The spinal minimally invasive channel system consists of an outer hook and an inner hook.
The outer hook has a double-head design, which can rotate with any head as fulcrum during surgery, and the other head can be used to expose the surgical site. As the traditional hook can easily compress the surrounding tissues and cause damage, our hook handle joint is designed as "fish mouth" to avoid this damage. The angle was made between the handle and the pull hook to ensure that the part holding the handle remains in an upright position to reduce the influence of the tissue around the incision on the placement of the pull hook. The lateral edge of the lamina was designed as a "double lingual process", so that the local lamina can be easily exposed during surgery, and the contact between the hook and the lamina will remain stable (Fig. 1A and B).
The inner hook was designed to create a small incision and was based on the local bone anatomy. It can easily pull the multifidus muscle to the inner side, is convenient to use, and can be easily adjusted. Traditional surgery required to the removal of the surrounding soft tissue to expose the location of nail placement. Based on the anatomical characteristics of the lumbar facet joints, the distal end of the medial lamina hook has an "arc concave crescent shaped", which can avoid damage to the surrounding soft tissue and bone structure and can easily expose the nail area. An obtuse angle was made between the handle and the pull hook to ensure that the part holding the handle remains in an upright position to reduce the influence of tissue around the incision on the placement of the pull hook. Moreover, according to the patient's body shape and individual needs during the surgery, the hooks have various depths and angles (Fig. 1C and D).
A total of 127 patients (73 men and 54 women; aged from 19 to 73 years) with thoracic and lumbar vertebral fractures without neurological symptoms who underwent pedicle screw fixation between January 2015 and December 2017 in the First Affiliated Hospital of Nanjing Medical University were selected. Of them, 36 were treated using the modified Wiltse's paraspinal approach and the remaining were operated using the traditional approach. All patients had a fresh single-level thoracolumbar compression fracture 2 weeks prior to surgery. They had a thoracolumbar injury severity score of equal to or less than four. The demographics and clinical characteristics of the patients are shown in Table 1. The procedure was approved by the ethical committee of the First Affiliated Hospital of Nanjing Medical University. The digital radiography, computed tomography, and magnetic resonance imaging scans of all patients were assessed to provide an accurate diagnosis. We divided the patients into two groups for determining the effective surgical option of the two approaches. Group A consisted of 36 patients who underwent surgery using the spinal minimally invasive channel system, while group B underwent traditional pedicle screw fixation. The operations of the two groups were separately performed by a single senior surgeon.
Characteristic Group A Group B Cases (n) 36 91 Age (year, mean±SD) 47.8±14.2 51.9±11.6 Sex (male/female) 23/13 50/41
Table 1. Patients' baseline data
Group A patients were treated by the modified Wiltse's approach with the help of the spinal minimally invasive channel system. All procedures were performed under general anesthesia in the prone position. The fracture site was confirmed using a radiograph, and the entry point was set. A posterior midline incision or several paramedian incisions were made, and the integrity of the supraspinous ligament and interspinous ligament were explored after the deep fascia was opened. A posterior midline incision was used for obese or muscular young individuals to prevent fat liquefaction and excessive bleeding, as we found longer incision was required for these patients to adequately expose the operative field. The intermuscular spatium between the medial multifidus and lateral longissimus muscles was bluntly separated via the Wiltse's approach, exposing the bilateral articular processes and transverse processes of the fractured vertebra, and the adjacent vertebrae. The entry point to the pedicle was easily exposed by the spinal minimally invasive channel system between the lateral border of the superior articular processes and the bisecting line of the transverse process. The angle was set at 90 degrees, keeping the trajectory of the screw perpendicular to the supraspinal ligament. Pedicle screws were then inserted into the adjacent vertebra above and below the fractured vertebral body. A shorter pedicle screw was inserted into the bilateral or unilateral pedicles of the fractured vertebra. The spinal minimally invasive channel system was used throughout the process of screw implantation (Fig. 2 and Fig. 4).
Figure 2. Preoperative, postoperative, and follow-up radiographs of the patients who underwent surgery using the spinal minimally invasive channel system.
Group B patients were treated using the traditional surgical approach. All procedures were performed under general anesthesia in the prone position. The fracture site was confirmed by C-arm fluoroscopy, and the entry point was set. A midline incision was made. The paraspinal muscle was separated to expose the supraspinatus and interspinous ligaments. The bilateral articular processes and transverse processes of the fractured vertebra were exposed using the help of the toothed retractor or other routine hooks. Pedicle screws were then inserted into the fractured vertebra, along with the adjacent vertebra after consideration.
Preoperative, postoperative, and follow-up radiographs were evaluated to determine the success of the surgery. The frequency of X-ray fluoroscopy use, sagittal Cobb's angle, the accuracy of pedicle screw insertion, visual analogue scale (VAS), intraoperative bleeding, surgical duration, and length of postoperative hospital stay were determined to evaluate the efficacy of fracture-level screw incorporation in patients. The frequency of radiographs was measured every time when deciding the location of incision, determining the fractured vertebra before implanting screws, and determining the location of the positioning needles or screws after implantation. C-arm fluoroscopy was performed ones, while lateral and frontal views of X-rays were counted twice. The sagittal Cobb's angle between the superior endplate of the upper and the inferior endplate of the lower vertebrae was measured.
The Prism 5 statistical software (GraphPad Software, USA) was used to perform all statistical analyses. Data were expressed as mean±standard deviation (SD). Count data were expressed as rate (%) and compared using the chi-square test. The VAS score, vertebral compression degree, and other data were compared using the t-test. A P value of <0.05 was considered significantly.
A total of 127 patients were included in this study. The baseline clinical characteristics of the study participants are listed in Table 1 which summarizes the demographic data. The mean age of the new channel system group (group A) was (47.8±14.2) years, while that of the traditional group (group B) was (51.9±11.6) years. Group A comprised 23 men, while group B comprised 50 men. There was no significant difference in sex and age between the two groups.
There was a significant difference in X-ray exposure times between the two groups (P<0.01). The new channel system group underwent radiographic evaluation 4.2 times [95% confidence interval (CI), 2.6–5.8], while the traditional group underwent X-ray 6.0 time (95% CI, 3.9–8.1). Group A had the surgical duration of 120.8 minutes (95% CI, 82.1–159.5), which was similar to that of group B (121.2 minutes; 95% CI, 80.3–162.1; P=0.96).
The accuracy rate of pedicle screw insertion in the new channel system group (97.4%, CI 90.0% to 100%) was similar to that in the traditional group (97.9%, CI 91.5% to 100%) (Table 2). The Cobb's angle in the two groups was measured before, after, and 3 months after surgery (Table 3 and Fig. 3). The preoperative VAS scores of the two groups had no significant difference (P>0.05). The postoperative VAS scores of the two groups were significantly different as compared to the preoperative scores (P<0.05) (Table 4). Three patients of the traditional group experienced surgical complications. All of them developed infection at the incision site, which eventually healed after receiving an anti-infective treatment.
Variable Group A Group B P value Estimated blood loss (mL, mean±SD) 107.0±115.7 114.5±110.7 0.742 Length of stay in the hospital (day, mean±SD) 6.3±1.3 6.2±3.3 0.662 Duration of operation (minute, mean±SD) 120.8±38.7 121.2±40.9 0.956 Major complications no./total (%) 0/36 (0) 4/91 (4) 0.577 Times of C-arm exposure (mean±SD) 4.2±1.6 6.0±2.1 <0.010
Table 2. Clinical findings
Cobb's angle (degree) Group A Group B Preoperative 14.8±7.9 13.4±8.5 Immediate postoperative 10.1±6.0 9.3±6.1 3 months after surgery 11.6±6.1 11.2±6.4 Total correction loss 1.6±4.2 1.9±5.6 Data were expressed as mean±SD.
Table 3. Changes in radiological findings
VAS scores Group A Group B P value Preoperative 8.1±1.2 8.2±1.5 0.530 Postoperative 1.8±0.9 2.1±1.0 0.138 P value <0.001 <0.001 VAS: visual analogue scale. Data were expressed as mean±SD.
Table 4. VAS scores of the two groups
Comparison of the modified Wiltse's approach with spinal minimally invasive system and traditional approach for the therapy of thoracolumbar fracture
- Received Date: 2020-01-10
- Rev Recd Date: 2020-05-21
- thoracolumbar fracture /
- Wiltse's paraspinal approach /
- spinal minimally invasive channel system
Abstract: Thoracolumbar fractures are usually treated by open posterior pedicle screw fixation. However, this procedure involves massive paraspinal muscle stripping, inflicting surgical trauma, and prolonged X-ray exposure. In this study, we observed 127 patients with single-segment injury thoracolumbar fractures. Thirty-six patients were treated by the modified Wiltse's paraspinal approach with minimally invasive channel system, while 91 patients were treated via traditional posterior approach. Operation time, intraoperative blood loss, intraoperative fluoroscopy frequency, screw placement accuracy, visual analogue scale score, and Cobb's angle of two groups were compared. The X-ray exposure times were notably reduced (4.2±1.6) in the new approach group (P<0.05). The pedicle screw placement accuracy and Cobb's angle after surgery were similar in the two groups. We conclude that modified Wiltse's paraspinal approach with spinal minimally invasive channel system surgery can significantly reduce the X-ray exposure times and is an alternative therapy for the thoracolumbar fracture.△Jie Chang, Jiang Cao Ziyan Huang and Boyao Wang contributed equally to this work.
|Citation:||Jie Chang, Jiang Cao, Ziyan Huang, Boyao Wang, Tao Sui, Xiaojian Cao. Comparison of the modified Wiltse's approach with spinal minimally invasive system and traditional approach for the therapy of thoracolumbar fracture[J]. The Journal of Biomedical Research. doi: 10.7555/JBR.34.20200008|