Study On The Mechanism Of Knee Joint Degeneration On KLS Lumbar Motion Unit Load

Objective: To investigate the changes of biomechanical lines of the pelvis and lumbar spine and the biomechanical effects on the lumbar motion unit,and clarify the biomechanical mechanism of lumbar motion unit load changes in KLS compensation process.Content and Methods: This is the first experiment to study KLS on coronal plane combined with imaging and three-dimensional finite element method of lumbar vertebrae.The changes of pelvic and lumbar biomechanical lines in degenerative changes of knee joint were studied by measuring physical parameters of imaging students.Thus,the correlation of biomechanical parameters of KLS was studied,and the biomechanical compensation method of KLS in coronal plane was preliminarily explored.On this basis,the three-dimensional finite element modeling of the lumbar vertebrae with normal and degenerative lateral bend changes due to varus deformity of the knee joint was carried out.By analyzing the biomechanical properties of the lumbar spine under these two different physiological conditions,the specific stress mode and mechanical conduction process of the lumbar spine were determined,and the mechanism of the mechanical conduction of KLS was expounded.Result: In the imaging study,the statistically significant changes in biomechanical parameters of knee joint OA after independent sample t-test were realized as knee varus angle VKA>3°,lumbar spine Cobb>0° and pelvic horizontal angle PHA>0°;Correlation analysis showed that VKA and Cobb was positively correlated(r = 0.819,P < 0.01),VKA and PHA was positively correlated(r = 0.809,P < 0.01),and Cobb was also positively correlated with PHA(r = 0.802,P < 0.01);After partial correlation analysis,the correlation between VKA and Cobb and PHA was significantly decreased.Three-dimensional finite element modeling of lumbar vertebrae showed that the lower lumbar vertebral body was more loaded,and the stress distribution of lumbar vertebrae changed with body position.There were differences in the stress peaks between the normal lumbar vertebrae and the degenerative lateral lumbar vertebrae in the forward,lateral and left rotation conditions.Among them,in the anterior flexion position(-16.3%),the left side bend position(-47.6%)and the right rotation position(-17%),the degenerative lateral lumbar vertebrae showed increased stress compared with the normal lumbar vertebrae,while in the posterior extension position(2.92%),the right side bend(65%)and the left rotation position(7.70%)showed a stress reduction.The maximum stress vertebral body of the normal lumbar spine is L4,and the maximum stress vertebral body of the degenerative lateral lumbar vertebra changes with working conditions.The maximum position of the normal lumbar vertebrae and the degenerative lateral lumbar vertebrae is the L1 plane,and the lateral curvature of the vertebral body changes with the working conditions.Conclusion: KLS with knee-lumbar syndrome is accompanied by biomechanical changes.When the knee is varus deformed,the pelvis tilts to the knee inversion side horizontally,and the lumbar vertebra changes to the knee inversion.Lumbar physiologic changes lead to finite element biomechanical differences in the lumbar spine.The normal lumbar vertebrae are bilaterally equivalent stress changes under flexion,extension,lateral bending and rotation.In the left side of the lumbar vertebrae,the lateral bending and rotation conditions showed significant bilateral stress change imbalance,and the left half of the vertebral body and posterior tissue were in a long-term high stress state.The correction mechanism exists in knee-lumbar syndrome.The knee joint,pelvis and lumbar vertebrae interact with each other in the KLS,during the whole compensation process,lumbar vertebrae directly compensate for knee joint changes and indirect compensation of knee joint changes through pelvic conduction,and this two mechanisms exists at the same time.There is mechanical conduction in knee-lumbar syndrome,the displacement of lumbar vertebrae changes during lumbar lateral bending,and the range of lumbar spine movement is concentrated on the side of lateral bending.Too small range of activities makes the facet joint in a high stress state for a long time,aggravating the lumbar spine injury and forming a vicious circle,which makes the condition more serious.