title: A controlled anterior sequential interbody dilation technique for correction of cervical kyphosis.
abstract: OBJECTIVE
  Cervical kyphosis can lead to spinal instability, spinal cord injury, and disability. The correction of cervical kyphosis is technically challenging, especially in severe cases. The authors describe the anterior sequential interbody dilation technique for the treatment of cervical kyphosis and evaluate perioperative outcomes, degree of correction, and long-term follow-up outcomes associated with the technique.
  
  
  METHODS
  In the period from 2006 to 2011, a consecutive cohort of adults with cervical kyphosis (Cobb angles ≥ 0°) underwent sequential interbody dilation, a technique entailing incrementally increased interbody distraction with the sequential placement of larger spacers (at least 1 mm) in the discectomy and/or corpectomy spaces. The authors retrospectively reviewed these patients, and primary outcomes of interest included kyphosis correction, blood loss, hospital stay, complications, Nurick grade, pain, reoperation, and pseudarthrosis. A subgroup analysis among patients with preoperative kyphosis of 0°-9° (mild), 10°-19° (moderate), and ≥ 20° (severe) was performed.
  
  
  RESULTS
  One hundred patients were included in the study: 74 with mild preoperative cervical kyphosis, 19 with moderate, and 7 with severe. The mean patient age was 53.1 years, and 54.0% of the patients were male. Mean estimated blood loss was 305.6 ml, and the mean length of hospital stay was 5.2 days. The overall complication rate was 9.0%, and there were no deaths. Sixteen percent of patients underwent supplemental posterior fusion. There was significant correction in cervical alignment (p < 0.001), and the mean overall kyphosis correction was 12.4°. Patients with severe preoperative kyphosis gained a correction of 24.7°, those with moderate kyphosis gained 17.8°, and those with mild kyphosis gained 10.1°. A mean correction of 32.0° was obtained if 5 levels were addressed. The mean follow-up was 26.8 months. The reoperation rate was 4.7%. At follow-up, there was significant improvement in visual analog scale neck pain (p = 0.020) and Nurick grade (p = 0.037). The pseudarthrosis rate was 6.3%.
  
  
  CONCLUSIONS
  Sequential interbody dilation is a feasible and effective method of correcting cervical kyphosis. Complications and reoperation rates are low. Similar benefits are seen among all severities of kyphosis, and greater correction can be achieved in more severe cases.
authors.affiliation: Department of Neurological Surgery, University of California, San Francisco, California.
authors.forename: Darryl
authors.initials: D
authors.lastname: Lau
authors.affiliation: Department of Neurological Surgery, University of California, San Francisco, California.
authors.forename: John E
authors.initials: JE
authors.lastname: Ziewacz
authors.affiliation: Department of Neurological Surgery, University of California, San Francisco, California.
authors.forename: Hai
authors.initials: H
authors.lastname: Le
authors.affiliation: Department of Neurological Surgery, University of California, San Francisco, California.
authors.forename: Rishi
authors.initials: R
authors.lastname: Wadhwa
authors.affiliation: Department of Neurological Surgery, University of California, San Francisco, California.
authors.forename: Praveen V
authors.initials: PV
authors.lastname: Mummaneni
mesh_terms: D000328:Adult; D000368:Aged; D002574:Cervical Vertebrae / Q000601:surgery*; D017586:Diskectomy / Q000379:methods*; D005260:Female; D006801:Humans; D007738:Kyphosis / Q000601:surgery*; D007902:Length of Stay; D008297:Male; D008875:Middle Aged; D019637:Orthopedic Procedures / Q000379:methods*; D012086:Reoperation; D012189:Retrospective Studies; D013123:Spinal Fusion / Q000379:methods; D016896:Treatment Outcome
keywords: BMP = bone morphogenetic protein; PEEK = polyetheretherketone; VAS = visual analog scale; cervical; corpectomy; deformity; discectomy; fusion; kyphosis