Objective To investigate the amount of bone grafting, bone defect gap residual rates, and biomechanical stability of the injured vertebral body after reduction of thoracolumbar burst fractures, pedicle screw-rods fixation, and bone graft by bilateral pedicle or unilateral spinal canal. Methods Eighteen fresh lumbar spine (L1-5) specimens of calves (aged 4-6 months) were collected to establish the burst fracture model at L3 and divided into 3 groups randomly. After reduction and fixation with pedicle screws, no bone graft was given in group A (n=6), and bone graft was performed by bilateral pedicles in group B (n=6) and by unilateral spinal canal in group C (n=6). The amount of bone grafting in groups B and C was recorded. The general situation of bone defect gaps was observed by the DR films and CT scanning, and the defect gap residual rates of the injured vertebrae were calculated with counting of grids. The compression stiffness was measured by ElectreForce-3510 high precision biological material testing machines. Results The amount of bone grafting was (4.58 ± 0.66) g and (5.72 ± 0.78) g in groups B and C respectively, showing signficant difference (t=2.707, P=0.022). DR films and CT scanning observation showed large bone defect gap was seen in injured vertebrae specimens of group A; however, the grafting bone grains was seen in the “eggshell” gap of the injured vertebral body, which were mainly located in the posterior part of the vertebral body, but insufficient filling of bone graft in the anterior part of the vertebral body in group B; better filling of the grafting bone grains was seen in injured vertebral body of group C, with uniform distribution. The bone defect gap residual rates were 52.0% ± 5.5%, 39.7% ± 2.5%, and 19.5% ± 2.5% respectively in groups A, B, and C; group C was significantly lower than groups A and B (P lt; 0.05), and group B was significantly lower than group A (P lt; 0.05). Flexion compressive stiffness of group C was significantly higher than that of groups A and B (P lt; 0.05), but no significant difference was found between groups A and B (P gt; 0.05). Extension compressive stiffness in group C was significantly higher than that in group A (P lt; 0.05), but no significant difference was found between groups A and B, and between groups B and C (P gt; 0.05). The compression stiffness of left bending and right bending had no significant difference among 3 groups (P gt; 0.05). Conclusion Thoracolumbar burst fracture pedicle screws fixation with bone grafting by unilateral spinal canal can implant more bone grains, has smaller bone defect gap residual rate, and better recovery of flexion compression stiffness than by bilateral pedicles.
Objective To design the surgical strategy of percutaneous full-endoscopic bilateral decompression via unilateral posterior approach for bilateral lumbar spinal stenosis (LSS) and to evaluate the effectiveness. Methods The percutaneous full-endoscopic bilateral decompression via unilateral posterior approach for bilateral LSS was designed according to the pathological features of LSS. The technique was used to treat 42 patients with LSS between January 2016 and January 2018. There were 18 males and 24 females with an average age of 61.7 years (range, 46-81 years). The duration of symptoms was 1-20 years, with an average of 9.7 years. The surgical segment at L4, 5 were 27 cases, at L5, S1 were 15 cases. The operation time and perioperative complications were recorded. Lumbar X-ray, CT, and MRI examinations were performed at 1 week, 3 months, and 1 year after operation. Visual analogue scale (VAS) score was used to evaluate the low back pain and leg pain, Oswestry disability index (ODI) was used to evaluate the lumbar function, and single continuous walking distance (SCWD) was used to evaluate lower extremity nerve function. The clinical efficacy was evaluated by MacNab criteria at 1 year after operation. Results All patients underwent surgery successfully. The operation time was 68-141 minutes with an average of 98.2 minutes. All 42 patients were followed up 12-24 months with an average of 18.8 months. There were 2 cases of dural tears during operation, and 1 case of transient dysfunction of the lower limbs of the decompression channel after operation. All of them were cured after corresponding treatment. No serious complications such as death, major bleeding, or irreversible nerve injury occurred during follow-up. No segmental instability was found according to postoperative lumbar hyperextension and flexion X-ray films, and postoperative CT and MRI imaging showed that the stenotic lumbar spinal canal was significantly enlarged, and the compression of the nerve root was sufficient. The VAS score of low back pain and leg pain, ODI score, and SCWD at each time point after operation were significantly improved when compared with those before operation (P<0.05); the indexes were significantly improved over time after operation, and the differences were significantly (P<0.05). The clinical efficacy was evaluated by MacNab standard at 1 year after operation, and the results were excellent in 18 cases, good in 20 cases, fair in 3 cases, and poor in 1 case. The excellent and good rate was 90.5%. Conclusion The percutaneous full-endoscopic bilateral decompression via unilateral posterior approach for LSS is a safe and effective procedure. A well-designed surgical strategy and mastery of its technical points are important guarantees for successful operation and satisfactory results.