Extensor mechanism disruption remains a challenging problem in total knee arthroplasty (TKA) with historically poor outcomes. The purpose of our study is to determine if patients undergoing acute extensor mechanism repair had different outcomes than patients undergoing allograft reconstruction.
We reviewed a series of 126 total knee arthroplasty patients requiring surgical repair or reconstruction of an extensor mechanism injury from 2005 to 2014 with a minimum of 24 months of follow-up. Demographics, comorbidities, Knee Society Scores, time from injury, and reoperations were all recorded from the medical record. A poor outcome was defined as an extensor lag >30°, postoperative Knee Society Scores <60, or a reoperation. A multivariate analysis was then performed to identify independent risk factors for a poor outcome.
Of the 126 patients, there were 58 patients who underwent direct extensor repair (46%) and 68 patients who underwent allograft reconstruction (54%) at a mean postsurgical follow-up of 81.2 months. Rates of poor outcomes were comparably high in both groups (33% vs 44%, P = .192). Patella tendon repair had the highest rate of poor outcomes compared to quadriceps repair and patella fixation (63% vs 22% vs 8%, P = .002). Independent risk factors for poor outcomes included patients with a history of infection (odds ratio 4.559, P = .002) and injury greater than 2 weeks duration (odds ratio 4.237, P = .031).
Outcomes following direct extensor mechanism are comparable to extensor mechanism allograft reconstruction; however, patients should be counseled regarding poor outcomes. Direct repair of patellar tendon injuries should likely be avoided due to prohibitively high complication rate.