Incidence, predictors, and effects of residual flexion contracture on clinical outcomes of total knee arthroplasty.

Abstract

Patients who present with large flexion contracture (FC) but have well maintained maximum flexion tend to have a flexion-extension gap mismatch, which can cause residual FC or flexion instability after TKA. We routinely use posterior-stabilized implants, perform soft tissue balancing and additional distal femur resection, and determine the polyethylene insert thickness based on flexion-extension gap difference to avoid postoperative FC and flexion instability. We retrospectively reviewed 911 TKAs performed with this protocol to determine the incidence, predictors and effects of postoperative FC on clinical outcomes. Knees with postoperative FC ≥10° were identified, and their clinical outcomes were compared with knees without FC. The average follow-up period was 35months (range, 24-72months). Eighteen (2.0%) of the 911 knees presented with postoperative FC. The occurrence of postoperative FC was associated with preoperative FC and anterior knee pain, but not with a flexion-extension gap mismatch. A mild to moderate postoperative FC does not increase pain, but may be detrimental to quality of life.