Total Knee Arthroplasty Assessments Should Include Strength and Performance-Based Functional Tests to Complement Range-of-Motion and Patient-Reported Outcome Measures

Abstract

Range of motion (ROM) and pain often define successful recovery after total knee arthroplasty (TKA), but these routine clinical outcomes correlate poorly or not at all to functional capacity after TKA. The purpose of this Perspective is to underscore the importance of muscle strength and performance-based functional tests in addition to knee ROM and patient-reported outcome (PRO) measures to evaluate outcomes after TKA. Specifically: (1) muscle strength is the rate-limiting step for recovery of function after TKA; (2) progressive rehabilitation targeting early quadriceps muscle strengthening improves outcomes and does not compromise ROM after TKA; (3) ROM and PROs fail to fully capture functional limitations after TKA; and (4) performance-based functional tests are critical to evaluate function objectively after TKA. This Perspective also addresses studies that question the need for or benefit of physical therapy after TKA because their conclusions focus only on ROM and PRO measures. Future research is needed to determine the optimal timing, delivery, intensity, and content of physical therapy.

Keywords: Function; Range of Motion; Rehabilitation; Strength; Total Knee Arthroplasty.

Figure

Clinical assessments and research studies should evaluate strength and function (using performance-based functional tests) in addition to the commonly used outcomes, knee range of motion (ROM) and perceived function and pain (ie, patient-reported outcomes [PROs]). Note that the tests or outcome measures provided within each category are not comprehensive but provide a framework for clinical evaluations. These categories should be viewed as the “minimum dataset” rather than an all-encompassing list. KOOS JR = Knee Injury and Osteoarthritis Outcome Score [KOOS] joint replacement; NPRS = numeric pain rating scale; TKA = total knee arthroplasty.