Background/Purpose: Maintaining mobility in old age is an important public health goal for patients with hip or knee osteoarthritis (OA), who are vulnerable to functional decline and disability. Previous studies have observed that physical activity (PA) may improve physical function among OA patients and before undergoing total joint replacement (TJR) surgery for hip or knee OA. However, the association of PA with long-term functional outcomes after total hip (THR) or total knee (TKR) replacement for OA is less clear. We examined associations of leisure-time PA with late-life mobility limitation and death among women who underwent THR or TKR for OA.

Methods: The Women’s Health Initiative recruited women aged 65-79 years from 1993-1998 and followed them through 2012. Medicare claims data were used to determine THR (n=904) and TKR (n=1867) for OA. Women were followed for up to 18 years after receiving a TJR to determine mobility status at age 85. If women reported that their health limited their ability to walk one block or climb one flight of stairs in annual follow-up, they were classified as having mobility limitation. Women completed a questionnaire at baseline to determine engagement in activities of light, moderate, and vigorous intensities. PA variables were analyzed in metabolic equivalent-hours/week (MET-h/wk). Multinomial logistic regression analyses were performed to determine associations of PA variables with mobility limitation at age 85 and death before age 85 (reference category=mobility intact at age 85). Total PA, moderate-to-vigorous physical activity (MVPA), walking, and walking speed were analyzed in separate regression models adjusted for demographic, lifestyle, and health-related characteristics.

Results: Relative to women with the highest level of total PA (>17.42 MET-h/wk), women with THR (odds ratio [OR]=2.41; 95% confidence interval [CI]=1.29-4.51) or TKR (OR=1.56; 95% CI=1.04-2.34) who reported no PA had the highest risk of developing mobility limitation at age 85. Compared with women with the highest amount of MVPA (≥15 MET-h/wk), women with THR (OR=1.96; 95% CI=1.18-3.24) or TKR (OR=1.48; 95% CI=1.05-2.07) who reported no MVPA had increased risk of mobility limitation; the risk was also increased among women who did not meet federal guidelines of ≥7.5 MET-h/wk of MVPA. Women with THR (OR=2.03; 95% CI=1.16-3.58) or TKR (OR=1.54; 95% CI=1.05-2.27) who reported casual compared with fast walking speed were more likely to experience mobility limitation. Among women with THR, there were significant dose-response associations of total PA, MVPA, walking, and walking speed with mobility limitation and death. Among women with TKR, there were significant dose-response associations of total PA, MVPA, and walking speed with mobility limitation and death.

Conclusion: Among older women with hip or knee OA, higher levels of total PA and MVPA, as well as faster walking speed, before TJR were associated with better mobility in late life and decreased risk of death. Further studies are needed to determine whether physical activity before TJR is associated with better mobility later in life among women with hip or knee OA.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/association-of-leisure-time-physical-activity-with-late-life-mobility-limitation-among-women-with-total-joint-replacement-for-hip-or-knee-osteoarthritis/