Bisphosphonate therapy for spinal aneurysmal bone cysts.

Purpose: To assess the efficacy of bisphosphonate therapy in the management of spinal aneurysmal bone cysts (ABCs).

Methods: A prospective study of six consecutive patients aged between 7 and 22 years with spinal ABCs treated with pamidronate (1 mg/kg) or zoledronate (4 mg). A visual analogue scale (VAS) for pain and radiological (contrast-enhanced MRI and CT scan at 3 and 6 months, then yearly X-rays) follow-up was continued for a minimum of 6 years.

Results: One patient with an unstable C2/3 failed to respond to a single dose of bisphosphonate and required surgical resection and stabilisation with autologous bone grafting. Another, with a thoraco-lumbar ABC, experienced progression of neurological dysfunction after one cycle of bisphosphonate and, therefore, required surgical resection and stabilisation. In all other patients pain progressively improved and was resolved after two to four cycles (VAS 7.3-0). These patients all showed reduction in peri-lesional oedema and increased ossification by 3 months. No patients have had a recurrence within the timeframe of this study.

Conclusions: Bisphosphonate therapy can be used as the definitive treatment of spinal ABCs, except in patients with instability or progressive neurology, where surgical intervention is required. Clinicians should expect a patients symptoms to rapidly improve, their bone oedema to resolve by 3 months and their lesion to partially or completely ossify by 6-12 months.