Joint fluid injections help knee ligament heal

By David Douglas

NEW YORK (Reuters Health) - Injections of hyaluronic acid, a lubricating fluid found in joints, lead to early improvement in patients who have undergone anterior cruciate ligament (ACL) repair, according to Taiwanese researchers.

The ACL connects the thigh bone to the tibia, the larger of the two bones in the lower leg. The ligament, which is designed to prevent hyperextension at the knee joint, can be injured during sports activities, especially basketball, football, soccer and skiing.

"Our study findings imply that hyaluronic acid may increase the effect of rehabilitation for patients with ACL reconstruction," lead investigator Dr. Mao-Hsiung Huang told Reuters Health.

As reported in the Clinical Journal of Sports Medicine, Huang of Kaohsiung Medical University and colleagues studied 120 patients with an ACL injury who underwent reconstruction using part of a tendon connected to their knee cap.

All patients participated in a regular 16-week rehabilitation program and were randomly assigned to receive knee joint injections of hyaluronic acid or saline weekly for 3 weeks.

Thirty patients started hyaluronic acid injections at 4 weeks after surgery, 30 did so at 8 weeks, and 30 began at 12 weeks. The remaining 30 patients received normal saline starting 4 weeks after surgery.

Patients were regularly evaluated using tests measuring range of motion and walking speed, among other parameters.

There were improvements in all of the patients treated with hyaluronic acid shortly after receiving the agent, but not in patients given saline.

After the rehabilitation program, and at follow-up, patients who received hyaluronic acid after 8 or 12 weeks showed greater improvements in walking speed and maximum muscle strength. At 1 year, the best results were seen in patients who had started hyaluronic acid at 8 weeks.

In light of these findings, the researchers recommend using hyaluronic acid at 8 weeks in addition to rehabilitation in patients who have undergone ACL reconstruction.

SOURCE: Clinical Journal of Sports Medicine, July 2007.