The authors retropectively reviewed 378 total hip arthroplasties(THR) in placed in 321 patients between January 1987 and November 1991. We examined all of the radiographs at a minimum of 6 months afer operation and classified the
severity of
the heterotopic ossification by Brooker et al. The purpose of this study was to investigate the incidence of hetertopic ossification(HO) after THR and to find out the risk factor for HO development in Korea.
The overall incidence of heterotopic ossification was 435(162 cases). The degrees were class I in 108 hips(67%), class II in 37 hips(22%), class III in 14 hips(3.7%), and class IV in 4 hips(3%). The incidence were 68 hips(37.80%) in
avascular necrosis, 23 hips(53.8%) in osteoarthritis, 39 hips(56.5%) in fracture, 12 hips(48%) in tuberculous arthritis, 7 hips(58.3%) in fracture, 12 hips(48%) in tuberculous arthritis, 7 hips(58.3%) in pyogenic arthritis, 5 hips(83.4%) in
ankylosing spondylitis, 4 hips(50%) in rheumatoid arthritis and 3 hips (75%) in fused hip. Three cases of class IV belonged to tuberculous arthritis group. The incidence of heterotopic ossification had not a significant correlation
with
age, sox, preop hip function and weight. The Harris hip scores of class IV were significantly lower than any other classes. IN conclusion, the incidence of the hiterotopic ossification was 162(43%) in 378 cases. There was p predisposition
to
develop severe heterotopic ossification among patients with tuberculous arthritis.
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