Microvascular changes in the lower extremities of paraplegics with heterotopic ossification

Objectives: To investigate the morphological aspects of blood microvasculat ure of the skin and subcutaneous tissues in subjects with paraplegia with h eterotopic ossification (HO). Methods: In two patients with traumatic spinal cord injury and HO, punch bi opsies of skin and hypodermic soft tissue in the region of HO near the hip were studied with histological and ultrastructural methods. Results: Alterations of endothelial cell and basement membrane of capillari es and small vessels were observed. Hyperactive endothelium, thickening and reduplication of the basement membrane, changes of the perivascular connec tive tissues and microcalcifications in the subcutaneous fat tissue were al so seen. Conclusions: This present study indicates microvascular changes in the skin and subcutaneous tissue in the region of HO near the hip of two subjects w ith paraplegia. In our opinion the described vascular changes may induce hy poxiemic alterations of the soft para-articular tissues leading metabolic c hanges which may contribute to the development of HO. Therefore. it cannot be concluded whether these changes are directly responsible for HO inductio n.