Predicting Functional Performance and Range of Motion Outcomes After Total Knee Arthroplasty

Objective The aim of this study was to assess the predictive value of functional performance and range of motion measures on outcomes after total knee arthroplasty. Design This is a secondary analysis of two pooled prospective randomized controlled trials. Sixty-four subjects (32 men and 32 women) with end-stage knee osteoarthritis scheduled to undergo primary total knee arthroplasty were enrolled. Active knee flexion and extension range of motion, Timed Up and Go (TUG) test time, and 6-min walk test distance were assessed. Results Preoperative measures of knee flexion and extension were predictive of long-term flexion ( = 0.44, P < 0.001) and extension ( = 0.46, P < 0.001). Acute measures of knee flexion and extension were not predictive of long-term flexion ( = 0.09, P = 0.26) or extension ( = 0.04, P = 0.76). Preoperative TUG performance was predictive of long-term 6-min walk performance ( = -21, P < 0.001). Acute TUG performance was predictive of long-term functional performance on the 6-min walk test, after adjusting for the effects of sex and age (P = 0.02); however, once adjusted for preoperative TUG performance, acute TUG was no longer related to long-term 6-min walk performance (P = 0.65). Conclusions Acute postoperative measures of knee range of motion are of limited prognostic value, although preoperative measures have some prognostic value. However, acute measures of functional performance are of useful prognostic value, especially when preoperative functional performance data are unavailable.