Therapeutic effect of hyaluronic acid on experimental osteroarthrosis of ovine temporomandibular joint

A symptomatic relief by hyaluronic acid (HA, MW: 3.5 x 10(6)), which is syn thesized by Streptococcus spp, was investigated in experimental ovine osteo arthrosis. Bilateral osteoarthrosis (OA) of the temporo-mandibular joints ( TMJs) was induced by perforating discs and by scrapping subchondral condyla r surface, HA was intra-articularly injected into the left joints of 6 shee p on 7, 10, 14, 17 and 21 days after the operation and physiological saline as the control was injected into the contralateral (right) joints on the s ame day. Three sheep were killed at I month post-operation (MPO) and the re maining three sheep were killed at 3 MPO. Various responses such as prolife ration of fibrous tissue, denudation, erosion, osteophyte, formation, subco rtical cyst formation and ankylosis were observed radiographically and hist opathologically. The treatment of HA ameliorated the degenerative changes a nd lowered the osteoarthrotic score in the left joints at 1 MPO (9.96 vs 5. 81) and 3 MPO (10.86 vs 5.29) compared to the right joints. These results i ndicate that a repeated intra-articular injection of HA inhibits the progre ssion of OA in ovine TMJs by inducing the development of articular cartilag e and by reducing the proliferation of fibrotic tissue.