A Prolonged Time Interval Between Trauma and Prophylactic Radiation Therapy Significantly Increases the Risk of Heterotopic Ossification

Mourad, Waleed F.; Packianathan, Satyaseelan; Shourbaji, Rania A.; Zhang, Zhen; Graves, Mathew; Khan, Majid A.; Baird, Michael C.; Russell, George; Vijayakumar, Srinivasan

doi:10.1016/j.ijrobp.2011.06.1981

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Volume 82, Issue 3 , Pages e339-e344, 1 March 2012

A Prolonged Time Interval Between Trauma and Prophylactic Radiation Therapy Significantly Increases the Risk of Heterotopic Ossification

Presented at the 51st Annual Meeting of the American Society for Radiation Oncology, October 2009, Chicago, IL.

Waleed F. Mourad, M.D., M.Sc.
- Department of Radiation Oncology, University of Mississippi Medical Center, Jackson, MS
- Department of Radiation Oncology, Beth Israel Medical Center, New York, NY
- Reprint requests to: Waleed F. Mourad, M.D., M.Sc., 10 Union Square E. Suite 4 G, New York, NY 10003. Tel: (212) 844-8087; Fax: (212) 844-8086
Satyaseelan Packianathan, M.D., Ph.D.
- Department of Radiation Oncology, University of Mississippi Medical Center, Jackson, MS
Rania A. Shourbaji, M.P.H.
- Department of Epidemiology and Biostatistics, Jackson State University, Jackson, MS
Zhen Zhang, M.S.
- Department of Orthopedic Surgery, University of Mississippi Medical Center, Jackson, MS
Mathew Graves, M.D.
- Department of Orthopedic Surgery, University of Mississippi Medical Center, Jackson, MS
Majid A. Khan, M.D.
- Department of Radiology, University of Mississippi Medical Center, Jackson, MS
Michael C. Baird, M.D.
- Department of Radiation Oncology, University of Mississippi Medical Center, Jackson, MS
George Russell, M.D.
- Department of Orthopedic Surgery, University of Mississippi Medical Center, Jackson, MS
Srinivasan Vijayakumar, M.D.
- Department of Radiation Oncology, University of Mississippi Medical Center, Jackson, MS

Received 5 May 2011; received in revised form 17 June 2011; accepted 24 June 2011. published online 21 October 2011.

Purpose

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 and Materials

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 >21days.

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.

Keywords: Time interval, Prophylactic radiation therapy, Displaced traumatic acetabular fracture, Heterotopic ossification radiation prophylaxis