Assessment of risk factors for the vertebral body kyphotic deformity progression in patients with type A1 injuries of the thoracolumbar junction

More than 60% of traumatic injuries of the spine occur in the zone of the thoracolumbar junction (TLJ), and 60–75% of these fractures are of a compression nature. Type A1 injuries are characterized by the least osteo-destructive changes compared to other injuries. Traditionally, they are treated conservatively. A number of studies conducted in the last 10 years, shows a high rate of failure of conservative treatment, as evidenced by the progression of kyphotic deformity of the compressed vertebral body. Most of these publications are devoted to osteoporotic lesions in aged patients, while this aspect has been little studied in patients of working age with normal bone density. Objective: to evaluate the factors influencing the risk of kyphotic deformity progression in patients of working age with type A1 traumatic injuries of the thoracolumbar junction. Materials and methods. The analysis of clinical cases of patients who visited the outpatient department of Romodanov Neurosurgery Institute of National Academy of Medical Sciences of Ukraine in the period from 2019 to 2022 with traumatic damage to the TLJ zone. Forty-seven victims who met the selection criteria were selected. Gender, age, body mass index, level of damage, location of the damaged endplate (caudal or cranial), bone tissue radiodensity, angular kyphotic deformity of the vertebral body, and pain intensity were considered as predictors. Depending on the presence or absence of deformity progression 2 months after the injury, the patients were divided into two clinical groups. The most clinically significant predictors were identified using the LASSO (Least Absolute Shrinkage and Selection Operator) regression method. Results. LASSO screening identified five potential predictors. The final logistic regression model after regularization demonstrated high predictive performance: the area under the ROC curve (AUC) was 0.907, and the predictive accuracy was 85%. When assessing the risk of kyphotic deformity progression in traumatic injuries of type A1 of the TLJ zone, age, bone density, angular kyphotic deformity of the vertebral body, and pain intensity are of the greatest importance, demonstrating a directly proportional relationship. A compressed caudal endplate is also associated with a higher risk of post-traumatic progression of angular kyphosis. The nomogram developed using the mentioned factors makes it possible to quantify the degree of risk when choosing a therapy strategy. Conclusions. The performed analysis made it possible to create a nomogram for predicting the increase in kyphotic deformity of the vertebral body in A1 fractures of TLJ region. The proposed model can be used for a rational assessment of the risk degree when choosing the optimal tactics for treating patients

Surgical management of traumatic irreducible spondyloptosis of thoracolumbar junction

Introduction. The thoracolumbar junction is the most common location of traumatic spinal injuries. It accounts for 50-60% of all thoracic and lumbar spine injuries. Spondyloptosis is rather rare, but one of the most severe types of traumatic injury, that is characterized by a severe damage of spinal axis in one or more planes. Traumatic spondyloptosis is classified as reducible and irreducible, depending on the possibility of intraoperative restoration of the spinal axis without resection of the damaged vertebra. Objective. To determine the optimal surgical technique for traumatic irreducible spondyloptosis of thoracolumbar junction. Materials and methods. A retrospective analysis of the patients’ database treated at the Romodanov Neurosurgery Institute, Ukraine was performed over the past 4 years (2017 to 2020) to identify all cases with traumatic irreducible spondyloptosis of the thoracolumbar junction. Results. Treatment outcomes of five patients aged 18 to 52 years (mean age 31.2 years) were analyzed. The minimum period from the moment of injury to surgery was 14 days, the maximum was 3 months and 2 days (on average 42.2 days). At the time of admission all patients had a neurological deficit that corresponds to the functional class A on the American spine injury associatin ASIA scale of severity of spinal cord injury. The TLICS (Thoracolumbar injury classification and severity) score was 8 points. All the patients had the injury of lateral spondyloptosis: in three cases as an isolated displacement only in the coronal plane, in two – as a combined one - in the coronal and sagittal plane. Surgical intervention in all cases was performed from the posterior approach. As a body replacement system in 2 patients, a vertical cylindrical implant (Mesh) was used, in 3 patients - a telescopic body replacing implant. The method of bicortical implantation of pedicle screws was applied. The transpedicular system was strengthened by two cross links of the rod-to-rod type. In all cases the restoration of spinal axis was achieved in both the coronal and sagittal planes. Follow-up examinations were carried out 2, 6 and 12-18 months of the postoperative period. Regression of neurological disorders was registered in two patients, in one case to ASIA B, in the other to ASIA C. Conclusions. Isolated posterior approach has demonstrated high efficacy in the surgical management of traumatic irreducible spondyloptosis of the thoracolumbar junction both in restoring the axis of the spine and in ensuring the stability of fusion

Peripheral nerve traction injury. Literature review

Traction injury of the peripheral nerve (TIPN) is an injury that occurs as a result of stretching the nerve beyond its normal elastic properties. An analysis of the available literature has revealed the following. TIPN is the most common type of severe nerve injury in the setting of road traffic accidents, catatrauma, gunshot wounds, birth injuries, etc. The dynamics of TIPN during fast and slow stretching is the same and includes three phases: elastic, inelastic and tearing. The limits of elastic stretching of the nerve are determined by the degree of tortuosity of myelinated fibers and the elasticity of the connective tissue framework of the nerve. Stretching of the nerve beyond its elastic limits is characterized by rupture of axons and endoneurial sheaths, including at a considerable distance from the epicenter of pathomorphological changes, which determines the severity of the injury and the impossibility of effective nerve autoregeneration. The force of stretching and the direction of its application to the nerve trunk determine the severity of TIPN. The degree of nerve stretching varies along its length and reaches a maximum in the periarticular areas. A fairly moderate stretching of the nerve can lead to a noticeable change in the conductivity of electrical impulses. Unlike other localized types of nerve injury, the pattern of pathomorphological changes in TIPN includes various forms of damage to structural elements. Understanding the pathophysiology of TIPN is a prerequisite for the development of optimal treatment of this type of injury

The biomechanical state of the thoracolumbar junction with various options of transpedicular fixation under flexion load

Introduction. Morphological and biomechanical features of the thoracolumbar junction determine the large number of cases of traumatic bone injuries. Reconstructive and stabilizing surgeries performed in this area, due to the significant load on both the elements of hardware and bony structures, require high reliability of fixation. Objective. To study the stress-strain state of the model of the thoracolumbar section of the spine after the Th12-L1 vertebrae resection with various options of transpedicular fixation under the influence of flexion load. Materials and methods. The stress-strain state of the mathematical finite-element model of the thoracolumbar section of the human spine under the influence of flexion load was studied. The model simulated the condition after surgery for a significant traumatic lesion of the thoracolumbar junction with laminectomy, facetectomy, and corpectomy of the Th12 and L1 vertebrae. Four variants of transpedicular fixation were studied (using short or long bicortical fixation screws, two crosslinks and without them). Control points of the model characterizing the load distribution both in bony structures and on metal elements of fusion and body replacement systems were studied. Results. Crosslinks have the greatest effect on reducing the level of stress both in the bony elements of the models and in the metal elements. When comparing the length of the screws, the use of monocortical screws was determined to have minor biomechanical advantages. The stress analysis of the area of the screw entry into the pedicle of the arch of the fixed vertebrae (clinically significant zone) revealed that in the model with short screws and without crosslinks, the stress for the vertebrae Th10, Th11, L2 and L3 is 5.0, 1.9, 7.8 and 13.6 MPa, respectively, while the presence of crosslinks reduces the corresponding values to 4.6, 1.9, 7.3 and 12.7 MPa. In models with bicortical screws, the corresponding values are 5.1, 2.3, 10.2, and 12.7 MPa in the absence of crosslinks and 4.7, 1.8, 9.9, and 12.2 MPa with the presence. A similar trend is observed in other control points. When comparing the results with the compression load in the models studied earlier, it was established that flexion causes an increase in the stress of the models with monocortical screws by an average of 33.7%, with bicortical screws by 39.6%. Conclusions. In case of flexion load, the use of crosslinks makes it possible to reduce the level of stress in all control points of the models, regardless of the length of the used transpedicular screws, while the length of the screws does not have a fundamental effect on the stress distribution