[Scanning electron microscopic study of subchondral bone tissues in osteoarthritic femoral head]

In total hip replacement for 12 aged women with advanced osteoarthritis of the hip joint, three types of lesioned articular cartilage with various degrees of severity and ivory bone were obtained together with their subchondral bone tissues. These specimens were processed and studied under scanning electron microscope and were compared with sex and age-matched non-osteoarthritic femoral head articular cartilage specimens. In osteoarthritic femoral heads, with deepening of the articular lesion, the articular cartilage gradually became thinned out and eventually lost. The subchondral bone plate became markedly thickened in most of the specimens. The epiphyseal trabeculae were also thickened and turned rough so that the meshwork pattern gradually disappeared. The thickened trabeculae finally fused into a large piece of dense bone tissues without microfracture. These changes could be accounted for by the increased stress imposed on the subchondral bone tissues as a result of incompetence of the diseased articular cartilage. Consequently, the changes on the part of subchondral bone tissues of the osteoarthritic femoral heads were the sequent, rather than the cause, of the articular lesions.