Heterotopic Ossification following Tissue Transfer for Combat-Casualty Complex Periarticular Injuries

Although mechanisms underlying heterotopic ossification remain unknown, certain risk factors can influence heterotopic bone formation. The purpose of this study was to determine whether flaps used in periarticular reconstruction had any effect on heterotopic ossification formation.

A retrospective review of periarticular injuries requiring flap coverage from 2003 through 2014 was performed. Flap types, Injury Severity Scores, functional outcomes, and complications were reviewed. Radiology findings were assessed to determine heterotopic ossification rates and grades.

Three hundred eighty-nine flaps were performed for traumatic extremity coverage over the 13-year study period. Sixty-nine of these flaps were used for periarticular coverage. The rate of periarticular heterotopic ossification was 47 percent for fasciocutaneous versus 54 percent for muscle-based flap coverage (p = 0.88). There were no significant differences in Injury Severity Score (p = 0.44) or overall heterotopic ossification formation (p = 0.97) between groups; however, the grade of heterotopic ossification within muscle-based flap cohort was significantly higher (1.70 for muscle versus 1.06 for the fasciocutaneous cohort; p = 0.002).

Combat-related trauma is associated with high rates of heterotopic ossification, with an overall formation rate exceeding 85 percent for our patients requiring periarticular flap coverage. Although no difference in the rate of heterotopic ossification formation was found between fasciocutaneous and muscle flap coverages, a significantly increased severity of heterotopic ossification was seen in periarticular muscle-based flaps. These findings suggest that flap composition might not affect the rate of heterotopic ossification formation but may have an effect on ectopic bone formation severity.