43 patients with bilateral osteoarthritis of the knee were selected to have one of their knees treated with 5 weekly intra-articular injections of hyaluronic acid (HA), with the other knee serving as a control. The purpose of the study was to determine the efficacy of this regimen of hyaluronic injections in the knee, in terms of muscle strength and pain. The results indicated that HA injections caused a significant reduction in Lequesne score, improvements in isokinetic peak torque of flexors and extensors and total workload of the knee at both extension and flexion. Additionally, HA injections were shown to decrease VAS pain scores, after 5 weeks.