Return to Physical Activity at 24 to 48 Months Status Post Total Knee Replacement: A Needs Assessment Study

Abstract

The primary aim of this investigation was to determine the physical functioning and physical activity levels of patients 2 to 4 years status-post total knee replacement. Subjects were recruited from a pool of 248 subjects who were recent study participants in an RCT at the University of Pittsburgh’s Physical Therapy Clinical and Translational Research Center (PT-CTRC). Consenting subjects completed two self-report physical functioning questionnaires including the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and the Short Form 36 (SF-36). They also completed performance based physical function outcomes measures including Single-Leg Stance, Repeated Chair Stand Test, Stair Climb Test (STTotal-11), 4 Meter Walk, 40 Meter Walk and 6-minute Walk Test (6MWT). Subjects then completed an interview with questions developed from the Health Belief Model. Physical activity was measured via the SenseWear Armband (SWA) for seven consecutive days during “waking hours.”

The results of the needs assessment were mixed. Physical functioning declined for six of seven performance based tests, with four of the tests showing a statistically significant decline in status. The stair climb test was the only physical functioning test in which subjects show an improvement, which was statistically insignificant.

Physical activity compliance for the group was higher than previous studies and higher than physical activity compliance for the general population when compared to Healthy People 2020 Midcourse Review. Despite this rather impressive result, two thirds of the group did not meet physical activity guidelines and the lower quartile averaged only 3 mins of moderate physical activity per day. This was the result from a cohort of subjects which had a 21% higher compliance with PA guidelines than the full group of study participants from the benchmark study at the 6 month follow-up. Results also suggested that physical functioning and physical activity are not correlated statistically, with the exception of a weak correlation between physical activity and the 6 minute walk test and WOMAC scores. The clinical relevance of this study is that it justifies an extended late stage (9 to 12 month) intervention to promote physical activity following total knee replacement.