Comparing the impact of hyaluronic acid injections and exercise therapy alone and combined on the postural sway and base of support in individuals with knee osteoarthritis: a quasi-experimental study

Background/Aims Intra-articular hyaluronic acid injections and exercise therapy have been demonstrated to improve pain in knee osteoarthritis. The aim of this study was to evaluate the effectiveness of intra-articular hyaluronic acid injections and exercise both separately and in combination, on the centre of pressure sway and base of support in individuals with knee osteoarthritis. Methods In this quasi-experimental study, 36 participants with moderate knee osteoarthritis were divided into exercise therapy (n=12), intra-articular hyaluronic acid injection (n=12), and combined (exercise therapy and intra-articular hyaluronic acid injection) (n=12) groups. Intra-articular hyaluronic acid injections involved three consecutive weekly injections and exercise therapy was conducted three times a week for 5 weeks. The centre of pressure sway was measured in the medial-lateral and anterior-posterior directions, and the centre of pressure location on the base of support was also assessed using MATLAB software. Pain was assessed using a visual analogue scale. Physical function and postural balance were evaluated using the Lequesne Index, Timed Up and Go Test, Figure-of-8 Walk Test and Star Excursion Balance Test. Results All interventions were effective in reducing pain and improving function. In the medial-lateral direction, the combined group showed a significant decrease in centre of pressure velocity compared to the exercise therapy group (P=0.015) and a substantial reduction in centre of pressure displacement compared to the hyaluronic acid injection group (P=0.043). The base of support decreased significantly in the exercise therapy and hyaluronic acid injection groups (P=0.045 and P=0.007 respectively). The distance of the centre of pressure to the border of the base of support on the affected side significantly decreased in the hyaluronic acid injection group (P=0.001). Conclusions Using exercise therapy in conjunction with intra-articular hyaluronic acid injections is more effective in reducing centre of pressure sway than using intra-articular hyaluronic acid injections or exercises alone. However, the base of support parameters showed no significant difference for all groups, but intra-articular hyaluronic acid injections could lead to more weight loading on the affected knee joint. Without proper muscle strengthening, this could have negative effects that should be considered in future studies. Implications for practice Combining exercise therapy with intra-articular hyaluronic acid injections appears to provide superior control over the medial-lateral centre of pressure sway. This improvement in postural balance could be especially beneficial for patients with knee osteoarthritis.