Hyaluronic acid in synovial fluid. VI. Effect of intra-articular injection of hyaluronic acid on the clinical symptoms of arthritis in track horses.

Twelve horses with traumatic arthritis were treated with intraarticular injection of hyaluronic acid mixed with cortisone and the results compared with 6 horses treated only with cortisone. There was a significantly better improvement in the group injected with a mixture of hyaluronic acid and cortisone. Further studies have given the same results in traumatic arthritis in horses if hyaluronic acid alone is injected. After injection of hyaluronic acid a large number of granulated monocytes appeared in the synovial fluid, but no inflammatory signs were observed. It is possible that this macrophage invasion is instrumental in producing improvement in the condition of the joint. The injected hyaluronic acid may also adhere to the surface of articular cartilage producing an “clastic cushion” protecting the cartilage surface. Experimental mechanical damage was also inflicted on the surface of articular cartilage in dogs and monkeys, and smoother healing was achieved if hyaluronic acid was injected into the joints after the damage. Injections of hyaluronic acid seem to be of value in treating traumatic arthritis or similar conditions.