Pathophysiology and etiology of neurogenic heterotopic ossification

Abstract

Neurogenic heterotopic ossification (NHO) is the formation of pathological bone tissue in the soft tissues around joints after neurological injury, where ossification is not observed normally. This condition, frequently seen in patients with spinal cord injury (SCI) and traumatic brain injury (TBI), can cause complications such as severe limitation of motion, difficulty in daily living activities, nerve compression and pressure ulcers. NHO etiopathogenesis was reviewed with current literature, to enlighten the research studies planned on treatment and the precautions to prevent it. Etiology of NHO is not completely revealed in patients with SCI and TBI, however humoral, neural, immunological and local factors probably play a role in the pathophysiology. In patients with SCI, complete lesion, immobilization, exercise, microtrauma and proprioceptive alterations may possibly take a role in NHO development. The most important risk factors for patients with TBI are: spasticity, prolongation of coma state more than 2 weeks, immobilization, fractures of long bones, limitation of range of motion, infection, and development of autonomic disregulation. However, it is not known which of the factors affect the severity and the long-term outcomes of the disease. Considering the etiopathogenesis of NHO, it is concluded that more comprehensive studies are needed to detect and prevent the risk factors before it develops, to determine the type of therapeutic exercises and the suitable timing of exercises. Turk J Phys Med Rehab 2010;56:81-7. © Turkish Journal of Physical Medicine and Rehabilitation, Published by Galenos Publishing.