Preoperative irradiation versus the use of nonsteroidal anti-inflammatory drugs for prevention of heterotopic ossification following total hip replacement: the results of a randomized trial.

PURPOSE

Previous studies showed the effectiveness of early preoperative (4 h before operation) irradiation for prevention of heterotopic ossification (HO) after total hip replacement. This procedure can result in logistic problems, if there is a great distance between the department of radiotherapy and the orthopedic clinic. To avoid these organizational problems a prospective study was undertaken to analyze the effectiveness of preoperative irradiation on the day preceding surgery (16-20 h before operation).

METHODS AND MATERIALS

Between 1995 and 1996, 100 patients were randomized to receive a prophylactic therapy for prevention of heterotopic ossification. Forty-six patients were irradiated with 7 Gy single dose within 16-20 h before operation. Fifty-four patients were treated with nonsteroidal anti-inflammatory drugs (NSAID) (Voltaren resinat 2 x 75 mg/day for 2 weeks). Heterotopic ossification was scored according to the Brooker Grading system. One hundred patients receiving no prophylactic therapy after total hip arthroplasty between 1988 and 1992 were analyzed and defined as the historical control group.

RESULTS

Incidence of heterotopic ossification was 47.8% in the 7 Gy preoperative group (Brooker Score I: 36.9%; II: 8.7%; III: 2.2%; IV: 0%) and 11.1% in the NSAID group (Brooker Score I: 9.3%; II: 1.8%; III: 0%; IV: 0%). Regarding overall heterotopic ossification there was a significant difference between the NSAID group and the 7 Gy group (p < 0.01). Analyzing the clinically significant heterotopic ossification (Brooker Score III and IV) there was no significant difference between the two treatment arms (p > 0.05). In the untreated historical control group the incidence of heterotopic ossification was 65% (Brooker Score I: 26%; II: 15%; III: 19%; IV: 5%). Referring to overall and to clinically relevant heterotopic ossification the incidence of HO was greater in the control group than in the prophylactically treated groups (p < 0.05).

CONCLUSION

Irradiation within 16-20 h before operation and use of NSAID (Voltaren resinat) can reduce the incidence of clinically relevant heterotopic ossification after total hip replacement.