Surgical management of bilateral hip fractures in a patient with fibrodysplasia ossificans progressiva treated with the RAR-γ agonist palovarotene: a case report.

BACKGROUND: Fibrodysplasia ossificans progressiva (FOP) is an ultra-rare disorder marked by painful, recurrent flare-ups and heterotopic ossification (HO) in soft and connective tissues, which can be idiopathic or provoked by trauma, illness, inflammation, or surgery. There are currently no effective treatments for FOP, or for patients with FOP who must undergo surgery. Palovarotene, an investigational retinoic acid receptor-γ agonist, offers a potential avenue to prevent HO formation. CASE PRESENTATION: The patient is a 32 year-old male, who at age 29 enrolled in a study evaluating palovarotene to prevent HO formation in FOP. One year after starting palovarotene, he fell resulting in a left intertrochanteric fracture. He underwent intramedullary nailing of the femur shaft with screw placement at the distal femur. After surgery, he received palovarotene at 20 mg/day for 4 weeks, then 10 mg/day for 8 weeks. Imaging 12 weeks after surgery showed new bridging HO at the site of intramedullary rod insertion and distal screw. Nine months after the left hip fracture, the patient had a second fall resulting in a subdural hematoma, left parietal bone fracture, and right intertrochanteric fracture. He underwent intramedullary nailing of the right hip, in a modified procedure which did not require distal screw placement. Palovarotene 20 mg/day was started at fracture occurrence and continued for 4 weeks, then reduced to 10 mg/day for 8 weeks. HO also formed near the insertion site of the intramedullary rod. No HO developed at the right distal intramedullary rod. After each fracture, the patient had prolonged recurrent flare-ups around the hips. CONCLUSION: Surgery is only rarely considered in FOP due to the high risks of procedural complications and potential for inducing HO. This case emphasizes the risks of increased flare activity and HO formation from injury and surgery in patients with FOP. The efficacy of HO prevention by palovarotene could not be assessed; however, our observation that palovarotene can be administered in an individual with FOP following surgery with no negative impact on clinical fracture healing, osteointegration, or skin healing will help facilitate future trials testing the role of palovarotene as a therapy for HO.

¿Es la «fibrodisplasia osificante progresiva» una enfermedad de origen vascular? Un modelo patogénico innovador / Is «fibrodysplasia ossificans progressiva» a vascular disease? A groundbreaking pathogenic model

La fibrodisplasia osificante progresiva es la causa más grave de osificación ectópica en humanos. Se caracteriza por malformaciones esqueléticas congénitas y placas de hueso maduro (endocondral) en el músculo y en otras estructuras ricas en tejido conjuntivo. Se produce por una mutación espontánea en el gen del receptor de la activina A tipo I, similar a la activina-cinasa-2. A raíz de este hallazgo, se han producido importantes avances en el conocimiento de su base molecular y celular. Además de permitir una mejor comprensión de los mecanismos que gobiernan la osificación, evidencias recientes indican que la alteración primordial radica en mecanismos básicos de la diferenciación celular que son clave en varias vías fisiológicas y en la génesis de enfermedades de gran impacto. En el presente artículo, resumimos los últimos avances con implicaciones que trascienden los límites de esta devastadora enfermedad para postularse como un nuevo modelo dentro de la fisiopatología humana (AU)

Fibrodysplasia ossificans progressiva is the most severe and disabling disorder of ectopic ossification in humans. It is characterized by congenital skeletal abnormalities in association with extraskeletal widespread endochondral osteogenesis. Virtually all patients show the same mutation in the «activin A type-I/activin-like kinase-2» receptor encoding gene. As a result of this discovery there have been significant advances in the knowledge of the cellular and molecular basis of the disease. Besides allowing a better understanding of ossification process, recent evidence indicates that the primary disturbance lies within basic mechanisms of cell differentiation that are key in several physiological pathways and in the genesis of diseases with a major impact on health. In this article we summarize these breakthroughs, with implications that go beyond the limits of this devastating disease to insinuate a new model of human pathophysiology (AU)

Evaluation of 20 years experience of fibrodysplasia ossificans progressiva in Iran: lessons for early diagnosis and prevention.

Fibrodysplasia ossificans progressiva (FOP) is a rare genetic inflammatory disorder characterized by progressive heterotopic ossification presenting as recurrent soft tissue masses and swelling which may cause disabling, restricted joint mobility. Congenital malformations of the hallux are characteristic features of classic FOP, predating the appearance of disabling features. As no definite treatment is available, the early diagnosis and prevention of exacerbating factors may lead to significant benefits in terms of the life quality of patients. A retrospective study of 12 consecutive FOP patients referred to and admitted in the rheumatology unit at an urban tertiary care academic center between 1991 and 2011. Data, such as age, gender, and past medical history, were collected from the medical history, physical examination, and skeletal survey in order to characterize the clinical presentations. All 12 children (six boys and six girls; ages 2.0-13.5 years) had congenital malformations of the great toes (microdactyly and hallux valgus deformity), in addition to heterotopic ossification presenting as multiple soft tissue tumor-like swellings. Spinal involvement, most notably in the cervical region, suggestive of an early FOP, was present in 83.3 %. Eleven patients (91.6 %) had a prior history of direct physical trauma, while 7 of 11 (63.6 %) had undergone invasive diagnostic procedures, both correlating with the exacerbations of their condition. Clinical awareness of fibrodysplasia ossificans progressiva and its early diagnostic features, particularly congenital malformations of the hallux, during a thorough neonatal examination may lead to an early diagnosis preventing the development of disabling, practically irreversible lesions of heterotopic ossification. Genetic and molecular studies can play a considerable role in the diagnosis of FOP in suspected cases. Early institution of prophylactic and precautionary measures, such as categorical avoidance of trauma and invasive procedures, can significantly reduce the debilitating acute exacerbations of the condition.

Fibrodisplasia ossificante progressiva: relato de caso / Fibrodysplasia ossificans progressiva: a case report

Os autores descrevem um caso de fibrodisplasia ossificante progressiva, doença hereditária caracterizada por calcificações heterotópicas do tecido conectivo, geralmente induzida por trauma, gerando imobilidade permanente das articulações. Hálux valgo, clinodactilia e polegares curtos são as principais malformações congênitas associadas. Manifesta-se na infância, sendo o diagnóstico clínico-radiológico importante, pois procedimentos invasivos exacerbam a doença. Tratamentos disponíveis são apenas paliativos, tendo a prevenção relevância nesse contexto.

The authors describe a case of fibrodysplasia ossificans progressiva, a hereditary disease characterized by heterotopic ossification of the connective tissues, usually triggered by trauma, resulting in permanent immobility of the joints. Hallux valgus, clinodactyly and short thumbs are the main associated congenital anomalies. Fibrodysplasia ossificans progressiva usually develops during early childhood. Clinical and radiological diagnosis is essential, since invasive procedures exacerbate the disease. Only palliative treatments are available and prevention plays an important role in patients with fibrodysplasia ossificans progressiva.

Muscle contusion injury and myositis ossificans traumatica.

In athletic competition, muscle contusion injury is a frequent and debilitating condition. Found in traditional contact and noncontact sports, contusions also can occur to the nonathlete by simple falls and accidents. The injury consists of a well-defined sequence of events involving microscopic rupture and damage to muscle cells, macroscopic defects in muscle bellies, infiltrative bleeding, and inflammation. The repair of the tissue can be thought of as a race between remodeling and scar formation. In the current study, the authors describe the relevant body of research directed at delineating the incidence, factors that affect injury severity, and treatment of muscle contusion injury. Emphasis is given to animal models that allow reproducible, quantitative injury, and study of the effects of various treatment modalities. Myositis ossificans traumatica, one of the most debilitating consequences of contusion injuries, also is discussed. The incidence, causative factors, and prevention strategies are reviewed.

Heterotopic ossification in childhood and adolescence.

Heterotopic ossification, or myositis ossificans, denotes true bone in an abnormal place. The pathogenic mechanism is still unclear. A total of 643 patients (mean age, 9.1 years) admitted for neuropediatric rehabilitation were analyzed retrospectively with respect to the existence of neurogenic heterotopic ossification. The purpose of this study was to obtain information about incidence, etiology, clinical aspect, and consequences for diagnosis and therapy of this condition in childhood and adolescence. Heterotopic ossification was diagnosed in 32 patients (mean age, 14.8 years) with average time of onset of 4 months after traumatic brain injury, near drowning, strangulation, cerebral hemorrhage, hydrocephalus, or spinal cord injury. The sex ratio was not significant. In contrast to what has been found in adult studies, serum alkaline phosphatase was not elevated during heterotopic ossification formation. A persistent vegetative state for longer than 30 days proved to be a significant risk factor for heterotopic ossification. The incidence of neurogenic heterotopic ossification in children seems to be lower than in adults. A genetic predisposition to heterotopic ossification is suspected but not proven. As a prophylactic regimen against heterotopic ossification we use salicylates for those patients in a coma or persistent vegetative state with warm and painful swelling of a joint and consider continuous intrathecal baclofen infusion and botulinum toxin injection for those patients with severe spasticity. We prefer to wait at least 1 year after trauma before excision of heterotopic ossification.

Initiation of fracture repair by bone morphogenetic proteins.

The potential for regeneration and repair of bone is well known. This article conveys the current progress in the realm of bone morphogenetic proteins and their potential for initiating fracture repair cascade. Demineralized bone matrix induces bone formation and has served as a model for the bone repair cascade. A family of bone morphogenetic proteins has been identified, isolated, and cloned from the demineralized bone matrix. Bone morphogenetic proteins are pleiotropic regulators of chemotaxis, mitosis, and differentiation. The bone morphogenetic protein receptors, Types I and II, bind bone morphogenetic proteins and act in collaboration to transduce the phosphorylation of Smad 1 and Smad 5, which enter the nucleus in partnership with Smad 4 to initiate bone morphogenetic protein responses including fracture healing. The accumulated information on bone morphogenetic proteins may aid in accelerating fracture repair and the potential use of bone morphogenetic protein antibodies to inhibit heterotopic bone formation and fibrodysplasia ossificans progressiva.

Methylprednisolone has a preventive effect on heterotopic bone formation and on knee thickening and stiffening following manipulation of immobilized rabbit legs.

The effect of methylprednisolone administered following manipulation of the immobilized knee of 35 adult rabbits was investigated. In the legs of 15 control rabbits which received no methylprednisolone, heterotopic cartilage and bone in the periarticular tissues and in the vastus intermedius muscle, and extensive knee stiffening and thickening regularly developed. In the other rabbits, methylprednisolone showed a marked preventive effect on the development of all these pathological signs.

[Heterotopic ossifications from the trauma surgery viewpoint]. / Heterotope Ossifikationen aus unfallchirurgischer Sicht.

A heterotopic ossification is a non-neoplastic bone formation located in the soft tissues (so-called myositis ossificans). Important aspects of this condition, which is not uncommon after trauma or surgical procedures, are discussed from the trauma surgeon's viewpoint. The results of treatment of heterotopic ossifications are frequently unsatisfactory. Therefore, the importance of preventive measures is emphasized.

Prevention of ectopic bone formation by local application of ethane-1-hydroxy-1,1-diphosphonate (EHDP): an experimental study in rabbits.

This report shows that ectopic bone formation, a serious problem in orthopedic surgery, can be controlled in an animal model by local application of EHDP (disodium-ethane-1-hydroxy-1,1-diphosphonate). The results might be particularly pertinent to the clinical problem of preventing the recurrence of ectopic bone after surgical excision. Male New Zealand white rabbits were treated with immobilization and intermittent passive manipulation of the right knee. The treatment caused bone formation in the quadriceps muscle, which was visible on radiographs after 3 weeks. In this model, the effect of methacrylate implants containing EHDP was studied. A concentration of 16 g EHDP/100 g methacrylate inhibited bone formation in experimental cortical defects. Release of radiolabeled EHDP was studied in an in vitro system. The release of the drug was approximately 20 mg/day and implant initially, decreasing to about 0.1 mg/day/implant after 30 days. Standardized implants containing 16 g EHDP/100 g were then surgically attached to the femur, and the ectopic bone formation created by immobilization and intermittent manipulation was compared with that in rabbits treated with implants but without EHDP. The ectopic bone was measured from lateral and frontal radiograms and from radiograms of serial transverse sections of the thigh. We found that the EHDP implants were capable of preventing major ectopic bone formation in all cases, whereas all rabbits with an implant containing no EHDP had substantial ectopic bone formation at the end of the experiment. There was no difference between groups in the relative amount of cartilage, connective tissue, and normal bone. We conclude that local administration of EHDP may be a useful method for prevention of ectopic bone formation under the conditions and time employed.

Use and complications of high-dose disodium etidronate therapy in fibrodysplasia ossificans progressiva.

A boy with fibrodysplasia ossificans progressiva received nearly twice the usual therapeutic dose of disodium etidronate for 13 months in an attempt to prevent reossification following a second operation to correct severe torticollis. The operation was successful, but during therapy he developed weakness and distinctive bone lesions characterized by general osteopenia, widened physes, and unique radiolucent bands in the metaphyses. The osseous abnormalities were distinct from those of rickets and healed after withdrawal of the drug.