Long history: 67-year-old woman with recent cerebral infarction resulting in severe right-sided weakness now presenting with amorphous ossification around the right hip on radiographs 06/21/2007. Evaluate for heterotopic ossification.
Radiopharmaceutical: 20.1 mCi Tc-99m MDP i.v.
Discussion: Heterotopic ossification (HO) is the presence of bone in soft tissue where bone normally does not exist. The acquired form of HO most frequently is seen with musculoskeletal trauma, spinal cord injury, or central nervous system injury. The fever, swelling, erythema, and occasional joint tenderness seen in early HO can be difficult to distinguish from cellulitis, osteomyelitis, or thrombophlebitis. Bone scanning and other imaging tests frequently are used to distinguish between these diagnostic possibilities. Bone scanning may be requested to confirm the diagnosis of HO . In addition, surgical resection of HO is used to preserve joint mobility; however, HO is likely to recur and possibly progress if resection is undertaken before the ossification has become mature. With a view toward avoiding recurrent HO and other operative complications, serial bone scans are used to determine whether medical treatment is warranted, and to choose the appropriate time for surgical resection of HO.