Relation Between Subjective And Objective Activity In Patients With Knee Osteoarthritis

Abstract

Knee osteoarthritis (OA) is a leading cause of disability in the United States, impairing mobility and decreasing physical activity. Clinicians rely on patient self-reports of symptoms and physical activity to evaluate functional status, especially in this population. Considering the importance of maintaining a physically active lifestyle in preventing chronic disease, it is imperative to understand how accurately patients perceive their own impairments to determine if more objective measures of function are needed to properly evaluate physical activity in patients with knee OA. PURPOSE: Determine the relation between symptoms and physical activity in patients with knee OA. METHODS: A case series of eight females with physician diagnosed knee OA (age: 56.5±5.7years; body mass index: 28.4±2.5kg/m2) participated in a single testing session as part of an ongoing study. Symptoms were assessed via self-report knee pain, UCLA activity scale and WOMAC questionnaire. The WOMAC disability subscale was extracted to quantify self-reported disability. To determine physical activity levels, patients wore Actigraph GT3X activity monitors for 7 days. Physical activity levels (sedentary, light and moderate) were extracted and associations between symptoms and physical activity were calculated via Pearson product moment correlations (P<0.05). RESULTS: Knee pain was positively correlated with WOMAC (r=0.859, P=0.01). Time spent sedentary was negatively correlated with knee pain (r=-0.736, P=0.04) and WOMAC (r=-0.778, P=0.02). Time spent in moderate activity was positively correlated with UCLA score and (r=0.723, P=0.04). UCLA score was positively correlated with average steps/day (r=0.763, P=0.03). CONCLUSION: Knee OA patients who report higher UCLA scores take more steps per day and spend more time performing moderate intensity activities, suggesting these patients may accurately perceive their own physical activity levels. Additionally, patients with knee OA report knee pain is associated with self-reported disability during daily tasks. Importantly, patients who spend less time in sedentary activities report greater pain and disability during daily tasks. This study is one important step in optimizing interventions to relieve symptoms and keep these patients physically active across the lifespan.