Revision Total Hip Arthroplasty Using Acetabular Reinforcement Ring: Midterm Follow-up Result

PURPOSE: To evaluate the clinical and radiographic outcomes of the revision total hip arthroplasty using the acetabular reinforcement ring. MATERIALS AND METHODS: Thirty-six acetabular revisions were performed in 36 patients with use of the reinforcement ring and structural or morselized allograft, between 1997 and 2005, in thirty-six patients. According to the AAOS classification, thirty-four cases of acetabular defects were Ttype III, and two were Ttype IV. Mean follow-up period after surgery was 7.2 years. RESULTS: The mean Harris hip score was 92.3, which was significantly increased compared with the preoperative score. (p<0.001). There were five failures: a case of aseptic loosening of Muller ring, two cases of infection (5.4%) and two cases of hip dislocation (5.4%). Graft incorporation and bone remodeling occurred successfully in all hips, but in the case of aseptic loosening in which the ring fixation had been inadequate at the time of surgery. The success rate was 91.7% with a mean follow-up of 7.2 years, if the cases of revision or loosening of the component were classified into failure cases. CONCLUSION: Patients treated with acetabular revision with three kinds of reinforcement ring had reconstitution of periacetabular bone stock as well as good clinical and radiographic results. For the good results, the secure implant fixation during the surgery should be confirmed and we should completely understand the characters of the each kinds of reinforcement rings.

Pathologic Fracture in Radiation-induced Osteosarcoma Misdiagnosed as Delayed Femoral Neck Fracture / 대한정형외과학회잡지

Secondary osteosarcoma has a relatively higher incidence in middle aged persons than in children. Radiation-induced osteosarcoma occurs in approximately 1% of patients who have been treated with more than 2,500 cGy. The time interval from radiation to onset of secondary osteosarcoma is approximately 10 to 15 years. A 51-year-old female who have been treated with radiation for angiomyxoma was hospitalized due to right hip pain. She had a minor trauma 2 weeks prior to hospitalization. A day before hospitalization, she experienced a second trauma by fall, and then, severe hip pain developed. A radiograph of the patient showed femoral neck fracture with sclerotic change of fractured margin. We diagnosed the patient as having a neglected femoral neck fracture and treated it with closed reduction using cannulated screw fixation. At 6 months post-surgery, the patient had residual pain of the right hip and we could find overproduced callus at the fracture site. Through further evaluation, we diagnosed this as secondary osteosarcoma with pulmonary metastasis. We report this case to make a warning about a misdiagnosed osteosarcoma as a simple femoral neck fracture.