Microvascular changes in the lower extremities of paraplegics with heterotopic ossification

Abstract

Objectives: To investigate the morphological aspects of blood microvasculature of the skin and subcutaneous tissues in subjects with paraplegia with heterotopic ossi®cation (HO). Methods: 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. Results: 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 microcalci®cations in the subcutaneous fat tissue were also 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 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. Spinal Cord (2001) 39, 595 ± 598

Deep vein thrombosis and heterotopic ossification in spinal cord injury: a 3 year experience at the Swiss Paraplegic Centre Nottwil

“…15,17 An additional in¯ammatory component involved in the pathogenesis of HO 16 is supported by our laboratory parameters. It has been suggested that in¯ammation together with a high local concentration of Ca 2+ would favour transformation of undi erentiated cells of the connective tissue into chondroblasts and osteoblasts leading ®nally to ossi®cation in the muscle.…”

“…Despite many e orts the pathogenesis of HO is still not known (reviewed by Wang et al 15 ). Individual cases point to an in¯ammatory component 16,17 and other studies suggest a comorbidity of HO and DVT. 18 ± 20 A related aetiology was proposed but never proved.…”

Neurogenic heterotopic ossification in spinal cord injury

“…1,3,36,46,48,73,86 Indeed, several studies have shown that the initial stage of NHO is characterized by local microvascular alterations such as an increased vascularity, venous haemostasis and arterio-venous shunting in the involved tissues. 36,48,87 These modi®cations in the blood perfusion and oxygen levels of the soft tissues might play a critical role in the formation of NHO, 36,87,88 although it remains unclear whether these changes are secondary to or a causal factor in the NHO. Whether a disruption of the neuro-immunological pathways could result in an abnormal balance between osteoblast and osteoclasts and the subsequent induction of NHO is also still hypothetical.…”

Free radical scavengers are more effective than indomethacin in the prevention of experimentally induced heterotopic ossification

“…They suggested that these changes could be consequent upon edema-induced hypoxemia in periarticular tissues, which could lead to metabolic alterations contributing to the development of HO. 1 Primitive mesenchymal cells in the soft tissues of fasciae can transform into osteogenic cells. Mesenchymal cells can mutate in osteogenic cells, when stimulated by bone morphogenic protein.…”

“…The new bone may appear to be contiguous with the skeleton, but periosteum is not involved. 1 The condition was first described in 1692 by Patin in children with myositis ossificans progressiva, a childhood disease which leads to severe functional impairment later in life. In 75% of cases it is associated with congenital deformities.…”