Pseudarthrosis in multilevel anterior cervical fusion with rhBMP-2 and allograft: analysis of one hundred twenty-seven cases with minimum two-year follow-up

Spine (Phila Pa 1976). 2010 Apr 1;35(7):747-53. doi: 10.1097/BRS.0b013e3181bc3420.

Abstract

Study design: Consecutive case series.

Objective: The purpose of this study was to analyze the pseudarthrosis rate in a large series of recombinant human bone morphogenetic protein-2 (rhBMP-2) augmented multilevel (> or =3 levels) anterior cervical fusions.

Summary of background data: The reported pseudarthrosis rate following anterior cervical fusion varies from 0% to 20% for single-level and up to 50% for multilevel fusions. It has been postulated that the use of rhBMP-2 may decrease the pseudarthrosis rate.

Methods: A consecutive series of patients with cervical spondylosis and/or disc herniation who underwent anterior cervical fusion with rhBMP-2, structural allograft, and plate fixation with a minimum 2-year follow-up were analyzed by experienced, independent spine surgeons.

Results: A total of 127 patients (54 men and 73 women with mean age of 54 +/- 10 years [range, 32-79]) were examined. Seventy-five (59.1%) patients underwent a 3-level fusion, 34 (26.7%) underwent a 4-level fusion, and 18 (14.2%) underwent a 5-level fusion. Of the 451 fusion segments, 14 segments (3.1%) in 13 of 127 patients (10.2%) had evidence of pseudarthrosis at 6 months following surgery. Of the 13 patients with a pseudarthrosis, 3 had a 3-level fusion (3/75 patients [4.0%]), 6 had a 4-level fusion (6/34 patients [17.4%]), and 4 had a 5-level fusion (4/18 patients [22.2%]). Five patients were asymptomatic and were not revised, but the remaining 8 patients required additional surgery. In 12 of 13 patients with a pseudarthrosis, the nonunion occurred at the lowest fusion level and at the cervicothoracic junction. The only statistically significant risk factor for developing a pseudarthrosis was the number of fusion levels.

Conclusion: In a large series of rhBMP-2 augmented multilevel fusions, the pseudarthrosis rate was 10.2% at 6 months following surgery. Since the risk of pseudarthrosis increases with the number of fusion levels, a long fusion lever arm may biomechanically overwhelm the biologic advantage of rhBMP-2. While rhBMP-2 is known to enhance fusion rates, it does not guarantee fusion in all situations.

MeSH terms

  • Adult
  • Aged
  • Bone Morphogenetic Protein 2 / therapeutic use*
  • Bone Plates / adverse effects
  • Bone Transplantation / adverse effects
  • Bone Transplantation / methods
  • Cervical Vertebrae / surgery*
  • Female
  • Humans
  • Intervertebral Disc Displacement / surgery*
  • Male
  • Middle Aged
  • Odds Ratio
  • Pseudarthrosis / etiology*
  • Recombinant Proteins / therapeutic use
  • Risk Factors
  • Spinal Fusion / adverse effects*
  • Spinal Fusion / methods
  • Spondylosis / surgery*
  • Treatment Outcome

Substances

  • Bone Morphogenetic Protein 2
  • Recombinant Proteins