Objective. To explore the feasibility, fidelity, safety, and preliminary outcomes of a physical therapist-administered physical activity (PA) intervention after total knee replacement (TKR).Methods. People who had undergone a unilateral TKR and were receiving outpatient physical therapy (PT) were randomized to a control or intervention group. Both groups received standard PT for TKR. The intervention included being provided with a Fitbit Zip, step goals, and 1 phone call a month for 6 months after discharge from PT. Feasibility was measured by rates of recruitment and retention, safety was measured by the frequency of adverse events, and fidelity was measured by adherence to the weekly steps/day goal created by the physical therapist and participant monitoring of steps/day. An Actigraph GT3X measured PA, which was quantified as steps/day and minutes/week of engaging in moderate-to-vigorous PA. Our preliminary outcome was the difference in PA 6 months after discharge from PT between the control and intervention groups.Results. Of the 43 individuals who were enrolled, 53.4% were women, the mean ± SD age was 67.0 ± 7.0 years, and the mean ± SD body mass index was 31.5 ± 5.9 kg/m 2 . For both the control and intervention groups, the recruitment and retention rates were 64% and 83.7%, respectively, and adherence to the intervention ranged from 45% to 60%. No study-related adverse events occurred. The patients in the intervention group accumulated a mean 1,798 more steps/day (95% confidence interval [95% CI] 240, 3,355) and spent 73.4 more minutes/week (95% CI -14.1, 160.9) engaging in moderate-to-vigorous PA at 6 months than those in the control group.Conclusion. A physical therapist-administered PA intervention is feasible and safe, demonstrates treatment fidelity, and may increase PA after TKR. Future research is needed to establish the effectiveness of the intervention.ClinicalTrials.gov identifier: NCT02724137.

Time spent in MVPA was similarly low in those with symptomatic knee OA as in older adults without knee pain or OA.

* e within group difference from baseline significant p-value <0.05 on sign-ranked test. [ e between group significant p-value <0.05 on Wilcoxon sign test.

Not meeting these minimum performance thresholds on clinical tests of physical function may indicate inadequate physical ability to walk ≥6,000 steps/day for people with knee OA. Rehabilitation may be indicated to address underlying impairments limiting physical function.

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The goal of this randomized controlled trial is to increase PA after TKR. A protocol for investigating the efficacy, fidelity, and safety of a physical therapist-administered PA intervention for people after TKR is presented. The findings will be used to support a large multisite clinical trial to test the effectiveness, implementation, and cost of this intervention.

Objective To examine joint association of moderate-to-vigorous intensity physical activity (MVPA) and sedentary behavior with the risk of developing functional limitation 4 years later in adults with knee OA. Methods Using 48-month (baseline) accelerometry data from Osteoarthritis Initiative, , we classified participants as Active-Low Sedentary (≥1 10-minute bout/week of MVPA, lowest tertile for standardized sedentary time), Active-High Sedentary (≥1 10-minute bout/week of MVPA, top two tertiles for standardized sedentary time), Inactive-Low Sedentary (0 10-minute bout/week of MVPA, lowest tertile for standardized sedentary time) and Inactive-High Sedentary (0 10-minute bout/week of MVPA, top two tertiles for standardized sedentary time) groups. Functional limitation was defined as >12sec for five repetition sit-to-stand test (5XSST) and <1.22m/sec gait speed during 20-meter walk test. To investigate the association of exposure groups with risk of developing functional limitation 4 years later, we calculated risk ratios(aRR) adjusted for potential confounders. Results Of 1,091 and 1,133 participants without baseline functional limitation, based on 5XSST and 20-meter walk test, respectively, 15% and 21% developed functional limitation 4 years later. Active- High Sedentary group didn’t have, while Inactive-Low Sedentary, and Inactive-High Sedentary groups had increased risk of developing functional limitations compared to Active-Low Sedentary group. Inactive-Low Sedentary group had 72% (aRR[95% confidence interval]1.72[1.00, 2.94]) and 52% (1.52[1.03, 2.25]) more risk of developing functional limitation based on 5XSST and 20-meter walk test, respectively, compared to Active-Low Sedentary group. Conclusion Regardless of sedentary category, being inactive (0 10-minute bouts/week in MVPA) may increase risk of developing functional limitation in adults with knee OA.

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