Alterations in rat condylar cartilage following discectomy

The purpose of this study was to examine the effect of unilateral extirpation of the articular disc of the temporomandibular joint on selected metabolic and compositional characteristics of the condylar cartilage. Unilateral discectomy was performed in one group of growing (28-day-old) rats, while another group received only unilateral arthrotomy. The effect of the discectomy procedure was assessed by comparison of ratios of the operated to unoperated sides in the discectomy and arthrotomy groups. Total uronic acid content (micrograms/mg dry tissue wt) of the condylar cartilage and [35S]-sulfate incorporation (dpm/micrograms uronic acid) into the condylar cartilage were decreased in discectomy-group animals at nine, 16, and 28 days following surgery, while hydration of the cartilage was increased in discectomy animals at both 16 and 28 days post-surgery. Wet and dry tissue weights of the cartilage were dramatically increased in discectomy-group animals at all post-operative intervals. These metabolic and compositional changes were accompanied by pronounced structural alterations in the cartilage, including chondrocyte clustering and tears parallel to the articular surface. With the exception of [35S]-sulfate incorporation, the changes demonstrated in the condylar cartilage following discectomy were similar to early osteoarthritic alterations reported in limb articular cartilage following partial meniscectomy or cruciate ligament resection.