title: [Experimental anatomical study of transpedicular stabilization of the spine].
abstract: Currently transpedicular fixators (TPF) are widely used for stabilization in treatment of degenerative spine disease. Despite indisputable advantages of transpedicular stabilization (durability and comfort in use) there are certain drawbacks of their application: 1) degeneration of adjacent segments (development of protrusions, herniations, instability); 2) absence of cyclic load in tissues of stabilized segment which may lead to their degeneration and osteolysis. We studied effects of loading on mobility of lumbar spine using cadaver specimens with preserved bony, ligamentous and articular structures. Mechanical features of initial specimen was compared to its properties after surgical intervention (laminectomy, diskectomy etc.). Effects of altered tissue properties and different kinds of injuries on mechanical features of injured and intact segments and on strain in bony structures and elements of transpedicular system were evaluated using finite-element method. Performed studies demonstrated the following: 1) after removal of posterior column (according to Dennis) by decompressive laminectomy, TPF with stiffness below 20 N/mm (e.g., using nitinol bars) is ideal for stabilization of lumbar spine. It provides close to normal stability of lumbar region and its certain segments as well. 2) in simultaneous injury of posterior and anterior columns of lumbar spine (in decompressive laminectomy like in case of using transpedicular constructions for treatment of spondylolisthesis, spinal canal stenosis, disk herniations etc.) its stabilization should be performed using TPF with stiffness 30-45 N/mm (nitinol of titanium alloy bars). Application of more rigid TPF (steel bars) increases difference in stiffness between segments which leads to hypermobility of adjacent segments in certain functional loads (flexion and extension).
mesh_terms: D000328:Adult; D006801:Humans; D008297:Male; D008953:Models, Anatomic; D013122:Spinal Diseases / Q000473:pathology / Q000601:surgery*; D013131:Spine; D053831:Surgical Fixation Devices