Stationary Behavior and the Step-Defined Sedentary Lifestyle Index in Older Adults After Total Knee Arthroplasty

Objectives: To measure stationary behavior in a cohort of older adults after total knee arthroplasty (TKA) and determine the clinical utility of the step-defined sedentary lifestyle index (SLI) as a measure of stationary behavior after TKA. Design: Cross-sectional measurement study. Setting: Participants were recruited from a community intake clinic for hip and knee surgeries. Participants: Sixty-five older adults 3 months after TKA (N=65). Interventions: Not applicable. Main Outcome Measures: Stationary behaviors, including stationary time, stationary bouts, breaks from stationary time, and the proportion of par-ticipants meeting the SLI, were measured in older adults 3 months post TKA using accelerometry. A 2-way analysis of variance test (a=0.05) was conducted to determine the effects of SLI (< 5000 or >= 5000 daily steps) and possible interactions with sex on stationary behavior. Results: Participants spent 80% (13.17 +/- 2.3h) of their waking time in stationary time and had an average of 6.06 bouts of stationary time > 30 minutes per day. Forty (61.5%) of the participants fell below the SLI of 5000 steps/d. SLI had significant effects on both waking sta-tionary time (P <.001) and number of breaks in stationary time (P <.001), with participants taking < 5000 daily steps having longer station-ary times and fewer breaks in stationary time. Sex had a significant effect on the number of breaks in stationary time (P=.04), with men (n=23, 35%) reporting more breaks than women (n=42, 65%) (mean difference 13.36; 95% confidence interval,-2.67 to 18.69). No inter-actions were found between SLI and sex. Conclusions: Both women and men had high levels of stationary behavior 3 months post TKA. The SLI discriminated waking stationary time and breaks in stationary time and may have clinical utility in measurement of stationary behavior. Archives of Physical Medicine and Rehabilitation 2021;102:1926-31 (c) 2021 The American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

Automated summary

The study found that three months after TKA, older adults exhibited high levels of sedentary behavior, and the SLI can be a useful measure for assessing stationary behavior.