Introduction: Traditional treatment options for unicameral bone cysts (UBCs) include observation, sequential steroid injections, and open curettage and bone grafting, which are all associated with high recurrence rates, persistence and complications. Due to these factors, a new minimally invasive percutaneous technique (MIPT) utilizing calcium sulfate pellets was instituted. The purpose of the study was to evaluate the effectiveness and morbidity of MIPT for the treatment of unicameral bone cysts (UBCs) in children utilizing osteoconductive calcium sulfate pellets.

Material and methods: Eighteen children (8 girls, 10 boys) with UBCs were surgically treated using MIPT and had an average followup of 26 months (range, 24-42 months). Average age at the time of surgery was 11 years (range, 5-17 years), and 16 were skeletally immature. The patients underwent aspiration, cystogram, and biopsy under fluoroscopic guidance, followed by percutaneous intramedullary decompression, curettage and grafting with calcium sulfate pellets through a specially designed trocar system. To protect against fracture, the extremity was protected in a sling (for proximal humerus) or cast (for selected cases of lower extremity) for several weeks until structural integrity was sufficient. Followup was performed for each patient through clinical evaluation and radiographic review. Cyst healing was determined radiographically and defined as opacification and cortical thickening.

Results: All patients returned to daily activities with complete clinical recovery. Radiographically, 13 (72%) patients demonstrated complete healing and 5 patients (28%) showed significant partial healing (> 80% obliteration with cortical thickening) of the cyst. None of the patients required additional treatment. There were no recurrences or complications.

Conclusion: MIPT utilizing calcium sulfate pellets is potentially an effective treatment for UBCs in children with high healing and low reoperation and complication rates.