High rate of failure after revision extensor mechanism allograft reconstruction

Patients who fail initial extensor mechanism allograft (EMA) reconstruction for extensor mechanism disruption after total knee arthroplasty (TKA) are left with few options. This study evaluated outcomes in patients that underwent revision EMA reconstruction following a failed EMA.

Ten patients that underwent revision EMA for failed index EMA with minimum 1-year follow-up were retrospectively reviewed. Patients receiving fresh-frozen EMA (quadriceps tendon, patella, patellar tendon, and tibial tubercle) at index and revision EMA were included. The primary outcome was EMA failure defined as revision surgery, extensor lag > 30°, or Knee Society Score (KSS) < 60 at last follow-up. Descriptive statistics were performed, with p < 0.05.

Mean extensor lag improved from 55.6°±26.7° pre-revision to 32.8°±29.6° (p = 0.13) at mean follow-up of 43.8 months (range, 12-124 months). Mean KSS improved from 41.0 ± 9.5 pre-revision to 73.4 ± 14.5 at last follow-up (p < 0.001). All patients required assistive devices for ambulation at final follow-up: one (10.0%) required a wheelchair, five (50.0%) required a walker, and four (40.0%) required a cane. Seven (70.0%) patients experienced EMA failure at a mean of 33.6 months (range, 2-124) following revision EMA: three (30.0%) were revised for periprosthetic joint infection (one of which also had extensor lag > 30°), three (30.0%) additional patients had extensor lag > 30°, and one (10.0%) patient had KSS < 60 (this patient developed PJI and was treated nonoperatively with chronic antibiotic suppression).

Revision EMA reconstruction fails at a high rate despite leading to improvements in KSS. Further research is needed to develop effective prevention and treatment strategies for failure after initial EMA reconstruction.