Kinetics features changes before and after intra-articular hyaluronic acid injections in patients with knee osteoarthritis.

OBJECTIVES:To examine the kinetic features in patients with knee osteoarthritis (OA) after intra-articular hyaluronic acid (IAHA) injections in different time periods. DESIGN:A single group repeated measures study. SETTING:Gait laboratory in a tertiary hospital. PARTICIPANTS:Twenty-five subjects with bilateral symptomatic knee OA and 15 healthy control subjects. INTERVENTION:Gait analyses were performed in both control and OA groups before (baseline), and after the completion of IAHA injections (1 week, 3 months, and 6 months). MAIN OUTCOME MEASURES:Knee pain and functional indices were assessed using a visual analogue scale (VAS) and the Lequesne function Index (LI). Joint kinetic changes were analyzed in the frontal and sagittal planes with 6-camera motion analysis system and two AMTI force plates. RESULTS:VAS and LI scores were both improved in OA group after IAHA injections (p<0.001). In the frontal plane, increased knee adduction moment (p<0.001) after IAHA treatment was observed and would last up to a period of 6 months. In the sagittal plane, lower knee extension moments at early stance, and larger knee flexion moments at terminal stance were demonstrated after the completion of IAHA injections (p<0.05). CONCLUSIONS:This study revealed that IAHA injections can provide significant pain relief and improvement in activity of daily living function for patients with knee OA. However, the reduction in pain and the increase in knee adduction moment may last up to 6 months. This may cause excessive loading on the knee joints, which may further accelerate the rate of knee degeneration. As a result, longer study time is needed to determine whether the observed kinetic findings in this study are associated with detrimental outcomes on the knee joints.