A prolonged time interval between trauma and prophylactic radiation therapy significantly increases the risk of heterotopic ossification.
OBJECTIVE
To ascertain whether the time from injury to prophylactic radiation therapy (RT) influences the rate of heterotopic ossification (HO) after operative treatment of displaced acetabular fractures.


METHODS
This is a single-institution, retrospective analysis of patients referred for RT for the prevention of HO. Between January 2000 and January 2009, 585 patients with displaced acetabular fractures were treated surgically followed by RT for HO prevention. We analyzed the effect of time from injury on prevention of HO by RT. In all patients, 700 cGy was prescribed in a single fraction and delivered within 72 hours postsurgery. The patients were stratified into five groups according to time interval (in days) from the date of their accident to the date of RT: Groups A ≤3, B ≤7, C ≤14, D ≤21, and E >21 days.


RESULTS
Of the 585 patients with displaced acetabular fractures treated with RT, (18%) 106 patients developed HO within the irradiated field. The risk of HO after RT increased from 10% for RT delivered ≤3 days to 92% for treatment delivered >21 days after the initial injury. Wilcoxon test showed a significant correlation between the risk of HO and the length of time from injury to RT (p < 0.0001). Chi-square test and multiple logistic regression analysis showed no significant association between all other factors and the risk of HO (race, gender, cause and type of fracture, surgical approach, or the use of indomethacin).


CONCLUSIONS
Our data suggest that there is higher incidence and risk of HO if prophylactic RT is significantly delayed after a displaced acetabular fracture. Thus, RT should be administered as early as clinically possible after the trauma. Patients undergoing RT >3 weeks from their displaced acetabular fracture should be informed of the higher risk (>90%) of developing HO despite prophylaxis.
Department of Radiation Oncology, University of Mississippi Medical Center, Jackson, MS, USA. Waleed246@gmail.com
Waleed F
WF
Mourad
Satyaseelan
S
Packianathan
Rania A
RA
Shourbaji
Zhen
Z
Zhang
Mathew
M
Graves
Majid A
MA
Khan
Michael C
MC
Baird
George
G
Russell
Srinivasan
S
Vijayakumar
D000077:Acetabulum / Q000000981:diagnostic imaging / Q000293:injuries*; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000627:therapeutic use; D016009:Chi-Square Distribution; D005260:Female; D050723:Fractures, Bone / Q000000981:diagnostic imaging / Q000209:etiology / Q000601:surgery*; D006801:Humans; D007213:Indomethacin / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D009999:Ossification, Heterotopic / Q000000981:diagnostic imaging / Q000209:etiology* / Q000517:prevention & control; D011183:Postoperative Complications / Q000000981:diagnostic imaging / Q000517:prevention & control; D011859:Radiography; D011879:Radiotherapy Dosage; D012044:Regression Analysis; D012189:Retrospective Studies; D012306:Risk; D018709:Statistics, Nonparametric; D013997:Time Factors; D055815:Young Adult
D000894:Anti-Inflammatory Agents, Non-Steroidal; D007213:Indomethacin