[Unusual site of heterotopic ossification in the area of a laparotomy scar]

We report on a patient with spinal cord injury and an unusual localization of heterotopic ossification (HO) in the area of a laparotomy scar, with a large quantity of foreign bodies from residual suture material. This makes it obvious that extraskeletal cells can differentiate for osteogenesis. However, neither the mechanism of the induction process of HO nor the stimulating agents are precisely known. It must be stressed, however, that the occurrence of HO can be influenced by foreign bodies in the presence of favourable microenvironmental conditions.