OSTEOID OSTEOMAS OF THE LIMBS

Purpose: Osteoid osteoma is a benign small-sized painful osteoblastic tumour usually observed in young subjects. The purpose of this work was to study the epidemiological, clinical, radiological, and histological features, focusing on clinical course after treatment and differences by location. Material and methods: We report a retrospective series of 56 osteoid osteomas located in limbs treated over a 25-year period from 1976 to 2001. The tumour involved the femur (n=21), the tibia (n=14), the hand (n=8), the foot (n=7), and the olecranon, the lateral humeral condyle, the humeral neck, and the acetabulum (n=1 each). Pain was the pain symptom, found in all patients. The aspirin test was positive in 82%. The joint locations led to an arthropathy in 87%. The typical nidus aspect was found on 78.5% of the plain x-rays. Computed tomography was performed in 25 patients and scintigraphy in 10. Magnetic resonance imaging was performed in 4. Surgical treatment consisted in en bloc resection (n=48), intra-lesions curettage (n=6), computed tomography-guided percutaneous resection (n=2). Mechanical protection was obtained with a plaster cast (n=21) and osteosynthesis material (n=7). A bone graft was used in 22 patients. Pathology confirmed osteoid osteoma in all patients. Lymphocyte plasma cell infiltrations were observed in seven of the articular localisations. Results: Mean follow-up was 5 years. Complete pain relief was achieved after a single resection in 53 patients and after re-operation of a second resection in the others. For the joint localisations, complete joint movement was recovered in three-quarters of the patients. Postoperative x-rays were performed in all cases. The main early complications were iatrogenic fracture (9%), mainly in patients with a tibial tumour. Late complications included osteoarthritis for the acetabular tumour and two cases of talal degeneration. Conclusion: Osteoid osteoma is an uncommon tumour general easy to recognise. Atypical clinical and radiological presentations are rare. Computed tomography is the key to diagnosis and provides important therapeutic information.