The effect of hyaluronic acid on experimental temporomandibular joint osteoarthrosis in the sheep

Purpose The purpose of this study was to test the effect of repeated injections of hyaluronic acid (HA) on the sheep model of osteoarthrotic temporomandibular joint (TMJ) disease. Materials and Methods Bilateral Osteoarthrosis (OA) was induced in the TMJs of six sheep. HA was injected into one joint on 7, 10, 14, 17, and 21 days postoperatively. Normal saline was injected into the contralateral joint. Three sheep were killed at 1 month and 3 at 3 months. The joints were removed and examined macroscopically and histologically. A special scoring system was applied following the modified Mankin's score to evaluate the histologic changes. Results The control group showed severe osteoarthrotic changes in the condyle, deviation in form from normal morphology, and marked marrow fibrosis. The HA-treated group showed less deviation from normal condylar morphology. The histologic scores at 1 month were HA 12.6, control 24.2 ( P