eMedicine Specialties > Pediatrics: General Medicine > Rheumatology

Myositis Ossificans

Author: Donald A Person, MD, Medical Director, Senior Scientist, Department of Clinical Investigation, Tripler Army Medical Center, Honolulu; Professor of Pediatrics, F Edward Herbert School of Medicine, USUHS, John A Burns School of Medicine, University of Hawaii at Manoa
Coauthor(s): Mandar A Pattekar, MD, MS, Consulting Staff, Department of Radiology, Methodist Hospital
Contributor Information and Disclosures

Updated: Jul 17, 2006

Introduction

Background

Myositis ossificans is a misnomer and the term fibrodysplasia ossificans progressiva (FOP), as used by McKusick, is preferred. It is a rare autosomal dominant disorder characterized by skeletal malformation and progressive, disabling heterotopic osteogenesis. The condition was first described by Guy Patin in 1692.

Pathophysiology

Myositis ossificans manifests in 2 forms.

Myositis ossificans circumscripta can develop either in response to soft tissue injury (eg, blunt trauma, stab wound, fracture/dislocation, surgical incision) or can occur without known injury. Proposed mechanisms for atraumatic myositis ossificans include nondocumented trauma, repeated small mechanical injuries, and nonmechanical injuries caused by ischemia or inflammation.

Recently Shore et al reported mapping FOP to chromosome 2q23-24 by linkage analysis. They have further identified an identical heterozygous mutation (617G ® R206H) in the glycine-serine (GS) domain of the activin A receptor type I (ACVR1) gene, a bone morphogenic protein (BMP) type I receptor in all affected individuals thus far examined.

Frequency

International

A recent report suggested the incidence of FOP to be less than 1 in 10-7.

Race

Myositis ossificans progressiva occurs in all races.

Sex

Myositis ossificans progressiva demonstrates no definitive sexual predilection because the slight male predominance overall probably relates to differences in physical activity levels between the genders.

Age

  • Nonhereditary myositis ossificans is uncommon in children; fewer than 6.7% of cases occur in the first decade of life.
  • In FOP, average age of onset is 5 years, with a reported onset range from fetus to 25 years.

Clinical

History

  • Nonhereditary myositis ossificans
    • Pain, tenderness, focal swelling, and joint/muscle contractions occur.
    • The condition can be asymptomatic and may be diagnosed incidentally.
    • The history of trauma causing the condition may be difficult to elicit.
    • Most (ie, 80%) ossifications arise in the thigh or arm. Other sites include intercostal spaces, erector spinae, pectoralis muscles, glutei, and the chest wall.
  • FOP
    • The condition produces painful lumps and stiffness in the adjoining joint. Lumps decrease in a few weeks, but joint mobility reduction persists.
    • Exacerbating factors for ossifications at new sites includes sometimes very minor trauma, such as venipuncture, biopsy of lumps, IM injections, dental treatments, and excision of masses.
    • The most common sites are the sternocleidomastoid muscle, paraspinal muscles, the masticatory muscles, and shoulder and pelvic girdle muscles. Spared are the abdominal muscles, extraocular muscles, and GI tract and tongue muscles.
    • Ossification progresses from proximal to distal and cranial to caudal.

Physical

  • Myositis ossificans circumscripta
    • Tender mass, with or without cutaneous erythema
    • Associated joint motion abnormalities
    • Fever (uncommon)
  • FOP
    • Digits: Short hallux with synostosis and, less often, short thumbs
    • Fibrous Tissues: Swelling (sometimes with pain and fever) in aponeuroses, fasciae, and tendons, which leads to ossification in muscles and fibrous tissues, most prominent in the neck dorsal trunk and proximal extremities (The sternocleidomastoid muscle is commonly affected.)
    • Kyphoscoliosis: Restricted shoulder and pelvic girdle movements

More on Myositis Ossificans

Overview: Myositis Ossificans
Differential Diagnoses & Workup: Myositis Ossificans
Treatment & Medication: Myositis Ossificans
Follow-up: Myositis Ossificans
Multimedia: Myositis Ossificans
References
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References

  1. Ackerman LV. Extra-osseous localized non-neoplastic bone and cartilage formation (so-called myositis ossificans). Clinical and pathological confusion with malignant neoplasms. J Bone Joint Surg (Am). 1958;40(2):279-298.

  2. Amendola MA, Glazer GM, Agha FP, et al. Myositis ossificans circumscripta: computed tomographic diagnosis. Radiology. Dec 1983;149(3):775-9. [Medline].

  3. Delatycki M, Rogers JG. The genetics of fibrodysplasia ossificans progressiva. Clin Orthop. Jan 1998;(346):15-8. [Medline].

  4. Enzinger FM, Weiss SW. Osseous soft tissue tumors. In: Soft tissue tumors. St. Louis, Mo:. Mosby-Year Book Inc;1995:1013-1021.

  5. Futani H, Itohara S, Maruo S, Tateishi H. A report on 2 cases of myositis ossificans in childhood. Acta Orthop Scand. Dec 1998;69(6):642-5. [Medline].

  6. Hait G, Boswick JA Jr, Stone NH. Heterotopic bone formation secondary to trauma (myositis ossificans traumatica). J Trauma. May 1970;10(5):405-11. [Medline].

  7. Harmon D. Case records of the Massachusetts General Hospital. Weekly clinicopathological exercises. Case 38-1994. A 55-year-old man with a paraspinal mass and a history of radiation treatment of a testicular tumor. N Engl J Med. Oct 20 1994;331(16):1079-84. [Medline].

  8. Kransdorf MJ, Meis JM, Jelinek JS. Myositis ossificans: MR appearance with radiologic-pathologic correlation. AJR Am J Roentgenol. Dec 1991;157(6):1243-8. [Medline].

  9. Nuovo MA, Norman A, Chumas J, Ackerman LV. Myositis ossificans with atypical clinical, radiographic, or pathologic findings: a review of 23 cases. Skeletal Radiol. 1992;21(2):87-101. [Medline].

  10. Okayama A, Futani H, Kyo F, et al. Usefulness of ultrasonography for early recurrent myositis ossificans. J Orthop Sci. 2003;8(2):239-42. [Medline].

  11. Resnick D. Soft tissues. In: Diagnosis of Bone and Joint Disorders. 3rd ed. Philadelphia, Pa:. WB Saunders Co;1995:4577-4584.

  12. Shafritz AB, Shore EM, Gannon FH, et al. Overexpression of an osteogenic morphogen in fibrodysplasia ossificans progressiva. N Engl J Med. Aug 22 1996;335(8):555-61. [Medline].

  13. Shore EM, Xu M, Feldman GJ, et al. A recurrent mutation in the BMP type I receptor ACVR1 causes inherited and sporadic fibrodysplasia ossificans progressiva. Nat Genet. May 2006;38(5):525-7. [Medline].

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Further Reading

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Keywords

myositis ossificans, fibrodysplasia ossificans progressiva (hereditary type), myositis ossificans circumscripta, myositis ossificans progressiva, soft tissue ossification, progressive ossifying myositis, myositis ossificans traumatica, heterotopic osteogenesis, progressive osseous heteroplasia

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Contributor Information and Disclosures

Author

Donald A Person, MD, Medical Director, Senior Scientist, Department of Clinical Investigation, Tripler Army Medical Center, Honolulu; Professor of Pediatrics, F Edward Herbert School of Medicine, USUHS, John A Burns School of Medicine, University of Hawaii at Manoa
Donald A Person, MD is a member of the following medical societies: Ambulatory Pediatric Association, American Academy of Pediatrics, American College of Rheumatology, American Medical Association, American Pediatric Society, American Society for Microbiology, American Society of Tropical Medicine and Hygiene, Association of Military Surgeons of the US, Clinical Immunology Society, Federation of American Societies for Experimental Biology, Pediatric Infectious Diseases Society, and Society for Pediatric Research
Disclosure: Nothing to disclose.

Coauthor(s)

Mandar A Pattekar, MD, MS, Consulting Staff, Department of Radiology, Methodist Hospital
Mandar A Pattekar, MD, MS is a member of the following medical societies: American College of Radiology, American Roentgen Ray Society, and Radiological Society of North America
Disclosure: Nothing to disclose.

Pharmacy Editor

Mary L Windle, PharmD, Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy, Pharmacy Editor, eMedicine.com, Inc
Disclosure: Pfizer Inc Stock Investment from broker recommendation; Avanir Pharma Stock Investment from broker recommendation

Managing Editor

David D Sherry, MD, Professor of Pediatrics, Division of Rheumatology, University of Pennsylvania; Director of Clinical Rheumatology, Children's Hospital of Philadelphia
David D Sherry, MD is a member of the following medical societies: American College of Rheumatology and American Pain Society
Disclosure: Nothing to disclose.

CME Editor

Daniel Rauch, MD, FAAP, Director, Pediatric Hospitalist Program, Associate Professor, Department of Pediatrics, New York University School of Medicine
Daniel Rauch, MD, FAAP is a member of the following medical societies: Ambulatory Pediatric Association, American Academy of Pediatrics, and Society of Hospital Medicine
Disclosure: Baxter Honoraria Consulting; Pfizer Honoraria Consulting

Chief Editor

Barry L Myones, MD, Associate Professor, Departments of Pediatrics and Immunology, Pediatric Rheumatology Section, Baylor College of Medicine; Director of Research, Pediatric Rheumatology Center, Texas Children's Hospital
Barry L Myones, MD is a member of the following medical societies: American Academy of Pediatrics, American Association of Immunologists, American College of Rheumatology, American Heart Association, American Society for Microbiology, Clinical Immunology Society, and Texas Medical Association
Disclosure: Nothing to disclose.

 
 
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