| Heterotopic ossification | |
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| Heterotopic ossification around the hip joint in a patient who has undergone hip arthroplasty |
Heterotopic ossification (HO) is the process by which bone tissue forms outside of the skeleton in muscles and soft tissue. [1]
In traumatic heterotopic ossification (traumatic myositis ossificans), the patient may complain of a warm, tender, firm swelling in a muscle and decreased range of motion in the joint served by the muscle involved. There is often a history of a blow or other trauma to the area a few weeks to a few months earlier. Patients with traumatic neurological injuries, severe neurologic disorders or severe burns who develop heterotopic ossification experience limitation of motion in the areas affected.[ citation needed ]
Heterotopic ossification of varying severity can be caused by surgery or trauma to the hips and legs. About every third patient who has total hip arthroplasty (joint replacement) or a severe fracture of the long bones of the lower leg will develop heterotopic ossification, but is uncommonly symptomatic. Between 50% and 90% of patients who developed heterotopic ossification following a previous hip arthroplasty will develop additional heterotopic ossification.[ citation needed ]
Heterotopic ossification often develops in patients with traumatic brain or spinal cord injuries, other severe neurologic disorders or severe burns, most commonly around the hips. The mechanism is unknown. This may account for the clinical impression that traumatic brain injuries cause accelerated fracture healing. [2]
There are also rare genetic disorders causing heterotopic ossification such as fibrodysplasia ossificans progressiva (FOP), a condition that causes injured bodily tissues to be replaced by heterotopic bone. Characteristically exhibiting in the big toe at birth, it causes the formation of heterotopic bone throughout the body over the course of the sufferer's life, causing chronic pain and eventually leading to the immobilisation and fusion of most of the skeleton by abnormal growths of bone.[ citation needed ]
Another rare genetic disorder causing heterotopic ossification is progressive osseous heteroplasia (POH), is a condition characterized by cutaneous or subcutaneous ossification.
During the early stage, an x-ray will not be helpful because there is no calcium in the matrix. (In an acute episode which is not treated, it will be 3– 4 weeks after onset before the x-ray is positive.) Early laboratory tests are not very helpful. Alkaline phosphatase will be elevated at some point, but initially may be only slightly elevated, rising later to a high value for a short time. Unless weekly tests are done, this peak value may not be detected. It is not useful in patients who have had fractures or spine fusion recently, as they will cause elevations.[ citation needed ]
The only definitive diagnostic test in the early acute stage is a bone scan, which will show heterotopic ossification 7 – 10 days earlier than an x-ray. The three-phase bone scan may be the most sensitive method of detecting early heterotopic bone formation. However, an abnormality detected in the early phase may not progress to the formation of heterotopic bone. Another finding, often misinterpreted as early heterotopic bone formation, is an increased (early) uptake around the knees or the ankles in a patient with a very recent spinal cord injury. It is not clear exactly what this means, because these patients do not develop heterotopic bone formation. It has been hypothesized that this may be related to the autonomic nervous system and its control over circulation. [3]
When the initial presentation is swelling and increased temperature in a leg, the differential diagnosis includes thrombophlebitis. It may be necessary to do both a bone scan and a venogram to differentiate between heterotopic ossification and thrombophlebitis, and it is even possible that both could be present simultaneously. In heterotopic ossification, the swelling tends to be more proximal and localized, with little or no foot/ankle edema, whereas in thrombophlebitis the swelling is usually more uniform throughout the leg. [4]
There is no clear form of treatment. Originally, bisphosphonates were expected to be of value after hip surgery but there has been no convincing evidence of benefit, despite having been used prophylactically. [5]
Depending on the growth's location, orientation and severity, surgical removal may be possible.
Radiation Therapy.
Prophylactic radiation therapy for the prevention of heterotopic ossification has been employed since the 1970s. A variety of doses and techniques have been used. Generally, radiation therapy should be delivered as close as practical to the time of surgery. A dose of 7-8 Gray in a single fraction within 24–48 hours of surgery has been used successfully. Treatment volumes include the peri-articular region, and can be used for hip, knee, elbow, shoulder, jaw or in patients after spinal cord trauma.
Single dose radiation therapy is well tolerated and is cost effective, without an increase in bleeding, infection or wound healing disturbances. [6]
Other possible treatments.
Certain antiinflammatory agents, such as indomethacin, ibuprofen and aspirin, have shown some effect in preventing recurrence of heterotopic ossification after total hip replacement. [7]
Conservative treatments such as passive range of motion exercises or other mobilization techniques provided by physical therapists or occupational therapists may also assist in preventing HO. A review article looked at 114 adult patients retrospectively and suggested that the lower incidence of HO in patients with a very severe TBI may have been due to early intensive physical and occupational therapy in conjunction with pharmacological treatment. [8] Another review article also recommended physiotherapy as an adjunct to pharmacological and medical treatments because passive range of motion exercises may maintain range at the joint and prevent secondary soft tissue contractures, which are often associated with joint immobility. [9]
A head injury is any injury that results in trauma to the skull or brain. The terms traumatic brain injury and head injury are often used interchangeably in the medical literature. Because head injuries cover such a broad scope of injuries, there are many causes—including accidents, falls, physical assault, or traffic accidents—that can cause head injuries.
An injury is any physiological damage to living tissue caused by immediate physical stress. Injuries to humans can occur intentionally or unintentionally and may be caused by blunt trauma, penetrating trauma, burning, toxic exposure, asphyxiation, or overexertion. Injuries can occur in any part of the body, and different symptoms are associated with different injuries.
A spinal cord injury (SCI) is damage to the spinal cord that causes temporary or permanent changes in its function. It is a destructive neurological and pathological state that causes major motor, sensory and autonomic dysfunctions.
Arachnoiditis is an inflammatory condition of the arachnoid mater or 'arachnoid', one of the membranes known as meninges that surround and protect the central nervous system. The outermost layer of the meninges is the dura mater and adheres to inner surface of the skull and vertebrae. The arachnoid is under or "deep" to the dura and is a thin membrane that adheres directly to the surface of the brain and spinal cord.
Ossification in bone remodeling is the process of laying down new bone material by cells named osteoblasts. It is synonymous with bone tissue formation. There are two processes resulting in the formation of normal, healthy bone tissue: Intramembranous ossification is the direct laying down of bone into the primitive connective tissue (mesenchyme), while endochondral ossification involves cartilage as a precursor.
Fibrodysplasia ossificans progressiva, also called Münchmeyer disease or formerly myositis ossificans progressiva, is an extremely rare connective tissue disease in which fibrous connective tissue such as muscle, tendons, and ligaments turn into bone tissue (ossification). It is the only known medical condition where one organ system changes into another. It is a severe, disabling disorder with no cure.
Myositis ossificans comprises two syndromes characterized by heterotopic ossification (calcification) of muscle. The World Health Organization, 2020, has grouped myositis ossificans together with fibro-osseous pseudotumor of digits as a single specific entity in the category of fibroblastic and myofibroblastic tumors.
Spondylolysis is a defect or stress fracture in the pars interarticularis of the vertebral arch. The vast majority of cases occur in the lower lumbar vertebrae (L5), but spondylolysis may also occur in the cervical vertebrae.
Activin A receptor, type I (ACVR1) is a protein which in humans is encoded by the ACVR1 gene; also known as ALK-2. ACVR1 has been linked to the 2q23-24 region of the genome. This protein is important in the bone morphogenic protein (BMP) pathway which is responsible for the development and repair of the skeletal system. While knock-out models with this gene are in progress, the ACVR1 gene has been connected to fibrodysplasia ossificans progressiva, an extremely rare progressive genetic disease characterized by heterotopic ossification of muscles, tendons and ligaments. It is a bone morphogenetic protein receptor, type 1.
Orthopedic pathology, also known as bone pathology is a subspecialty of surgical pathology which deals with the diagnosis and feature of many bone diseases, specifically studying the cause and effects of disorders of the musculoskeletal system. It uses gross and microscopic findings along with the findings of in vivo radiological studies, and occasionally, specimen radiographs to diagnose diseases of the bones.
Posterior spinal artery syndrome(PSAS), also known as posterior spinal cord syndrome, is a type of incomplete spinal cord injury. PSAS is the least commonly occurring of the six clinical spinal cord injury syndromes, with an incidence rate of less than 1%.
Facial trauma, also called maxillofacial trauma, is any physical trauma to the face. Facial trauma can involve soft tissue injuries such as burns, lacerations and bruises, or fractures of the facial bones such as nasal fractures and fractures of the jaw, as well as trauma such as eye injuries. Symptoms are specific to the type of injury; for example, fractures may involve pain, swelling, loss of function, or changes in the shape of facial structures.
Harry Raymond Eastlack, Jr. was the subject of the most recognized case of fibrodysplasia ossificans progressiva (FOP) from the 20th century. His case is also particularly acknowledged, by scientists and researchers, for his contribution to medical advancement. After living with a rare, disabling, and currently incurable genetic disease, Eastlack decided to have his skeleton and medical history donated to the Mütter Museum of the College of Physicians of Philadelphia in support of FOP research. His skeleton is one of the few FOP-presenting, fully articulated ones in existence, and it has proved valuable to the study of the disease.
Metastatic breast cancer, also referred to as metastases, advanced breast cancer, secondary tumors, secondaries or stage IV breast cancer, is a stage of breast cancer where the breast cancer cells have spread to distant sites beyond the axillary lymph nodes. There is no cure for metastatic breast cancer; there is no stage after IV.
Progressive osseous heteroplasia is a cutaneous condition characterized by cutaneous or subcutaneous ossification.
The International Fibrodysplasia Ossificans Progressiva Association (IFOPA) is a US-based 501(c)(3) non-profit organization supporting medical research, education and communication for those afflicted by the rare genetic condition Fibrodysplasia Ossificans Progressiva (FOP). IFOPA's mission is to fund research to find a cure for FOP while supporting, connecting, and advocating for individuals with FOP and their families, and raising awareness worldwide. IFOPA is governed by a volunteer board of directors which may range in number from 9 to 15, at least one of whom must have FOP. The association's location is 1520 Clay St., Suite H2, North Kansas City, MO, 64116, part of the Kansas City, Missouri metropolitan area.
Palovarotene, sold under the brand name Sohonos, is a medication used for the treatment of heterotopic ossification and fibrodysplasia ossificans progressiva. It is a highly selective retinoic acid receptor gamma (RARγ) agonist. It is taken by mouth.
Cancer pain can be caused by pressure on, or chemical stimulation of, specialised pain-signalling nerve endings called nociceptors, or by damage or illness affecting nerve fibers themselves.
Frederick S. Kaplan is an American medical doctor specializing in research of musculoskeletal disorders such as fibrodysplasia ossificans progressiva (FOP).
Eileen M. Shore is an American medical researcher and geneticist specializing in research of muscoskeletal disorders such as fibrodysplasia ossificans progressiva.
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