Lipochondral degeneration of capsular tissue in osteoarthritic hips.

Lipochondral degeneration (LCD) was found in the capsular tissue of 33 of 74 resected osteoarthritic hips studied retrospectively and in 14 of 35 studied prospectively, but never in a control group (n = 46). The process arose in the ligamentous structures that had undergone nodular chondroid metaplasia. The lesion was characterized by vacuolar distention of chondrocytes, eventual necrobiosis, and formation of acellular pools of lipid material. The latter was shown by oil red O staining and electron microscopy. Matrix alterations included glycosaminoglycan depletion, formation of elastin-related material, and degeneration of collagen fibers. There was no significant correlation (p = 0.05) between the occurrence of LCD and the severity of the osteoarthritis; neither was any association found with age, sex, calcium pyrophosphate dihydrate deposition, diabetes mellitus, or coronary artery disease.