Men and Women Demonstrate Differences in Early Functional Recovery after Total Knee Arthroplasty

Objective: To investigate whether sex affects the trajectory of functional recovery after total knee arthroplasty (TKA). Design: Retrospective analysis from a historical database containing data from 3 prospective clinical trials and a pilot study. Setting: Clinical laboratory setting. Participants: Recruitment across studies was restricted to patients who underwent an elective unilateral TKA for the treatment of osteoarthritis and were between 50 and 85 years of age (N=301). Interventions: Across all 4 studies, patients received a TKA and physical therapy intervention. Measures of physical function and strength were assessed before TKA and 1, 3, and 6 months after TKA. Main Outcome Measures: Using a repeated-measures maximum likelihood model, statistical inference was made to estimate the changes in outcomes from before surgery to 1, 3, and 6 months after TKA that were stratified by sex. Muscle strength was assessed during maximal isometric quadriceps and hamstrings contractions. Muscle activation was assessed in the quadriceps muscle. Physical function outcomes included timed Up and Go (TUG) test, stair climbing test, and 6-minute walk test (6MWT). Results: Women demonstrated less decline in quadriceps strength than did men at 1, 3, and 6 months after TKA (P<.04), whereas women demonstrated less decline in hamstrings strength 1 month after TKA (P<.0001). Women demonstrated a greater decline than did men on the TUG test (P=.001), stair climbing test (P=.004), and 6MWT (P=.001) 1 month after TKA. Sex differences in physical function did not persist at 3 and 6 months after TKA. Conclusions: Sex affected early recovery of muscle and physical function in the first month after TKA. Women demonstrated better preservation of quadriceps strength but a greater decline on measures of physical function than did men.