The role of osteophytic growth in hip osteoarthritis.

We studied the appearance and frequency of the medial epiarticular osteophyte in human femoral heads. Specimens were sampled from 24 men and 31 women who underwent total hip arthroplasty. On radiography, medial epiarticular osteophytes were present in two thirds of the cases. However, histological examination revealed endochondral ossification in all. Presumably, the bone formation was preceded by the formation of canals and cavities containing vessels. Due to the ossification around these canals and cavities, the histological picture frequently featured two layers of cartilage with bone in the middle. Also in the marginal osteophytes, bone was formed by endochondral ossification. However, this bone appeared more irregular. The new bone formation most likely indicates a reactivated growth as an attempt to repair the osteoarthritic lesions rather than a process of degradation.