Optimization of Spondylosynthesis for Certain Thoracolumbar Burst Fractures.

Intermediate transpedicular fixation, i.e. additional insertion of transpedicular screws into the injured vertebrae, is an improvement to the most popular surgical intervention for spinal injuries, currently gaining widespread use in clinical practice. Unilateral insertion of transpedicular screws into the injured vertebrae allows combining the advantages of intermediate transpedicular fixation with the possibility to perform anterior column support without remounting the transpedicular system. The aim of the study was to use biomechanical computer modeling for evaluating the stability of intermediate transpedicular fixation components, which allow performing anterior column support if necessary. MATERIALS AND METHODS: DICOM files obtained during CT scan of a patient with intermediate thoracolumbar spine injury and the ANSYS software were used. Stability of the transpedicular system and supportability of the complementary Mesh implant installed with unilateral intermediate transpedicular screws were evaluated using computer modeling based on the finite element method. RESULTS: The values of stress and displacement fields for spine-hardware systems with various arrangements have been obtained. The maximum loads exceeding bone tissue strength (153-161 MPa) were registered for standard 4-screw system (190 MPa) when modeling the load equivalent for walking and falling from a standing position. The use of the proposed fixation system arrangement supplemented with intermediate screws allows obtaining loads in the spine-hardware system not exceeding these thresholds. Complementary eccentric Mesh implant enhances fixation stability of the transpedicular system with intermediate screws. CONCLUSION: The results show the high degree of mechanical stability of the proposed hardware arrangement and its potential efficacy for thoracolumbar transitional vertebra stabilization.

Treatment Tactics for Patients with Isolated Injuries of the Fifth Lumbar Vertebra.

The major management technique for lumbar burst fractures is transpedicular fixation (TPF). However, in relation to fractures of the L5 vertebra, this tactic often has no advantages over conservative treatment, and, therefore, it is expected to be supplemented with anterior decompression and reconstruction of the anterior column of the L5 vertebra. The aim of the study was to determine the most optimal treatment tactics for patients with isolated burst fractures of the fifth lumbar vertebra. Materials and Methods: We performed a retrospective study of 58 patients treated for isolated burst L5 fractures. 12 patients refused to undergo surgery and received conservative outpatient treatment. TPF was performed in 27 patients; circular spondylosynthesis (TPF + anterior column support with a Mesh implant) - in 19 patients. The effectiveness of the treatment was assessed by clinical and introscopic research methods. Results: The radiological and functional outcomes of surgery with conventional TPF for isolated L5 burst fractures are generally comparable with the outcomes of conservative treatment. In 26% of the patients, the instability of the metal construction developed within 12 months after surgical intervention. Supplementing the transpedicular system with wedging anterior column support with a Mesh implant ensures preservation in 21%, and improves the parameters of the sagittal profile of the lumbosacral transition in 79% of cases.

[Functional state of spinal cord and its radices in patients with thoracic and lumbar spine injuries]. / Élektrofiziologicheskii monitoring funktsional'nogo sostoianiia spinnogo mozga i ego koreshkov u bol'nykh s povrezhdeniiami grudnogo i poiasnichnogo otdelov pozvonochnika.

AIM: To estimate the character of neurophysiological monitoring in patients with thoracic and lumbar spine injuries at different treatment stages. MATERIAL AND METHODS: Thirty-eight patients with non-complicated (22 patients, group 1) and complicated (16 patients, group 2) thoracic and lumbar spine injuries underwent electroneuromyography (ENM) and transcranial magnetic stimulation (TMS). The examination was performed at early (up to 2 weeks) and later (more than 1 month) post-injury periods, before the operation and on the 10th day after decompressing-stabilizing interventions. RESULTS: Before the operation, 71.4% patients of group 1 had ENM-signs of suppressed motor neuron activity in L5 segment of the spinal cord with peroneal nerve axonopathy. The most significant changes in ENM-indexes were observed in medullary channel stenosis of more than 30%. TMS parameters in group 1 were normal while in the 2nd group, EMN and TMS results before the operation demonstrated preserved motor neuron activity at the injury level despite gross neurological symptoms and 100% of medullary channel lumen deficit. In the postoperative period, ENM and TMS revealed no definite negative dynamics in patients of both groups. Patients with locomotor disorders, who underwent surgery at late post-injury periods, showed neurophysiological dynamics on the 10th day postoperatively. Low amplitude motor evoked potentials (kMEP), which were not present before, suggested initial signs of conductibility restoration (in 22% of patients) that proved the effectiveness of decompressive interventions in the long-term post-injury period. CONCLUSION: ENM- and TMS monitoring in patients with complicated and non-complicated injuries of thoracic and lumbar spine allowed revealing the positive influence of decompressing-stabilizing operations conducted both at early and late post-injury periods on the state of spinal cord conductibility and segmental apparatus.

[Modern aspects of pathogenesis of the trauma of the spinal cord and trunks of peripheral nerves].

In pathogenesis of the traumatic disease of the spinal cord, two mechanisms of the injuries of its neuronal apparatus are defined: primary (necrosis) and secondary (apoptosis). In the work a participation of a number of internal causes in the progression of apoptosis in injury of the spinal cord and peripheral nerve trunks, the role of those remains little-studied up to date, is discussed.