Clinical outcome following surgical intervention for a solitary bone cyst: emphasis on treatment by curettage and steroid injection.

BACKGROUND: Solitary bone cysts are benign, fluid-filled, expansive lesions in children. The success rate of bone consolidation in the case of a solitary bone cyst is unpredictable following steroid injection.
METHODS: Among 24 patients with a solitary bone cyst, 11 (femur 8; pelvic bone 3) underwent curettage plus bone grafting for stabilization. The remaining 13 patients--8 long bones (humerus 6; femur 2) and 5 non-long bones (calcaneus 5)--underwent curettage plus steroid injections.
RESULTS: Among the 11 patients, 2 treated by curettage plus bone grafting suffered recurrence and needed a second procedure. One of the 13 patients treated by curettage plus steroid injection as the initial treatment later developed a pathological fracture and underwent bone grafting. The remaining 12 patients treated by curettage plus steroid injection eventually achieved bone consolidation, after an average of 1.6 injections (range 1-3). One injection was enough to achieve bone consolidation in two of seven of the long-bone cases (29%) and in all of the five non-long-bone cases.
CONCLUSIONS: Steroid injection remains a useful method for treating solitary bone cysts owing to its low invasiveness. The very favorable results achieved in the five calcaneus cases following a single steroid injection may be attributable to curettage. Regardless of the relatively small number of cases, the different prognosis between long bones and the calcaneus following the same procedure suggests a varying pathogenesis and/or etiology among solitary bone cysts.