Superiority of percutaneous minimally invasive technology and O-arm navigation technology
Traditional posterior open surgery has more bleeding, longer incision, more paravertebral muscle dissection, severer postoperative pain, and slower recovery than novel percutaneous minimally invasive surgery[10]. The advantages of percutaneous minimally invasive technology are more obvious in avoiding above-mentioned problems, especially for patients with multiple injuries combined with trauma in other parts[11]. In recent years, with the development of minimally invasive technology and patients' demand for minimally invasive surgery, percutaneous minimally invasive surgery has been widely used in the treatment of spinal fractures[12, 13]. Percutaneous minimally invasive technology can effectively reduce intraoperative bleeding and intraoperative and postoperative blood transfusion, which is conducive to reduce the use of blood products and promote the early recovery of patients. On the other hand, it can also reduce bed-related complications and hospitalization costs[14]. However, compared with the traditional open approach technique, percutaneous pedicle screw technique requires more anatomical knowledge, operational skills and experience of the surgeon which has a longer learning curve. Moreover, increasing the operation time and intraoperative bleeding may happen if the surgeon is not familiar with the minimally invasive operation[15, 16]. In addition, percutaneous nailing can also increase the risk of damaging the pedicle, resulting in damage to nerve function and facet joints[17–19]. The addition of screws to the injured vertebra will further increase the above risks and surgical costs. Current studies have shown that 3D navigation technology can significantly improve the precision of screw placement by orthopedic surgeons, reduce surgical time, and enable finish the learning curve of percutaneous screw placement technology in a reasonable time[20].
At the present, the common navigation technologies in clinic include preoperative CT navigation, isocentric C-arm three-dimensional navigation, and intraoperative O-arm real-time navigation, among which intraoperative O-arm real-time navigation is the most advanced. O-arm in navigation can provide real-time 3D reconstruction, high-definition images, which can show a variety of anatomical structure clearly to greatly improve the accuracy of pedicle screw insertion and the operation time can be greatly reduced at the same time. In addition, O-arm allows many young surgeons with less experience to get access to the practice. Of course, O-arm also has some disadvantages, such as high price, increased surgery costs, intraoperative changes in patient position will lead to decreased accuracy of navigation, and the use of navigation also requires a certain amount of time to learn and experience.
There was no statistical difference in operation time, intraoperative bleeding in these two groups in this study. Although incision length contrast is statistically significant, the difference is very small, the reason may be two more screws were inserted in the injured vertebra in fractured vertebra screwing group. Compared with the traditional open surgery, the incision of two groups were shorter, which can help patients reduce postoperative pain, shorten the recovery time.
Whether the injured vertebra should be inserted
Injured vertebral space was indirectly opened by the force between the upper and lower vertebral body from the nail rod system in the traditional across injured vertebral four pedicle screw fixation surgery. The intraoperative and postoperative clinical effect of this surgery maybe satisfactory in the short term, while in the long run, the loss of the correction effect and the failure of internal fixation may happened bacause four pedicle screw fixation is a kind of double plane fixation, easy resulting to quadrilateral effect and suspension effect[21]. Dick et al. reported that additional pedicle screw placement in the injured vertebra can improve the biomechanical stability of the screw rod system by reducing the stress of each pedicle screw by supporting the anterior column[22]. This operation of six pedicle screws placement can change the original double plane fixation way into three plane fixation by the injured vertebra pedicle screws placement, avoiding the quadrilateral effect and suspension effect effectively[21]. During the procedure, the injured vertebral can be thrust forward directly, which is beneficial to the reduction of kyphosis of the injured vertebra. In addition, the increased screws disperse stress and reduce fatigue of internal fixation, preventing internal fixation failure. Mahar et al. examined biomechanical property of L1-3 in six specimens of human corpse, they adopted L2 segment as a simulative damage section, divided into two groups respectively (fractured vertebra screwing group and fractured vertebra screwing group)[23], the results showed that the biomechanics of fractured vertebra screwing group significantly stronger than no fractured vertebra screwing group. It was also proved by Baaj et al. [24]through similar experiments on human cadaver. Bolesta et al. simulated the L2 vertebral body burst fracture on the calf spine, and conducted the biomechanical test[25], the results showed that the stability of fixed segment could be increased by 68% on average in the fractured vertebra screwing group, even as much as in the long-segment fixation. Saglam et al. conducted a study on four groups of patients receiving 4-segment cross-injury vertebra fixation, 3-segment cross-injury vertebra fixation, 4-segment cross-injury vertebra fixation and 5-segment cross-injury vertebra fixation, and obtained similar results[26].
In addition to the real-time correction effect of injured vertebra in the surgery, the long-dated corrective effect is also very ideal in the fractured vertebra screwing surgery[27, 28], but compared with across the injured vertebra fixation, two more screws need to be inserted in fractured vertebra fixation surgery. If the traditional posterior midline open access procedure was adopted, there would be more complications including longer operation time, larger incision length, more intraoperative bleeding[29]. Ye et al. studied the short-term and long-term clinical efficacy of 24 patients receiving no injured vertebra fixation and 20 patients receiving injured vertebra fixation, the results showed that the maintenance of the curative effect of injured vertebra fixation group was better[9]. In a meta analysis[30], comparation clinical curative effects of 310 patients in 6 groups receiving injured vertebra fixation and no injured vertebra fixation respectively found that missing of AVH% of injured vertebra fixation group was less than no injured vertebra fixation group after correction of the Cobb angle, and the internal fixation failure rate is lower, but the operation time and intraoperative bleeding of injury of vertebral fixation group was slightly higher.
In this study, Cobb angle, AVH%, VAS score and ODI score were statistical significant preoperatively, one week after surgery and one year after surgery in the respective group. It was proved that both injured vertebra screwing and no injured vertebra screwing had the relatively accurate clinical effect of restoration and the effect of pain relief. Postoperative incision pain and discomfort after internal fixation resulting to daily life limited would get relief and basically returned to normal one year after the surgery. However, the Cobb angle and the AVH% of the injured vertebra screwing one year after surgery was statistically different from that in the no injured vertebra screwing group, indicating that the maintenance effect of injured vertebral screwing group was better. The possible reason was that injured vertebra fixation could directly exert forward force on the injured vertebra. In the long term, the distraction effect of the upper and lower vertebra and nail rod system was better and the stability of internal fixation was higher with the injured vertebra fixed.
In this study, short-term curative effect of percutaneous short segment pedicle screw fixation with screwing of the fractured vertebra with O-arm navigation in the treatment of thoracolumbar fractures was similar to that without screwing of the fractured vertebra with O-arm navigation in the treatment of thoracolumbar fractures, but the long-term efficacy was better. Of course, there were still some deficiencies in this study, due to the strict inclusion criteria and need of at least one year follow-up, the number of cases meeting the requirements is relatively small. In addition, only one year postoperative follow-up was collected in this study, and the results of the longer follow-up were not included. Therefore, the longer follow-up was necessary to evaluate the efficacy, and the subsequent follow-up was needed to further verify the conclusions of this paper.