Safety and efficacy of bioabsorbable cervical spacers and low-dose rhBMP-2 in multi-level ACDF.

INTRODUCTION: Many options for interbody spacer and graft biologic exist for multilevel anterior cervical discectomy and fusion (ACDF). The objective of this study is to evaluate the safety and efficacy of a bioabsorbable cervical spacer (BCS) (Cornerstone HSR, Medtronic Sofamor Danek) filled with low-dose rhBMP-2 (INFUSE, Medtronic Sofamor Danek) in multilevel ACDF. METHODS: 72 consecutive patients treated with a multi-level ACDF using BCS and rhBMP-2 (dosage between 0.5 to 0.7 mg per level) at a single institution were followed in an IRB-approved, prospective registry. A total of 187 levels were treated (mean = 2.6), with 37 (51%) patients undergoing a 2-level procedure and 35 (49%) undergoing a 3- or 4-level procedure. Statistical analysis included frequency and ANOVA tests. Significance was accepted for p < 0.001. RESULTS: Average follow-up was 13.8 months. Mean patient age was 55.3 years, 70.8% were female, and 16.7% had undergone a previous cervical procedure. 29 (40%) patients had cervical spondylitic myelopathy, 27 (38%) had radiculopathy, 15 (21%) had a combination of both, and 1 (1%) patient had a previous nonunion. A total of 187 levels were treated with an ACDF, with 37 (51%) 2-level, 27 (38%) 3-level, and 8 (11%) 4-level cases. Average OR time, EBL, and LOS were 144 minutes, 49 mL, and 1.1 days, respectively. Major complications occurred in 5 (7%) patients: 2 returns to OR (1 nonunion, 1 seroma), 1 recurrent laryngeal nerve injury, and 2 hospital readmissions for excessive pre-vertebral swelling/dysphagia treated with steroids and observation. Minor complications occurred in 3 (4%) patients: 2 exacerbations of pre-existing medical conditions (1 atrial fibrillation, 1 COPD), and 1 hospital readmission for nausea/ headache due to narcotics. At last follow-up, NDI improved 43% from 43.6% to 25.0%. VAS neck pain improved 60% from 5.5 to 2.2 and VAS arm pain improved 52% from 5.8 to 2.6. SF-36 PCS improved 24% from 37.5 to 46.3 and MCS improved 18% from 43.2 to 50.9. All clinical improvements were statistically significant (p < 0.001). Patient satisfaction was high, with 97% of patients reported being satisfied with their surgical outcome, and 90% would undergo the procedure again. CONCLUSION: Patients in this series experienced significant clinical improvements, low complication rates, and high patient satisfaction. Symptomatic pseudoarthrosis was rare. BCS filled with low-dose rhBMP-2 appears to be a safe and effective option in multilevel ACDF. Further investigation is warranted.