Thoracolumbar fractures are a common orthopedic injury, accounting for approximately 50% to 70% of all spinal cord injuries [1], and the thoracolumbar segment (thoracic 11 to lumbar 2) of the spine is prone to injury due to the specificity of its anatomical structure: the thoracolumbar segment is the site of spinal stress concentration, and the change in the direction of the articular eminence joint becomes an intrinsic factor in the high incidence of spinal injury in the thoracolumbar segment. In addition, the thoracolumbar segment is an expanded part of the spinal cord and the relative volume of the spinal canal is small, so fractures are often accompanied by different degrees of spinal cord injury and lead to serious complications such as paraplegia, which seriously affect the quality of life of patients.
I. Problems in the diagnosis and treatment of thoracolumbar fractures
1. Fracture typing of thoracolumbar segment and selection of treatment method
The most commonly used clinical classification systems for thoracolumbar spine damage are the AO and Denis systems, with the former having average reliability, overly complicated classification, and difficult clinical application, and the latter having higher reliability than the AO system, but too simple classification to cover all fracture types and poor clinical guidance.The TLICS scoring system [2] takes into account the mechanism of spinal injury, the posterior ligament complex ( PLC) integrity and neurological functional status, which has high reliability, comprehensiveness, and practicality, and can comprehensively and accurately guide patients with thoracolumbar segment fractures whether to use surgical treatment: a score of less than 3 suggests conservative treatment, while ≥5 suggests surgical treatment [3]. Due to the difference of each patient’s actual condition, this score can guide the choice of treatment, but cannot completely replace clinical judgment.
2. Selection of the timing of surgery for thoracolumbar segment fractures
Duh’s study showed that surgery within 24 hours after injury can reduce the occurrence of complications, and the best results are achieved when performed within 8 h of injury. Decompression is also helpful for the recovery of neurological function, but the effect of early decompression is better. Multicenter studies have shown that the timing of surgery after trauma selected within 25 hours, 25-200 hours, and after 200 hours has no significant effect on the recovery of neurological function. For patients with posterior surgery, it is appropriate to perform the surgery within 2 weeks after the injury.
3.The choice of surgical approach
Parker and other three aspects are evaluated according to the degree of vertebral body comminution, the extent of the bone block into the spinal canal and the degree of posterior convexity deformity, etc. Each item is scored 3 points, the lowest is 3 points and the highest is 9 points. 3-6 points can be performed posterior surgery alone, ≥7 branches alone anterior surgery.
Posterior surgery is a traditional orthopedic procedure with simple anatomy, less trauma, less bleeding, easier operation, short-segment fixation, and maximum preservation of spinal motor function. The disadvantage of posterior approach alone for short segment fixation is the potential risk of internal fixation failure, secondary kyphosis, spinal instability, and neurological dysfunction.
Anterior internal fixation allows for adequate decompression of the spinal canal, better fracture repositioning, and more reliable fixation for spinal stability thus allowing for early rehabilitation, and is appropriate for patients with neurological deficits caused by anterior compression. However, anterior surgery has problems such as high technical requirements, long surgical and anesthetic times, high blood loss, and a tendency to affect urinary function.
The advantages of combined anterior and posterior surgery are that it can maximize the restoration of vertebral body height, reset fracture dislocation and spinal deformity, and provide a good opportunity for neurological recovery by adequately decompressing the spinal canal. However, the surgery is very invasive and complex. In conclusion, theoretically, 360° anterior-posterior fusion is the ideal fixation, but the cost is considerable, so caution should be exercised.
The above surgical approaches have their own advantages and disadvantages, and the choice should be based on the type of fracture, the patient’s condition and the characteristics of various internal fixators to maximize the patient’s recovery and reduce postoperative complications.
4.Whether the injured spine needs to be fixed
The pedicle screw fixation can increase the strength of internal fixation and disperse the stress to achieve a more stable and reliable fixation, which is more in line with biomechanics while ensuring the strength of fixation, without posterior fusion during fixation, and can be removed after the fracture heals to preserve the motor function and reduce the postoperative long-term complications.
5. The necessity of laminectomy decompression
In the past, most scholars believed that decompression could maximize neurological recovery, but it was clinically discovered that the bony component intruding into the spinal canal could be resorbed [5]: with the posterior longitudinal ligament intact, the fracture block could be returned by surgical bracing, and for the posterior longitudinal ligament incomplete, the implant block could be absorbed due to the circulation of cerebrospinal fluid. In contrast, posterior decompression destroys the only remaining and undamaged posterior column of the spine, destroying the posterior ligament complex, and this instability will cause further development of deformity and neurological problems, and for the absence of neurological symptoms, there is even less need for laminectomy decompression. Therefore, for cases where the laminae are not invaginated and do not constitute compression of the spinal cord, removal of the laminae for posterior decompression should be taken with caution.
Second, the spinal cord injury drug treatment and experimental research
1, drug treatment of spinal cord injury
Spinal cord injury is still not found clinically very effective treatment, although methylprednisolone shock therapy is considered the standard treatment plan for spinal cord injury, inhibit the secondary reaction of spinal cord injury, with neuroprotective effect, but when more than 48 hours, the secretion of neurotrophic factors produce inhibitory effect, so for 48 hours, it is not recommended to continue the application of methylprednisolone treatment, and recommended the use of gangliosides and other neuro neurotrophic drug treatment [6].
2. Cell transplantation for spinal cord injury and application prospects
Cell transplantation for spinal cord injury has become the focus of research by scientists in recent years, with stem cell transplantation being the most important. Stem cells have the ability of self-renewal and multi-directional differentiation, and can differentiate into neurons and glial cells after in vitro culture and induction. After transplantation, stem cells can replenish the neurons lost after spinal cord injury and increase the signal connection between neurons on the one hand, and secrete neurotrophic factors at the injury site to protect and promote the regeneration of neurons and axons on the other hand. The main types of cell transplantation are: Schwann cells, olfactory sheath cells, neural stem cells, embryonic stem cells, and mesenchymal stem cells [7-9].
After spinal cord injury, primary and secondary injuries lead to the formation of a spinal cord cavity at the injury site, which can affect the microenvironment for the survival of own and transplanted cells and is not conducive to growth and axonal extension. At the same time, due to massive cell necrosis, the nutrient factors produced by the residual cells cannot meet the needs of tissue regeneration, making nerve regeneration difficult. Therefore, transplantation of autologous activated Chevron cells can fill the tissue defect and fill the spinal cord cavity, which is conducive to axonal extension and synaptic connection of nerve regeneration; on the other hand, it can produce a large amount of cytokines to provide nutritional support for nerve regeneration. The authors found that autologous activated Schwann cells can survive for a long time in the central nervous system after transplantation; autologous activated Schwann cells can secrete neurotrophic factors and stimulate and induce neural stem cells to differentiate towards neurons.
Spinal cord injury mostly stays in experimental studies, and the evaluation of a few clinical studies is still subjective, but we should increase exploratory studies with a view to breakthrough. At the same time, we should be more clear that pre-hospital treatment is very important, and rehabilitation is even more important throughout the whole process of spinal cord injury, for the effective and standardized treatment of spinal cord injury, multi-center collaborative research is needed.