Objective
To investigate whether sex impacts the trajectory of functional recovery following total knee arthroplasty (TKA).
Design
Retrospective analysis from a historical database containing data from three prospective clinical trials and a pilot study.
Setting
All studies were performed in a 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 50–85 years of age (N=301).
Intervention
Across all four studies patients received a TKA and physical therapy intervention. Measures of physical function and strength were assessed prior to TKA, 1, 3, and 6 months after TKA.
Main Outcome Measures
Statistical inference using a maximum likelihood model for repeated measures was done to estimate the changes in outcomes by sex from pre-surgical assessment compared to 1, 3, and 6 months after TKA. 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), Stair Climbing Test (SCT), and the Six-Minute Walk Test (6MWT).
Results
Women demonstrated less decline in quadriceps strength than men at 1, 3, and 6 months after TKA (p<0.04), whereas women demonstrated less decline in hamstrings strength 1 month after TKA (p<0.0001). Women demonstrated a greater decline than men on the TUG (p=0.001), SCT (p=0.004), and 6MWT (p=0.001) 1 month after TKA. Sex differences in physical function did not persist at 3 and 6 months following TKA.
Conclusions
Sex impacted early recovery of muscle and physical function within the first month after TKA. Women demonstrated better preservation of quadriceps strength, but demonstrated greater decline on measures of physical function compared to men.