Do Surrogates of Injury Severity Influence the Occurrence of Heterotopic Ossification in Fractures of the Acetabulum?

OBJECTIVES

To determine the relationship between injury severity surrogates and other patient factors with the development and severity of heterotopic ossification (HO) following open reduction internal fixation of acetabular fractures treated with a posterior approach.

DESIGN

Retrospective review.

SETTING

Academic level 1 trauma center.

PARTICIPANTS

Two hundred forty-one patients who were treated through a posterior approach with a minimum of 6-month radiographic follow-up were identified from an acetabular fracture database.

INTERVENTION: None.

MAIN OUTCOME MEASURES: The occurrence and severity (Brooker Grade III/IV) of HO 6 months postsurgery.

RESULTS

Length of stay (LOS) in the intensive care unit (ICU), non-ICU LOS >10 days, and HO prophylaxis with external radiation beam therapy (XRT) were significantly associated with the development of HO in a multivariate model [ICU LOS: 1-2 days, odds ratio (OR) = 4.33, 95% confidence interval (CI): 1.03-18.25; 3-6 days, OR = 4.1, 95% CI, 1.27-13.27; >6 days, OR = 11.7, 95% CI, 3.24-42.22; non-ICU LOS >10 days (vs. 0-6 days): OR = 7.6, 95% CI, 2.6-22.25; XRT HO prophylaxis: OR = 0.29, 95% CI, 0.10-0.85]. Other variables evaluated in multivariate modeling not significantly associated with development and severity of HO included age, gender, mechanism of injury, injury severity score, presence of neurologic injury, Letournel fracture type, occurrence of hip dislocation, interval from injury to surgery, operative time, and estimated blood loss.

CONCLUSIONS

Surrogates of injury severity, including days in the ICU and non-ICU hospital LOS >10 days, were associated with the development of HO in our cohort of acetabular fracture patients. Prophylaxis with XRT was significantly protective against the development of HO, and the ability to provide prophylaxis is very likely related to the severity of injury.

LEVEL OF EVIDENCE: Prognostic Level II. See Instructions for Authors for a complete description of levels of evidence.