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.