Reducing the extent of facetectomy may decrease morbidity in failed back surgery syndrome

Abstract

Background Percutaneous transforaminal endoscopic discectomy (PTED) is widely used for the treatment of lumbar disc herniation. Facetectomy in PTED is necessary for accessing the intraspinal region and for decompressing the exiting nerve roots in patients who suffer from hypertrophy of the facet joints. However, this may increase morbidity in failed back surgery syndrome (FBSS) and has not been clearly elucidated. Methods A three-dimensional lumbosacral model was reconstructed and validated. And corresponding models after PTED with one-quarter and one-half excisions of the superior articular process were reconstructed. The maximum shear stress on the annulus in L5, von Mises stress of the facet cartilage, maximum principle capsular strain and deformation of the lumbosacral model were calculated using finite element methods. Results Calculated results show no significant differences in the complete model and the model with one-quarter excision of the superior articular process, but all biomechanical indexes have been deteriorated under most of the loading conditions tested in the model with one-half excision of the superior articular process. Conclusions Less facetectomy is better because it may reduce the risk of biomechanical deterioration and consequently, that of FBSS.

Measurement and calibration of the nucleus position and its cross-sectional area ratio to increase the accuracy of finite element analysis

“…4 and Table. 1), with smaller sizes (mesh re nement) being used in areas that experienced serious mesh distortion. The contact type of each surface, excluding facet cartilage, was de ned as bounded, and the cartilage-cartilage contact was de ned as frictionless [8,9,14,18,28,29]. Six degrees of freedom were rigidly xed under the inferior of L5, and moments were applied to the superior of L4 [6,12,16,21].…”

“…Biomechanical deterioration is a key trigger for lumbar disc degenerative diseases (DDDs) [1][2][3][4][5]. Therefore, optimized nite element analysis (FEA), which is a widely used biomechanical research method, is an ideal approach for the accurate investigation of DDD pathogenesis and treatments [6][7][8][9][10][11][12][13][14][15]. A series of model validation methods have been implemented by comparing the differences in the range of motion (ROM), which is a key index for lumbar motility and stability, between the FEA results and those from widely cited in vitro studies [7,10,11,[14][15][16][17][18].…”

Measurement and calibration of the nucleus position and its cross-sectional area ratio to increase the accuracy of finite element analysis

“…Construction of the normal model Bone structures from L1 to S1 were reconstructed on the basis of the high-resolution computed tomography (CT) imaging data and were used as templates for model construction [4,9,10]. Fitted curves were used in the drawing of smooth surfaces to replace irregular surfaces in the reconstructed model.…”

“…4), with smaller sizes (mesh re nement) being used in areas that experienced serious mesh distortion, and the cartilage-cartilage contact was de ned as frictionless [4,15,25]. Material properties of current models was de ned in consistent with our published studies [10,23,24]. Six degrees of freedom were rigidly xed under the inferior of L5, and moments were applied to the superior of L4 [13,14].…”

“…Therefore, optimized nite element analysis (FEA), which is a widely used biomechanical research method, is an ideal approach for the accurate investigation of DDD pathogenesis and treatments [4][5][6][7][8][9]. A series of model validation methods have been implemented by comparing the differences in the range of motion (ROM), which is a key index for lumbar motility and stability, between the FEA results and those from widely cited in vitro studies [5,6,[9][10][11][12][13]. The accuracy (ACC) of the FEA models has been improved via model calibrations that used annulus and bone structures [13,14].…”