Introduction: Posterior atlantoaxial fusion is an important armamentarium for neurosurgeons to treat several pathologies involving the craniovertebral junction as well as the upper cervical region. Although the potential advantages of rhBMP-2 over autograft and/or allograft alone are well-documented in the lumbar spine, its indication in posterior atlantoaxial fusion has not been well-characterized. In our institution, for selected adult cases of posterior atlantoaxial fusion, we apply rhBMP-2 to the C1-2 joint, either (A) alone or with hydroxyapatite and/or locally harvested autograft chips, or (B) with conventional structural autogenic/allogenic bone graft (SAABG). Here, we will compare clinical outcomes of the two groups with special attention to their fusion rates to elucidate feasibility of the techniques.
Methods: Single-center, retrospective data review from 2008 to 2014 identified 58 patients who underwent posterior atlantoaxial fusion with rhBMP-2: (A) 34 patients without SAABG and (B) 24 patients with SAABG. Clinical records of these 58 patients were collected and statistically analyzed. P values <.05 were regarded as statistically significant.
Results: Baseline characteristics such as age, sex, BMI, and smoking status, no statistically significant differences were identified. The overall fusion rate was 94.8% (55/58), which was comparable to other conventional techniques documented in the literature. The (A) group had significantly shorter operative time (p=0.03) and less estimated blood loss than the (B) group (p=0.003). Long-term complication rates were similar between the two groups: one-year C1-2 instability/pseudoarthrosis rate, (A)5.8% versus (B)4.2%, p=1; one-year instrumentation failure rate, (A)8.8% versus (B)12.5%, p=0.68; one-year revision surgery rate, (A)8.8% versus (B)16.7%. p=0.43.
Conclusions: Albeit retrospective, single-center nature of the study, it was demonstrated that the use of rhBMP-2 at the C1-2 joint without conventional SAABG was a safe, reasonable alternative with the long-term outcomes comparable to rhBMP-2 with SAABG or historical controls in the literature.
Patient Care: Use of rhBMP-2 with or without structual allo/autogenic bone graft resulted in acceptable clinical outcomes in patients deemed to have a relatively higher risk of C1-2 pseudoarthrosis, and thus be beneficial to them, potentially reducing operative time and blood loss.
Learning Objectives: By the conclusion of this session, participants should be able to: 1) Describe the importance of ..., 2) Discuss, in small groups