Course of limitations in activities in osteoarthritis of the hip or knee: the influence of physical impairments, comorbidity and cognitive dysfunction.

Objectives: to describe the course of limitations in activities in elderly patients with osteoarthritis of the hip or knee, and (ii) to identify age related factors that predict the course of limitations in activities in patients with osteoarthritis of hip or knee. Methods: A longitudinal cohort study was conducted. Patients (n= 288) with hip or knee OA were recruited from rehabilitation centres and hospitals (departments of orthopaedics, rheumatology and rehabilitation). Apart from demographic and clinical data, physical impairments (pain, muscle strength and range of joint motion: ROM), comorbidity, cognitive dysfunction and limitations in activities (both self reported (WOMAC) and observed (timed walking test) were assessed. Statistical analyses included multilevel analysis, univariate regression analysis and multivariate regression analysis. Results: Preliminary results showed that in operated patients self reported functioning improved, where as observed functioning remained unchanged. In patients, that had not undergone surgery, limitations in activities did not change. No differences were found between hip and knee OA. The course of self reported limitations in activities was significantly associated with change in ROM hip flexion during the first year of follow-up, change in pain during the first year of follow-up and morbidity count. Furthermore, muscle strength hip abduction, change in muscle strength hip abduction during the first year of follow-up, morbidity count, cognitive function, age and BMI were associated with observed limitations in activities. Conclusion: Patients with osteoarthritis of the hip or knee show differences in the course of limitations in activities. Some of the patients improve, where as others show no changes or worsening of limitations in activities. This difference can be partly explained by the fact that some of the patients underwent surgery and others did not. In not operated patients, the course of limitations in activities remained unchanged. Patients that had had surgery reported improvement. Furthermore, protective factors and risk factors for the course of limitations in activities were identified. Pain and morbidity count were found as risk factors for worsening where as an improvement in ROM could be seen as a protective factor for self reported limitations in activities. Risk factors that were identified for observed limitations in activities were morbidity count and BMI. Protective factors were muscle strength and cognitive functioning. (aut. ref.)