Background/Purpose: Knee osteoarthritis (OA) is a common cause of pain that often leads to limitations in physical function, e.g., difficulty walking or climbing stairs, in middle to older aged adults. Strength and endurance exercises are universally recommended treatments for knee OA but yield only modest improvements in pain and physical function. Modifying daily behaviors, such as time spent sitting and standing, may be an additional treatment to improve physical function. However, it is not known whether changes in daily behaviors, such as inactive standing, light stepping, or active sitting, are related to changes in physical function. To address this gap, we explored the relation of changes in these previously uncaptured daily behaviors with changes in patient-reported physical function in adults with knee OA who participated in a 12-week intervention focused on increasing physical activity, strength training, and education.

Methods: We conducted a secondary analysis of the Delaware Physical Exercise and Activity for Knee OA study. Briefly, the intervention aimed to improve knee pain and physical function by focusing on physical activity, strength training, and education. Two accelerometers worn at the hip and thigh over 7 days measured energy expenditure and body position. Using the posture and physical activity index, we classified each participant’s behaviors into six daily behaviors: sedentary behavior, inactive standing, active sitting, active standing, light stepping, and moderate-to-vigorous physical activity. We measured physical function as it relates to basic activities of daily living and sport and recreational activities using the Knee Osteoarthritis Outcome Score (KOOS) Activities of Daily Living (ADL) and Sports and Recreation subscales. Participants with > 1 valid wear day and who completed the KOOS ADL and Sport and Recreation subscales at baseline and the 24-week data collection were included in the analysis. Multiple linear regression, adjusted for baseline characteristics, was used to determine the relationship between change in daily behaviors with change in KOOS ADL and Sport and Recreation from baseline to 24 weeks.

Results: From 37 participants with knee OA (Age 59.9 ± 9.0 years, 85% Female, Body Mass Index 35.0 ± 9.0 kg/m², 16% Non-white, 30% Rural) with complete activity and outcome data at baseline and 24-weeks, changes in time spent light stepping were positively associated with changes in KOOS ADL (β = 0.27, p < 0.05). Changes in time spent performing inactive standing (β = 0.18, p < 0.05), active sitting (β = 0.55, p < 0.05), and sedentary behavior (β = 0.16, p < 0.05) were positively associated with changes in KOOS Sport and Recreation over 24 weeks.

Conclusion: More time spent light stepping, inactive standing, and active sitting were related to improvements in physical function over 24 weeks among adults with knee OA. This exploratory analysis suggests changes in previously uncaptured daily behaviors may influence changes in physical function in adults with knee OA.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/exploring-changes-in-daily-behaviors-with-changes-in-physical-function-over-24-weeks-in-adults-with-knee-oa/