Benign+Heterotopic+Bone

Heterotopic bone formation or heterotopic ossifications occur in 30 percent of patients that have a partial or total hip replacement. 1 This incidence increases to roughly 80 percent if the patients has had previous ossification to the ipsilateral or contralateral hip. 1 || The exact known cause of heterotopic ossification is unknown. However, there are a few causes that may play some role in developing ossifications. 2 These include: a genetic disposition, surgical procedures (hip replacement), and/ or spinal or brain injury. 2 Total or partial hip replacement is by far the most common cuase of this condition. || This condition is as result of abnormal ossification after bone fracture or replacement. The bone may become mineralized in joints or areas of soft tissue that limit mobility and give the patient severe pain. Signs and symptoms appear during the healing period of fracture or replacement and the patient experiences severe pain, progressive swelling and decreased mobility. 3 Unfortunately, the patient will still experience significant pain even if the motion is non-weight bearing and can interfere with sleep. 3
 * **Epidemiolgy:** || Brandon
 * **Etiology:** || Brandon
 * **Signs & Symptoms:** || Ashley

|| Because this type of growth is likely to happen after a surgery or bone replacement, this is the biggest indication of heterotopic bone(s). To verify the diagnosis, the physician may order a(n): 3 Hetrotropic ossifications are classified as: 5 Histology subtypes: 5 || Since heterotopic bone formation is benign, there cannot be metastasis as in malignant tumors. 6 || There is no grading system for heterotopic bone formation. || Staging describes the extent or severity of the tumor and spread. This included the primary tumor site, size, nodal involvement, cell grade, and metastasis. Benign lesions are not cancerous and no staging is available. 7 || Radiation treatments for HO increases the risk of bony nonunion. Studies have shown that nonunion occurs in 20-30% of cases prophylactically treated with RT and only in 2-15% of cases not treated with RT 8 || This is a benign condition, the prognosis is good. Radiation therapy can cause cancer, but in this case no such complication has been documented in medical literature. || Treatment traditionally is given in the immediate postoperative period, with radiation doses ranging from 7Gy or 8Gyin a single fraction. 9 || Although the TD 5/5 is not used in the case of Heterotopic bone, the TD 5/5 for bone is thought to be about 60 Gy with conventional fractionation. 10 ||
 * **Diagnostic Procedures:** || Ashley
 * X-ray
 * MRI or CT scan
 * A bone scan (to rule out other diagnosis for a malignancy if other imaging is not conclusive) ||
 * **Histology:** || Amanuel
 * Neurogenic hetrotropic ossification
 * Traumatic myositis ossification
 * Fibrodsyplasia ossificans progressiva [Muchmeyer’s disease]
 * Mature fatty bone marrow
 * Mature trebucular bone
 * **Lymph node drainage:** || Since hetrotropic bone does not metastasize to other sites, there is no lymph node drainage. ||
 * **Metastatic spread:** || Lindsey
 * **Grading:** || Lindsey
 * **Staging:** || Kevin
 * **Radiation side effects:** || Kevin
 * **Prognosis:** || Jenn
 * **Treatments:** || Jenn
 * **TD 5/5:** || Rachel
 * **References:** || # Chao K, Perez C, Brady L. //Radiation Oncology Management Decisions//. 2nd ed. Philadelphia, PA: Lippincott William & Wilkins; 2002: 685.
 * 1) Heterotopic Ossification. Web site. []. Accessed July 9, 2013.
 * 2) Overivew of Bone and Joint Tumors. The Merck Manual Web site. http://www.merckmanuals.com/professional/. Updated November 12, 2012. Accessed July 2, 2013.
 * 3) Pitfalls in MR image interpretation Prompting Referrals to an Orthopedic Oncology Clinic. RadioGraphics Web site. []. Accessed July 2, 2013.
 * 4) Woon C. Hetrotropic ossification. http://www.orthobullets.com/pathology/8044/heterotopic-ossification. Accessed July 8, 2013.
 * 5) Understanding cancer series. National Cancer Institute Web Site. []. Accessed on July 9, 2013.
 * 6) Cancer staging/ grading. Available at: []. Accessed on July9, 2013.
 * 7) Baird E, Kang Q. Prophylaxis of heterotopic ossification - an updated review. Journal of Orthopaedic Surgery & Research. January 2009;4:1-8. Available from: Academic Search Complete, Ipswich, MA. Accessed July 9, 2013.
 * 8) Chao KS, Perez CA, Brady LW. //Radiation Oncology Management Decisions//. 3rd . Philadelphia, PA: Lippincott, Williams & Wilkins; 2011: 788-789.
 * 9) Late Bone and Cartilage Reactions. OzRadOnc Website. []. Accessed on July 3, 2013. ||

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