Table 2 Summary of risk factors for posttraumatic heterotopic ossification and synostosis. Blank fields represent no data/undetermined. N/A: not applicable because of conservative treatment

Demographic

Young age (< 30) at the injury

Yes

No

Yes

Male sex

Yes

Yes

Yes

Yes

African American race

Yes

No

Trauma-related

Systemic injury severity

Yes

:Systemic

Head Trauma

Yes

Yes

Spinal cord injury

Yes

Yes

Yes

:Local

Extensive soft tissue damage¹

Yes

Yes

High-energy injury mechanism

Yes

Yes²

Yes

Yes

Yes

Fractures in both sides of synostosis at the same level

Yes

Fracture-dislocation³

Yes

Yes

Yes

Yes

Comminuted fracture

Yes

Yes

Dissemination of bone dust or debris

Yes

Yes

Yes

Hematoma formation

Yes

Surgery-related

Extensive surgical dissection

Yes

Yes

N/A

Prolonged waiting time for surgery

Yes

N/A

Yes

Prolonged immobilization

Yes

Delayed rehabilitation

Yes

Yes

Prominent implant

Yes

Possible⁴

N/A

Local infection

Possible⁵

Yes

Primary bone graft

Yes

N/A

Yes