Randomized trial comparing preoperative versus postoperative irradiation for prevention of heterotopic ossification following prosthetic total hip replacement: preliminary results.

PURPOSE

Previous in vivo data support effectiveness of preoperative irradiation in suppressing heterotopic ossification (HTO) in a rat model. A prospectively randomized, multiinstitution clinical trial to assess the comparative efficacy of preoperative vs. postoperative irradiation in preventing HTO in total hip replacement patients was undertaken.

METHODS AND MATERIALS

One hundred and twenty-two patients (124 hips) with significant risk factors for HTO following elective total hip replacement were randomized to receive irradiation via either preoperative (< 4 h before surgery) or "standard" postoperative (< 48 h after surgery) schedules. Single 7-8 Gy fractions were administered. Treatment volume included soft tissues between periacetabular region of pelvis and intertrochanteric portion of femur. All but nine patients had biologic fixation prostheses, the porous-coated portions of which were shielded. Radiographs of treated hips were obtained immediately and at 2 and 6 months postsurgery. Heterotopic ossification was scored according to the Brooker Grading system.

RESULTS

Ninety-eight patients are evaluable (55 preoperative, 43 postoperative) with median follow-up of 38 weeks. No significant differences were noted in the incidence of overall HTO (26% preoperative vs. 28% postoperative, p = 1.0) or clinically significant Brooker grade 3 or 4 HTO (2% preoperative vs. 5% postoperative, p = 0.58). No significant differences in treatment variables (including time interval between preoperative irradiation and surgery) were evident on comparing preoperatively treated patients forming HTO with those who did not.

CONCLUSION

Prophylactic irradiation of the operative site within 4 h prior to elective total hip replacement appears to be comparably effective to the currently accepted postoperative treatment schedules in prevention of clinically significant HTO about the hip. This finding is of importance in terms of patient comfort, ease of treatment, and avoidance of possible complications associated with moving the patient to the radiotherapy department in the immediate postoperative period.