Preoperative irradiation for prevention of heterotopic ossification following prosthetic total hip replacement results of a prospective study in 462 hips.
BACKGROUND
The effectiveness of pre- or postoperative radiotherapy for prevention of heterotopic ossification (HO) following total hip replacement (THR) has already been demonstrated in the past. Thereby, in most studies using preoperative radiotherapy patients were irradiated < 6 h before surgery. The purpose of this prospective study was to analyze the effectiveness of preoperative irradiation on the evening before surgery and to identify risk factors for HO in a homogeneous collective of patients.


METHODS
From July 1997 to July 2001, 416 patients (462 hips; 235 males, 227 females) received preoperative radiotherapy of the hip on the evening before surgery with a 7-Gy single fraction. The patients' median age was 67.1 years. The most frequent indication for radiotherapy was hypertrophic osteoarthritis (383 hips, 82.9%). Treatment results were assessed by comparison of pre- and postoperative hip X-rays (immediately and 6 months after surgery). The analysis of radiographs was performed according to the Brooker score.


RESULTS
The overall incidence of HO was 18.1% (n = 84), Brooker score 1 12.3% (n = 57), score 2 3.9% (n = 18), score 3 1.5% (n = 7), and score 4 0.4% (n = 2). Sex, body height, hypertrophic osteoarthritis of higher degree, size of the femoral component of the prosthesis, previous ipsi- or contralateral HO, and short course of nonsteroidal anti-inflammatory drug (diclofenac) therapy significantly influenced the HO rate in univariate analysis. In multivariate analysis, an interdependence of prosthesis size, sex and patient's height was found. From these three variables, only prosthesis size was statistically significant in multivariate analysis. The cumulative dose of diclofenac (< or = 300 mg or > 300 mg) within the first 7 postoperative days and previous ipsi- or contralateral HO influenced the incidence of HO in multivariate analysis.


CONCLUSIONS
Preoperative radiotherapy on the evening before surgery is an effective treatment modality to reduce overall (Brooker 1-4) and clinically relevant, severe HOs (Brooker 3-4), and includes several advantages compared to postoperative irradiation. Previous ipsi- and contralateral HOs were identified as high risk factors for HO in this study. In patients with these risk factors, the incidence of HO increased.
Koelbl
Oliver
O
Clinic and Policlinic for Radiotherapy, University of Würzburg, Germany. Koelbl_O@klinik.uni-wuerzburg.de
Seufert
Julia
J
Pohl
Fabian
F
Tauscher
Annette
A
Lehmann
Harald
H
Springorum
Hans-Werner
HW
Flentje
Michael
M
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000627:therapeutic use; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects*; D016009:Chi-Square Distribution; D004008:Diclofenac / Q000627:therapeutic use; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009765:Obesity / Q000150:complications; D009999:Ossification, Heterotopic / Q000453:epidemiology / Q000517:prevention & control*; D010003:Osteoarthritis / Q000150:complications; D011300:Preoperative Care; D011446:Prospective Studies; D011878:Radiotherapy; D011879:Radiotherapy Dosage; D012307:Risk Factors; D013997:Time Factors
D000894:Anti-Inflammatory Agents, Non-Steroidal; D004008:Diclofenac