Extensor mechanism failure in total knee arthroplasty.

Extensor mechanism failure in total knee arthroplasty (TKA) can present as quadriceps tendon rupture, patella fracture or patella tendon rupture.Component malrotation, excessive joint line elevation and previous lateral release are some of the risk factors contributing to extensor mechanism failure in TKA.Partial quadriceps tendon rupture and undisplaced patella fracture with intact extensor mechanism function can be treated conservatively.Extensor mechanism failure in TKA with disruption of the extensor mechanism function should be treated operatively as it is associated with poor function and extensor lag.It is recommended that acute repair of patella or quadriceps tendon rupture are augmented due to the high risk of re-rupture.Chronic ruptures of the extensor mechanism must be reconstructed as repair has a high failure rate. Reconstruction can be performed using autograft, allograft or synthetic graft. Cite this article: 2021;6:181-188. DOI: 10.1302/2058-5241.6.200119.