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Full article available online at OrthoSuperSite.com. Search: 80662
Heterotopic ossification is the abnormal formation of mature lamellar bone within extraskeletal soft tissues where bone does not exist. Heterotopic ossification has been classified into posttraumatic, nontraumatic or neurogenic, and myositis ossificans progressiva or fibrodysplasia ossificans progressive. The pathophysiology is unknown. Anatomically, heterotopic ossification occurs outside the joint capsule without disrupting it. The new bone can be contiguous with the skeleton but generally does not involve the periosteum. Threephase technetium-99m (99mTc) methylene diphosphonate bone scan is the most sensitive imaging modality for early detection and assessing the maturity of heterotopic ossification. Nonsurgical treatment with indomethacin and radiation therapy is appropriate for prophylaxis or early treatment of heterotopic ossification. Although bisphosphonates are effective prophylaxis if initiated shortly after the trauma, mineralization of the bone matrix resumes after drug discontinuation. During the acute inflammatory stage, the patient should rest the involved joint in a functional position; once acute inflammatory signs subside, passive range of motion exercises and continued mobilization are indicated.
Surgical indications for excision of heterotopic ossification include improvement of function, standing posture, sitting or ambulation, independent dressing, feeding and hygiene, and repeated pressure sores from underlying bone mass. The optimal timing of surgery has been suggested to be a delay of 12 to 18 months until radiographic evidence of heterotopic ossification maturation and maximal recovery after neurological injury. The ideal candidate for surgical treatment before 18 months should have no joint pain or swelling, a normal alkaline phosphatase level, and 3-phase bone scan indicating mature heterotopic ossification.
Heterotopic ossification is the abnormal formation of mature lamellar bone within extraskeletal soft tissues where bone normally does not exist; it involves true osteoblastic activity and bone formation. Since the initial description in 1883 by Reidel and in 1918 by Dejerne and Ceillier,1 various forms of heterotopic ossification have been described according to the clinical setting and location of the lesions, and progressive or isolated occurrence; these include traumatic and nontraumatic heterotopic ossification, panniculitis ossificans (heterotopic ossification confined to subcutaneous fat), rider's bones (heterotopic ossification located in the adductor muscles), shooter's bones (heterotopic ossification located in the deltoid muscle), and heterotopic ossification following spinal cord injury, traumatic brain injury, stroke, encephalitis, poliomyelitis, tetanus, tabes dorsalis, syringomyelia, anoxic encephalopathy,...