CHECK cohort: The course of physical functioning in early osteoarthritis of the knee and hip

CHECK cohort: The course of physical functioning in early osteoarthritis of the knee and hip

Background

  1. Activity Limitations is one of the primary health complaints in patients with osteoarthritis (OA). Especially at the first stage of osteoarthritis, it is still unclear which processes are responsible for the development and worsening of activity limitations. Several physical and psychological factors have been identified as potential determinants of activity limitations in OA. Scientific research has been primarily aimed at established OA. The first aim of this study is to determine the course of activity limitations in an early stage of osteoarthritis, and to identify determinants of, and early signs for, an unfavourable course.
  2. A possible explanation for the development and worsening of activity limitations in OA, is given by the avoidance model: a theoretical model for the development and worsening of activity limitations in OA (Steultjens et al. 2002). According to this model, a patient will initially experience pain during activity. As a consequence, the patient will fear that renewed physical activity will increase the pain, and will therefore start avoiding physical activity. In the short term, pain can be reduced by avoiding physical activity. In the long term, however, low activity levels will result in a deterioration of the patient's physical condition, most notably in muscle weakness. Due to this muscle weakness, the stability of joints will be affected, and the joints' ability to carry a load will be reduced. This results in increased activity limitations. Consequently, the patient will avoid activity even more, thus entering a downward spiral towards increasing activity limitations.

    It is our expectation that the relationships described in the avoidance model will be most pronounced in the early stages of OA. Patients first experience pain during activity, leading to the process of mental and physical adaptation depicted in the model. In later stages of OA, with well-established disability present, this process will have stabilized, resulting in little additional change over time. Therefore, the second aim of this study is to investigate the validity of the avoidance model.
  3. Reduced range of joint motion (ROM) is a characteristic feature of OA. Furthermore, ROM measurements are often used to quantify limitations at the start of treatment, and as outcome measure to justify or evaluate the effectiveness of interventions. There is increasing evidence that reduced ROM contributes to development of activity limitations in knee and hip OA patients (Dekker et al. 2009). Already in early OA we found that reduced hip flexion was a predictor for a poor functional outcome after two years. However, ROM is not frequently studied. Therefore, our third aim was to examine determinants and the diagnostic value of knee and hip ROM in OA.