Myositis ossificans

From Wikipedia, the free encyclopedia
Jump to: navigation, search

Myositis ossificans comprises two syndromes characterized by heterotopic ossification (calcification) of muscle.

Heterotopic Ossification Elbow1

Classification[edit]

  • In the first, and by far most common type, nonhereditary myositis ossificans (commonly referred to simply as "myositis ossificans", as in the remainder of this article), calcifications occur at the site of injured muscle, most commonly in the arms or in the quadriceps of the thighs.
    • The term myositis ossificans traumatica is sometimes used when the condition is due to trauma.[1][2] Also Myositis ossificans circumscripta is another synonym of myositis ossificans traumatica refers to the new extraosseous bone that appears after trauma.[3]
  • The second condition, myositis ossificans progressiva (also referred to as fibrodysplasia ossificans progressiva) is an inherited affliction, autosomal dominant pattern, in which the ossification can occur without injury, and typically grows in a predictable pattern. Although this disorder can be passed to offspring by those afflicted with FOP, it is also classified as nonhereditary, as it is most often attributed to a spontaneous genetic mutation upon conception.

Most (i.e. 80%) ossifications arise in the thigh or arm, and are caused by a premature return to activity after an injury. Other sites include intercostal spaces, erector spinae, pectoralis muscles, glutei, and the chest. On planar x-ray, hazy densities are sometimes noted approximately one month after injury, while the denser opacities eventually seen may not be apparent until two months have passed.

Pathophysiology of myositis ossificans traumatica[edit]

The specific cause and pathophysiology are unclear - it may be caused by an interaction between local factors (e.g., a reserve of available calcium in adjacent skeletal tissue or soft tissue edema, vascular stasis tissue hypoxia or mesenchymal cells with osteoblastic activity) and unknown systemic factors. The basic mechanism is the inappropriate differentiation of fibroblasts into bone-forming cells (osteoblasts). Early edema of connective tissue proceeds to tissue with foci of calcification and then to maturation of calcification and osifications

Sonographic diagnosis[edit]

Calcification is typically depicted 2 weeks earlier at US when compared to radiographs.[4] The lesion develops in two distinct stages with different presentations at US.[5] In the early stage, termed immature, it is depicts a non-specific soft tissue mass that ranges from a hypoechoic area with an outer sheet-like hyperechoic peripheral rim to a highly echogenic area with variable shadowing. In the late stage, termed mature, myositis ossificans is depicted as an elongated calcific deposit that is aligned with the long-axis of the muscle, exhibits acoustic shadowing, and has no soft tissue mass associated. US may suggest the diagnosis at early stage, but imaging features need to evolve with successive maturation of the lesion and formation of the characteristic late stage changes before they become pathognomonic.

The differential diagnosis includes many tumoral and nontumoral pathologies. A main concern is to differentiate early myositis ossificans from malignant soft-tissue tumors, and the latter is suggested by a fast-growing process. If clinical or sonographic findings are dubious and extraosseous sarcoma is suspected, biopsy should be performed. At histology, detection of the typical zonal phenomenon is diagnostic of myositis ossificans, though microscopic findings may be misleading during the early stage.[6]

Radiologic diagnosis[edit]

The radiological features of myositis ossificans are ‘faint soft tissue calcification within 2–6 weeks, (may have well-defined bony margins by 8 weeks) separated from periosteum by lucent zone and on CT, the characteristic feature is peripheral ossification’.[7][8][9]

Prevention[edit]

Radiation therapy subsequent to the injury or as a preventive measure of recurrence may be applied but its usefulness is inconclusive.[10] if the surgery performed next step in accordance with literature postoperative single low-dose radiation with 3 weeks of oral indomethacin regimen will be preventive for recurrence.[11][12][13]

Treatment[edit]

Treatment is initially conservative, as some patients' calcifications will spontaneously be reabsorbed, and others will have minimal symptoms. In occasional cases, surgical debridement of the abnormal tissue is required, although success of such therapy is limited.

Treatment of myositis ossificans:

  • Rest
  • Reduction
  • Immobilization
  • Anti-inflammatory drugs
  • Physiotherapy management

Surgical removal of the myositis ossificans is rarely warranted. If the myositis ossificans is excised before its maturation, it will likely reoccur. Consequently, most healthcare providers wait 6–12 months before considering excision. There is a chance of relapse even when removed in a mature state. In general, myositis ossificans is removed surgically if it limits the range of motion of the joint, irritates a nerve or lowers quality of life.

References[edit]

  1. ^ Sodl JF, Bassora R, Huffman GR, Keenan MA (January 2008). "Traumatic myositis ossificans as a result of college fraternity hazing". Clin. Orthop. Relat. Res. 466 (1): 225–230. doi:10.1007/s11999-007-0005-6. PMC 2505309. PMID 18196398. 
  2. ^ Chadha M, Agarwal A (December 2007). "Myositis ossificans traumatica of the hand". Can J Surg 50 (6): E21–2. PMC 2386223. PMID 18067695. 
  3. ^ Henry D. Myositis ossificans. http://www.bonetumor.org/unknown-tumor-soft-tissue/ myositis-ossificans (accessed 15 Jun 1999).
  4. ^ Peetrons P. Ultrasound of muscles. Eur Radiol 2002; 12:35-43.
  5. ^ Arend CF. Ultrasound of the Shoulder. Master Medical Books, 2013. Chapter on ultrasound evaluation of myositis ossificans of the pectoralis major muscle available at ShoulderUS.com
  6. ^ Mirra JM, Picci P, Gold RH. Osseous soft tissue tumors. In: Mirra JM, Picci P, Gold RH (editors). Bone tumors: clinical, radiologic, and pathologic correlations. Philadelphia: Lea & Febiger; 1989.
  7. ^ Crundwell N, O’Donnell P, Saifuddin A. Nonneoplastic conditions presenting as soft-tissue tumours. Clin Radiol 2007;62:18–27.
  8. ^ Parikh J, Hyare H, Saifuddin A. The imaging features of post-traumatic myositis ossificans, with emphasis on MRI. Clin Radiol 2002;57:1058–66.
  9. ^ Gokkus K, Sagtas E, Suslu FE, Aydin AT.Myositis ossificans circumscripta, secondary to high-velocity gunshot and fragment wound that causes sciatica.BMJ Case Rep. 2013 Oct 17;2013. pii: bcr2013201362. doi: 10.1136/bcr-2013-201362.
  10. ^ http://emedicine.medscape.com/article/390416-overview
  11. ^ Pakos EE, Pitouli EJ, Tsekeris PG, et al. Prevention of heterotopic ossification in high-risk patients with total hip arthroplasty: the experience of a combined therapeutic protocol. Int Orthop 2006;30:79–83.
  12. ^ Knelles D, Barthel T, Karrer A, et al. Prevention of heterotopic ossification after total hip replacement. A prospective, randomised study using acetylsalicylic acid,indomethacin and fractional or single-dose irradiation. J Bone Joint Surg Br 1997;79:596–602
  13. ^ Heyd R, Strassmann G, Schopohl B, et al. Radiation therapy for the prevention of heterotopic ossification at the elbow. J Bone Joint Surg Br 2001;83:332–4.

External links[edit]