title: Thickness of subcutaneous fat as a risk factor for infection in cervical spine fusion surgery.
abstract: BACKGROUND
  Surgical site infections increase the incidence of morbidity and mortality as well as health-care expenses. The cost of care increases threefold to fourfold as a consequence of surgical site infection after spinal surgery. The aim of the present study was to determine the role of subcutaneous fat thickness in the development of surgical site infection following cervical spine fusion surgery.
  
  
  METHODS
  We performed a retrospective review of a consecutive cohort of 213 adult patients who underwent posterior cervical spine fusion between 2006 and 2008 at Duke University Medical Center. The horizontal distance from the lamina to the skin surface at the C5 level and the thickness of subcutaneous fat were measured, and the ratio of the fat thickness to the total distance at the surgical site was determined. Previously identified risk factors for the development of surgical site infection were also recorded.
  
  
  RESULTS
  Twenty-two of the 213 patients developed a postoperative infection. Obesity (body mass index ≥ 30 kg/m2) was not a significant risk factor for surgical site infection; the body mass index (and 95% confidence interval) was 29.4 ± 1.2 kg/m2 in the patients who developed a surgical site infection compared with 28.9 ± 0.94 kg/m2 in the patients without an infection. However, the thickness of subcutaneous fat and the ratio of the fat thickness to the lamina-to-skin distance were both significant risk factors for infection. The thickness of subcutaneous fat was 27.0 ± 2.5 mm in the patients who developed a surgical site infection group compared with 21.4 ± 0.88 mm in the patients without an infection (p = 0.042). The ratio of fat thickness to total thickness was 0.42 ± 0.019 in the patients who developed a surgical site infection compared with 0.35 ± 0.01 in the patients without an infection (p = 0.020). Multivariate analysis revealed this ratio to be an independent risk factor for developing a postoperative infection (odds ratio, 3.18; 95% confidence interval, 1.02 to 9.97).
  
  
  CONCLUSIONS
  The study demonstrated that the thickness of subcutaneous fat at the surgical site is a factor in the development of surgical site infection following cervical spine fusion and deserves assessment in the preoperative evaluation.
authors: Division of Neurosurgery, Department of Surgery, Duke University Medical Center, Box 3807, Durham, NC 27710, USA.
authors: Ankit I
authors: AI
authors: Mehta
authors: Ranjith
authors: R
authors: Babu
authors: Richa
authors: R
authors: Sharma
authors: Isaac O
authors: IO
authors: Karikari
authors: Betsy H
authors: BH
authors: Grunch
authors: Timothy R
authors: TR
authors: Owens
authors: Vijay J
authors: VJ
authors: Agarwal
authors: John H
authors: JH
authors: Sampson
authors: Shivanand P
authors: SP
authors: Lad
authors: Allan H
authors: AH
authors: Friedman
authors: Maragatha
authors: M
authors: Kuchibhatla
authors: Carlos A
authors: CA
authors: Bagley
authors: Oren N
authors: ON
authors: Gottfried
mesh_terms: D000328:Adult; D000368:Aged; D015992:Body Mass Index; D002574:Cervical Vertebrae / Q000601:surgery*; D016009:Chi-Square Distribution; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009657:North Carolina / Q000453:epidemiology; D015995:Prevalence; D012189:Retrospective Studies; D012307:Risk Factors; D013123:Spinal Fusion / Q000379:methods*; D050151:Subcutaneous Fat / Q000033:anatomy & histology*; D013530:Surgical Wound Infection / Q000175:diagnosis / Q000453:epidemiology / Q000209:etiology*; D014057:Tomography, X-Ray Computed