Heterotopic ossification

1. In what joints does HO most frequently occur in SCI?
2. How soon after injury is HO usually seen?
3. What are early clinical symptoms of HO?
4. What are risk factors for HO?
5. How is HO usually diagnosed?
6. What are treatments for HO?
7. What are possible complications of HO?

Answers:
1. 1)Hip, 2) Knee, 3) Shoulder, 4) Elbow.
2. 1-4 months post injury.
3. Heat, soft tissue swelling, decreased ROM, joint erythema/effusion, low grade fever.
4. Spasticity, complete injury, trauma to joint, age, pressure ulcer near joint.
5. Bone scan shows HO one week from onset, can be seen 7-10 days later on plain film. Elevated alk phos is also seen, but is nonspecific.
6. Treat with etidronate 20mg/kg/day for 2 weeks, then 10mg/kg/day for 10 weeks, indomethacin, maintain ROM, surgery once HO is mature (12-18 mo post injury).
7. Peripheral nerve entrapment, loss of ROM/function, increased pressure ulcers.