Many studies have investigated the kinematics of the lumbar spine and the morphological features of the lumbar discs. However, the segment-dependent immediate changes of the lumbar intervertebral space height during flexion-extension motion are still unclear. This study examined the changes of intervertebral space height during flexion-extension motion of lumbar specimens. First, we validated the accuracy and repeatability of a custom-made mechanical loading equipment set-up. Eight lumbar specimens underwent CT scanning in flexion, neural, and extension positions by using the equipment set-up. The changes in the disc height and distance between adjacent two pedicle screw entry points (DASEP) of the posterior approach at different lumbar levels (L3/4, L4/5 and L5/S1) were examined on three-dimensional lumbar models, which were reconstructed from the CT images.Objectives
Methods
The mean scoliosis improved from 80.7° to 30.5° after surgery with a corrective rate of 62.2% and in latest follow.-up was 34.7° The length of the growth of the instrumented spine was average 13.3mm. No severe complications in our series. When PRSS is placed in place, compressive stress was found to exert on the convex side, while tensile stress on the concave side of the curvature which were reflected by the changes on the color band in the photo-elastic test and by the changes in width of the disc spaces, and more type X collagen expressed on convex side than concave side, it suggest that compressive stress leads to increase earlier cartilage degeneration of end plate in convex side correlating with the decreased growth of the end plate of this side, and resulting in maximum spinal realignment.
