Heterotopic Ossification Clinical Presentation

Updated: Jan 27, 2021
  • Author: John Speed, MBBS; Chief Editor: Elizabeth A Moberg-Wolff, MD  more...
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  • The onset of HO usually is 1-4 months after injury in SCI patients, although it may occur as early as 19 days or as late as 1 year following injury.

  • The condition may occur later with other precipitating circumstances (eg, fracture, surgery, severe systemic illness). [21, 6, 22]

  • Not uncommonly, incidental HO that was not noted clinically may be detected much later on radiographs.

  • HO always occurs below the level of injury in SCI patients, and most authors agree that there is no relation to presence or absence of spasticity in SCI patients.

  • HO tends to occur more frequently with complete injuries.

  • In SCI patients with HO, the hips are most commonly involved.

    • At the hip, the flexors and abductors tend to be involved more frequently than are the extensors or adductors.

    • At the knee, the medial aspect is most commonly affected by HO.

    • Shoulders and elbows are the most commonly affected upper extremity joints.

    • One report in the literature notes involvement of the metacarpophalangeal joints of the hand.

    • The lumbar paravertebral region also has been mentioned as an infrequent site.

  • In patients who have sustained head injury or stroke, the story is a bit different. HO almost always occurs on the affected side, and most authors have noted that HO is more frequent in patients with spasticity than in those without it.

    • Garland and colleagues studied 496 patients with severe head injuries. [23] Clinically significant HO, causing pain and decreased ROM, was noted in 100 joints in 57 patients. Of the 100 involved joints, 89 were in spastic extremities. The frequency of involvement of different joints was slightly different than it was in patients with SCI; the hips were most commonly involved (44), followed by the shoulders (27) and elbows (26). HO was detected in only 3 knee joints.

    • Spielman also looked at the occurrence of HO in patients with head injuries. In that study, the inclusion criteria were (1) initial Glasgow Coma Scale score of 8 or less and (2) coma lasting more than 2 weeks. All patients had passive range of motion (PROM) of unknown frequency. Once again, HO was more common in the limbs of patients with severe spasticity. Prolonged coma also appeared to increase the likelihood of HO development.

  • In patients with neurologic deficits, increased limb spasticity, decreased joint ROM, and inflammatory signs near a joint strongly suggest the possibility of HO.



See the list below:

  • A diagnosis of HO can be made clinically if localized inflammatory reaction, palpable mass, or limited ROM is observed.

  • Clinically, the onset of larger masses of HO is often characteristic of any inflammatory reaction.

  • Fairly suddenly, a warm and swollen extremity becomes obvious, and fever is present.

  • If sensation is intact, the area of swelling is painful.

    • The swelling usually is localized more than it is in thrombophlebitis, and within several days, a more circumscribed, firmer mass is palpable within the edematous area.

    • If the mass is adjacent to a joint, gradual loss of PROM may follow.

  • With the development of early HO at the hip or knee, effusion may be noted at the knee.



See Pathophysiology.