RESUMEN
BACKGROUND: In contrast to traditional drafting techniques, the superposition structure of the bed air column of spinal manipulation contributes to controlling the duration of traction. Finite element analysis is used to calculate the stress of adjacent lumbar segments with different traction durations. It provides a better theoretical basis for lumbar traction prescription in clinical spinal manipulative bed. OBJECTIVE: To analyze the stress and distribution of adjacent lumbar segments with different traction durations using the finite element analysis when the spine manipulation bed is used for traction. METHODS: A healthy male volunteer, aged 26 years, with a height of 174 cm and a weight of 60 kg, was selected, who was fully informed of the study protocol and signed an informed consent. The study protocol was approved by the Ethics Committee of Rehabilitation Hospital Affiliated to Fujian University of Traditional Chinese Medicine with an approval No. 2016XJS-001-01. According to the CT images of volunteers T12-S1, an effective three-dimensional finite element model of the lumbar spine was established. By means of three-dimensional finite element analysis, the stress changes of the lumbar vertebrae and facet joint adjacent to the L3 were calculated when the traction was maintained for 10, 20 and 30 seconds respectively. The internal law and mechanism of the changes were analyzed and discussed. RESULTS AND CONCLUSION: (1) When the pushing height was 5 cm and the action time was 1.25-17 seconds, the stress value of adjacent lumbar segments increased continuously. For the intervertebral disc, the stress value was 4.60-5.68 MPa for L2-L3, and 5.26-6.61 MPa for L3-L4; for the facet joint, the stress value was 7.01-8.67 MPa for L2-L3 and 5.22-6.50 MPa for L3-L4. (2) The stress of adjacent vertebral segments and facet joints remained basically unchanged after pushing for more than 24 seconds. Therefore, when the spine manipulation bed acts on the lumbar spine, it will not damage the adjacent lumbar segments, and the duration of action should be between 25 and 30 seconds.