How to select the fusion and fixation range of thoracolumbar and lumbar tuberculosis: A retrospective clinical study

Purpose To investigate the clinical data of thoracolumbar and lumbar spinal tuberculosis with diseased and non-diseased intervertebral surgery, evaluate the clinical efficacy of the two surgical methods, and explore how to choose the fusion of fixation range. Methods Among 221 patients with thoracolumbar and lumbar tuberculosis were categorized into two groups. 118 patients were in the diseased intervertebral surgery group (lesion vertebral pedicle fixation, group A) and there were 103 patients in the non-diseased intervertebral surgery group (1 or 2 vertebral fixation groups at the above and below levels of the affected vertebra, group B). Both groups of patients were treated with primary or staging, anterior combined complete lesion removal, bone graft fusion, and internal fixation. By analyzing of clinical data and the clinical efficacy of the two surgical methods in thoracolumbar and lumbar tuberculosis was evaluated. root symptoms, cerebrospinal fluid leakage, etc. Group A: psoas abscess occurred in 2 patients with recurrence of tuberculosis, which was cured by reoperation and intensive supervision of anti-tuberculosis chemotherapy. 4 cases of incisional fat liquefaction, 3 cases of incisional infection, dressing change, anti-infective cure; 2 cases underwent a bone graft, and the pedicle screw was loosened and cured again by surgery. Antituberculous drug-related complications were reported in 12 cases. Group B: 2 cases of bone graft fracture, 2 cases of bone graft absorption and pedicle screw loosening, 3 cases of psoas abscess, tuberculosis recurrence, reoperation and intensive supervision of anti-tuberculosis chemotherapy to cure; Fat liquefaction was found in 2 patients, and infection was found in 2 patients. The mean postoperative time of the 5 patients was 2.8 years. Antituberculous drug-related complications were reported in 10 cases. The complication rates of group A and group B were 19.48% (23/118) and 23.30%(26/103) respectively, with no significant difference ( χ 2 = 1.054 , P = 0.305 ) adjacent vertebral degeneration in the non-diseased intervertebral surgery group. The fixed segment was prolonged, the operative time was extended and the intraoperative blood loss was increased; with the addition of fixed segments the internal fixation materials used doubled so that the economic burden of patients also doubled. This study showed that the diseased intervertebral surgery group was significantly better than the non-diseased intervertebral surgery group in terms of operation


Introduction
Ant-tuberculosis drugs are the foundation and fundamentals for the cure of spinal tuberculosis, but surgery can significantly improve the cure rate of spinal tuberculosis, reduce its recurrence and related complications [1]. After the spinal tuberculosis lesions are removed, it is very important to repair the bone defect with autologous repairing bone and internal fixation to restore the biomechanical stability of the spine [2; 3]. However, there are no clear guidelines or literature reports on the fixation method after the removal of spinal tuberculosis lesions. The vertebral body from thoracic 10 to sacral 1 is a completely isolated bone structure, and reconstruction of the spine after the removal of tuberculosis lesions in the segment is demanding. How to choose the clinical scope of internal fixation is a controversial issue. The conventional fixation methods to restore spine stability are includes: short-segment fixation, that is, fixation of one normal motor unit in the upper and lower parts of the diseased vertebra; Long segment fixation refers to fixing two or more normal motor units in the upper and lower parts of the diseased vertebra. Besides, partial or total normal intervertebral space or/and posterolateral were fused with diseased intervertebral fusion and fixed range [4; 5].
Although the fixation and fusion methods above can meet the biomechanics requirements of spinal stiffness, they sacrifice the normal motor units of the spine, leading to the degeneration of adjacent segments and the occurrence of chronic lower back pain [6]. It is urgent to consider whether the fixed range can be reduced, and the mechanical strength of the spine can be fully reconstructed. In the treatment of vertebral fractures, the biomechanics of single-segment fixation, short-segment fixation, and long-segment fixation stability have been compared. The single-segment fixation method that fixes only injured vertebrae has been successfully applied in the treatment of thoracic and lumbar spine fractures [7; 8]. This group studies of multiple segmental spinal tuberculosis by the method of continuous multiple single-segment surgeries thoroughly remove the lesions, bone graft fusion, instrument internal fixation is conducted in lesions involving the movement of the motor unit and no normal motor units were involved, is the disease intervertebral surgery (Fig. 1), while the short and long segment surgery are non-disease intervertebral surgery (Fig. 2).
Therefore, a retrospective case-control study was conducted to collect the case data of patients with thoracolumbar and lumbar tuberculosis treated by diseased intervertebral surgery and non-diseased intervertebral surgery in our hospital and to evaluate the clinical efficacy of the two surgical methods in thoracolumbar and lumbar tuberculosis. Therefore, it provides a reference for the rational selection of fusion and fixation range of spinal tuberculosis.  Fig. 1, and the general preoperative information of the two groups were shown in Table 1.

Surgery group and method
According to the scope of the operation, it is divided into the inter-lesion surgery group and the non- range. The approach was selected according to the severity of vertebral damage and the size range of abscess. The abscess was exposed layer by layer. First, the thick needle was used to detect the accurate position of the abscess, expand the acupuncture site, draw out the pus with the suction device, open the abscess cavity, and scrape off the abscess moss and case-like substances; to find the bone fistula hole, the diseased vertebral body was found along the orifice of the bone; the vessels of the vertebral segment were ligated, and the damaged bone of the diseased disc and vertebral body was fully exposed and removed; Bone knife or scraping instruments was used to remove the bone from the edge of the lesion to the periphery of the lesion until the "subnormal bone," is grit-like in section, without hardening, dead space, cheese-like material, and granulation tissue, and a fresh bone surface appears. After the lesions were completely removed, the wound was repeatedly washed with normal saline. If the vertebral endplate bone can be preserved during resection of the vertebral body, it should be retained as much as possible to reduce the fixed and fusion segments. 1.6 Statistical processing SPSS 21.0 statistical software was used for analysis. The measurement data were expressed as mean ± standard deviation (x ± s)and the counting data as a percentage (%). T-test was used for measurement data, the chi-square (χ 2 ) test or non-parametric test was used for counting data, and P < 0.05 was considered statistically significant.

Perioperative evaluation Indexes
All patients had complete follow-up data. Patients in group A followed up for 55-82 months, and patients in group B followed up for 50-86 months. There were statistically significant differences between the two groups of patients in terms of surgical time, intraoperative blood loss, postoperative drainage, and whether or not blood transfusion (P < 0.05. The diseased intervertebral surgery group was significantly better than the non-diseased intervertebral surgery group. There was no significant difference in the VAS score between the two groups at the last follow-up (P > .05), and no considerable pain was found in the two groups at the last follow-up (Table 2).

Imaging evaluation indexes
There were no significant differences in the Cobb angle between the two groups of patients before, after, and at the last follow-up (P > 0.05). There was also no significant difference in the Cobb angle correction rate and the comparison between the angle loss groups. P > 0.05), which indicates that the diseased intervertebral surgery also has a good effect in correcting kyphosis caused by thoracolumbar and lumbar spinal tuberculosis, and is more conducive to the recovery of the physiology of thoracolumbar and lumbar spine (Table 3) Table 3 Comparison of Cobb Angle changes in the two groups before, after and at the last follow-up ( Spinal tuberculosis bone graft fusion was evaluated by CT three-dimensional reconstruction. The lesion cure rate was > 85% at 6 months after surgery, and > 95% at 1 year after surgery. The bone graft was completely healed at the last follow-up, and there was no statistical difference between the groups. Significance (P > 0.05) ( Table 4).

Laboratory test indicators
There were no statistically significant differences in ESR and CRP between the two groups before, 6 months after surgery, and at the last follow-up (P>, 0.05). ESR and CRP were close to normal at 6 months after surgery and normal at the last follow-up (Table 5).

Postoperative neurological functions recovered
Neurological function at the last follow-up between the two groups of patients was significantly better than before surgery (

Clinical efficacy
The Macnab method was used to evaluate the clinical effectiveness of the two groups of patients. The excellent and good rates of the patients in the two groups were 91.25% and 92.23%, respectively, with no significant difference (P>, 0.05). The excellent and good rates of the last follow-up were 96.6% and 97.09%, respectively, with no significant difference (P > 0.05).  The method adopted by most scholars is to fix multiple standard motor units in addition to the fixation between the pathological motor units. For thoracolumbar or lumbar spinal tuberculosis, long-segment fixation is widespread. Although long segment fusion and fixation can obtain stable fixation, it sacrifices more spinal motor function and reduces the physiological curvature of the thoracolumbar and lumbar spine and also cause adjacent segment disease (ASD). Gotzen et al. [12] first proposed the concept of single-segment fixation under the principle of reducing fusion, fixing segments, and maintaining standard motor units. Since then, many scholars have performed basic [13][14][15]  al. [18] found that the stability of single-segment after screw placement in the injured vertebra was enhanced; our team made a model of bone graft reconstruction of the defect of the middle column before the construction of the bovine spine. The study showed that single segment fixation was sufficient to correct the instability of the spine and restore the stability of the spine. The above biomechanical research conclusions provide a strong theoretical basis for our clinical implementation of thoracolumbar or lumbar tuberculosis intervertebral surgery.
For thoracolumbar and lumbar tuberculosis, compared with disease intervertebral operation, short segmental fixation with long-segment fixation, respectively; at the expense of more than two and four normal motor unit, a small fixed segments limited spinal movement function, activity; the longer the fixed segment corresponding adjacent unit vicarious movement, the more concentrated the stress of the adjacent segment, the intervertebral disc pressure increase, thereby accelerating the degeneration of the adjacent segment [19][20][21]. Increased the probability of ASD. In this study, although there was no significant difference in postoperative symptoms between the two groups, there were 5 cases of postoperative adjacent vertebral degeneration in the non-diseased intervertebral surgery group. The fixed segment was prolonged, the operative time was extended and the intraoperative blood loss was increased; with the addition of fixed segments the internal fixation materials used doubled so that the economic burden of patients also doubled. This study showed that the diseased intervertebral surgery group was significantly better than the non-diseased intervertebral surgery group in terms of operation time, intraoperative blood loss, postoperative drainage volume, and whether blood transfusion is better in the diseased intervertebral surgery group than in the non-diseased intervertebral surgery group, and it can also achieve long-segment fixation with reduced fixed segments Clinical efficacy. The incidence of long-segment fixation prosthesis is increased, and there is a higher risk of fracture and loosening of internal fixation after surgery; it may also cause suspension effect due to stress shielding of internal fixation, which is not conducive to early fusion of bone graft; and the risk of bone graft absorption, displacement, and fracture risk is increased [22; 23]. There is no significant difference between the Cobb angle correction rate and the angle loss between the groups. The diseased intervertebral surgery also has a good effect in correcting kyphosis caused by thoracolumbar and lumbar spinal tuberculosis, and it is more conducive to the physiology of the thoracolumbar and lumbar spine. There was no significant difference in the recovery of curvature between the two groups of patients with bone graft fusion rates. Spine surgery can also achieve the purpose of bone graft fusion and deformity correction. Therefore, for surgical treatment to restore the anatomical structure and motor function of the spine, diseased intervertebral surgery is a more accurate and reasonable method. This operation does not need to sacrifice the normal exercise unit and retains the spine's motor function to the greatest extent. It has fewer traumas and simple process, reduces the patient's financial burden, and meets the principles of minimally invasive and economical medical treatment.
The internal fixation of the instrument only obtains the instant stability of the spine, the permanent stability reconstruction depends on the fusion of the spine [24]. In this study, all patients underwent bone graft fusion only in the diseased vertebra, and no fusion was required for normal motor units.

Conclusion
In summary, under strict conditions of surgical indications, intervertebral surgery for thoracolumbar and lumbar tuberculosis is safe, effective, and feasible, and it can effectively restore its physiological curvature and reduce the degeneration of adjacent vertebrae; which is worthy of clinical application and promotion. Although the results of this study are satisfactory, there are still some shortcomings. This study is a retrospective case-control study; case study evidence level is not high, and its single-center research; Long-term follow-up was rare. The present study was approved by the Ethics Committee of the General Hospital of Ning Xia Medical University.
Informed consent was obtained from each patient's guardian.