A unicameral bone cyst is a common benign tumor, which frequently presents in the long bones in the pediatric population. The humerus is particularly prone to develop unicameral bone cysts. There have been many methods to manage these cysts including bone grafting, total resection, subtotal resection with bone grafting, and a variety of bone substitution products. Decompression and intralesional injections have also been recommended. Early reports have indicated positive outcomes with the insertion of intramedullary devices through unicameral bone cysts. This study assesses the results of elastic intramedullary nailing in 56 children affected by unicameral bone cysts with a long-term follow-up in 47 children. No case underwent previous treatment. The study cohort consisted of 47 children between the ages of 4 and 13 years. The cyst was located in the humerus in 36 patients and in the femur in 11. Forty-five patients presented with pathological fracture, and 43 were managed immediately with intramedullary fixation. The technique performed was described by Métaizeau et al. with retrograde placement of the intramedullary nail. Diameter and length of the nails were selected based upon preoperative radiographs. The diameter was selected such that two nails would occupy approximately two thirds of the medullary canal without interference into the growth plate.
The results were evaluated on plain x-ray and the cyst was classified as completely filled with bone or healed with residual radiolucency. The cyst was also classified as a recurrence when it had initially healed and had become filled with bone, but subsequent large areas radiolucency and cortical thinning developed. No response was defined as no evidence of any effect of treatment. In this study, 31 (70%) were classified as completely healed and 16 (34%) were classified as healed with residual radiolucency. There were no cases of recurrences or no cases of “no response.” The majority of cysts healed within a three-year duration. Only 14 patients required removal of the intramedullary nails. Complications such as physeal damage, infection, refracture, or problems related to the protruding nail ends were not encountered.
The true etiology of unicameral bone cyst remains obscure. In addition, there is no universal agreement as to the best treatment for this benign tumor. Traditionally, curettage and bone graphing was recommended. However, there are problems with this technique including complications such as physeal arrest and limb shortening. The other popular treatment involves injection of corticosteroids with or without cyst wall disruption. Recent studies indicate that this technique is relatively unpredictable. The efficacy of intramedullary roding may be related to decompression of the cyst via drainage of fluids through the cyst wall into the medullary canal. This decreases the intralesional pressure and may promote consolidation of the cyst. Nailing has the added benefit of early stabilization to allow early mobilization and return to normal activities. The authors report excellent results using a relatively straight forward technique. This method should be considered in the treatment of unicameral bone cysts in the long bones of children, especially that of the humerus.
Unicameral, Bone, Cyst, Humerus, Children, Tumor, Nailing
J Pediatr Ortho