Microvascular changes in the lower extremities of paraplegics with heterotopic ossification

To investigate the morphological aspects of blood microvasculature of the skin and subcutaneous tissues in subjects with paraplegia with heterotopic ossification (HO).

In two patients with traumatic spinal cord injury and HO, punch biopsies of skin and hypodermic soft tissue in the region of HO near the hip were studied with histological and ultrastructural methods.

Alterations of endothelial cell and basement membrane of capillaries and small vessels were observed. Hyperactive endothelium, thickening and reduplication of the basement membrane, changes of the perivascular connective tissues and microcalcifications in the subcutaneous fat tissue were also seen.

This present study indicates microvascular changes in the skin and subcutaneous tissue in the region of HO near the hip of two subjects with paraplegia. In our opinion the described vascular changes may induce hypoxiemic alterations of the soft para-articular tissues leading metabolic changes which may contribute to the development of HO. Therefore, it cannot be concluded whether these changes are directly responsible for HO induction.