Degenerative changes of the human temporomandibular joint : A radiological, microscopical, histomorphometrical and biochemical study

Abstract: In five autopsy specimen studies human temporomandibular joints were investigated by conventional tomography, macroscopy, and microscopy for degenerative changes, in particular erosive hard-tissue changes.In the microscopical evaluation special attention was paid to the calcified cartilage. The calcified cartilage was outlined by a flat or gently undulating basophilic tidemark and an irregular osteochondral junction. A significant correlation was found between the thickness of the calcified cartilage and that of the total articular cartilage. Two types of erosive changes were found; an extensive type with complete loss of overlying cartilage and a local type with retained cartilage. The erosive changes were generally more extensive in the condyle. Microscopically, the erosive changes in the condyle were evenly distributed. In the temporal component there was a slight predominance of these changes located to the lateral part of the tubercle. Tomography underestimated both the presence and the extent of the erosive changes. Positive predictive values and negative predictive values were 0.70 and 0.83, respectively, for changes in the condyle and 0.91 and 0.68 for changes in the temporal component. The likelihood ratio for a positive test was 10.6 in the temporal component and 5.6 in the condyle. The likelihood ratio for a negative test was comparable in the two joint components 0.49 and 0.47 respectively. Three different techniques of computer-aided bone histomorphometry (manual, automatic and semi-automatic) were assessed. The variation when assessing the total and trabecular bone volume was evaluated. Good reproducibility in the assessment of the total and trabecular bone volume was achieved with the aid of a single observer and a semi-automatic technique. This technique was therefore used to assess the total and trabecular bone volume in condyles and temporal components of joints with and without microscopically verified erosive changes. Condyles with erosive changes demonstrated both a higher trabecular bone volume (P< 0.05) and higher total bone volume (P< 0.01) than condyles without erosive changes. In a clinical study on patients undergoing diskectomy, the two cartilage matrix macromolecules aggrecan and cartilage oligomeric matrix protein (COMP) were quantified by enzyme-linked immunosorbent assay in lavage fluids from temporomandibular joints before and six months after surgery. The aggrecan/COMP ratio was higher in the lavage fluid of all joints at follow-up as compared to preoperatively. All joints developed radiographic changes indicative of degenerative changes (osteoarthrosis) during the postoperative period.

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