Do signs of an effusion of the temporomandibular joint on magnetic resonance imaging correlate with signs and symptoms of temporomandibular joint disease?

Effusions are common among patients with disorders of the temporomandibular joint (TMJ), but publications are limited and results inconsistent about the correlation between them and important clinical variables, in particular severity of pain and degenerative disease. We organised a retrospective study of patients who presented for the evaluation and management of arthralgia of the TMJ and myofascial pain at the University of Michigan between 2011 and 2014. Inclusion criteria were: patients who had pain that was primarily arthrogenous, and coexisting myogenous pain, who had had initial non-surgical treatment, and arthroscopy of the TMJ with or without intramuscular injection of onabotulinumtoxinA (Botox,® Allegan, Weston, Fl, USA). The primary outcome variables were pain at rest as measured by visual analogue score (VAS) and the presence of degenerative disease of the joint. The secondary outcome variables included the position of the disc and whether it was perforated, signs of synovitis, maximal interincisal opening (MIO), and duration of symptoms. We studied 47 patients (94 TMJ) who met the inclusion criteria. We found no significant differences in pain at rest before or after arthroscopy, between patients with and without effusions, or in maximal MIO or duration of symptoms between the two groups. There was, however, a significant relation between effusions and degenerative joint disease. Effusions were also associated with a lower probability of the disc being in a normal position and a higher probability of anterior disc displacement without reduction.