OBJECTIVE A variety of aggressive benign bone tumors often require wide bone and soft tissue excision for adequate local control, but this creates a large defect and a seriously weakened extremity. Restoration of limb function presents a difficult problem. METHODS The treatment of 104 patients with space occupying lesions of the long bone were analyzed. Deep-frozen (-70 degrees C) cortical strut allografts with or without allogeneic cancellous bone graft were implanted into the defects after extensive intralesional curettage. Thirty-six patients had fibrous dysplasias, 29 unicameral bone cysts, 22 giant cell tumors, 12 aneurysmal bone cysts, 3 benign fibrous histiocytomas, and 2 ossifying fibromas. Fifty-six patients had pathologic fracture. The average volume after curettage was 210 ml (range 60-460 ml). The average follow-up period was 50 months. RESULTS At follow-up evaluation, the radiographs demonstrated complete incorporation of the allogeneic implant and new bone formation in the cavity in 83% of the patients (86/104). All fractures healed. There was no local recurrence or fracture of the cortical graft; neither were there other serious complications except one avascular necrosis of the femoral head. Good or excellent functional results were found in 97% (101/104) of the patients. CONCLUSIONS For large osseous defects, the reconstructive technique using cortical stent allograft provides increased strength, easy fixation, remodeling of the cystic defect, and healing of the fracture and prevents deformity. However, remodeling occurs slowly and may never be complete.