Unicameral bone cysts are benign fluid-filled cystic lesions most commonly found in the metaphysis of long bones in skeletally immature patients. Many of these simple cysts involve the humerus. A multitude of treatment methods have been recommended ranging from steroid injections to open bone grafting. The authors report a low-morbidity procedure using curettage with calcium sulfate. The goal is to enhance cyst resolution and minimize morbidity. Twenty-eight children were treated with the above technique. Four patients were lost to follow-up and the remaining 24 patients were evaluated at approximately two years. Six of the 24 children had previous treatment of the unicameral bone cysts. The surgical technique is performed in an outpatient setting. A needle is inserted into the cyst and renografin dye injected to confirm the diagnosis of a unicameral bone cyst. The puncture site is then enlarged with an arthroscopy trochar and the cyst lining removed. An angled curette or flexible intramedullary nail is used to perform the intramedullary decompression with connection of the intramedullary nail to the cyst. A pellet injector was then inserted into the entry hole and calcium sulfate pellets were inserted. The upper extremities were protected in a sling for several weeks then range of motion instituted.
Ten of the 24 patients had the unicameral bone cysts within the humerus. Follow-up radiographs revealed complete healing in 22 patients defined as greater than 95% opacification. Partial healing was demonstrated in one patient and persistence was demonstrated in one patient. All patients were fully active and pain-free at the time of final follow-up. The authors present an established way of treating unicameral bone cysts involving decompression and curettage. The authors do add calcium sulfate pellets as an adjunct treatment. A variety of bone matrix products have been inserted in these cysts with fairly uniform results. The excellent results in this study are encouraging. The only outstanding question is whether any calcium or bone product within the cyst is necessary. Simple decompression and connection of the intramedullary contents to the cysts may very well be adequate.