Between January 2015 to December 2018, a series of 67 patients (38 males and 29 females) with LSTB underwent the surgery of one-stage posterior pedicle screw internal fixation combined with anterior lesion removal and bone grafting fusion performed by the same spine team were evaluated retrospectively. This retrospective study was approved by the Hangzhou Chest Hospital Affiliated with Zhejiang University Medical College. The methods used in this study were conducted in strict accordance with the Declaration of Helsinki and informed consent was obtained from all patients. The main clinical symptoms of patients include low back pain and typical TB toxicity symptoms, such as weakness， low fever, night sweats， and anorexia, while some patients showed neurological impairment. All patients had varying degrees of increased sedimentation (ESR) and C-reactive protein (CRP), indicating that the body was in the active phase of STB disease. In addition， the imaging, laboratory examination, postoperative pathological examination, and bacterial culture of the patients met the diagnostic criteria for LSTB. Depending on the reconstructive material chosen during the anterior approach， a total of 67 patients were divided into two groups: the n-HA/PA66 group（n-HA/PA66 nano-hydroxyapatite/polyamide 66 strut:32 patients), and the AIBG group（Autologous iliac bone graft:35 patients).
Preoperative examination and treatment
All 67 patients underwent preoperative radiographs（ X-ray）, computed tomography (CT), and magnetic resonance imaging (MRI). The imaging examination suggested that there were different degrees of intervertebral space involvement, bone destruction, cold abscess formation, kyphotic deformity, or dural compression. Thus patients were required to be strictly bedridden to avoid the progression of the disease. A standard quadruple anti-tuberculosis regimen (HRZE) is administered on an individual basis for at least 2 weeks, including oral rifampicin, isoniazid, pyrazinamide, and ethambutol. Patients were provided intensive nutritional support to improve hypoproteinemia and anemia preoperatively. At the same time, the relevant departments will consult and assist in the treatment of patients with serious underlying diseases. Surgery was performed when the patient's general nutritional status improved, CRP and ESR normalized or showed a significant downward trend, and relieved systemic symptoms.
Inclusion and exclusion criteria
The Indications for surgery in this study included：(1). Paraplegia or developing spinal cord nerve impairment caused by compression of a TB lesion;(2).Severe vertebral destruction with spinal instability;(3).Severe or progressive kyphotic deformity due to paraspinal abscess;（4）. Severe or persistent pain in the back or lumbar， inefficacious conservative treatment.
（1）. Patients aged older than 25 years and less than 75;
（2）. Spinal tuberculosis in L1-L5 segments with surgical indications, and the destroyed segments were no more than 2 vertebral bodies;
（3）. Underwent surgical treatment with combined posterior-anterior approaches and complete follow-up data;
（1）. The focus of tuberculosis lesions beyond the L1-5 segment;
（2）. Prior history of lumbar surgery and/or other spinal diseases that may affect postoperative evaluation, such as ankylosing spondylitis, severe scoliosis, etc;
（3）. Absence of complete follow-up data for any reason;
All the patients were treated with one-stage posterior pedicle screw fixation combined with anterior lesion removal and bone grafting fusion. After successful tracheal intubation with general anesthesia, the patient was first placed in the prone position and intraoperative neurophysiological monitoring was performed. C-arm machine fluoroscopy was used to locate the lesioned segment and mark it with a line. A posterior median incision is made with the diseased vertebrae as the center, the skin, subcutaneous tissue, and deep fascia are incised layer by layer, and the paravertebral muscle tissue such as the bilateral erector spinae interval is separated. Expose the superior and inferior responsible vertebral articular processes and laminae from the multifidus interval, mark the pedicle screw entry point with a needle, and implant bilateral pedicle screws in the corresponding responsible vertebrae after fluoroscopic clarification of accurate positioning. Final install appropriate length bilateral titanium rods and transverse joints. The incision was thoroughly cleaned with a flushing gun, the negative pressure drainage tube was placed and the wound was sutured.
After the posterior surgery is completed, the patient was changed to the lateral position for the mini-open anterior approach of focal cleaning(Fig.1). The length of the incision was determined according to the lesion segment and the size of the abscess of the psoas major muscle. Take the line between the tip of the 11th rib and the pubic symphysis， and make an oblique incision along the mid-axillary line forward incision blunt separation along with the muscle fiber direction layer by layer was performed, including the external oblique abdominal muscle, internal oblique abdominal muscle, transverse abdominal muscle, posterior peritoneum, and lumbar major muscle, which was to fully reveal the diseased vertebrae and intervertebral disc. The lesion was adequately debrided through a curet and nucleus pulposus forceps. For patients with combined neurological dysfunction or compressive substances in the spinal canal, adequate decompression of the diseased segment is performed. The bone structure at the posterior margin of the diseased segment should be partially preserved, and the bone defect area was carefully trimmed using the piezosurgery device 、bone knife, and biting forceps to form a bone graft bed until there was petechial hemorrhage on the surface. At last, after measuring the length of the bone defect, hydrogen peroxide, povidone-iodine solution, saline, and isoniazid solution were repeatedly rinsed into the lesion area and the surgical area. Bone grafting and fusion are then performed.
In the n-HA/PA66 group： Choose a suitable length of n-HA/PA66 strut according to the size of the bone defect area, and filled the middle of the strut cavity with the bone fragments removed during posterior fixation， allogeneic bone can be added if necessary. Then implanted into the bone defect site(Fig.1).
In the AIBG group: An oblique incision of approximately 4 cm was made at the iliac crest site ipsilateral to the anterior incision. Depending on the size of the bone defect site, a suitable length of iliac bone is cut at about 1.5 cm from the anterior superior iliac spine and then implanted in the bone defect site after trimming.
After confirming the good position of the implanted material under fluoroscopy, the incision was thoroughly rinsed, and it was reconfirmed that there was no active bleeding, no foreign body residue, and no rupture of the posterior peritoneum in the incision, then gelatin sponge was wrapped with streptomycin and isoniazid was placed near the lesion, a drainage tube was placed and the wound was sutured layer by layer to complete the operation.
The postoperative prophylactic broad-spectrum antibiotics to prevent infection and nutritional support therapy were routinely administered. The drainage tube was removed when drainage flow was less than 30 mL per 24 hours. Patients were bedridden for 2-3 weeks after surgery, during which they were encouraged to perform functional exercises of the limbs and muscles of the low back in bed， and then they were permitted to start walking with the spinal protective brace after 4-6 weeks. And Patients with neurological impairment should receive neurorehabilitation timely under the guidance of the rehabilitation department. Strengthened quadruple anti-tuberculosis therapy with HRZE was administered for at least 3 months， then the HRE chemotherapy was continued for 12 to 15 months. During this period, the blood biochemical parameters, as well as liver and kidney functions are regularly reviewed and evaluated.
The operative time, intraoperative bleeding, bone fusion time， and the occurrence of postoperative complications were recorded in both groups. The Patient pain severity was evaluated using a visual analog scale（VAS, 0: no pain at all; 10: worst pain imaginable）. The Japanese Orthopaedic Association (JOA) and Oswestry Disability Index (ODI) were applied to evaluate lumbar spine dysfunction and quality of life. American Spinal Injury Association（ASIA ） impairment scale was applied to evaluate neurologic injury status. Regular postoperative Lumbar X-ray, CT, and MRI examinations were performed to evaluate the loosening and displacement of the internal fixation, as well as the fusion of the implant, and the Cobb angle of the lesioned segment. The VAS score, JOA, ODI, ASIA grade, and Cobb angle were recorded before surgery, three months after surgery, and at the last follow-up.
SPSS26.0 statistical software was used for statistical analysis. The clinical data between the two groups were compared by Student's t-test and χ2 test. A paired t-test was used to compare the changes in indices between the groups before surgery, three months after surgery, and at the last follow-up. The rank-sum test was used to analyze any differences in the normal data distribution. P values <0.05 were considered statistically significant.