Total vertebrectomy and spine shortening for the treatment of T12-L1 spine dislocation: Management with suboptimal resources

Biomechanical comparison of spinal column shortening - a finite element study

BACKGROUND

At present, research on spinal shortening is mainly focused on the safe distance of spinal shortening and the mechanism of spinal cord injury, but there is no research on the biomechanical characteristics of different shortening distances. The purpose of this study was to study the biomechanical characteristics of spine and internal fixation instruments at different shortening distances by the finite element (FE) method.

METHODS

An FE model of lumbar L1-S was established and referred to the previous in vitro experiments to verify the rationality of the model by verifying the Intradiscal pressure (IDP) and the range of motion (ROM) of the motion segment. Five element models of spinal shortening were designed under the safe distance of spinal shortening, and the entire L3 vertebra and both the upper and lower intervertebral discs were resected. Model A was not shortened, while models B-E were shortened by 10%, 20%, 30% and 50% of the vertebral body, respectively. Constraining the ROM of the sacrum in all directions, a 7.5 N ·m moment and 280 N follower load were applied on the L1 vertebra to simulate the motion of the lumbar vertebrae in three planes. The ROM of the operated segments, the Von Mises stress (VMS) of the screw-rod system, the VMS of the upper endplate at the interface between the titanium cage and the L4 vertebral body, and the ROM and the IDP of the adjacent segment (L5/S) were recorded and analysed.

RESULTS

All surgical models showed good stability at the operated segments (L1-5), with the greatest constraint in posterior extension (99.3-99.7%), followed by left-right bending (97.9-98.7%), and the least constraint in left-right rotation (84.9-86.3%) compared with the intact model. The VMS of the screw-rod system and the ROM and IDP of the distal adjacent segments of models A-E showed an increasing trend, in which the VMS of the screw-rod system of model E was the highest under flexion (172.5 MPa). The VMS of the endplate at the interface between the cage and L4 upper endplate of models A-E decreased gradually, and these trend were the most obvious in flexion, which were 3.03, 2.95, 2.83, 2.78, and 2.61 times that of the intact model, respectively.

CONCLUSION

When performing total vertebrae resection and correcting the spinal deformity, if the corrected spine has met our needs, the distance of spinal shortening should be minimized to prevent spinal cord injury, fracture of internal fixations and adjacent segment disease (ASD).

A Anchoring Technique Using Long Bent Rods for Open Reduction of Thoracolumbar Dislocation

OBJECTIVE

The purpose of this study was to evaluate the effectiveness of a novel surgical open reduction method for thoracolumbar dislocation.

MATERIALS AND METHODS

This study included a total of 15 patients of thoracolumbar dislocation. All patients underwent posterior thoracolumbar open reduction and fixation using this technique. Preoperative x-ray, computed tomography (CT), and magnetic resonance imaging were used to evaluate the dislocation. The American Spinal Injury Association grade of spinal cord injury before and afer the operation were record. All patients were followed up for 2 years, and x-ray, CT were used to observe postoperative reduction and fusion.

RESULTS

Postoperative x-ray and CT images of all patients indicated good recovery of the spinal sequence, and no neurological deterioration or surgically related complications occurred. All patients were followed up for 2 years, no patients were lost to follow-up. During the follow-up period, x-ray and CT images showed no complications related to internal fixation such as fracture and loosening of screws and rods were found.

CONCLUSION

A anchoring technique using long bent rods is a safe, simple, accurate, and easy to replicate and implement method, which can be applied in the surgical treatment for thoracolumbar dislocation.

Thoracolumbar fracture dislocation (AO type C injury): A systematic review of surgical reduction techniques

Spinal injuries constitute about 3% of all injury cases and most of these injuries affect the thoracolumbar region, but thoracolumbar fracture-dislocations are much rarer. Dislocations (AO Type C injuries) of the thoracic and lumbar vertebrae, with or without associated fractures, happen due to very high energy trauma involving simultaneous, multidirectional, distractive and compressive forces across various spinal elements, which results in translational and rotational instability of the spinal column. Various reduction maneuvers have been described for thoracolumbar fracture-dislocations in the literature aiming to provide standardization in surgery for this situation. The aim of this review article is to systematically review the literature till date and describe various reduction maneuvers which help to achieve adequate sagittal and coronal balance as well as vertebral alignment with minimal soft tissue trauma. We searched the PubMed, the Cochrane Library (the most recent issue), Scopus, Cochrane Bone, Joint and Muscle Trauma Group Specialised Register, Web of Science, International Clinical Trials Registry Platform (WHO), ClinicalTrials.gov and Google Scholar databases, besides other sources and general internet search. The strategy used in the search was briefly(''thoracolumbar'' OR ''dorsolumbar'') AND "dislocation" in PubMed. Similar searches were made in the other databases.Reference lists of the relevant papers were also examined and any further relevant studies, which were also included in the review. The initial search revealed 332 papers in Pubmed, out of which 302 were human studies. A similar search on Scopus revealed 528 documents and on WoS revealed 289 papers. Searching the Cochrane library revealed 9 trials, which were already revealed in Pubmed search results. All the references were imported into Endnote and we had 632 references after excluding duplicates and 126 papers were left in endnote after manual title screening and duplicate removal. Finally, 70 relevant papers were selected for consideration based on inclusion criteria, after excluding unrelated papers manually. We have summarised the published literature on the surgical management of thoraco-lumbar fracture dislocations and described the reduction maneuvers used in detail.