Hip and Knee Loading During Walking, Running, Hopping, Jumping, Landing, and Change of Direction After Hip or Knee Arthroplasty

OBJECTIVE: To compare joint implant loads in high-functioning individuals with hip or knee joint arthroplasties during selected high-impact tasks against a baseline of walking. DESIGN: Exploratory, cross-sectional descriptive laboratory study METHODS: Adults with a total hip arthroplasty (THA, n=11), total knee arthroplasty (TKA, n=4), or unicompartmental knee arthroplasty (UKA, n=3) performed a selected range of low- to high-impact tasks. Musculoskeletal modelling was used to quantify three-dimensional hip (HCF) and knee joint contact forces (KCF). Linear mixed-effects models were used to rank implant loads relative to walking (baseline) and to compare against healthy controls from a prior study. RESULTS: For people with THA, a 45° change of direction generated the highest predicted HCF (8.38 BW, 95% CI 7.70-9.06), followed by running and unilateral hopping. In the small TKA/UKA samples, unilateral hopping and running produced the highest predicted KCF (8.0-9.1 BW). Compared with healthy controls, participants with THA had a lower predicted HCF during walking only (-1.58 BW, 95% CI −2.46 to −0.69). CONCLUSION: Not all high-impact activities produced greater predicted loads than walking. These preliminary data may help inform future efforts to refine activity recommendations, improve regulatory implant testing protocols, and develop computational simulations of implant performance under realistic loading conditions.