Bilateral central acetabular fracture dislocations secondary to sustained myoclonus

This case report presents a patient with bilateral central acetabular fracture dislocations secondary to sustained myoclonus treated with delayed bilateral total hip arthroplasty. This is an unusual mechanism of injury, but is similar to other uncontrolled muscular contractions, such as electroconvulsive therapy and seizures. Because of ongoing myoclonus, the patient initially was treated nonoperatively. The patient then successfully had staged bilateral total hip arthroplasty 15 months after injury. This case exemplifies that forceful, uncontrolled muscular contraction can cause bilateral symmetric fracture dislocations. In patients with a history of seizure or myoclonic contracture with subsequent pain or loss of function, radiographs are indicated and skeletal fracture or joint dislocation must be ruled out. Secondary reconstruction can be recommended when the patient is medically stable.

Histochemical and immunohistochemical characterization of cells constituting the giant cell tumor of bone

Enzymatic activity and cell membrane proteins were characterized in cells from five giant cell tumors of bone (GCTs). Naphthyl alpha esterase (NAE) and acid phosphatase (AP) activity was noted within both the mononuclear and multinucleated cells of each tumor. In each tumor, all mononucleated cell populations displayed tartrate-sensitive AP activity, whereas the multinucleated cell populations demonstrated variable expression of tartrate-sensitive and tartrate-resistant AP activity. Analysis of cell membrane proteins included attempts at immunodetection of mannose receptor, OKM-1 antigen (OKM-1a), colony-stimulating factor-1 receptor (CSF-1r), and platelet-derived growth factor receptor (PDGFr). None of these membrane antigens were elicited on multinucleated cells. In contrast, the mannose receptor, OKM-1a, and PDGFr all were detected on the mononucleated cells within each tumor. These data demonstrate that a population of mononucleated, not multinucleated cells, expresses features unique to mature mononuclear phagocytes and establishes the presence of a membrane receptor, PDGFr, associated with mitogenesis of mesenchymal cells.