Use of Recombinant Human Bone Morphogenetic Protein-2 at the C1-2 Lateral Articulation Without Posterior Structural Bone Graft in Posterior Atlantoaxial Fusion in Adult Patients.

INTRODUCTION: Posterior atlantoaxial fusion is an important armamentarium for neurosurgeons to treat several pathologies involving the craniovertebral junction. Although the potential advantages of recombinant human bone morphogenetic protein -2 (rhBMP-2) are well-documented in the lumbar spine, its indication in C1-2 fusion has not been well-characterized. In our institution, we apply rhBMP-2 to the C1-2 joint either alone or with hydroxyapatite, locally harvested autograft chips, and/or morselized allogenic bone graft for selected cases - without conventional posterior structural bone graft. Here, we will report the clinical outcomes of the surgical technique to elucidate its feasibility.

METHODS: Single-center, retrospective data review from 2008 to 2016 identified 69 patients who underwent posterior atlantoaxial fusion with rhBMP-2. Clinical records of these patients were reviewed and clinical data such as baseline characteristics, operative data, and postoperative complications were collected and statistically analyzed.

RESULTS: The average age of 69 patients was 60.8 ± 4.5 (female: 55.1%). With the average follow-up period of 21.1 ± 4.2 months, C1-2 fusion rate was 94.3% (65/69), and the time-to-fusion was 11.4 ± 2.6 on average [range: 5-23]. The overall reoperation rate was 10.1% (7/69), which was attributed to instrumentation failure (seven patients, 10.1%), adjacent segment disease (two patients, 2.9%), and postoperative dysphagia and dyspnea (two patients, 2.9%). No ectopic bone formation or soft-tissue edema was observed in our cohort.

CONCLUSIONS: Albeit retrospective, single-center nature of the study, the use of rhBMP-2 at the C1-2 joint without posterior structural bone graft was deemed a safe, reasonable surgical option.