Dinamik omurga implantının geliştirilmesi ve l3-l4 segmentinin sonlu elemanlar yöntemi ile modellenmesi

Low back pain due to disc degeneration is a worldwide major health problem at any age, but especially at an elderly age. In the treatment of low back pain, dynamic stabilization may provide a more physiologic alternative to fusion. In this study, initial model of dynamic implant was developed that limit abnormal motion at the segment while preserves the motion within normal physiological limits. The effects of design parameters to strength and flexibility of the implant were investigated. Initial design was improved to final design that builds balance between flexibility and strength.Finite element model of an intact L3-L4 lumbar segment was developed. Load sharing characteristic of implant and effect of implant to segmental range of motion are two main criteria in evaluation of the newly developed implant. Finite element analysis were performed to investigate effects of newly developed implant to the segmental range of motion and load sharing characteristics in lateral bending, flexion, extension, and axial rotation. In this study, intact L3-L4 model and four types of screw-implant systems were investigated. These systems were rigid screw-rigid rod system, rigid screw-dynamic implant system, polyaxial screw-rigid rod system, and polyaxial screw dynamic implant system.The polyaxial screw-dynamic implant system exhibits the best results for range of motion and load sharing characteristics within four stabilization systems. The reduction of motion for the polyaxial screw-dynamic implant system in all loading is minimum within four stabilization systems. This stabilization system shares load with the intervertebral disc and the facet joints. The rigid screw-rigid implant system greatly reduces the motion in all loading. Performances of other two stabilization systems in range of motion and load sharing are lying between the polyaxial screw-dynamic implant system and the rigid screw-rigid implant system.