Internal derangement (ID) and osteoarthritis (OA) are often encountered in temporomandibular joint (TMJ) disorders. It is known that high concentrations of interleukin (IL)-1β and tumor necrosis factor (TNF)-α are detected in the synovial fluids of patients with ID and OA. IL-1β and TNF-α play key roles in intracapsular pathological conditions of the TMJ. Gene expressions induced by IL-1β and/or TNF-α in synoviocytes obtained from human TMJ were analyzed using microarrays. Microarray analysis showed that levels of IL-6 and leukemia inhibitory factor (LIF), which are in the IL-6 cytokine family, were up-regulated in synoviocytes stimulated with IL-1β and/or TNF-α. The IL-6 cytokine family, which contains IL-6, LIF, oncostatin M (OSM), IL-11, and IL-12, is associated with inflammation and tissue destruction. We examined the gene expressions of IL-6 cytokine family members and their receptors in synoviocytes stimulated with IL-1β and/or TNF-α using RT-PCR, and real-time PCR. The up-regulated levels of IL-6 and LIF were greatest following stimulation with both IL-1β and TNF-α and least following stimulation with only TNF-α. Protein production of IL-6 and LIF also increased in synoviocytes stimulated with IL-1β and/or TNF-α. The up-regulated levels of IL-6 and LIF protein productions reflected the gene expression levels. The gene expressions of OSM, IL-11, and IL-12 were not detected in synoviocytes. Glycoprotein 130 (gp130), which is a receptor subunit for signal transduction of the IL-6 cytokine family, LIF receptor, OSM receptor, and IL-11 receptor were expressed in synoviocytes constitutively. In conclusion, IL-1β and TNF-α may cause abnormalities associated with intracapsular pathological conditions of the TMJ through the enhanced expression of IL-6 and LIF in synoviocytes.

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The patient was a 38-year-old female who visited our hospital with the chief complaints of disturbance of mouth opening and left temporomandibular arthralgia. On MRI, closed lock due to bilateral non-reducible anterior disc displacement was noted. After pumping manipulation, sufficient mouth opening was temporarily obtained and arthralgia remitted, but it aggravated. A reduced mouth opening distance, shooting pain of temporomandibular arthralgia, and spontaneous frontal headache developed. Lavage, bite raising with a splint, and the repeated injection of sodium hyaluronate were performed but ineffective. Suspecting articular disc adhesion, arthroscopic dissection and mobilization were performed. Bilateral synovitis and adhesions were noted, and the condition was severe on the left side. After surgery, mouth opening training was actively performed. The mouth opening distance was 53 mm after 7 weeks, and arthralgia was completely remitted at 3 months. The patient showed strong anxiety after surgery. Arthralgia remitted as symptoms of anxiety were alleviated by treatment.

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We report a case of prolonged dislocation of the unilateral temporomandibular joint who was treated by eminoplasty and removal of fibrous adhesive lesions in the upper joint cavity. A 78-year-old woman was referred to our department because of difficulty in closing the mouth for over 1 month. CT and MR images showed that the right condyle was dislocated in front of the articular eminence. Since conservative treatment failed, open reduction was performed under general anesthesia. She could recover normal masticatory function without no evidence of dislocation.

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