title: The Role of C2-C7 Angle in the Development of Dysphagia After Anterior and Posterior Cervical Spine Surgery.
abstract: METHODS
  This is a retrospective clinical study.
  
  
  OBJECTIVE
  To analyze the relationship between cervical alignment and the development of dysphagia after anterior and posterior cervical (PC) spine surgery [anterior cervical discectomy and fusion (ACDF), cervical disk replacement (CDR), and PC].
  
  
  BACKGROUND
  Dysphagia is a known complication of cervical surgery and may be prolonged or occasionally serious. A previous study showed dysphagia after occipitocervical fusion was caused by oropharyneal stenosis resulting from O-C2 (upper cervical lordosis) fixation in a flexed position. However, there have been few reports analyzing the association between the C2-C7 angle (middle-lower cervical lordosis) and postoperative dysphagia.
  
  
  METHODS
  In total, 452 patients were reviewed in this study, including 172 patients who underwent the ACDF procedure, 98 patients who had the CDR procedure, and 182 patients who had the PC procedure between June 2007 and May 2010. The presence and duration of postoperative dysphagia were recorded via face-to-face questioning or telephone interview performed at least 1 year after the procedure. Plain cervical radiographs before and after surgery were collected. The O-C2 angle and C2-C7 angle were measured. The change of O-C2 angle and C2-C7 angle were defined as dO-C2 angle=postoperative O-C2 angle-preoperative O-C2 angle and dC2-C7 angle=postoperative C2-C7 angle-preoperative C2-C7 angle. The association between postoperative dysphagia with dO-C2 angle and dC2-C7 angle was studied.
  
  
  RESULTS
  A total of 12.8% ACDF, 5.1% CDR, and 9.4% PC patients reported dysphagia after cervical surgery. The dC2-C7 angle has considerable impact on postoperative dysphagia. When dC2-C7 angle is >5 degrees, the chance of developing postoperative dysphagia of this patient is significantly greater. The dO-C2 angle, age, sex, body mass index, operative time, blood loss, procedure type, revision surgery, most cephalic operative level, and number of operative levels did not significantly influence the incidence of postoperative dysphagia. No relationship was found between the dC2-C7 angle and the degree of dysphagia.
  
  
  CONCLUSIONS
  Postoperative dysphagia is common after cervical surgery. The dC2-C7 angle may play an important role in the development of dysphagia in both anterior and PC spine surgery. Overenlargement of cervical lordosis should be avoided to reduce the development of postoperative dysphagia.
authors.affiliation: Department of Spinal Surgery, Beijing Jishuitan Hospital, The 4th Clinical Medical College of Peking University, Beijing, P.R. China.
authors.forename: Wei
authors.initials: W
authors.lastname: Tian
authors.forename: Jie
authors.initials: J
authors.lastname: Yu
mesh_terms: D000328:Adult; D000368:Aged; D016063:Blood Loss, Surgical; D015992:Body Mass Index; D002574:Cervical Vertebrae / Q000601:surgery*; D003680:Deglutition Disorders / Q000453:epidemiology / Q000209:etiology*; D017586:Diskectomy / Q000009:adverse effects*; D005260:Female; D006801:Humans; D015994:Incidence; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D061646:Operative Time; D011182:Postoperative Care; D011183:Postoperative Complications / Q000453:epidemiology / Q000209:etiology*; D012086:Reoperation; D012307:Risk Factors; D013123:Spinal Fusion / Q000009:adverse effects*; D055815:Young Adult