We treated 75 patients with benign bone tumours by curettage and filling the defect with calcium hydroxyapatite (HA). There were 28 women and 47 men with a mean age of 27.7 years (3 to 80). The mean follow-up was for 41.3 months. Postoperative radiological assessment revealed that the implanted HA was well incorporated into the surrounding host bone in all patients. Two patients suffered fractures in the postoperative period. Two patients complained of pain associated with HA in the soft tissues, but this diminished within six months. No patient had local pain at the final follow-up. Recurrence of the tumour was seen in three cases. Histopathological study of the implanted area showed removal of the HA by histiocytes and multinucleated giant cells, and the formation of much appositional bone. We conclude that HA is an excellent bone-graft substitute in surgery for benign bone tumours.

Much of the basic research on calcium hydroxyapatite (HA) has concerned its clinical use as a bone-graft substitute. Biological, 1,2 histological 3-12 and biomechanical surveys of its implantation into bone [13][14][15] reveal that the material is safe and has excellent osteoconductive properties. It is often used as a coating for prostheses as well as to fill bone defects. [16][17][18] There have, however, been few reports on the outcome of its clinical use in surgery for bone tumours. 19,20 Since 1988, we have implanted HA for bone defects after resection of benign bone tumours. Patients and MethodsWe analysed the outcome in 75 patients with benign bone tumours. There were 28 women and 47 men, with a mean age of 27.7 years (3 to 80). All the lesions were imaged by plain radiography, CT and MRI. All patients had curettage of the tumour and filling of the resulting bone defect with HA, without autologous bone. Cortical fenestration was carried out using an osteotome and the intraosseous tumours were removed by a curette. When sclerotic margins were present they were drilled to establish a connection to healthy bone marrow. After filling the bone defect with HA, the cortical window was replaced. No other adjuvant treatment such as phenol or cryotherapy was used after curettage. Internal fixation was not employed. External stabilisation with splints or slings was utilised postoperatively for patients judged to be at risk of pathological fracture. The tumours were located in the femur (26 patients), phalanx or metacarpal (18), tibia (11), humerus (9), calcaneus (4), pelvis (3), radius or ulna (3) and fibula (1). Histological examination revealed that 21 were enchondromas, 18 fibrous dysplasias, 12 non-ossifying fibromas, eight solitary bone cysts, six Langerhans-cell histiocytomas, three chondroblastomas, two giant-cell tumours of bone, one aneurysmal bone cyst, one intraosseous haemangioma, one osteofibrous dysplasia, one osteoid osteoma and one enostosis (bone island).We used an HA compound ([Ca 10 (PO 4 ) 6 (OH) 2 ]) with tricalcium phosphate (TCP) in a ratio of 70% HA to 30% TCP (Chugai Inc, Tokyo, Japan). The porosity was 3% to 55% and the pore size 1 to 15 m. The sintering temperature ranged from 900° to 1300°C, and the bending strength from 50 to 800 kg/cm 2 . Variously shaped pieces of HA were used in the operations, depending on the location and size of the tumour. The mass of implanted HA ranged from 3 to 55 g. After surgery radiographs were assessed according to the criteria of Uchida et al 19 to determine changes in the radiolucent zone around the HA and the amount of incorporation and displacement of HA. Postoperative CT was carried out on some patients. The mean follow-up was 41 months (5 to 140). Of the 30 patients with lesions of the upper limb, 24 were immobilised in a sling or a splint. All 18 patients with lesions in the phalanges and metacarpals had splints. The mean period of immobilisation was 3.5 weeks. Of the 42 patients with lesions in the lower limb, six were immobilised in splints. The me...

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