Predictive factors of hyaluronic acid injections short-term effectiveness for TMJ degenerative joint disease

This study attempted to identify baseline predictors of positive outcome of arthrocenteses plus hyaluronic acid injections in degenerative temporomandibular joint disease (TMJ DJD). Ninety (n=90) consecutive patients with Research Diagnostic Criteria for Temporomandibular Disorders TMJ osteoarthritis (RDC/TMD 1.0 Axis I Group IIIb) underwent a cycle of five arthrocenteses with injections of 1mL hyaluronic acid and were followed up for 3months. Eight potential predictors of positive treatment outcome (sex, age, pain duration, baseline pain at chewing, presence of uni- or bilateral arthritis, presence of other concurrent RDC/TMD diagnoses, type of intervention and tolerability of treatment) were included in a logistic regression model to identify baseline predictors of treatment effectiveness. At follow-up, 85·6% of patients improved with respect to baseline VAS values, and 64·4% had a 50% or more decrease (positive outcomes). Correlation with positive outcomes existed only for unilateral osteoarthritis, and the logistic regression identified the side of arthritis (unilateral/bilateral) as the only predictor of positive treatment outcome (P=0·032). The achievement of any treatment improvement was predicted by high baseline pain levels (P=0·016). The regression models explained only 7·7-15% of the variance in the outcome variable. The attempts to find predictors of positive treatment outcome with HA injections for TMJ degenerative joint disease have been successful only in part. The search for other outcome predictors is likely to benefit from the assessment of psychosocial features associated with TMJ disorders.