Few data are available on the level of actual physical activity in patients with osteoarthritis (OA) of the hip and knee. The aim of this study was to measure the level of actual physical activity of patients with end-stage OA of the hip and the knee, to compare this with that of matched healthy controls, and to analyze the data in order to ascertain the factors of influence.
The actual physical activity was measured with an activity monitor (AM) in 40 hip and 44 knee OA patients, and compared with measurements obtained from healthy controls. Data were also collected on pain and psychological aspects as anxiety, depression and mental functioning. The primary outcome parameter of the actual physical activity was the percentage of movement-related activity.
The percentage of movement-related activity did not differ between the two OA groups. It was 8.8 (4.2)% for the hip and 8.1 (3.8)% for the knee OA patients. The matched controls were significantly higher movement-related active than OA patients (about 11.0 (2.9)%). Increasing age and body mass index were negatively associated with the percentage of movement-related activity (beta=-0.29 and beta=-0.25, respectively), whereas mental functioning was positively related (beta=0.30).
The impact of end-stage OA on the level of actual physical activity is equal for hip and knee OA patients. The actual physical activity for both of the OA groups was significantly and clinically relevantly lower compared to controls. However, this difference was smaller than expected and less dominant than patients' perception of limitations in daily life. Clinicians must be aware that the patients' perception of physical functioning in daily life does not always correspond to the actual physical activity.