Osteoid osteoma: resection with CT guidance.

Background: Osteoid osteoma is a benign bone lesion characterized by nocturnal pain mostly, which may be relieved by non-steroidal prostaglandin inhibitors. Treatment by complete resection of the nidus immediately relieves the pain. Intraoperative location of the nidus may be difficult, and extensive bone resection may be necessary to ensure complete excision. Few studies have described resection of osteoid osteoma under CT guidance, and little attention has been given to lesions near the neurovascular bundle. Objective:. To report our results of osteoid osteoma resection under CT guidance, with specific attention to lesions lying near the neural structure. Methods: Nine patients with suspected osteoid osteoma underwent resection with a 6.8 mm core drill under CT guidance. Results: Histologic confirmation was obtained in seven patients, while in two there was no evidence of the nidus in the excised bone material. All nine reported complete pain relief immediately after the surgery. Postoperative CT scan showed complete removal of the osteoid osteoma. Conclusions: Removal of osteoid osteoma under CT guidance is simple, safe and allows complete removal of the nidus with low morbidity. IMAJ 2000;2:151–153 Osteoid osteoma is a benign bone lesion characterized by the formation of a small nidus of variably calcified osteoid tissue in the stroma of loose vascular connective tissue, surrounded by a margin of dense sclerotic bone. The lesion causes considerable pain, more marked at night, which may be relieved by non-steroidal prostaglandin inhibitors [1]. Treatment consists of complete resection of the nidus, which immediately relieves the pain. Intraoperative location of the nidus may be difficult, and extensive bone resection may be necessary to ensure complete excision, with possible risk of fracture and an extended period of healing. Few studies have described resection of osteoid osteoma under CT guidance [2–5]. Moreover, little attention has been given to lesions located near the neurovascular bundle. We report our results of osteoid osteoma resection under CT guidance, with specific attention to lesions lying near the neural structure. Materials and Methods The study population included nine patients, seven males and two females, aged 10 to 22 years, who had pain from osteoid osteoma for 3–12 months. The patients reported that the pain was more severe at night and was relieved with naproxen. The preoperative diagnosis was based on clinical history, plain radiography, bone scan and computed tomography studies. Bone scan indicated an increased area of intake at the site of the lesion. The osteoid osteoma was located in the proximal tibia in two patients, the femoral shaft in two, the posteromedial cortex of the femoral neck near the sciatic nerve in two, the posterior cortex of the medial condyle of the humerus near the ulnar nerve in one, proximal humerus in one, and both the medial malleolus and talus of the same leg in one patient. In each case the patient was positioned on the CT table to allow the shortest access to the lesion, as determined at the initial diagnostic CT scan. The lesions were initially localized on CT scan by imaging continuous 2 mm thick sections. The site was then marked on the skin surface. A guide wire was inserted under general anesthesia through the marked skin into the nidus by a direct route. Its position was verified by CT scan and, if necessary, corrected. A small incision was made on both sides of the wire and a blunt cannulated obturator and sleeve were inserted over the guide wire. The obturator was then removed and a 6.8 mm core biopsy drill was inserted over the guide wire. The depth of the drill into the bone and past the cortex was also verified by CT scan and the whole lesion was excised in one step. Bone curettage was then performed with a small spoon to remove residual debris. At the end of the procedure, CT scanning was repeated to confirm complete removal of the nidus. The excised core was sent for histological examination.