title: The incidence of adjacent segment disease after lumbar discectomy: A study of 751 patients.
abstract: BACKGROUND
  The objective of this study is to determine the incidence and prognostic factors of adjacent segment disease (ASD) following first-time lumbar discectomy (LD).
  
  
  METHODS
  We retrospectively reviewed all neurosurgical patients who underwent first-time LD for degenerative lumbar disease from 1990 to 2012. ASD was defined as a clinical and radiographic progression of degenerative spinal disease that required surgical decompression (with or without fusion) at the level above or below the index discectomy. Adjusted odds ratios were calculated from multivariable logistical regression controlling for sex and age, as well as postoperative sensory deficit, motor deficit, back pain, neurogenic claudication, and radiculopathy.
  
  
  RESULTS
  Of the 751 patients who underwent single-level LD, the cumulative reoperation rate for degenerative spinal disease was 10.79%. The incidence of ASD requiring reoperation was 4% over 3.11years. More specifically, the incidence of adjacent level discectomy was 1.86% over 3.45years. The annualized reoperation rate for ASD was 1.35% (1.35 ASD reoperations per 100 person-years). The 63.33% incidence of cranial ASD requiring reoperation was statistically significantly higher than the 40.00% incidence of caudal ASD requiring reoperation. Following multivariable logistical regression, the strongest (and only) statistically significant predictor of ASD requiring reoperation was lower extremity radiculopathy after the index discectomy operation (OR=14.23, p<0.001).
  
  
  CONCLUSIONS
  In the first series on ASD following first-time LD without fusion, the rate of reoperation for ASD was 4% and the cumulative reoperation rate 10.79%. Rostral ASD is more common than caudal ASD and lower extremity radiculopathy is the strongest predictor of ASD.
authors.affiliation: Department of Neurologic Surgery, Mayo Clinic, Rochester, MN, USA; Mayo Clinic Neuro-Informatics Laboratory, Rochester, MN, USA. Electronic address: Bydon.mohamad@mayo.edu.
authors.forename: Mohamad
authors.initials: M
authors.lastname: Bydon
authors.affiliation: Department of Neurosurgery, Henry Ford Hospital, Detroit, MI, USA.
authors.forename: Mohamed
authors.initials: M
authors.lastname: Macki
authors.affiliation: Department of Neurologic Surgery, Mayo Clinic, Rochester, MN, USA; Mayo Clinic Neuro-Informatics Laboratory, Rochester, MN, USA.
authors.forename: Panagiotis
authors.initials: P
authors.lastname: Kerezoudis
authors.affiliation: Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
authors.forename: Daniel M
authors.initials: DM
authors.lastname: Sciubba
authors.affiliation: Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Wolinsky
authors.affiliation: Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
authors.forename: Timothy F
authors.initials: TF
authors.lastname: Witham
authors.affiliation: Department of Neurosurgery, Warren Alpert Medical School of Brown University, Providence, RI, USA.
authors.forename: Ziya L
authors.initials: ZL
authors.lastname: Gokaslan
authors.affiliation: Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
authors.forename: Ali
authors.initials: A
authors.lastname: Bydon
mesh_terms: D000328:Adult; D000368:Aged; D017586:Diskectomy / Q000009:adverse effects*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D008159:Lumbar Vertebrae / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000175:diagnosis / Q000453:epidemiology* / Q000601:surgery*; D012086:Reoperation / Q000639:trends; D012189:Retrospective Studies; D013118:Spinal Cord Diseases / Q000175:diagnosis / Q000453:epidemiology* / Q000601:surgery*; D016896:Treatment Outcome
keywords: Adjacent level discectomy; Adjacent segment disease; Lumbar discectomy; Reoperation