in the nonresurfaced group and one patient (3.5%) in the resurfaced group underwent revision for a patellofemoral-related complication. Equivalent clinical results for resurfaced and nonresurfaced patellae in total knee arthroplasty were demonstrated in this 10-year randomized clinical trial. LEVEL OF EVIDENCE: Level I, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Extensor mechanism allograft reconstruction in TKA at a mean of 56 months.

Extensor mechanism disruption in total knee arthroplasty (TKA) occurs infrequently but often requires surgical intervention. We compared two cohorts undergoing extensor mechanism allograft reconstruction and presumed both types of extensor mechanism allograft reconstruction will be successful but for different indications and forms of extensor failure. Nineteen consecutive patients with extensor mechanism disruption after TKA were treated. Two different types of extensor mechanism allografts were used: quadriceps tendon-patella-patella tendon-tibial tubercle, and Achilles tendon allograft. Demographic factors, diagnosis at extensor failure, Knee Society clinical rating scores, radiographs, and patient satisfaction were recorded. The average time from extensor mechanism disruption to surgery was 6.6 months (range, 1-24 months). At a mean followup of 56 months (range, 24-96 months), all patients were community ambulators. The mean Knee Society score improved from 27 points preoperatively to 76 points postoperatively. There was no loss of knee flexion postoperatively. The mean postoperative lag was 14 degrees. Fifteen patients had an extensor lag of less than 10 degrees. All patients thought their functional status had improved, and 89% were satisfied with the results of the allograft reconstruction. The total extensor mechanism allograft and Achilles tendon allograft both were successful in the treatment of the failed extensor mechanism.