Complications following total knee arthroplasty in patients with prior extensor mechanism dysfunction: A retrospective review

Background: Extensor mechanism disruption following total knee arthroplasty (TKA) is a rare, yet serious complication. While previous patellar abnormalities are a theoretical risk factor for this complication, there is a scarcity of literature describing the impact of prior extensor mechanism dysfunction (EMD) on this and other complications following TKA. In this study, we describe our institutional experience with complications following TKA after EMD.

Methods: Sixty-one knees that underwent total knee arthroplasty between April 2007 and April 2023 in patients with previous EMD were identified. Extensor mechanism dysfunction types included patellar fracture, patellar tendon rupture, patellar realignment surgery, previous patellar dislocation, and a chronic laterally tracking patella impacting extensor mechanism function. Primary outcomes included extensor mechanism failure, infection, dislocation, aseptic loosening, revision surgery, and stiffness requiring manipulation under anesthesia (MUA).

Results: A total of 61 knees, comprised of 53-patients, were included. There were complications witnessed in fifteen patients, leading to a 24.6 % overall complication rate. There was one extensor mechanism disruption in the form of a partial quadriceps tendon tear requiring repair. There was one patellar dislocation requiring reoperation. There were five superficial infections successfully treated non-operatively and four deep infections requiring reoperation. A total of nine reoperations were performed, four of which were revisions. Four patients underwent MUA due to severe post-operative stiffness.

Conclusion: In this study, we found a high complication rate following TKA in patients with previous extensor mechanism dysfunction. There was one case of partial quadriceps tendon rupture requiring repair.