THE BIOMECHANICS OF GRAVITY-DEPENDENT TRACTION OF THE LUMBAR SPINE

Study Design. This study evaluated the biomechanical responses evoked by the use of a gravity-dependent, self-operated traction device. Thes e responses were determined by radiographs and were correlated with th e body weight of the patient who was supported by a seat strap. Object ives. To examine the biomechanical effectiveness of the LTX 3000 Lumba r Rehabilitation System. Summary of Background Data. The LTX 3000(TM) Lumbar Rehabilitation System (Spinal Designs International, Minneapoli s, MN) was used to administer the lumbar traction. No previous study h as been conducted on this device. Methods. For each of the 14 healthy male patients (age range, 19-69 years), lumbar lengthening, alteration s in spinel curvature, and thoracic spine movement were assessed using radiographs taken: 1) before traction; 2) at 2; 10, and 15 minutes af ter the onset of traction; and 3) 2 minutes after traction was complet ed. Strain on the buttocks-supporting seat strap was recorded continuo usly during study sessions. Results. The entire patient pool displayed an average maximal lumbar lengthening of 5.39 +/- 4.21 mm. The amount of lumbar lengthening was influenced by the degree of thoracic immobi lization and by the amount of prior LTX 3000 (Spinal Designs Internati onal) use. Significant curvature reduction was observed during and aft er traction for the entire patient pool. Strain measurements correlate d well with the measured response in the radiographs. Conclusions. Pro per use of the LTX 3000(TM) (Spinal Designs International) induces sig nificant lumbar lengthening: and curvature reduction in healthy patien ts. Measurements of body weight supported by the seat strap could help determine if thoracic immobilization has been achieved and if the pat ient is responding to the lumbar unloading.