The osteoblastic response to osteoarthritis of the hip. Its influence on the long-term results of arthroplasty.

We have followed up a series of total hip arthroplasties performed for secondary osteoarthritis and analysed the results in relation to the osteoblastic response to the disease. This was assessed pre-operatively from the radiographic appearance, according to Bombelli's criteria (1983). Of 63 hips in 55 patients followed up for five to 13 years, 17 were hypertrophic, 24 normotrophic and 22 atrophic in type. The atrophic-type hips showed a high incidence of acetabular loosening, leading to unsatisfactory clinical results in 32%. By contrast, the hypertrophic-type hips had a low incidence of acetabular loosening, while the normotrophic type showed intermediate results. It was concluded that the osteoblastic response to osteoarthritis is closely related to acetabular loosening and to late clinical failure.