Exaggerated Inflammatory Response After Use of Recombinant Bone Morphogenetic Protein in Recurrent Unicameral Bone Cysts

Background: Recurrent unicameral bone cysts (UBCs) can result in significant morbidity during a child's physical and emotional development. Multiple treatment options are available and a review of the literature fails to clearly define the optimal treatment for UBCs. Recombinant bone morphogenetic protein (BMP) has been used with success in other disorders of poor bone formation. This manuscript is the first to report on the use of recombinant BMP in the treatment of UBCs. Methods: Three patients with recurrent UBCs underwent revision surgery with recombinant BMP. Radiographic and medical review was performed and is reported here. Results: In these patients, the use of BMP failed to fully resolve their UBC; 2 patients had complete recurrence that required further surgery. In addition to poor radiographic results, all patients developed exaggerated inflammatory responses in the acute postoperative period. Each child developed clinically significant limb swelling and pain that mimicked infection. Conclusions: On the basis of our poor radiographic results and a paradoxical clinical result, we no longer recommend the use of recombinant BMP in the manner reported here for the treatment of recurrent UBCs. Level of Evidence: Level IV, case series.