This study investigates the histological effects of Hyaluronic acid injections in the treatment of induced temporomandibular joint (TMJ) osteoarthritis in rats.
Twenty-four male Wister rats were subjected to induced mechanical osteoarthritis by manual hypermobility for 10 successive days. Animals were then divided into two groups; group I (control) and group II (experimental). Ten days after the induction of hypermobility, the right TMJ of the experimental animals was injected with a dose of 0.12 mg HA intra-articularly and 0.12 mg saline was injected into the left joint; while animals in the control group were left without any treatment. Two rats from group I were killed at one, two and six weeks; while 6 animals from group II were killed at one, two and four weeks post injection.
The disk of the right joints in the experimental animals was of normal thickness and there was an increase in the thickness of the fibrocartilagenous layer. In the left joint; ulcerative changes in the disk were evident where the fibres were not well oriented and scalloped areas in the temporal bone area were present denoting osteoclastic activity.
Repeated intra-articular TMJ injection of Hyaluronic acid appears to be a safe and effective way of inhibiting the progression of osteoarthritic changes in the joint through development of articular cartilage and reducing fibrous tissue proliferation.