The effects of intra-articular deposition of betamethasone in the goat temporomandibular joint

Purpose: This study evaluated the response of the articular surfaces of the normal goat temporomandibular joint (TMJ) to intra-articular injections of betamethasone suspension. Methods: Thirty female goats were divided into four experimental groups of seven each and one control group of two animals. The design resulted in 24 joints receiving from one to nine weekly injections of betamethasone suspension, 0.085 mg/kg. The 24 contralateral joints received an identical array of saline injections. In the remaining 12 joints, four were unilaterally injected with saline, four were unilateral uninjected joints, and four were bilateral uninjected joints. All of the joints were inspected grossly and histologically assessed for any intra-articular changes associated with corticosteroid injections. Results: Comparative examination of the gross and histologic features of the injected joints and the eight normal joints showed no significant adverse effects on nondiseased TMJs. Conclusion: Intra-articular injection of betamethasone suspension at the dosage and delivery rate used had no harmful effects on the TMJs of nondiseased adult female goats. Because of possible differences between species, these results should not be taken as an indication that betamethasone suspension will not have adverse effects in the human TMJ. These findings support the need for further investigations into the physical and biochemical responses of normal and diseased articular fibrocartilage to different glucocorticosteroids at various concentrations and delivery rates using the goat and other animal models.