Preoperative Quadriceps Muscle Strength and Functional Ability Predict Performance-Based Outcomes 6 Months After Total Knee Arthroplasty: A Systematic Review.

Background: One-third of individuals report limitations in activities of daily living even 6 months after total knee arthroplasty (TKA). Moderate-quality evidence exists for several sociodemographic and clinical predictors of patient-reported outcome measures of perceived functionality. Objectively measured performance-based measures (PBMs) provide a less subjective approach to informing patient treatment after TKA; however, information about predictors of functionally relevant PBMs is scarce. Purpose: This systematic review synthesized the available research on preoperative predictors of PBMs after primary TKA for osteoarthritis. Data Sources: In June 2016 and January 2017, MEDLINE, EMBASE, and PsycINFO databases were searched. Study Selection: Cohort studies exploring preoperative predictors of stair climbing, walking speed, and gait speed measured ≥6 months after primary TKA were included. Screening of abstracts and selection of full texts were undertaken by 2 independent reviewers. Data Extraction: Information on study design, patient characteristics, analysis, and results was extracted using pilot-tested forms. Two independent reviewers assessed risk of bias using modified Quality in Prognostic Studies criteria. Data Synthesis: Of the eligible 12 studies involving 6 prospective cohorts, 10 studies reported information on baseline predictors. Meta-analysis of predictors was not possible because of missing information on effect size or standard errors. Narrative synthesis of evidence of predictors was therefore performed. Limitations: The quality of evidence was low because of the risk of bias and heterogeneity of included studies as well as nonreporting of measures of effect. Conclusions: Low-quality evidence exists for an association of preoperative functional ability and quadriceps muscle strength with functionality at 6 months after TKA. Improved reporting of predictor analyses is needed to enable evidence generation for clinical management.