Bone Abstracts

Introduction: Heterotopic ossification (HO) means deposition of bone within the soft tissue around peripheral joints, first described by Guy Patin in 1692. This may occurs in up to 50% of spinal cord injury (SCI) patients. HO begins at mean of 12 weeks after injury. Only 10–20% of patients have clinical symptoms with decreased range of motion and inflammatory symptoms in the affected joints. The large joints below the levels of injury are typically affected, most commonly the hip. HO classified to four classes according to Booker’s intensity of ossification, Class 1: a few small islands of periarticular soft tissue bone formation, Class 2: more than 1 centimeter distance between two adjacent bones, and Class 3:<1 centimeter distance between two adjacent bones, Class 4: complete bony ankylosis of the subjacent joint.

Materials and methods: Pelvic plane radiography of 453 patients with chronic SCI that admitted in the hospital for check up, studied in years 2010–2013.

Results: The age of patients was between 25–82 years with mean of 50 years. 97% of patients were males and 3% was females. The most common cause of injury was bullet and quiver in 77.7% of patients and the most injury level in thoracic vertebra (in th12). 91% of patients were paraplegic and 9% quadriplegic. The mean time of post spinal injury was 26 years. 35.3% of patients had HO that 11.3% in Class 1, 11.5% in Class 2, 5.3% in Class 3 and 7.3% in Class 4.

Conclusions: In our study the incidence of HO in SCI patients was 35.3% that was higher than Guttman (1976) 5%, Freehafer (1966) 17%, Scher (1976) 19%, Warton & Morgan (1977) 20%, Soulie (1927) 27% and lower than Dejerine and Callier (1919) 48.7%, Abramson & Kamberg (1949) 41%, and Paeslack (1965) 40%.