Osteoarthritis and internal derangement of the temporomandibular joint: a light microscopic study.

To describe osteoarthritic changes of the temporomandibular joint (TMJ) and their relation to internal derangements, 22 randomly selected TMJ autopsy specimens were dissected and studied by light microscopy. Normal disc position was seen in eight joints, partial anterior displacement of the discs in eight joints, and complete anterior displacement of the discs in five joints; one joint had a perforated disc. Degenerative changes, such as horizontal splitting, clustering of chondrocytes, bone marrow fibrosis, sclerosis, erosion, cyst formation, and reduction in TMJ size, were found in 11 of the 14 joints with displacement or perforation of the disc and in four of the eight joints with normal disc position. Internal derangement appeared to be associated with osteoarthritis. The relations between remodeling, aging, internal derangement, and osteoarthritis are discussed.