title: Posterior Cervical Fusion With Recombinant Human Bone Morphogenetic Protein-2: Complications and Fusion Rate at Minimum 2-Year Follow-Up.
abstract: Retrospective case series.
  
  
  
  The purpose of this study was to determine the fusion rate and evaluate the complications associated with the application of recombinant human bone morphogenetic protein-2 (rhBMP-2) in posterior cervical fusion.
  
  
  
  The rates of fusion and complications associated with the use of rhBMP-2 in posterior cervical fusion is unclear, though recent work has shown up to a 100% fusion rate.
  
  
  
  We independently reviewed consecutive series of patients who underwent posterior cervical, occipitocervical, or cervicothoracic instrumented fusion augmented with rhBMP-2. Two surgeons at a tertiary-referral, academic medical center performed all operations, and each patient had a minimum of 2-year follow-up. Fusion status was determined by bony bridging on computed tomography scans, absence of radiolucency around instrumentation, and absence of motion on lateral flexion/extension radiographs.
  
  
  
  Fifty-seven patients with a mean age of 56.7±13.2 years and mean follow-up of 37.7±20.6 months were analyzed. Forty-eight patients (84.2%) had undergone previous cervical surgery, and 42.1% had a preexisting nonunion. Constructs spanned 5.6±2.6 levels; 19.3% involved the occiput, whereas 61.4% crossed the cervicothoracic junction. The mean rhBMP-2 dose was 21.1±8.7 mg per operation. Iliac crest autograft was used for 29.8% of patients. Six patients (10.5%) experienced nonunion; only 2 required revision. In each case of nonunion, instrumentation crossed the occipitocervical or cervicothoracic junction. However, none of the analyzed variables was statistically associated with nonunion. Fourteen patients (24.6%) suffered complications, with 7 requiring additional surgery.
  
  
  
  The observed fusion rate of rhBMP-2-augmented posterior cervical, occipitocervical, and cervicothoracic fusions was 89.5%. This reflects the complicated nature of the patients included in the current study and demonstrates that rhBMP-2 cannot always overcome the biomechanical challenges entailed in spanning the occipitocervical or cervicothoracic junction.
authors.affiliation: Departments of *Neurosurgery†Orthopaedic Surgery, Washington University School of Medicine, Saint Louis, MO.
authors.forename: Ian G
authors.initials: IG
authors.lastname: Dorward
authors.forename: Jacob M
authors.initials: JM
authors.lastname: Buchowski
authors.forename: Geoffrey E
authors.initials: GE
authors.lastname: Stoker
authors.forename: Lukas P
authors.initials: LP
authors.lastname: Zebala
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D055396:Bone Morphogenetic Protein 2 / Q000627:therapeutic use*; D002574:Cervical Vertebrae / Q000601:surgery*; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000209:etiology*; D011542:Pseudarthrosis / Q000209:etiology; D011994:Recombinant Proteins / Q000627:therapeutic use; D012307:Risk Factors; D013122:Spinal Diseases / Q000601:surgery; D013123:Spinal Fusion / Q000009:adverse effects* / Q000706:statistics & numerical data; D014057:Tomography, X-Ray Computed; D016212:Transforming Growth Factor beta / Q000627:therapeutic use*; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D055396:Bone Morphogenetic Protein 2; D011994:Recombinant Proteins; D016212:Transforming Growth Factor beta; C499469:recombinant human bone morphogenetic protein-2