Osteoid osteoma and osteoblastoma of the spine. Factors associated with the presence of scoliosis.

STUDY DESIGN: A retrospective study of 44 museum cases of spinal osteoid osteoma or osteoblastoma and a meta-analysis using 421 additional cases from a review of the literature.

OBJECTIVES: To identify the factors that are associated with the development of scoliosis in these patients.

SUMMARY OF BACKGROUND DATA: Painful scoliosis is a well recognized presentation of spinal osteoid osteoma and osteoblastoma and is considered to be secondary to pain-provoked muscle spasm on the side of the lesion. Previous studies have been based on small numbers of patients that did not permit statistical validation of the reported observations.

METHODS: Eight factors were assessed including: age, gender, duration of symptoms, site of lesion in the spine, vertebral level of lesion, site of lesion in the individual vertebra, type of lesion, and Cobb angle at presentation. Reports were reviewed only if the presence or absence of scoliosis could be determined. Statistical analyses initially were performed on the museum cases and then on a combination of museum cases and cases from the literature.

RESULTS: Overall, 63% of subjects had scoliosis. The lesions were typically present on the concave aspect of the curve. Three cases of scoliosis from the literature involved lesions that were reported to be on the convexity. Scoliosis is significantly more common in cases of osteoid osteoma than in cases of osteoblastoma (P < 0.0001); lesions are more common in the thoracic and lumbar regions than in the cervical region (P < 0.0001), in lower cervical region than in the upper cervical region (P value = 0.0027), and they are more commonly located to one side of the midline (P < 0.0001). Age, gender, and duration of symptoms were of no significance.

CONCLUSIONS: The findings support the concept that scoliosis is secondary to asymmetric muscle spasm in patients with spinal osteoid osteoma or osteoblastoma.