Osteoarthritis in the Temporomandibular Joint and Knee Joint: A Macroscopic Study of Cadaver Specimens

In this study, thirty-one TMJs and twenty-eight knee joints were dissected from seventeen cadaveric subjects aged 69 to 95. Degenerative/osteoarthritic changes on the mandibular condyles, mandibular fossae, and femoral condyles were evaluated macroscopically and assigned a score on a disease severity scale (DSS) from 0 signifying “normal cartilage” to 4 signifying “severe OA”. Osteoarthritic changes were found in all TMJ and knee specimens. The average mandibular condyle DSS score was 2.68 ± 0.96, while the average mandibular fossa score was 2.90 ± 0.76; this difference in scores was significant (P = 0.035). Additionally, the mandibular fossa was equally or more severely degenerated than the mandibular condyle in 87% of the TMJ specimens. The majority of degenerative changes observed in this study were found along the lateral aspects of the TMJ components. No statistically significant correlation was found between TMJ OA severity and subject age or TMJ OA severity and subject gender. While studies have been published comparing OA in the TMJ to OA in other joints, to the authors’ knowledge the work presented here is the first to directly compare macroscopic degenerative changes in the TMJ to those in the knee joints of the same subjects. The DSS scores of the femoral condyles were found to be statistically comparable to those of the mandibular fossa, while the mandibular condyles were found to be less degenerated than the femoral condyles (P=0.04). Previous studies have shown a weak correlation between degenerative changes in the metatarsophalangeal joints and the TMJs in the same subjects, but no significant correlation or mixed results when comparing the TMJs to the hand or sternoclavicular joints. It is therefore hypothesized that the statistically comparable degeneration found in this study in the temporomandibular and knee joints is due to their load-bearing functions.