The Changes Of Lumbar Intervertebrale Foramen And Nerve Root In Different Body Positions

Objective: By using the magnetic resonance imaging(MRI) technology, to measure and analysis the pore sizes of lumbar intervertebral forame, the deviations of dural sac or nerve root, and the angles between dural sac and travel root in different body positions. Then we appraised the safety of percutaneous endoscopic lumbar discectomy(PELD) in different body positions.Methods:40 volunteers were selected(20 male, 20 female, age 21-39, height 152-184cm) in this study. All of them were investigated by MRI in two different positions, left lateral position and prone position, respectively. The silicone pads were placed under the both sides of the abdomen in prone position, and the left ilium in lateral position. After preparation is done, the longitudinal diameter, sagittal diameter and area of intervertebral foramen of L3-L4, L4-L5, L5-S1 segments were measured in sagittal images. The distances of travel root or dural sac to the midpoint of the inner edge of the vertebral pedicle and angles between dural sac and travel root also were estimated in coronal images. Monitoring morphology of intervertebral foramen and the migration of the dural sac in different position by using MRI. Sorting and analysising data by using SPSS22.0 statistical software.Results:The average longitudinal diameter, sagittal diameter and area of intervertebral foramen in lateral position is 20.7±4.93 mm, 8.79 + 1.29 mm and 113.73 + 40.64mm2, and in prone position is 19.4±3.84 mm, 8.12±2.66 mm and 94.71±35.01mm2. There are no statistically significant difference between the two body positions(P>0.05). In lateral position the average distance between the travel root and the midpoint of the inner edge of the vertebral pedicle is 4.95±0.55 mm, and the distance between the dural sac and the midpoint of the inner edge of the vertebral pedicle is 14.39±3.22 mm. In prone position is 3.59±0.63 mm and 6±1.52 mm. Meanwhile, the average angle between the dural sac and the travel root is 10.12±2.2°, in prone position is 13.71±2.03°. Distances of travel root or dural sac to pedicle, angles of dural sac and travel root in different body positions have statistically significant differences(P<0.01).Condusion:The MRI images in different positions were observed and analysed. The intervertebral forame area of the left lateral position with a silicone pad under is bigger than that of the prone position, which may provide a broader vision and a greater motion range of working canula and microendoscope. These advantages significantly increase the posibility of complete decompression. Compared with the prone position, the angle between dural sac and travel root was lessened and the nerve roots and dural sac have an obvious contralateral migration in lateral position, which proves lateral position is safer than prone position in PELD.