Periarticular heterotopic ossification after total hip arthroplasty for primary coxarthrosis.

Periarticular heterotopic ossification (PHO) is a common roentgenographic finding, occurring in more than two-thirds of patients after total hip arthroplasty (THA) for coxarthrosis. In the present study, 56 patients treated with bilateral THA were analyzed to determine the correlation between heterotopic ossification on the two sides. A strong correlation was found between the grade of PHO on the two sides: patients who developed severe PHO after the first THA invariably developed considerable PHO after surgery on the other side. The incidence and grade of PHO were higher in men than in women.