[Clinical outcomes and bone resection analysis of unilateral double-channel endoscopic technique in treating lumbar disc herniation].

OBJECTIVE: To explore clinical outcomes and bone resection of interlaminar fenestration decompression and unilateral biportal endoscopic (UBE) technique in treating lumbar disc herniation(LDH). METHODS: A retrospective study was performed on 105 patients with single-level LDH treated from December 2019 to December 2021. Fifty-four patients in UBE group,including 32 males and 22 females,aged from 18 to 50 years old with an average of(38.7±9.3) years old,were treated with UBE,29 patients with L4,5 and 25 patients with L5S1. There were 51 patients in small fenestration group,including 27 males and 24 females,aged from 18 to 50 years old with an average of (39.9±10.0) years old,were treated with small fenestration,25 patients with L4,5 and 26 patients with L5S1. Perioperative indexes,such as operation time,postoperative time of getting out of bed and hospital stay were observed and compared between two groups. Visual analogue scale (VAS) and Oswestry disability index (ODI) were compared between two groups before operation and 1,3,6 and 12 months after operation,respectively;and modified MacNab evaluation criteria was used to evaluate clinical efficacy. Amount of bone resection and retention rate of inferior articular process laminoid complex were compared between two groups. RESULTS: All 105 patients were successfully completed operation. Both of two groups were followed up from 6 to 12 months with an average of (10.69±2.49) months. Operation time,postoperative time of getting out of bed and hospital stay were (58.20±5.54) min,(2.40±0.57) d and (3.80±0.61) d in UBE group,and (62.90±7.14) min,(4.40±0.64) d and (4.40±0.64) d in small fenestrum group,respectively;and had statistically difference between two groups(P<0.05). Postoperative VAS of low back and leg pain and ODI in both groups were significantly lower than those before surgery (P<0.05). VAS of lumbar pain in UBE group (1.37±0.49) score was lower than that of small fenestration group (2.45±0.64) score,and had statistically difference (t=9.745,P<0.05). Postoperative ODI in UBE group at 1 and 3 months were (28.54±3.31) % and (22.87±3.23) %,respectively,which were lower than those in small fenestra group (36.31±9.08) % and (29.90±8.36) %,and the difference was statistically significant (P<0.05). There were no significant difference in VAS and ODI between two groups at other time points (P>0.05). According to the modified MacNab evaluation criteria at the latest follow-up,49 patients got excellent result,3 good,and 2 fair in UBE group. In small fenestration group,35 patients got excellent,12 good,and 4 fair. In UBE group,amount of bone resection on L4,5 segment was (0.45±0.08) cm3 and (0.31±0.08) cm3 on the segment of L5S1. In small fenestration group,amount of bone resection on L4,5 segment was (0.57±0.07) cm3 and (0.49±0.04) cm3 on the segment of L5S1,and amount of bone resection of lower articular process laminar complex on the same segment in UBE group was less than that in small fenestration group (P<0.05). In UBE group,retention rate of laminoid complex on L4,5 segment was (0.73±0.04) and L5S1 segment was (0.83±0.03),while L4,5 segment was(0.68±0.06) and L5S1 segment was (0.74±0.04) in small fenestration group,the lower articular process laminar complex retention rate in UBE group was higher than that in small fenestration group(P<0.05). CONCLUSION: Both unilateral double-channel endoscopy and small fenestration of laminae could achieve good clinical results in treating LDH,but UBE has advantages of less trauma,higher efficiency,faster postoperative recovery and less damage to bone structure.

Finite element mechanical analysis of ipsilateral approach and contralateral approach in unilateral bilateral endoscopic spine surgery.

BACKGROUND: Unilateral bilateral endoscopic spine surgery (UBE) is often performed to treat lumbar spinal stenosis and disc herniation. It has become a prominent method in endoscopic spine surgery because of its very low learning curve and broader operative field of vision. Currently, the ipsilateral approach and contralateral approach have been established for disc herniation in the foraminal area, intervertebral foramen region, or pedicle region. The contralateral method offers many benefits over the ipsilateral approach, including less bone labour during microsurgical decompression and the preservation of facet joints. However, because it uses the interlaminar window approach, it inevitably involves osteotomy of the patient's superior and inferior articular processes, which may result in corresponding deterioration in the spine's biomechanical stability and subsequent adjacent facet joint diseases caused by facet joint degeneration postoperatively. OBJECTIVE: As a result, the purpose of this work is to use a finite element model to evaluate how the ipsilateral approach and contralateral approach in unilateral bilateral endoscopic spine surgery affect spinal stability while treating identical intervertebral disc herniation. STUDY DESIGN: In this study, a three-dimensional lumbar-sacral spine model was built and verified. Osteotomies were conducted for armpit-type lumbar disc herniation (LDH), periradicular-type LDH, and shoulder-type LDH. Postoperative lumbar spine models of the ipsilateral approach and contralateral approach in unilateral bilateral endoscopic spine surgery were developed. The von Mises stress on the endplate, shear force on the annulus fibrosus, pressure inside the intervertebral disc, and range of motion (ROM) of the L3 segment were all determined. The results of our well-validated model showed that osteotomy done in the ipsilateral approach deteriorated most biomechanical metrics. RESULTS: In the majority of loading conditions, the contralateral approach caused the intervertebral disc's biomechanical properties to increase, and the ipsilateral approach caused the intervertebral disc's biomechanical properties to increase sharply more than the contralateral approach. CONCLUSION: The contralateral approach, which is now extensively employed in unilateral bilateral endoscopic spine surgery, may be regarded as an ideal surgical alternative for treating lumbar disc herniation without producing iatrogenic instability. This approach has a low facet joint reduction rate, minimum soft tissue injury, and precisely identifies the midline of the central spinal canal during the retraction of the thecal sac and nerve roots.

Large-scale fisheries during the COVID-19 pandemic: The case of the oceangoing groundfish fleet in Norway.

Small-scale fisheries have received most of the attention in the literature investigating negative impacts of the COVID-19 pandemic on seafood production. Larger fishing vessels are often perceived to be more resilient as they are better able to alter harvest patterns in response to supply shocks than smaller, less mobile vessels. In addition, larger fishing vessels often deliver storable frozen products contributing to resiliency. The supply and demand shocks caused by the COVID-19 pandemic provides an opportunity to test this hypothesis and is investigated here on the large-scale groundfish fleet in Norway. The results indicate that during the first two whole years of the pandemic the impact on price was small, but also that there were several secondary effects showing how negative shocks in some supply chains/markets are overcome.

Are environmentally friendly firms more vulnerable during the COVID-19 pandemic?

The COVID-19 pandemic has affected supply and demand to a large extent. Declining demand for firms' output has caused significant financial stress for all kinds of firms worldwide. Production that requires environmental measures usually gets constrained when firms, especially small and medium-sized firms (SMEs), have difficulty in accessing credit. Firms thus face the dilemma of whether to continue environmental behaviors or to fulfill financial commitments to suppliers, employees, and so on. As such, an empirical question is whether the economic consequences of COVID-19 vary by firms' types and their environmental behaviors. Using 4,888 sample firms from 14 EU member states, this study finds evidence that the severity of damage caused by COVID-19 depends on firm size and whether firms invested in pollution abatement techniques. Specifically, eco-friendly firms perform better during the COVID-19 pandemic, and SMEs are less vulnerable than large firms. In particular, eco-friendly SMEs are less affected by the pandemic than conventional SMEs and large firms. These findings are probably related to the efficacy of government relief programs targeted to eco-friendly SMEs and/or the healthy financial status of these firms prior to the pandemic.

Credit constraints and the severity of COVID-19 impact: Empirical evidence from enterprise surveys.

The COVID-19 pandemic decreases firm revenue and raises the demand for liquidity, resulting in increased financial stress for firms throughout the world. In attempts to mitigate the impact of the COVID-19 crisis, governments have established a range of credit programs to provide credit to firms with poor liquidity. However, the efficacy of those relief programs has been low, and the relief funds do not reach the businesses most in need of liquidity injection, indicating a need to identify firms that are the most vulnerable during the crisis. We first combine the standard Enterprises Surveys and the follow-up surveys on the economic consequences of the COVID-19 pandemic. The sample firms are used to test how credit constraint conditions and firm characteristics affect the severity of the COVID-19 impact on firm performance. Our empirical results indicate that small firms and firms with limited access to finance are more likely to be severely affected by the crisis. Firms with foreign ownership and that are located in small cities are less at-risk. Compared to the 2008 Global Financial Crisis, COVID-19 less severely affects credit-constrained firms and foreign-owned firms and more severely affects small and medium-sized enterprises (SMEs).

[Kyphoplasty using an enhanced balloon expander: an experimental study].

OBJECTIVE: To test the efficacy of kyphoplasty using an enhanced balloon expander in restoring the height of vertebral compression fractures (OVCF). METHODS: Fifteen lumbar vertebral bodies (L1-L5) were harvested from 3 young male fresh cadavers and separated into individual vertebral bodies with the bilateral pedicles of the vertebral arch removed. Before operation, plain X-ray films of all the vertebral bodies were obtained. All the vertebral bodies were compressed lengthwise to approximately 80% of their original heights using a universal material-testing machine to result in compression fractures. Post-compression vertebral bodies were then repaired using an enhanced balloon expander, and the delivery of the bone cement into the vertebral bodies was observed. The heights of the anterior and posterior borders of the vertebral bodied were measured before and after compression as well as after kyphoplasty. RESULTS: The inflation of the balloon expander averaged 2.95-/+0.18 ml and the pressure was 122.67-/+27.89 psi (1 psi=6895 Pa). Kyphoplasty resulted in significant restoration of the vertebral body height lost due to the compression (P<0.01). CONCLUSION: Kyphoplasty using an enhanced balloon expander may restore vertebral body height damaged by compression and correct the kyphotic deformity. The balloon expander can be a effective and economic choice for kyphoplasty for its relatively low cost.