| Background:In the mid to late stages of spinal tuberculosis,imaging of some patients shows diseased vertebrae with varying degrees of bone loss.Although many papers describe this phenomenon,few biomechanical studies have been performed.Objective:A biomechanical analysis of patients with lumbar spinal tuberculosis with combined bone defects was performed using finite element analysis to investigate which bone defect conditions predispose lumbar spinal tuberculosis to pathological fracture.Methods:The CT data of lumbar vertebrae L4～5 segments of a normal volunteer were used to create a 3D model with assignment and validation.The original model was pathologically classified into four types:marginal(anterior,posterior,left,right and central endplate types),central vertebral,subperiosteal and accessory(pedicle,transverse process,and spinous process types),and there were five models with different defect sizes derived from each subtype.The biomechanical analysis was performed under vertical loading,flexion,extension,lateral bending,and rotation loading conditions.Results:With the increase of defect volume(group A:normal group B:1/5 defect group C:2/5 defect group D:3/5 defect group E:4/5 defect group F:5/5 defect group),the anterior endplate type(group B→C),posterior endplate type(group E→F),left endplate type(group B→C),right endplate type(group B→C),central endplate type(group E→F),central vertebral type(group E→F group),subperiosteal type(E→F group),pedicle type(D→E group),transverse process type(E→F group),and spinous process type(E→F group)had the greatest magnitude of comprehensive stress change and significantly increased stress concentration for the seven conditions,implying an increased risk of vertebral fracture if conservative treatment was continued at this time.Conclusions:When the defect volume reaches the anterior endplate type 1/5 defect group,the posterior endplate type 4/5 defect group,the left endplate type 1/5 defect group,the right endplate type 1/5 defect group,the central endplate type 4/5 defect group,the central vertebral type 4/5 defect group,the subperiosteal type 4/5 defect group,the pedicle 3/5 type defect group,the transverse process type 4/5 defect group,and the spinous process type 4/5 defect group,continued conservative treatment increases the risk of vertebral fracture and surgical treatment should be considered. |
