[Application expansion of unilateral biportal endoscopy in spine surgery and its related issues].

At the beginning of clinical application, unilateral biportal endoscopy (UBE) was mainly applied to lumbar degenerative diseases, and lumbar disc herniation or lumbar spinal stenosis accounted for the majority. With the improvement of technology and equipment, the range of diseases being treated continues to expand, and the indications are extended to cervical and thoracic spinal decompression, and it can also be used in conjunction with minimally invasive techniques such as percutaneous pedicle screws and oblique lumbar interbody fusion, which plays an important role in lumbar interbody fusion. However, the development of unilateral biportal endoscopic technology is still in its initial stage in China and has not been widely applied. There are still relevant issues that need to be clarified and further studied. Therefore, this paper discusses the technical superiority, the application expansion and the shortcomings of UBE technique and related issues.

[Efficacy comparison of unilateral biportal endoscopic decompression and extended interlaminar fenestration for lumbar lateral recess stenosis].

Objective: To analyze and compare the clinical efficacy of unilateral biportal endoscopic(UBE) decompression and extended interlaminar fenestration for lumbar lateral recess stenosis. Methods: A retrospective analysis of 103 patients treated with UBE decompression or extended interlaminar fenestration for lumbar lateral recess stenosis from July 2017 to June 2020 in the Second Hospital of Anhui Medical University was performed. Eighty patients aged 40 to 86 (63.2±9.8) years were included in this study, including 42 males and 38 females. Forty patients received UBE decompression (UBE group) and 40 patients received extended interlaminar fenestration (fenestration group). Operative time, length of incision, hospital stay and complications were recorded. The visual analogue scale (VAS) scores of low back pain and leg pain and Oswestry dysfunction index (ODI) scores were recorded preoperatively and at 1, 3 and 6 months after the operation and at the final follow-up, and the modified Macnab scale was used to evaluate the clinical efficacy at the final follow-up. Results: Patients in both groups successfully received lumbar lateral recess decompression and were followed up for (12.9±5.4) months in the UBE group and (14.9±3.5) months in the fenestration group, respectively. The operation time in the UBE group was (63.9±11.6) min, it was higher than that in the fenestration group ((54.1±9.2) min, P<0.001). The average incision length in the UBE group was (18.2±1.7) mm, it was lower than that in the fenestration group ((73.5±11.6) mm, P<0.001). Postoperative hospital stay in the UBE group was (4.1±2.2) d, it was lower than that in the fenestration group ((7.6±3.1) d, P<0.001). VAS scores of low back pain were improved after operation in both groups. Low back pain VAS scores of UBE group were lower than those in fenestration group at 1 and 3 months post operation (both P<0.05). The VAS scores of lower limb pain were improved after operation in both groups and there was no statistically significant difference between the two groups at postoperative 1, 3, 6 months after the operation and at the last follow-up (all P>0.05). ODI scores were improved after operation in both groups. ODI scores of UBE group were lower than those in fenestration group at postoperative 1 month and 3 months(both P<0.05). Intraoperative dural tear occurred in 2 cases(5.0%) in the UBE group and 1 case(2.5%) in the fenestration group, with no statistically significant difference between the two groups (P=0.556). According to the modified Macnab scale at the last follow-up, 35 cases were excellent, 3 cases were good, and 2 cases were fair in the UBE group, and 37 cases were excellent, 2 cases were good, and 1 case was fair in the open group. The difference was not statistically significant between the two groups (P=0.745). Conclusion: Compared with the extended interlaminar fenestration, UBE technique can not only reduce the early postoperative low back pain, shorten hospital stay, but also achieve the same long-term clinical efficacy with less trauma.

[Biomechanics changes of lumbar spine caused by foraminotomy via percutaneous transforaminal endoscopic lumbar discectomy].

Objective: To analyze the biomechanics changes of lumbar spine caused by foraminotomy via percutaneous transforaminal endoscopic lumbar discectomy using the finite element method. Methods: Three healthy adult males (aged 35.6 to 42.3 years) without spinal diseases were enrolled in this study and 3D-CT scans were carried out to obtain the parameters of lumbar spine. Mimics software was applied to build a 3D finite element model of lumbar spine. Graded resections (1/4, 2/4, 3/4 and 4/4) of the left superior articular process of L(5) were done via percutaneous transforaminal endoscopic lumbar discectomy. Then, the pressure of the L(4/5) right facets, the pressure of the L(4/5) intervertebral disc and the motion of lumbar spine were recorded after simulating the normal flexion and extension, lateral flexion and rotation of the lumbar spine model during different resections. The data were compared among groups with analysis of variance. Results: Comparing with the normal group, after 1/4 resection of the left superior articular process of L(5), the pressure of the L(4/5) right facets showed significant differences during left lateral flexion and rotation of lumbar spine (q=8.823, 8.248, both P<0.05); and the pressure of L(4/5) intervertebral disc also changed significantly during extension and right rotation of lumbar spine (q=6.918, 6.438, both P<0.05); the motion of lumbar spine showed obvious differences during right lateral flexion and rotation (q=6.845, 7.772, 13.58, all P<0.05). Comparing with the normal group, after 2/4 resection of the left superior articular process of L(5), the pressure of the L(4/5) right facets presented significant differences during all conditions (q=5.670-17.830, all P<0.05); the pressure of L(4/5) intervertebral disc changed significantly during flexion, extension, lateral flexion and right rotation (q=5.260, 17.150, 5.727, 8.890, 15.660, all P<0.05); the motion of lumbar spine also existed differences during extension, lateral flexion and rotation (q=9.106, 5.431, 12.060, 11.160, 17.260, all P<0.05). However, after 3/4 resections, the pressure of the L(4/5) right facets, the pressure of the L(4/5) intervertebral disc and the motion of lumbar spine presented differences during all conditions when compared with those in normal group (q=6.303-25.48, all P<0.05). After 4/4 resections, the pressure of the L(4/5) right facets and the pressure of the L(4/5) intervertebral disc and the motion of lumbar spine showed significant differences during all conditions when compared with those in normal group (q=8.065-45.70, all P<0.05). Conclusions: The biomechanics and the stability of lumbar spine changed partly after 1/4 resection of the superior articular process and obviously after more than 2/4 is resected. The superior articular process should be paid more attention during foraminotomy via percutaneous transforaminal endoscopic lumbar discectomy.

Improved differentiation of oligodendrocyte precursor cells and neurological function after spinal cord injury in rats by oscillating field stimulation.

Oscillating field stimulation (OFS) has been used in attempts to treat spinal cord injury (SCI) and has been shown to improve remyelination after SCI in rats. However, some controversies regarding the effects of OFS have been presented in previous papers. Oligodendrocytes (OLs) are the main cell for remyelination and are derived from the differentiation of oligodendrocyte precursor cells (OPCs). To date, it has been unclear whether the differentiation of OPCs can be regulated by OFS. The goal of this study was to determine if OFS can improve the differentiation of OPCs and promote the recovery of neurological function after SCI in rats. Immature and mature OLs were observed in spinal cord slices through immunofluorescence staining. Levels of adenosine triphosphate (ATP) and the cytokine leukemia inhibitory factor (LIF) were detected by enzyme-linked immunosorbent assay (ELISA). Basso-Beattie-Bresnahan (BBB) scores and transcranial magnetic motor-evoked potentials (tcMMEPs) were used to evaluate the locomotor outcomes of rats after SCI. Our results showed a significant improvement in the differentiation of OPCs and the content of ATP and LIF in the injured spinal cord in the OFS group. Furthermore, BBB scores and tcMMEPs were significantly improved in the rats stimulated by OFS. These findings suggest that OFS can improve the differentiation of OPCs and promote the recovery of neurological function following SCI in rats.

[Effect of prolonging time for sampling on preservation of ultrastructure during the specimen preparation].

The ultrastructural change of rat liver, which was not immediately fixed after separation from the animal, was observed under electron microscope. The results showed that the ultrastructure of hepatocytes still satisfied the needs for diagnostic electron microscopy if the isolated livers were soaked in normal saline for 30 minutes, at room temperature, or placed in 4 degrees C refrigerator for 60 minutes, then they were fixed. After the isolated samples were put at room temperature for over 30 minutes, ultrastructure of hepatocytes were damaged so severely as to lose value for observation under electron microscope.