title: Preoperative Risk Factors for Recurrent Lumbar Disk Herniation in L5-S1.
abstract: BACKGROUND
  Although numerous studies have reported on recurrent lumbar disk herniation (rLDH), few have reported on recurrence of L5-S1 level.
  
  
  OBJECTIVE
  We investigated whether the preoperative risk factors, such as disk degeneration, disk height, sagittal range of motion (sROM), width of L5 vertebral transverse process, and iliac crest height, have any effect on rLDH in L5-S1.
  
  
  METHODS
  A retrospective case control study.
  
  
  METHODS
  A total of 467 patients were enrolled in this study.
  
  
  METHODS
  The disk degeneration, disk height, sROM, width of L5 vertebral transverse process, and iliac crest height were calculated using magnetic resonance imaging and simple radiography.
  
  
  METHODS
  We compared the clinical parameters (age, sex, body mass index, symptom duration, diabetes, smoking, preoperative visual analogue scale, herniation type, annular defect size) and preoperative radiologic parameters [disk degeneration, disk height, sROM, relative width of L5 vertebral transverse process (RT), iliac crest height index (IHI)] of recurrent and nonrecurrent groups.
  
  
  RESULTS
  Patient with rLDH had its onset 39.4±17.9 months (7-90 mo) after primary surgery. Of the 39 rLDH cases, herniation was ipsilateral to previous LDH in 29 patients and contralateral in 10. Multiple logistic regression analysis showed that moderate disk degeneration with preserved height (group B), a large sROM, a small RT, a low IHI, and being male were significant risk factors for rLDH.
  
  
  CONCLUSIONS
  Moderate disk degeneration, a large sROM, a small RT, and a low IHI are biomechanical risk factors of rLDH in L5-S1. The results also suggested being male and having a large annular defect increase recurrence after discectomy, especially in cases of ipsilateral rLDH.
authors.affiliation: *Department of Neurosurgery, School of Medicine, Kyungpook National University, Daegu †Department of Neurosurgery, School of Medicine, Chung-Ang University, Seoul, Republic of Korea.
authors.forename: Kyoung-Tae
authors.initials: KT
authors.lastname: Kim
authors.forename: Dong-Hyun
authors.initials: DH
authors.lastname: Lee
authors.forename: Dae-Chul
authors.initials: DC
authors.lastname: Cho
authors.forename: Joo-Kyung
authors.initials: JK
authors.lastname: Sung
authors.forename: Young-Baeg
authors.initials: YB
authors.lastname: Kim
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D007405:Intervertebral Disc Displacement / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D010147:Pain Measurement; D011300:Preoperative Care; D011859:Radiography; D016059:Range of Motion, Articular; D012008:Recurrence; D012307:Risk Factors; D055815:Young Adult