Cytokine-Mediated Inflammatory Reaction Following Posterior Cervical Decompression and Fusion Associated With Recombinant Human Bone Morphogenetic Protein-2 A Case Study

Study Design. Case study with unique laboratory analysis. Objective. To present a potentially serious adverse event that may occur in unique individuals when using recombinant human bone morphogenetic protein-2 (rhBMP-2) to augment fusion in posterior cervical spine surgery. Summary of Background Data. The use of rhBMP-2 to augment posterior cervical decompression and fusion has not been approved by the Food and Drug Administration but has been advocated as safe to use by case series studies and multiple authors. Methods. A 66-year-old patient with myelopathy underwent posterior cervical decompression and fusion, using rhBMP-2 as a bone graft substitute. The patient had complete resolution of symptoms after surgery until day 6, when she experienced increasing pain and weakness. T2 magnetic resonance images revealed a high intensity fluid collection compressing the cervical cord posteriorly. Emergent decompression was performed and the patient improved until postoperative day 12 when the same clinical scenario occurred. Symptoms again improved with surgical debridement. The clear, nonsanguineous fluid was sent for a quantitative cytokine panel each time. The case is reviewed with specific reference to the evolving literature regarding rhBMP-2 use in the spine, and the findings of seroma analysis. Results. The fluid analysis of the seroma fluid at the time of both debridements showed impressive elevations in inflammatory cytokines, especially IL-6 and IL-8. Conclusion. Acute inflammatory reactions to rhBMP-2 can occur in the posterior cervical spine and can lead to significant morbidity. Host factors, BMP-2 dosage, and carrier factors all likely play a role in these complex reactions and must be considered every time an off label usage of rhBMP-2 is considered. More study is clearly indicated.