STABILO: a randomised controlled trial of knee joint stabilisation therapy in osteoarthritis of the knee (WC2009-058)

Background

Starting date: 01/12/2008

Exercise therapy has been shown to be an effective intervention for improving the daily functioning of patients with knee OA. However, on average the beneficial effects of exercise therapy are moderate and there is also considerable heterogeneity in its effectiveness between patients. Therefore, there is cause for further optimisation of exercise therapy, by both improving the content of therapy and by adequate selection of patients in whom improvement can be expected. 

Recently, the biomechanical process of knee joint stabilisation has become a focus of research. It has been shown that this process of knee joint stabilisation is closely related to functional ability in patients with knee OA. Firstly, the relationship between muscle strength and functional ability in OA has been well established. Recently, we have shown that this relationship is affected by other factors involved in the knee joint stabilisation process: laxity and proprioception. Additionally, it has been shown that varus malalignment of the knee (i.e., “bow knee”) during walking is independently related to more limitations in functioning. It was also found that self-reported instability of the knee was indicative of limitations in daily functioning. 

These findings imply that patients with inadequacies in factors involved in the joint stabilisation process (i.e., muscle weakness, laxity, proproceptive inaccuracy, varus malalignment, self-reported instability) are most at risk of being severely limited in their functioning, and might benefit most from interventions specifically tailored to improve joint stabilisation. 

Based on the biomechanical model of joint stabilisation presented above, we have developed a 12-week exercise therapy program. In the first four weeks, the patients are specifically trained in improving the stabilisation of the knee joint, through proprioceptive training, stability exercises, and attending to neutral alignment of the knee. These proprioceptive instructions will continue for the rest of the exercise programme. In the second four weeks, muscle strengthening has primarily the focus of the training. In the last four weeks the functional training of daily activities relevant to the patient, e.g. walking, stair climbing or other transfers, will have the focus of the training. 

It is expected that an exercise programme which initially focuses on knee joint stabilisation, followed by muscle strengthening and applied functional training of daily activities, is more effective in improving the functional status of patients with OA than current exercise programmes, which are primarily aimed at muscle strengthening, in combination with functional training.