title: The biomechanics of gravity-dependent traction of the lumbar spine.
abstract: METHODS
  This study evaluated the biomechanical responses evoked by the use of a gravity-dependent, self-operated traction device. These responses were determined by radiographs and were correlated with the body weight of the patient who was supported by a seat strap.
  
  
  OBJECTIVE
  To examine the biomechanical effectiveness of the LTX 3000 Lumbar Rehabilitation System.
  
  
  BACKGROUND
  The LTX 3000 Lumbar Rehabilitation System (Spinal Designs International, Minneapolis, MN) was used to administer the lumbar fraction. No previous study has been conducted on this device.
  
  
  METHODS
  For each of the 14 healthy male patients (age range, 19-69 years), lumbar lengthening, alterations in spinal curvature, and thoracic spine movement were assessed using radiographs taken: 1) before traction; 2) at 2, 10, and 15 minutes after the onset of traction; and 3) 2 minutes after traction was completed. Strain on the buttocks-supporting seat strap was recorded continuously during study sessions.
  
  
  RESULTS
  The entire patient pool displayed an average maximal lumbar lengthening of 6.39 +/- 4.21 mm. The amount of lumbar lengthening was influenced by the degree of thoracic immobilization and by the amount of prior LTX 3000 (Spinal Designs International) use. Significant curvature reduction was observed during and after traction for the entire patient pool. Strain measurements correlated well with the measured response in the radiographs.
  
  
  CONCLUSIONS
  Proper use of the LTX 3000 (Spinal Designs International) induces significant lumbar lengthening and curvature reduction in healthy patients. Measurements of body weight supported by the seat strap could help determine if thoracic immobilization has been achieved and if the patient is responding to the lumbar unloading.
authors.affiliation: Biomedical Engineering Institute, University of Minnesota, Minneapolis, USA.
authors.forename: A W
authors.initials: AW
authors.lastname: Janke
authors.forename: T A
authors.initials: TA
authors.lastname: Kerkow
authors.forename: H J
authors.initials: HJ
authors.lastname: Griffiths
authors.forename: E M
authors.initials: EM
authors.lastname: Sparrow
authors.forename: P A
authors.initials: PA
authors.lastname: Iaizzo
mesh_terms: D000328:Adult; D000368:Aged; D001696:Biomechanical Phenomena; D005069:Evaluation Studies as Topic; D006112:Gravitation; D006801:Humans; D007403:Intervertebral Disc / Q000502:physiology; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D011859:Radiography; D013904:Thoracic Vertebrae / Q000000981:diagnostic imaging / Q000502:physiology; D014143:Traction / Q000295:instrumentation* / Q000379:methods*