Device-Measured Physical Activity in 3,511 Individuals with Knee or Hip Arthroplasty

BackgroundPhysical activity is a key contributor to overall health, with low activity levels associated with a higher risk of all-cause mortality. Hip and knee arthroplasty aims to reduce joint pain, increasing functional mobility and the ability to be more physically active. However, the degree to which arthroplasty is associated with higher physical activity is unclear. The current study sought to assess the association of hip and knee arthroplasty with objectively measured physical activity. MethodsThis cross-sectional study analysed seven days of wrist-worn accelerometer data collected in 2013-2016 from UK Biobank participants (aged 43-78), with a median 6.8 years of follow-up. From a cohort of 94,794 participants with valid accelerometer wear time and complete self-reported data, electronic health records were used to identify 3,511 participants having undergone primary or revision hip or knee arthroplasty and 68,450 non-arthritic controls. Multivariable linear regression was performed to assess activity in terms of steps, cadence, acceleration, and behavioural classification between end-stage arthritic and >12 month postoperative cohorts, controlling for demographic and behavioural confounders. FindingsAny combination of one or more hip or knee arthroplasties was associated with participants taking 694 more daily steps [95% CI: 346, 1,041] (p<0.001) than participants with end-stage osteoarthritis, though these participants took 542 fewer daily steps [95% CI: 403, 680] (p<0.001) than non-arthritic controls. Unilateral primary hip and knee arthroplasty were associated with 858 [95% CI: 255, 1,461] (p=0.005) and 879 [95% CI: 209, 1,549] (p=0.010) more steps than end-stage osteoarthritic participants, respectively. Postoperative hip arthroplasty participants demonstrated levels of moderate-to-vigorous physical activity and cadence equivalent to non-arthritic controls. InterpretationHip and knee arthroplasty are associated with higher levels of physical activity compared to participants with end-stage arthritis. Hip arthroplasty patients, in particular, approach equivalence with non-arthritic peers in peak cadence and time spent in moderate-to-vigorous activity. Accelerometer-based activity monitoring of arthroplasty patients may provide an objective means for the assessment of postoperative recovery and interventional effectiveness.