Pressure-pain thresholds and MRI effusions in TMJ arthralgia

It has been suggested that MRI-depicted effusions identify patients with TMJ arthralgia. The Research Diagnostic Criteria (RDC) propose a pressure-pain threshold (PPT) of 1 pound for the identification of TMJ arthralgia. The hypotheses in this study were that: (1) there is no association between MRI-depicted effusions and TMJ arthralgia, and (2) a PPT of 1 pound does not discriminate between subjects with and those without arthralgia. Thirty females with TMJ disc displacement with reduction were divided into two groups based on the presence or absence of the self-report of TMJ pain. Bilateral TMJ PPTs and MRIs were obtained. Increasing palpation pressure from 1 to 3 pounds increased the sensitivity for identifying arthralgia from 22% to 100%, with a corresponding decrease in the specificity from 100% to 81%. The sensitivity and specificity of effusions for identifying arthralgia were 85% and 28%, respectively. These results suggest that the use of palpation pressures greater than 1 pound is a valid test for TMJ arthralgia. However, TMJ effusions lack adequate specificity for identifying TMJ arthralgia and were not associated with pain.