title: Indirect foraminal decompression after anterior lumbar interbody fusion: a prospective radiographic study using a new pedicle-to-pedicle technique.
abstract: BACKGROUND
  A frequently quoted advantage of anterior lumbar interbody fusion (ALIF) is indirect foraminal decompression, although there are few studies substantiating this statement. Also, there are no clinical studies using a standardized method to measure the foraminal area (FA) and the correlation with disc height (DH) parameters. This study is proposed to measure the degree of indirect foraminal decompression radiologically using a standardized method and correlate with the intervertebral disc parameters.
  
  
  OBJECTIVE
  To standardize the foramen measurement technique. To measure indirect neural foraminal decompression in surgically operated patients after ALIF using radiographic measurement and elucidate factors affecting foraminal restoration.
  
  
  METHODS
  A prospective cohort study.
  
  
  METHODS
  A continuous cohort of patients undergoing ALIF surgery.
  
  
  METHODS
  It included FA, foraminal height (FH), and foraminal width.
  
  
  METHODS
  This is a prospective analysis of a single surgeon series of consecutive patients undergoing an ALIF from 2011 to 2013. Pre- and postoperative computed tomography scans were used to obtain a standardized foramen snapshot using the pedicle-to-pedicle (P-P) technique, and measurements were obtained using image j software. Radiologic parameters such as DH, local disc angle (LDA), and lumbar lordosis (LL) were measured using radiographs and Surgimap software.
  
  
  RESULTS
  One-hundred forty patients with 184 levels were operated. Anterior lumbar interbody fusion resulted in a statistically significant (p<.01) improvement in foraminal dimensions (area=67%, height=21%, and width=38%). Other parameters also significantly improved, including anterior DH (90%), posterior DH (77%), LDA, and LL (6%). Posterior DH correlated significantly with FH improvement. Statistically, the P-P technique presented with high intra- and interclass reliabilities.
  
  
  CONCLUSIONS
  Anterior lumbar interbody fusion results in significant indirect foraminal decompression based on the new P-P technique. Posterior DH is a significant factor in the restoration of the FH.
authors.affiliation: Department of Neurosurgery, Neurospine Clinic, Level 7, Prince of Wales Private Hospital, Randwick, New South Wales, NSW 2031, Australia; Prince of Wales Hospital, University of New South Wales, Level 7, Prince of Wales Private Hospital, Randwick, New South Wales, NSW 2031, Australia; Department of Neurosurgery, University of New South Wales, Level 7, Prince of Wales Private Hospital, Randwick, New South Wales, NSW 2031, Australia. Electronic address: Prashanthdr@gmail.com.
authors.forename: Prashanth J
authors.initials: PJ
authors.lastname: Rao
authors.affiliation: Department of Neurosurgery, Neurospine Clinic, Level 7, Prince of Wales Private Hospital, Randwick, New South Wales, NSW 2031, Australia; Department of Neurosurgery, University of New South Wales, Level 7, Prince of Wales Private Hospital, Randwick, New South Wales, NSW 2031, Australia.
authors.forename: Monish M
authors.initials: MM
authors.lastname: Maharaj
authors.affiliation: Department of Neurosurgery, Neurospine Clinic, Level 7, Prince of Wales Private Hospital, Randwick, New South Wales, NSW 2031, Australia.
authors.forename: Kevin
authors.initials: K
authors.lastname: Phan
authors.affiliation: Department of Neurosurgery, Neurospine Clinic, Level 7, Prince of Wales Private Hospital, Randwick, New South Wales, NSW 2031, Australia; Department of Neurosurgery, University of New South Wales, Level 7, Prince of Wales Private Hospital, Randwick, New South Wales, NSW 2031, Australia.
authors.forename: Manil
authors.initials: M
authors.lastname: Lakshan Abeygunasekara
authors.affiliation: Department of Neurosurgery, Neurospine Clinic, Level 7, Prince of Wales Private Hospital, Randwick, New South Wales, NSW 2031, Australia; Prince of Wales Hospital, University of New South Wales, Level 7, Prince of Wales Private Hospital, Randwick, New South Wales, NSW 2031, Australia; Department of Neurosurgery, University of New South Wales, Level 7, Prince of Wales Private Hospital, Randwick, New South Wales, NSW 2031, Australia.
authors.forename: Ralph J
authors.initials: RJ
authors.lastname: Mobbs
mesh_terms: D000328:Adult; D000368:Aged; D000818:Animals; D019299:Decompression, Surgical / Q000295:instrumentation / Q000379:methods*; D005260:Female; D006801:Humans; D007403:Intervertebral Disc / Q000000981:diagnostic imaging / Q000601:surgery*; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D065289:Pedicle Screws / Q000009:adverse effects*; D011446:Prospective Studies; D011859:Radiography; D013123:Spinal Fusion / Q000295:instrumentation / Q000379:methods*
keywords: Anterior lumbar interbody fusion; Disc height; Fine cut CT; Foramen measurement; Indirect decompression; P-P technique