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

ABSTRACT

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 participants meeting the SLI, were measured in older adults 3 months post TKA using accelerometry. A 2-way analysis of variance test (α=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 stationary time (P<.001) and number of breaks in stationary time (P<.001), with participants taking <5000 daily steps having longer stationary 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 interactions 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.