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


BACKGROUND
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.


CONCLUSIONS
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.
Shen
Hong Xing
HX
Department of Orthopaedic Surgery, Washington University in St. Louis, St. Louis, MO, USA.
Buchowski
Jacob M
JM
Yeom
Jin S
JS
Liu
Gabriel
G
Lin
Nan
N
Riew
K Daniel
KD
D000328:Adult; D000368:Aged; D055396:Bone Morphogenetic Protein 2 / Q000627:therapeutic use*; D001860:Bone Plates / Q000009:adverse effects; D016025:Bone Transplantation / Q000009:adverse effects / Q000379:methods; D002574:Cervical Vertebrae / Q000601:surgery*; D005260:Female; D006801:Humans; D007405:Intervertebral Disc Displacement / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D011542:Pseudarthrosis / Q000209:etiology*; D011994:Recombinant Proteins / Q000627:therapeutic use; D012307:Risk Factors; D013123:Spinal Fusion / Q000009:adverse effects* / Q000379:methods; D055009:Spondylosis / Q000601:surgery*; D016896:Treatment Outcome
D055396:Bone Morphogenetic Protein 2; D011994:Recombinant Proteins