HETEROTOPIC OSSIFICATION - INCIDENCE IN CEMENTED VERSUS CEMENTLESS TOTAL HIP-ARTHROPLASTY

To resolve the debate whether cementless total hip arthroplasty (THA) carries an increased risk of heterotopic ossification (HO) as compared with cemented THA, 100 patients undergoing primary cemented THA (both acetabulum and femur) were individually matched to 100 patients under going primary cementless THA. Preoperative, 6-week postoperative, and 2-year postoperative radiographs were reviewed for the presence of HO using the Brooker classification. No subject in either group received any postoperative prophylaxis for HO. The matching parameters were age (+/- 10 years), sex, weight (+/- 10 Ib.), diagnosis (all were osteoar thritis), Charnley class (A/B), and surgical approach (trochanteric os teotomy or modified Hardinge). The overall incidence of HO was 68% in the cemented group and 65% in the cementless group. The extent of HO ( grade III) was significant in 9% of the cemented group and 5% of the c ementless group. There was no grade IV HO (bone ankylosis) in either g roup. Neither the overall incidence nor the incidence of grade III HO was statistically different between the two groups. Patient sex and su rgical approach had no interactive effect with type of component fixat ion on the incidence of HO. Fear of HO should not be a factor in the c hoice of fixation for THA.