The biomechanical effects of foraminoplasty of different areas under lumbar percutaneous endoscopy on intervertebral discs: A 3D finite element analysis

Abstract

Background:We set out to evaluate the biomechanical influence of foraminoplasty on intervertebral discs in different areas under lumber percutaneous endoscopy through the use of a three-dimensional finite element.Methods:We established a normal 3D finite element mode of L3-5, using simulate lumbar percutaneous endoscopy by carrying out cylindrical excision of a bone whose diameter was 7.5 mm on the L5 superior articular process and the L4 inferior articular process, respectively. We therefore obtained 3 models. The first was the normal lumbar model, the second the L4 inferior articular process shaped model, while the third was the L5 superior articular process shaped model. We compared the biomechanics of discs of L3/4 and L4/5 in states of forward flexion, backward extension, left and right flexion as well as left and right rotation.Results:When the L4 inferior articular process shaped model was in backward extension, left rotation, and right rotation, the stress of the L4/5 disc was greater than in the normal model, especially in the state of extension. When the L5 superior articular process shaped model was in left and right rotation, the biggest stress of the L4/5 disc increased slightly. However, no matter which way the L5 superior articular process or the L4 inferior articular process of model was shaped, the stress impact of the L3/4 disc was small.Conclusions:There is more biomechanical influence on the L4/5 disc when carrying out a foraminoplasty on L4 inferior articular process under a lumber percutaneous endoscopy. In addition, the influence of both types of surgery on the stress of L3/4 disc is small.