title: Disc height and segmental motion as risk factors for recurrent lumbar disc herniation.
abstract: METHODS
  Retrospective review and multivariate analysis.
  
  
  OBJECTIVE
  Recurrent lumbar disc herniation (rLDH) is a repeated disc herniation at a previously operated disc level in patients who experienced a pain-free interval of at least 6 months after surgery. We investigated whether the preoperative radiologic biomechanical factors (disc height index [DHI] and sagittal range of motion [sROM]) have any effect on rLDH.
  
  
  BACKGROUND
  rLDH has been reported in 5% to 15% of patients. There have been many studies suggesting various risk factors for rLDH, such as disc degeneration, trauma, age, smoking, gender, and obesity. However, these factors did not reflect a biomechanical effect on the affected joint directly. Investigation of DHI and sROM would be helpful to understand the biomechanical impact on the occurrence of rLDH.
  
  
  METHODS
  This study enrolled 157 patients who underwent surgery for L4-L5 LDH. We divided the patients into the recurrent and the nonrecurrent group and compared their clinical parameters (age, sex, body-mass index, symptom duration, diabetes, smoking, herniation type, preoperative visual analogue scale) and preoperative radiologic parameters (disc degeneration, DHI, sROM).
  
  
  RESULTS
  rLDH occurred at 40.8+/-15.5 months (7-70 months) after primary surgery. Mean DHI was 0.37+/-0.09 and 0.29+/-0.09 in the recurrent and the nonrecurrent group, respectively (P<0.05). Mean sROM was 11.3 degrees+/-2.9 degrees and 5.9 degrees+/-3.7 degrees in the recurrent and the nonrecurrent group, respectively (P<0.05). Both smoking and disc degeneration were related with the development of rLDH (P<0.05).
  
  
  CONCLUSIONS
  Together with our data, DHI and sROM showed a significant correlation with the incidence of recurrent lumbar disc herniation, suggesting that preoperative biomechanical conditions of the spine can be an important pathogenic factor in the site of lumbar disc surgery.
authors.affiliation: Department of Neurosurgery, College of Medicine, Chung-Ang University, Chung-Ang University Hospital, Seoul, Korea.
authors.forename: Kyoung-Tae
authors.initials: KT
authors.lastname: Kim
authors.forename: Seung-Won
authors.initials: SW
authors.lastname: Park
authors.forename: Young-Baeg
authors.initials: YB
authors.lastname: Kim
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001696:Biomechanical Phenomena; D015331:Cohort Studies; D005260:Female; D051445:Fibrocartilage / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology; D006801:Humans; D007403:Intervertebral Disc / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology*; D007405:Intervertebral Disc Displacement / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology*; D017116:Low Back Pain / Q000209:etiology / Q000473:pathology / Q000503:physiopathology; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D011843:Radiculopathy / Q000209:etiology / Q000473:pathology / Q000503:physiopathology; D011859:Radiography; D016059:Range of Motion, Articular / Q000502:physiology*; D012008:Recurrence; D012189:Retrospective Studies; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects; D013314:Stress, Mechanical; D016474:Weight-Bearing / Q000502:physiology; D055815:Young Adult