title: An institutional six-year trend analysis of the neurological outcome after lateral lumbar interbody fusion: a 6-year trend analysis of a single institution.
abstract: METHODS
  Retrospective case series.
  
  
  OBJECTIVE
  To evaluate the proportional trend over time of neurological deficits after lateral lumbar interbody fusion (LLIF) at a single institution.
  
  
  BACKGROUND
  Because lumbar nerve roots converge to run as the lumbar plexus within or less frequently underneath the posterior part of the psoas muscle, they are prone to iatrogenic damage during the transpsoas approach in LLIF, and adverse postoperative neurological sequelae remain a major concern.
  
  
  METHODS
  The electronic medical records and office notes of 451 patients who had consecutively undergone LLIF between March 2006 and April 2012 at a single institution were retrospectively reviewed for reports on postoperative neurological deficits.
  
  
  RESULTS
  A total of 293 patients (173 females and 120 males) met the study inclusion criteria and were followed postoperatively for a mean period of 15.4 ± 9.2 months (range: 6-53 mo). The number of included patients who underwent LLIF at our institution was 47 in the years 2006 to 2008 (group A), 155 in 2009 to 2010 (group B), and 91 in 2011 to 2012 (group C). Our data indicate a decreasing proportional trend during the past 6 years for postoperative sensory deficits (SDs), motor deficits (MDs), and anterior thigh pain (TP). The decreasing trends were statistically significant for the proportion of SDs in the immediate postoperative setting (P = 0.018) and close to statistically significant for SDs at last follow-up (P = 0.126), TP immediately after surgery (P = 0.098), and TP at last follow-up (P = 0.136).
  
  
  CONCLUSIONS
  To the authors' best knowledge, this study constitutes the largest series of this sort to date, with regard to both sample size and study period. The present data indicate a decreasing proportional trend over time for SDs, MDs, and anterior TP, which can be considered a representation of an institutional learning curve during a 6-year time period of performing LLIF.
authors.affiliation: *Department of Orthopaedic Surgery, Spine and Scoliosis Service, Hospital for Special Surgery, Weill Cornell Medical College, New York, NY; and †Sektion für Wirbelsäulenchirurgie, Centrum für Muskuloskeletale Chirurgie, Charité-Universitätsmedizin Berlin, Berlin, Germany.
authors.forename: Alexander
authors.initials: A
authors.lastname: Aichmair
authors.forename: Marios G
authors.initials: MG
authors.lastname: Lykissas
authors.forename: Federico P
authors.initials: FP
authors.lastname: Girardi
authors.forename: Andrew A
authors.initials: AA
authors.lastname: Sama
authors.forename: Darren R
authors.initials: DR
authors.lastname: Lebl
authors.forename: Fadi
authors.initials: F
authors.lastname: Taher
authors.forename: Frank P
authors.initials: FP
authors.lastname: Cammisa
authors.forename: Alexander P
authors.initials: AP
authors.lastname: Hughes
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002983:Clinical Competence; D005260:Female; D006801:Humans; D007049:Iatrogenic Disease; D059032:Learning Curve; D008159:Lumbar Vertebrae / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D009043:Motor Activity; D009460:Neurologic Examination; D010149:Postoperative Pain / Q000209:etiology; D059348:Peripheral Nerve Injuries / Q000175:diagnosis / Q000209:etiology* / Q000503:physiopathology; D012189:Retrospective Studies; D012677:Sensation; D012678:Sensation Disorders / Q000209:etiology / Q000503:physiopathology; D013123:Spinal Fusion / Q000639:trends*; D013126:Spinal Nerve Roots / Q000293:injuries* / Q000503:physiopathology; D013997:Time Factors; D016896:Treatment Outcome; D055815:Young Adult