Temporomandibular joint internal derangements in an orthognathic surgery population.

Of a selected group of 39 patients referred for orthognathic surgery, 38 were found to have some stage of internal derangement of the temporomandibular joint prior to surgery, a much higher incidence than previously reported in either symptomatic patients or asymptomatic individuals. Fifteen of 30 patients with follow-up greater than 12 months developed a new arthrosis after orthognathic surgery. All arthroses occurred in previously deranged joints. None of these patients has required joint surgery, but three have experienced pain. Internal derangement may be a contributing factor in the development of dentofacial deformities, and new loading of deranged joints after orthognathic surgery may be a cause of a new arthrosis and skeletal relapse.