Macroscopically normal cartilage from the human osteoarthritis femoral head. I. Histological evaluation

Thirty-five macroscopically "normal" cartilage specimens from 32 osteoarthritic (OA) femoral heads removed surgically were histologically analyzed, and found to be composed of both normal and abnormal cartilage. The latter showed either middle tissue layer alterations or invasion by new tissues of extracartilaginous origin. Middle cartilage layer alterations consisted of unmasked fibers and loss of matrix staining with alcian blue and were found to be closely related to the development of new osteophytic tissues. Thus in OA the appearance to the naked eye of normal cartilage is inappropriate for valid biochemical studies, and a microscopic control of "normal tissue" appears to be necessary for any study of early cartilage changes in OA.