Origin of bone hyperplasia in osteoarthritic femoral head. Tetracycline labelling and scanning electron microscopic study.

Total hip replacement was carried out in 7 patients with advanced osteoarthritis of the hip joint. The patients were given tetracycline orally before operation to label the newly formed bone tissues. The excised femoral heads were processed into undecalcified sections, which were subjected to both fluorescence microscopic and scanning electron microscopic (SEM) observation. Band-shaped golden fluorescence was detected along the trabeculae, reflecting newly formed bone tissues by the cambium layer of the periosteum. In the intertrabecular space, reticular and spherical golden fluorescence was detected, implying newly formed bone tissues by the marrow stromal cells. Under SEM, both reticular and spherical new bone tissues were discovered in the inter-trabecular space as mentioned above. There were two forms of reticular new bone tissues, a diffuse form and a tape-shaped new bone tissues. The diffuse bone tissues grew and expanded and eventually studded the inter-trabecular space. The tape shaped tissues, which were first deposited on the trabecular arch surface, increased in amount and then woven into thin and dense tapes of the reticulum. These tapes contacted in an end-to-end fashion, and appeared to shuttle back and forth through the trabecular arches, forming new secondary arch structures. The spherical new bone tissues were deposited on the surface of the trabecular arch structures and gradually packed the intertrabecular space. These new bone tissues were contributed to hyperplasia in the osteoarthritic femoral head.