Bisphosphonates in osteoid osteoma with difficult location in children

Osteoid osteoma is a benign bone tumor that may cause severe pain. Although percutaneous thermoablation is commonly performed and effective in approximately 90% of cases by rapidly relieving symptoms and avoiding surgery, this procedure may carry significant risks when lesions are located near sensitive anatomical structures such as neural, medullary, or cartilaginous tissues. In these situations, bisphosphonates (BP) may represent a less invasive therapeutic alternative by biologically reducing abnormal bone activity and inflammatory pain. Previous studies have demonstrated the efficacy of zoledronic acid in osteoid osteoma, but pediatric data remain scarce.

Bisphosphonates may represent an alternative therapeutic option for osteoid osteomas located in anatomically challenging areas unsuitable for conventional treatments.

This multicenter retrospective study included 11 pediatric patients with osteoid osteoma located close to neural or cartilaginous structures contraindicating surgical treatment or thermoablation and treated with bisphosphonates. Patients received 3 to 6 monthly infusions of zoledronic acid. Clinical pain assessment, NSAID and analgesic consumption, imaging outcomes, and treatment-related adverse events were collected before and after treatment.

Eleven patients (3 girls and 8 boys) were included between 2012 and 2024. Mean age was 13.5 years (range, 8-17 years). Mean baseline Visual Analog Scale (VAS) score was 70.6/100 (30-90). NSAID and analgesic consumption was reported in 91% of patients, while all patients presented with a visible nidus and reactive bone marrow edema on imaging. Mean duration of symptoms before BP treatment was 12.7 months (2-26). The mean number of infusions was 3.8 (3-6). Only one patient developed anterior uveitis, which did not require treatment discontinuation. At final follow-up, mean VAS score decreased to 30.4/100 (0-80), while NSAID and analgesic consumption decreased to 36%. Complete disappearance of both nidus and bone marrow edema was observed in 73% of patients. Mean follow-up duration was 7.2 months.

Zoledronic acid appears to be a promising therapeutic alternative for osteoid osteomas located in anatomically challenging areas in children. Its efficacy is reflected by nidus disappearance, pain reduction, and decreased NSAID consumption. Further studies with larger cohorts and longer follow-up are required to strengthen the level of evidence.

IV; retrospective study.