Microcracks in articular calcified cartilage of human femoral heads.

The purpose of this work was to determine whether microcracks occur in calcified cartilage in vivo, and to use histological techniques to separate these from artifacts caused by processing. Six femoral heads without disease were split in the frontal plane. Sections from one slab were cut to 150 microns and stained with basic fuchsin. The other slab was stained en bloc, and sections were cut to 150 microns after staining. Sections were examined microscopically, and microcrack density was calculated. Data show that microcracks occur routinely in calcified cartilage from nondiseased femoral heads of aged humans, and that they can be separated from processing artifact. Their physiological significance is unknown, but it is possible that microcracks may trigger vascular invasion of subchondral bone and may play a role in the initiation and progression of osteoarthrosis.