Influence of intra-articular injections of sodium hyaluronate on clinical features and synovial fluid nitric oxide levels of temporomandibular osteoarthritis

OBJECTIVE: This study was designed to assess the effect of intra-articular injection of sodium hyaluronate (SH) on clinical findings of temporomandibular osteoarthritis (OA) and on synovial fluid (SF) levels of nitric oxide (NO). METHODS: Twenty seven patients (7 men, 20 women, mean (SD) age 53.9 (11.8) years) with OA of the temporomandibular joint were randomly allocated to receive an injection of either SH (2 ml, Hyalgan, Fidia SpA, Abano T., P.M. 500-700.000, 20 mg/2 ml; once a week for 5 weeks) or a Ringer's lactate solution (once a week for 3 weeks). Clinical evaluation was done before each procedure, and at 1 week, 1, 3 and 6 months post-injection. Intensity of temporomandibular joint pain, jaw function, maximal mouth opening and lateral jaw movements were recorded at each visit. NO was measured on SF collected by rinsing the joint with saline 1 ml before the treatment. RESULTS: Injection of SH caused significant improvement in the main clinical symptoms until the last follow-up which was carried out 6 months after last injection. Among patients who received SH injection, those who reached a good outcome showed the lowest basal levels of NO. CONCLUSIONS: The results of this study showed that intra-articular injections of SH lead to a lasting improvement in the clinical symptoms of temporomandibular OA. Furthermore, our findings suggest that low NO levels in SF are related to a better outcome of temporomandibular OA among patients treated with SH intra-articular injection.