Risk factors for posttraumatic heterotopic ossification of the elbow: case-control study.

PURPOSE

Heterotopic ossification (HO) is well-known after surgical repair of elbow fractures, but little is known about risk factors for its development in these patients. The purpose of this study was to define factors associated with development of HO.

METHODS

We used a prospective fracture registry collected in 2 Level I trauma centers and medical chart review to examine all elbow fractures treated surgically between 2002 and 2009. We determined which of these patients developed HO with an impact on range of motion (Hastings class II and III). We conducted a matched case-control study to examine factors associated with risk of HO. We used conditional logistic regression to compare occurrences of risk factors between cases and controls, matched by fracture type, age, and sex.

RESULTS

Our database contained 786 elbow fractures treated surgically. Of these, 55 developed clinically relevant HO. The risk of HO varied among types of elbow fractures, with combined olecranon and radial head fractures having no HO and floating elbows (fractures on both sides of the elbow joint) having the highest incidence of HO at 36%. In multiple conditional logistic regression, risk factors for the development of HO were days to surgery, with subjects waiting 8 or more days having 12 times the odds of HO than subjects having surgery within a day of injury, and time to postoperative mobilization, with subjects who had at least 15 days to mobilization having greater odds of HO than those who had less than 7 days to mobilization.

CONCLUSIONS

Heterotopic ossification of the elbow occurs frequently after surgical repair of elbow fractures, with an incidence of 7% in this registry. In the case-control sample, conditions associated with development of HO included longer time to surgery and longer time to mobilization after surgery.