Paravertebral Nerve Block for Procedural Pain in Percutaneous Vertebroplasty

OBJECTIVES

This study aimed to unidimensionally measure procedural pain at each percutaneous vertebroplasty (PVP) stage and evaluate the effectiveness of paravertebral nerve block (PVNB) in reducing procedural pain.

METHODS

A retrospective study of prospectively collected data was conducted on 66 patients who underwent PVP for osteoporotic vertebral compression fractures. The patients were divided into 2 groups: group A (fluoroscopic-guided PVNB; 5 cm 3 of 0.75% ropivacaine on each side) and group B (local anesthesia). To investigate procedural pain associated with PVP, the visual analog scale score was assessed at each surgical stage: before the incision (stage 1), transpedicular approach (stage 2), and polymethylmethacrylate cement injection (stage 3). After the procedure, patients were asked about their surgical experience and satisfaction using the Iowa Satisfaction with Anesthesia Scale. Periprocedural complications were also recorded.

RESULTS

A total of 63 patients (78.65 y of age) were finally enrolled: 30 from group A and 33 from group B. In both groups, a significant ≥2-point increase in procedural pain was observed during PVP compared with that during stage 1 ( P < 0.001). In stages 2 and 3, the pain intensity was significantly lower in group A ( P < 0.001). Upon discharge, the visual analog scale score improved in all groups; however, the Iowa Satisfaction with Anesthesia Scale score was significantly higher in group A ( P < 0.001). There was no difference in periprocedural complications between the two groups ( P = 0.743).

CONCLUSION

PVP causes significant procedural pain, and PVNB is a potentially effective modality for enhancing patient satisfaction and reducing procedural pain.

Fusion Length Requiring Spinopelvic Fixation in Lumbosacral Fusion with Anterior Column Support at L5-S1: Assessment of Fusion Status Using Computed Tomography

Background

The lumbosacral (LS) junction has a higher nonunion rate than other lumbar segments, especially in long-level fusion. Nonunion at L5-S1 would result in low back pain, spinal imbalance, and poor surgical outcomes. Although anterior column support at L5-S1 has been recommended to prevent nonunion in long-level LS fusion, fusion length requiring additional spinopelvic fixation (SPF) in LS fusion with anterior column support at L5-S1 has not been evaluated thoroughly. This study aimed to determine the number of fused levels requiring SPF in LS fusion with anterior column support at L5-S1 by assessing the interbody fusion status using computed tomography (CT) depending on the fusion length.

Methods

Patients who underwent instrumented LS fusion with L5-S1 interbody fusion without additional augmentation and CT > 1 year postoperatively were included. The fusion rates were assessed based on the number of fused segments. Patients were divided into two groups depending on the L5-S1 interbody fusion status: those with union vs. those with nonunion. Binary logistic regression analyses were performed to identify risk factors for LS junctional nonunion.

Results

Fusion rates of L5-S1 interbody fusion were 94.9%, 90.3%, 80.0%, 50.0%, 52.6%, and 43.5% for fusion of 1, 2, 3, 4, 5, and ≥ 6 levels, respectively. The number of spinal levels fused ≥ 4 (p < 0.001), low preoperative bone mineral density (BMD; adjusted odds ratio [aOR], 0.667; p = 0.035), and postoperative pelvic incidence (PI) - lumbar lordosis (LL) mismatch (aOR, 1.034; p = 0.040) were identified as significant risk factors for nonunion of L5-S1 interbody fusion according to the multivariate logistic regression analysis.

Conclusions

Exhibiting ≥ 4 fused spinal levels, low preoperative BMD, and large postoperative PI-LL mismatch were identified as independent risk factors for nonunion of anterior column support at L5-S1 in LS fusion without additional fixation. Therefore, SPF should be considered in LS fusion extending to or above L2 to prevent LS junctional nonunion.

Concurrent expectation and experience-based metacontrol: EEG insights and the role of working memory capacity

We investigated the simultaneous influence of expectation and experience on metacontrol, which we define as the instantiation of context-specific control states. These states could entail heightened control states in preparation for frequent task switching or lowered control states for task repetition. Specifically, we examined whether "expectations" regarding future control demands prompt proactive metacontrol, while "experiences" with items associated with specific control demands facilitate reactive metacontrol. In Experiment 1, we utilized EEG with a high temporal resolution to differentiate between brain activities associated with proactive and reactive metacontrol. We successfully observed cue-locked and image-locked ERP patterns associated with proactive and reactive metacontrol, respectively, supporting concurrent instantiation of two metacontrol modes. In Experiment 2, we focused on individual differences to investigate the modulatory role of working memory capacity (WMC) in the concurrent instantiation of two metacontrol modes. Our findings revealed that individuals with higher WMC exhibited enhanced proactive metacontrol, indicated by smaller response time variability (RTV). Additionally, individuals with higher WMC showed a lower tendency to rely on reactive metacontrol, indicated by a smaller item-specific switch probability (ISSP) effect. In conclusion, our results suggest that proactive and reactive metacontrol can coexist, but their interplay is influenced by individuals' WMC. Higher WMC promotes the use of proactive metacontrol while attenuating reliance on reactive metacontrol. This study provides insights into the interplay between proactive and reactive metacontrol and highlights the impact of WMC on their concurrent instantiation.

Comparison of Primary Versus Revision Lumbar Discectomy Using a Biportal Endoscopic Technique

STUDY DESIGN

Retrospective study.

OBJECTIVE

To compare the clinical outcomes of the biportal endoscopic technique for primary lumbar discectomy (BE-LD) and revision lumbar discectomy (BE-RLD).

METHODS

Eighty-one consecutive patients who underwent BE-LD or BE-RLD, and could be followed up for at least 12 months were divided into two groups: Group A (BE-LD; n = 59) and Group B (BE-RLD; n = 22). Clinical outcomes included the visual analog scale (VAS), Oswestry Disability Index (ODI), and modified MacNab's criteria. Perioperative results included operation time (OT), length of hospital stay (LOS), amount of surgical drain, and kinetics of serum creatine phosphokinase (CPK) and C-reactive protein (CRP). Clinical and perioperative outcomes were assessed preoperatively and postoperatively at 2 days and at 3, 6, and 12 months. Postoperative complications were noted.

RESULTS

Both groups showed significant improvement in pain (VAS) and disability (ODI) compared to baseline values at postoperative day 2, which lasted until the final follow-up. There were no significant differences in the improvement of the VAS and ODI scores between the groups. According to the modified MacNab's criteria, 88.1 and 90.9% of the patients were excellent or good in groups A and B, respectively. OT, LOS, amount of surgical drain, and kinetics in serum CRP and CPK levels were comparable. Complications in Group A included incidental durotomy (n = 2), epidural hematoma (n = 1), and local recurrence (n = 1) and in Group B incidental durotomy (n = 1) and epidural hematoma (n = 1).

CONCLUSION

BE-RLD showed favorable clinical outcomes, less postoperative pain, and early laboratory recovery equivalent to BE-LD.

Biportal endoscopic discectomy versus tubular microscopic discectomy for treating single-level lumbar disc herniation in obese patients: a multicenter, retrospective analysis

PURPOSE

In microscopic lumbar discectomy in obese patients, a correlation is found between the operation time and increase in estimated blood loss according to the increase in body mass index; however, no studies have investigated the outcomes of biportal endoscopic lumbar discectomy in obese patients. Therefore, this study aimed to compare the clinical and radiographic outcomes of microscopic and endoscopic discectomy in obese patients with lumbar herniated discs.

METHODS

In this multicenter, retrospective study, clinical and radiological data were compared and analyzed in 73 obese patients with a body mass index of > 30 kg/m2 who underwent microscopic or biportal endoscopic lumbar discectomy. Clinical data on the visual analog scale (VAS), Oswestry disability index (ODI), and EuroQol-5D (EQ-5D) scores were measured, and radiological data were obtained using magnetic resonance imaging (MRI).

RESULTS

This study enrolled 43 patients who underwent microscopic discectomy and 30 who underwent biportal endoscopic discectomy. The VAS, ODI, and EQ-5D scores in both groups improved after surgery compared with those before surgery, although there was no difference between the two groups. Although there was a difference in the incidence of recurrent disc herniation confirmed by MRI after surgery, no difference was found in the number of patients requiring surgery between the two groups.

CONCLUSION

In obese patients with lumbar disc herniation that was not improved with conservative treatment, no significant clinical or radiological differences in outcomes were noted between microscopic and biportal endoscopic surgery methods. In contrast, minor complications were less common in the biportal group.

Effects of Vascular Risk Factors on the Association of Blood-Based Biomarkers with Alzheimer's Disease

Background

Comorbidities may influence the levels of blood-based biomarkers for Alzheimer's disease (AD). We investigated whether differences in risk factors or comorbid conditions might explain the discordance between clinical diagnosis and biomarker classifications in a multi-ethnic cohort of elderly individuals.

Aims

To evaluate the relationship of medical conditions and other characteristics, including body mass index (BMI), vascular risk factors, and head injury, with cognitive impairment and blood-based biomarkers of AD, phosphorylated tau (P-tau 181, P-tau 217), in a multi-ethnic cohort.

Methods

Three-hundred individuals, aged 65 and older, were selected from a prospective community-based cohort for equal representation among three racial/ethnic groups: non-Hispanic White, Hispanic/Latino and African American/Black. Participants were classified into four groups based on absence (Asym) or presence (Sym) of cognitive impairment and low (NEG) or high (POS) P-tau 217 or P-tau 181 levels, determined previously in the same cohort: (Asym/NEG, Asym/POS, Sym/NEG, Sym/POS). We examined differences in individual characteristics across the four groups. We performed post-hoc analysis examining the differences across biomarker and cognitive status.

Results

P-tau 217 or P-tau 181 positive individuals had lower BMI than P-tau negative participants, regardless of symptom status. Symptomatic and asymptomatic participants did not differ in terms of BMI. BMI was not a mediator of the effect of P-tau 217 or P-tau 181 on dementia. Frequencies of other risk factors did not differ between the four groups of individuals.

Conclusions

Participants with higher levels of P-tau 217 or P-tau 181 consistent with AD had lower BMI regardless of whether the individual was symptomatic. These findings suggest that weight loss may change with AD biomarker levels before onset of cognitive decline. They do not support BMI as a confounding variable. Further longitudinal studies could explore the relationship of risk factors with clinical diagnoses and biomarkers.

In vivo Comparison of Positive Microbial Culture by Wound Irrigation Methods: Biportal Endoscopic versus Open Microscopic Transforaminal Lumbar Interbody Fusion

STUDY DESIGN

OBJECTIVE

This study aimed to evaluate the risk factors and prevalence of intraoperative contamination (IoC) through the microbial culture of superficial and deep samples obtained during surgery.

SUMMARY OF BACKGROUND DATA

Surgical site infection (SSI) in spinal surgery is a serious complication. The prevalence of IoC may differ based on surgical approach and technique, even in the setting of the same procedure.

METHODS

In this in-vivo study, microbial cultivation was performed with superficial (ligamentum flavum, LF) and deep (nucleus pulposus, NP) surgical specimens to evaluate IoC in 132 patients undergoing single-level transforaminal lumbar interbody fusion (TLIF). Biportal endoscopic (BE) TLIF was performed under continuous wound irrigation (group A, n=66), whereas open microscopic (OM) TLIF was performed under intermittent wound irrigation (group B, n=66). LF and NP specimens were homogenized, gram-stained, and cultured in aerobic and anaerobic media for 14 days. Microbial culture results and occurrence of SSI in the two groups were assessed. The Chi-square test and Fisher's exact test were used to determine significant differences among categorical variables. Logistic regression analysis was used to assess the influence of patient characteristics on the prevalence of positive microbial cultures.

RESULTS

Of the 132 patients, 34 (25.8%) had positive microbial cultures, and positive culture required an incubation period of 72 h to 2 weeks in all these patients except for three. Overall positive culture was significantly higher in group B than in group A (P=0.029). The subgroups of LF- and NP-positive cultures were 18.18% (n=24) and 12.88% (n=17), respectively; the SSI was 0.76% (n=1). Group A had a significantly lower subgroup of NP-positive culture than group B (P=0.035). OM technique was an independent risk factor associatd with overall positive culture (P<0.05). The most common microorganism was Cutibacterium acnes (C. acnes).

CONCLUSION

BE-TLIF with continuous wound irrigation showed significantly lower overall, and NP-positive cultures, than OM-TLIF with intermittent irrigation. The most common strain of positive culture was C. acnes.

LEVEL OF EVIDENCE

II.

Mid-Thoracic Vertebral Compression Fracture after Mini-Trampoline Exercise: A Case Series of Seven Patients

Background and Objectives: Home-based training exercise gained popularity during the coronavirus disease 2019 pandemic era. Mini-trampoline exercise (MTE) is a home-based exercise that utilizes rebound force generated from the trampoline net and the motion of the joints of the lower extremities. It is known to be beneficial for improving postural balance, stability, muscle strength and coordination, bone strength, and overall health. However, we encountered several patients with mid-thoracic vertebral compression fractures (VCFs) following regular MTE, which was never reported previously, despite having no history of definite trauma. This study aims to report mid-thoracic VCFs after regular MTE and arouse public attention regarding this spinal injury and the necessity of appropriate prior instructions about the correct posture. Patients and Methods: All consecutive patients diagnosed with acute VCFs following regular MTE were included. We collected data on patient demographics, history of MTE, characteristics of symptoms, and radiological findings such as the location of fractures and anterior vertebral body compression percentage. Results: Seven patients (one man and six women) and ten fractures (T5 = 1, T6 = 3, T7 = 2, and T8 = 4) were identified. Symptoms started 2.57 ± 1.13 weeks after the beginning of regular MTE. All patients reported that they were never properly instructed on the correct posture. They also stated that they were exercising with a hunchback posture and insufficient joint motion of the lower extremities while holding the safety bar with both hands, which resulted in increased peak vertical force along the gravity z-axis in the mid-thoracic area and consequent mid-thoracic VCFs. Conclusions: Mid-thoracic VCFs can occur following regular MTE even without high-energy trauma in case of improper posture during exercise. Therefore, public attention on mid-thoracic VCFs following MTE and the appropriate prior instructions are imperative.

Biportal endoscopic paraspinal decompressive foraminotomy for lumbar foraminal stenosis: clinical outcomes and factors influencing unsatisfactory outcomes

BACKGROUND

Lumbar foraminal stenosis (LFS) is an important pathologic entity that causes lumbar radiculopathies. Unrecognized LFS may be associated with surgical failure, and LFS remains challenging to treat surgically. This retrospective cohort study aimed to evaluate the clinical outcomes and prognostic factors of decompressive foraminotomy performed using the biportal endoscopic paraspinal approach for LFS.

METHODS

A total of 102 consecutive patients with single-level unilateral LFS who underwent biportal endoscopic paraspinal decompressive foraminotomy were included. We evaluated the Visual Analogue Scale (VAS) score and the Oswestry Disability Index (ODI) before and after surgery. Demographic, preoperative data, and radiologic parameters, including the coronal root angle (CRA), were investigated. The patients were divided into Group A (satisfaction group) and Group B (unsatisfaction group). Parameters were compared between these two groups to identify the factors influencing unsatisfactory outcomes.

RESULTS

In Group A (78.8% of patients), VAS and ODI scores significantly improved after biportal endoscopic paraspinal decompressive foraminotomy (p < 0.001). However, Group B (21.2% of patients) showed higher incidences of stenosis at the lower lumbar level (p = 0.009), wide segmental lordosis (p = 0.021), and narrow ipsilateral CRA (p = 0.009). In the logistic regression analysis, lower lumbar level (OR = 13.82, 95% CI: 1.33-143.48, p = 0.028) and narrow ipsilateral CRA (OR = 0.92, 95% CI: 0.86-1.00, p = 0.047) were associated with unsatisfactory outcomes.

CONCLUSIONS

Significant improvement in clinical outcomes was observed for a year after biportal endoscopic paraspinal decompressive foraminotomy. However, clinical outcomes were unsatisfactory in 21.2% of patients, and lower lumbar level and narrow ipsilateral CRA were independent risk factors for unsatisfactory outcomes.

Stercoral Ulcer Presenting in a Patient with Cauda Equina Syndrome Secondary to Postoperative Epidural Hematoma

Chronic constipation can lead to fecal impaction in the large bowel, which can cause pressure necrosis followed by perforation, known as a stercoral ulcer. In extensive posterior thoracolumbar surgery, a long operation time, large blood loss, and perioperative narcotic use may aggravate constipation. Moreover, sacral root palsy due to cauda equina syndrome (CES) can lead to the deterioration of fecal impaction. This report describes the case of a 77-year-old woman with CES who presented with saddle anesthesia, neurogenic bladder, bowel incontinence, and paraplegia. Five days prior, she had undergone extended posterior lumbar interbody fusion from L1 to L5. Lumbar magnetic resonance imaging (MRI) showed an extended epidural hematoma. After urgent neural decompression, she gradually recovered from the saddle anesthesia, leg pain, and paraplegia over 3 weeks. Thereafter, the patient suddenly developed massive hematochezia and hemorrhagic shock. Urgent colonoscopy was performed, and a stercoral ulcer in the sigmoid colon was diagnosed. After 4 weeks of intensive care for hemorrhagic shock, pneumonia, and systemic sepsis, the patient was transferred to a general ward for intensive rehabilitation. One year after the operation, she was able to walk with assistance, and her urinary and bowel incontinence completely recovered. Chronic constipation, a common clinical problem, can sometimes cause relatively obscure but potentially life-threatening complications such as stercoral ulceration. Possible factors including advanced age, extensive spinal surgeries, prolonged operation time, significant blood loss, perioperative narcotic use, and the presence of spinal cord injury might contribute to the development of this condition. It highlights the importance of recognizing the potential development of stercoral ulcers in patients with CES and emphasizes the need for prompt diagnosis and management to avert catastrophic complications.

Safe Optimal Tear Drop View for Spinopelvic Fixation Using a Three-Dimensional Reconstruction Model of the Pelvis

Background

Spinopelvic fixation (SPF) has been a challenge for surgeons despite the advancements in instruments and surgical techniques. C-arm fluoroscopy-guided SPF is a widely used safe technique that utilizes the tear drop view. The tear drop view is an image of the corridor from the posterior superior iliac spine to the anterior inferior iliac spine (AIIS) of the pelvis. This study aimed to define the safe optimal tear drop view using three-dimensional reconstruction of computed tomography images.

Methods

Three-dimensional reconstructions of the pelvises of 20 individuals were carried out. By rotating the reconstructed model, we simulated SPF with a cylinder representing imaginary screw. The safe optimal tear drop view was defined as the one embracing a corridor with the largest diameter with the inferior tear drop line not below the acetabular line and the lateral tear drop line medial to the AIIS. The distance between the lateral border of the tear drop and AIIS was defined as tear drop index (TDI) to estimate the degree of rotation on the plane image. Tear drop ratio (TDR), the ratio of the distance between the tear drop center and the AIIS to TDI, was also devised for more intuitive application of our simulation in a real operation.

Results

All the maximum diameters and lengths were greater than 9 mm and 80 mm, respectively, which are the values of generally used screws for SPF at a TDI of 5 mm and 10 mm in both sexes. The TDRs were 3.40 ± 0.41 and 3.35 ± 0.26 in men and women, respectively, at a TDI of 5 mm. The TDRs were 2.26 ± 0.17 and 2.14 ± 0.12 in men and women, respectively, at a TDI of 10 mm.

Conclusions

The safe optimal tear drop view can be obtained with a TDR of 2.5 to 3 by rounding off the measured values for intuitive application in the actual surgical field.

Biportal endoscopic extraforaminal lumbar interbody fusion using a 3D-printed porous titanium cage with large footprints: technical note and preliminary results

PURPOSE

The aim of this study was to introduce biportal endoscopic extraforaminal lumbar interbody fusion (BE-EFLIF), which involves insertion of a cage through a more lateral side as compared to the conventional corridor of transforaminal lumbar interbody fusion. We described the advantages and surgical steps of 3D-printed porous titanium cage with large footprints insertion through multi-portal approach, and preliminary results of this technique.

METHODS

This retrospective study included 12 consecutive patients who underwent BE-EFLIF for symptomatic single-level lumbar degenerative disease. Clinical outcomes, including a visual analog scale (VAS) for back and leg pain and the Oswestry disability index (ODI), were collected at preoperative months 1 and 3, and 6 months postoperatively. In addition, perioperative data and radiographic parameters were analyzed.

RESULTS

The mean patient age, follow-up period, operation time, and volume of surgical drainage were 68.3 ± 8.4 years, 7.6 ± 2.8 months, 188.3 ± 42.4 min, 92.5 ± 49.6 mL, respectively. There were no transfusion cases. All patients showed significant improvement in VAS and ODI postoperatively, and these were maintained for 6 months after surgery (P < 0.001). The anterior and posterior disc heights significantly increased after surgery (P < 0.001), and the cage was ideally positioned in all patients. There were no incidences of early cage subsidence or other complications.

CONCLUSIONS

BE-EFLIF using a 3D-printed porous titanium cage with large footprints is a feasible option for minimally invasive lumbar interbody fusion. This technique is expected to reduce the risk of cage subsidence and improve the fusion rate.

Learning curve for biportal endoscopic posterior cervical foraminotomy determined using the cumulative summation test

BACKGROUND

Learning curves describe the rate of performance improvements corresponding to the surgeon's caseload, followed by a plateau where limited further improvements are observed. This study aimed to determine the learning curve for biportal full-endoscopic posterior cervical foraminotomy (BE-PCF) for the unilateral cervical foraminal disc.

METHODS

The learning curve was evaluated using a learning curve cumulative summation test (LC-CUSUM). The goal for the operation time was set to 78 min, which is the mean operation time (mOT) of percutaneous full-endoscopic posterior cervical foraminotomy (PE-PCF) performed by a senior surgeon. Moreover, clinical outcomes and post-operative complications were compared between the early and late learning periods 1 year post-operatively.

RESULTS

This study enrolled the first 50 patients who underwent single-level BE-PCF, performed by a single surgeon. The LC-CUSUM signalled competency for surgery at the 20th operation, indicating that sufficient evidence was obtained to prove that the surgeon was competent. The mOT was 71.29 ± 11.69 min in BE-PCF, 71.84 ± 12.61 min in the early learning period, and 67.83 ± 10.31 min in the late learning period (p = 0.254). There was no statistical difference in clinical outcomes, visual analogue scale scores, and neck disability index between both periods (p > 0.05). Four complications were recorded throughout the whole period, with three in the early period and one in the late period (p = 0.285).

CONCLUSION

Our study shows that BE-PCF has a learning curve of 20 caseloads to achieve 90% proficiency, and it significantly reduces the operation time based on the performance of a senior surgeon proficient in PE-PCF.

Oblique Lumbar Interbody Fusion with Selective Biportal Endoscopic Posterior Decompression for Multilevel Lumbar Degenerative Diseases

Oblique lumbar interbody fusion is a minimally invasive procedure for treating degenerative lumbar disease. Its advantages include correcting coronal and sagittal spinal alignment and indirect neural decompression. However, achieving a successful outcome is limited in some patients who need direct decompression for central canal lesions including hard stenotic lesions (endplate or facet articular osteophytes and ossification of posterior longitudinal ligaments) and sequestration of the disk. Biportal endoscopic spinal surgery is a minimally invasive technique, which directly decompresses the lesion. By taking advantage of two procedures, in a longlevel lumbar lesion, alignment correction and direct decompression can be both achieved. Herein, the authors introduce multilevel lumbar fusion through oblique lumbar interbody fusion and selective direct decompression through biportal endoscopic spinal surgery and discuss the surgical indications, surgical pitfalls, and recommendations for application. Consequently, it is regarded as a minimally invasive interbody fusion method for patients with multilevel lumbar degenerative degeneration.

Assessment and nonsurgical management of low back pain: a narrative review

Low back pain (LBP) is a common condition that affects people of all ages and income levels worldwide. The etiology of LBP may be mechanical, neuropathic, systemic, referred visceral, or secondary to other causes. Despite numerous studies, the diagnosis and management of LBP remain challenging due to the complex biomechanics of the spine and confounding factors, such as trivial degenerative imaging findings irrelevant to symptoms and psychological and emotional factors. However, it is imperative to identify the crucial signs ("red flags") indicating a serious underlying condition. While many recent guidelines emphasize non-pharmacologic management approaches, such as education, reassurance, and physical and psychological care, as the first option, LBP patients in many countries, including South Korea, are prescribed medications. Multidisciplinary rehabilitation combined with prudent use of medications is required in patients unresponsive to first-line therapy. The development of practical guidelines apposite for South Korea is needed with multidisciplinary discussion.

Clinical and radiologic outcomes of biportal endoscopic lumbar discectomy in obese patients: a retrospective case-control study

BACKGROUND

Obese patients have a higher risk of complications during spinal surgery than non-obese patients. To the best of our knowledge, no studies have examined the differences in clinical and radiological outcomes after biportal endoscopic lumbar discectomy (BELD) between obese and non-obese patients. The study evaluated the association between obesity and outcomes after BELD in patients with lumbar disc herniation.

METHODS

This was a retrospective case-control study conducted from March 2017 to March 2021 at two hospitals with 360 patients who underwent BELD after showing no improvement with conservative treatment. Clinical and radiologic outcomes were retrospectively analyzed after BELD in the non-obese (body mass index [BMI] < 30 kg/m²) and obese (BMI ≥ 30 kg/m²) groups. Demographic data and surgery-related factors were compared between the two groups. Clinical outcomes were followed up for 12 months after surgery and analyzed for differences.

RESULTS

A total of 211 patients were enrolled in this study, and through case-control matching, the data of 115 patients (29, obese group; 86, non-obese group) were analyzed. The two groups showed no significant differences in Oswestry Disability Index, European Quality of Life-5 Dimensions (EQ-5D), and visual analog scale scores measured immediately after BELD and 12 months after surgery. After surgery, back pain, radiating leg pain, and EQ-5D scores improved. However, there was no significant difference in improvement, residual herniated disc, hematoma, or recurrence between the groups.

CONCLUSIONS

Obese patients who underwent BELD for lumbar disc herniation showed no significant difference in clinical and radiologic outcomes compared with non-obese patients.

How I do it: biportal endoscopic paraspinal approach for recurrent lumbar disc herniation following percutaneous endoscopic lumbar discectomy

BACKGROUND

Although percutaneous endoscopic lumbar discectomy (PELD) has been popularized as an alternative to microscopic lumbar discectomy, it has been reported to be associated with a re-herniation rate of 5-11%. Recurrent lumbar disc herniation (RLDH) might occur not only at the same level previously operated upon but also at the annular penetration site created during PELD procedures.

METHOD

Biportal endoscopic paraspinal approach (BE-Para) was used for revisional foraminal lumbar discectomy. Procedures and some discussions regarding indications, advantages, potential complications, and ways to avoid complications were described.

CONCLUSION

BE-Para may be an effective modality for RLDH after PELD.

Percutaneous transpedicular intracorporeal cage grafting for Kümmell disease

BACKGROUND

Osteonecrosis with progressive collapse and segmental kyphosis can lead to intersegmental instability in some osteoporotic vertebral compression fractures (OVCFs). These conditions are known as Kümmell's disease and often require anterior column reconstruction in elderly patients.

METHODS

We attempted anterior column reconstruction by percutaneous transpedicular intracorporeal cage grafting (PTICG) with short-segment pedicle screw fixation and described the steps, with discussions on the surgical indications and pros and cons.

CONCLUSION

PTICG is expected to be an alternative to vertebral anterior column reconstruction, which can preserve the thoracolumbar posterior arch and paravertebral musculature.

Comparing the efficacy and safety of minimally invasive biportal endoscopic spine surgery versus conventional microscopic discectomy in single-level lumbar herniated intervertebral disc (ENDO-BH Trial): a multicenter, prospective, randomized controlled equivalence trial study protocol

Background

Biportal endoscopic surgery has recently been performed in lumbar discectomy, with advantages over conventional surgery, such as less skin scarring and muscle damage. However, the clinical results have not been established. Although previous studies reported no difference between the biportal endoscopic and microscopic discectomy clinical results, the evidence was weak. Therefore, this study aims to evaluate the efficacy and safety of the biportal endoscopic discectomy versus the microscopic discectomy.

Methods

This prospective multicenter randomized controlled equivalence trial is designed to compare the efficacy and safety outcomes of patients who underwent lumbar discectomy using biportal endoscopy or microscopy. We will include 100 participants (50 per group) with a lumbar herniated disc. The primary outcome will be the Oswestry Disability Index (ODI) score 12 months after surgery based on a modified intention-to-treat strategy. The secondary outcomes will include the visual analog scale score for low back and lower extremity radiating pain, the ODI score, the Euro-Qol-5-Dimensions score, surgery satisfaction, walking time, postoperative return to daily life period, postoperative surgical scar, and surgery-related variables, such as postoperative drainage, operation time, admission duration, postoperative creatine kinase, and implementation status of conversion to open surgery. Radiographic outcomes will also be analyzed using magnetic resonance imaging (MRI) or computed tomography (CT) and simple radiographs. Safety will be assessed by evaluating all adverse and severe adverse events and surgery-related effects. The participants will be assessed by a blinded assessor before surgery (baseline) and 2 weeks and 3, 6, and 12 months after surgery.

Discussion

This trial will be the first prospective, multicenter, randomized controlled trial to analyze the efficacy and safety of biportal endoscopic discectomy in lumbar herniated disc.

This trial is designed for evaluating the equivalence of the results between biportal endoscopic and microscopic discectomy including adequate sample size, blinded analyses, and prospective registration to reduce bias. This trial will provide enough data on the effectiveness and safety of biportal endoscopic surgery and will be an important study that allows clear conclusions.

Trial registration

Clinical Research Information Service (cris.nih.go.kr.) (KCT0006191). Registered on 27 March 2021

Biportal Endoscopic Technique for Transforaminal Lumbar Interbody Fusion: Review of Current Research

BACKGROUND

There are many types of minimally invasive lumbar interbody fusion procedures. Among them is the recently introduced biportal endoscopic lumbar interbody fusion surgery. Biportal endoscopic transforaminal lumbar interbody fusion (TLIF) might combine the advantages of minimally invasive TLIF and endoscopic spine approaches. However, clinical evidence in support of biportal endoscopic TLIF remains insufficient.

METHODS

A comprehensive review of English-language literature on biportal endoscopic lumbar interbody fusion was performed. Articles on biportal endoscopic TLIF in PubMed, the Cochrane Library, and Web of Science were searched using the terms "unilateral biportal endoscopy," "biportal endoscopic spine surgery," "transforaminal," and "lumbar interbody fusion" as well as their combinations. The clinical and radiological outcomes of biportal endoscopic TLIF were analyzed and are summarized here. The biportal endoscopic lumbar interbody fusion surgical techniques are then described.

RESULTS

There are 3 biportal endoscopic TLIF techniques. In the available literature, the postoperative 1-year outcomes of biportal endoscopic TLIF were comparable to those of posterior lumbar interbody fusion (PLIF) and minimally invasive (MIS)-TLIF. Clinical parameters were significantly improved after biportal endoscopic TLIF. Compared to PLIF or MIS-TLIF, biportal endoscopic-TLIF may have the advantage of a faster recovery. Biportal endoscopic TLIF showed no inferiority in fusion rates compared to PLIF or MIS-TLIF. The postoperative complications were usually minor.

CONCLUSIONS

The postoperative 1-year clinical and radiological outcomes of biportal endoscopic TLIF were favorable compared to those of PLIF and MIS-TLIF. However, long-term outcomes should be investigated through prospective, randomized controlled trials in the future.

CLINICAL RELEVANCE

This review article outlines the most current evidence-based medicine with regard to spinal surgery with an aim to introduce a new technique.

Unstable Non-isthmic Spondylolisthesis Following Unilateral Biportal Endoscopy Assisted Unilateral Laminotomy for Bilateral Decompression: A Case Report

Lumbar decompressive laminectomy is a standard treatment for degenerative lumbar spinal stenosis, but in some cases, can lead to iatrogenic spondylolysis and delayed segmental instability. Iatrogenic spondylolysis occurs in most cases in pars interarticularis, but rare cases have also been reported, pediculolysis in pedicle and laminolysis in lamina. Minimally invasive spine surgery (MIS) is known to have a low risk of developing these iatrogenic spondylolyses, and unilateral biportal endoscopy is the MIS that has been drawing attention. We present a case of a 72-year-old female who was diagnosed with L4-5 unstable non-isthmic spondylolisthesis and severe right central disc extrusion 10 weeks after UBE assisted unilateral laminotomy for bilateral decompression (ULBD) at the consecutive segments of L3-4 and L4-5. Pre-operative imaging studies revealed severe central stenosis without spondylolisthesis at L3-L4 and L4-L5 along with L4-L5 facet tropism. She was managed by anterior lumbar interbody fusion and cement augmented pedicle screw fixation, which resulted in the complete resolution of her clinical and neurologic symptoms.

Evaluation of the efficacy and safety of conventional and biportal endoscopic decompressive laminectomy in patients with lumbar spinal stenosis (ENDO-B trial): a protocol for a prospective, randomized, assessor-blind, multicenter trial

BACKGROUND

Recent studies on biportal endoscopic spine surgery in patients with lumbar spinal stenosis have reported good clinical results. However, these studies have been limited by the small sample sizes and use of a retrospective study design. Therefore, we aim to compare the efficacy and safety of biportal endoscopic decompressive laminectomy with those of conventional decompressive laminectomy in a multicenter, prospective, randomized controlled trial.

METHODS

This study will include 120 patients (60 per group, aged 20-80 years) with 1- or 2-level lumbar spinal stenosis, who will be recruited from six hospitals. The study will be conducted from July 2021 to December 2024. The primary outcome (Oswestry Disability Index at 12 months after surgery) will be evaluated through a modified intention-to-treat method. The secondary outcomes will include the following: visual analog scale score for low back and lower extremity radiating pain, EuroQol 5-dimensions score, surgery satisfaction, walking time, postoperative return to daily life period, postoperative surgical scars, and some surgery-related variables. Radiographic outcomes will be analyzed using magnetic resonance imaging or computed tomography. All outcomes will be evaluated before the surgery and at 2 weeks, 3 months, 6 months, and 12 months postoperatively. This protocol adheres to the Standard Protocol Items: Recommendations for Interventional Trials (SPIRIT) guidelines for reporting of clinical trial protocols.

DISCUSSION

It is hypothesized that the efficacy and safety of biportal endoscopic and conventional decompressive laminectomy will be comparable in patients with lumbar spinal stenosis. The results of this trial will provide a high level of evidence for the efficacy and safety of the biportal endoscopic technique in patients with lumbar spinal stenosis and facilitate the development of clinical practice guidelines. Furthermore, the results of this study may indicate the feasibility of the biportal endoscopic technique for other types of spinal surgery.

TRIAL REGISTRATION

The ENDO-B trial is registered at Clinical Research Information Service (CRIS, cris.nih.go.kr ) (KCT0006057; April 52,021).

Minimally invasive transforaminal lumbar interbody fusion using the biportal endoscopic techniques versus microscopic tubular technique

BACKGROUND CONTEXT

Minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) with microscopic tubular technique is an established surgical procedure with several potential advantages, including decreased surgical-related morbidity, reduced length of hospital stay, and accelerated early rehabilitation. A recently introduced biportal endoscopic technique for spine surgery presents familiar surgical anatomy and can be conducted using a conventional approach with a minimal footprint; it is also applicable to TLIF.

PURPOSE

To compare the clinical and radiological outcomes of biportal endoscopic technique transforaminal lumbar interbody fusion (BE-TLIF) and microscopic tubular technique transforaminal lumbar interbody (MT-TLIF) in patients with single- or two-segment lumbar spinal stenosis with or without spondylolisthesis.

STUDY DESIGN

A retrospective cohort study.

PATIENT SAMPLE

One hundred two participants with neurogenic intermittent claudication or lumbar radiculopathy with single- or two-level lumbar spinal stenosis with or without spondylolisthesis.

OUTCOME MEASURES

Clinical outcomes were assessed using the visual analog scale (VAS) score for the back and leg pain, Oswestry Disability Index (ODI), and the Short Form-36 health survey Questionnaire (SF-36). Demographic data, operative data (total operation time, estimated blood loss, amount of surgical drain, postoperative transfusion, and length of hospital stay), and laboratory results (plasma hemoglobin, serum creatine phosphokinase, and C-reactive protein) were also evaluated. The fusion rate was assessed using the Bridwell interbody fusion grading system. Postoperative complications were also noted.

METHODS

Patients were divided into two groups: group A (BE-TLIF) and group B (MT-TLIF). The clinical outcomes, including VAS-Back and VAS-Leg, ODI, and SF-36 scores, were evaluated at 1 month, 6 months, and 1 year after surgery. Differences in demographics, operative data, and the laboratory and radiological results were assessed between the two groups. The fusion rate was assessed using standard standing lumbar radiographs and computed tomography scans conducted 1 year after surgery.

RESULTS

Seventy-nine patients were analyzed in this study, 47 from group A and 32 from group B. Demographic and operative data were comparable for both the groups. The VAS-Back and SF-36 scores were more significantly improved in group A than in group B at 1 month after surgery. However, there were no significant differences between groups for the mean VAS-Back, VAS-Leg, ODI, and SF-36 scores at 1year after the surgery. Although the total operation time was significantly longer in group A, the estimated blood loss and the amount of surgical drainage was significantly higher in group B (p < .001). There were no between-group differences for the fusion rate and postoperative complications.

CONCLUSION

Both BE-TLIF and MT-TLIF provided equivalent and favorable clinical outcomes and fusion rates. Further large-scale, randomized, controlled trials with long-term follow-ups are warranted.

Contralateral retrodiscal transforaminal approach for percutaneous epidural adhesiolysis: A technical description and retrospective comparative study

OBJECTIVES

Retrodiscal transforaminal (RdTF) epidural steroid injection (ESI) is clinically comparable to conventional transforaminal ESI and can avoid catastrophic complications. However, it poses a risk of inadvertent intradiscal, intravascular, and intrathecal injections. Therefore, we aimed to evaluate the feasibility of percutaneous epidural adhesiolysis (PEA) using the contralateral (Contra)-RdTF approach.

METHODS

The electronic medical records of 332 patients with unilateral lumbar radiculopathy due to foraminal disk pathology were reviewed. Patients were categorized into two groups: Group A (ESI using the RdTF approach) and Group B (PEA using the Contra-RdTF approach). Effective pain relief (EPR; ≥50% pain relief from baseline) in patients was evaluated using the visual analog scale (VAS) at 4 and 12 weeks after the procedure. The presence of unintended fluoroscopic findings and complications was recorded.

RESULTS

A total of 119 patients were enrolled in the final analysis: 81 in Group A and 38 in Group B. Both groups showed lesser VAS scores after 4 and 12 weeks than at baseline (p < 0.05). However, the proportion of patients with EPR was significantly greater in Group B after 12 weeks (p = 0.015). No complications, including intrathecal injection, infectious discitis, and neurologic deterioration, were reported. However, inadvertent intradiscal and intravascular injections were reported to be significantly higher in Group A than in Group B (14.8% and 0%, respectively; p = 0.009).

CONCLUSIONS

Although applications of this study are limited by its retrospective design, the results suggest that PEA using the Contra-RdTF approach is feasible because it can achieve EPR and avoid unintended fluoroscopic findings.

Biportal endoscopic posterior lumbar decompression and vertebroplasty for extremely elderly patients affected by lower lumbar delayed vertebral collapse with lumbosacral radiculopathy

Background

Lower lumbar osteoporotic vertebral compression fracture in extremely elderly patients can often lead to lumbosacral radiculopathy (LSR) due to delayed vertebral collapse (DVC). Surgical intervention requires posterior instrumented lumbar fusion as well as vertebral augmentation or anterior column reconstruction depending on the cleft formation and intravertebral instability. However, it is necessary to decide on surgery in consideration of the patient’s frail status, surgical invasiveness, and rehabilitation. In the lower lumbar DVC without intravertebral instability, biportal endoscopic posterior lumbar decompression and vertebroplasty (BEPLD + VP) can be simultaneously attempted. This study aimed to assess the clinical outcomes of BEPLD + VP for the treatment of DVC-related LSR.

Methods

This retrospective case series enrolled 18 consecutive extremely elderly (aged ≥ 75-year-old) patients (6 men and 12 women) who had lower lumbar (at or below L3) DVC-related LSR. Patients who require anterior column reconstruction, such as cleft formation accompanied by intravertebral instability and patients who have not been followed for more than 6 months, were excluded from this study. All patients underwent BEPLD + VP under epidural anesthesia. Clinical results were evaluated by the visual analog scale (VAS) score and the modified Japanese Orthopedic Association (mJOA) scores.

Results

Most of the patients had DVC affecting level L4, with the deformation being a flat type or concave type rather than a wedge type. The VAS score (back and leg) significantly decreased from 7.78 ± 1.17 and 6.89 ± 1.13 preoperatively to 2.94 ± 0.64 and 2.67 ± 1.08 within 2 postoperative days (p < 0.001). The mJOA score significantly improved from 4.72 ± 1.27 preoperatively to 8.17 ± 1.15 in the final follow-up (p < 0.001). The mean recovery rate (RR) in the last follow-up was 56.07% ± 9.98. Incidental durotomy was reported in two patients and epidural hematomas in another two patients; however, all patients improved with conservative treatment, and no re-operation was required.

Conclusions

BELPD + VP was a type of salvage therapy that reduces surgical morbidity, requires major spine surgery under general anesthesia and provides good clinical outcomes in extremely elderly patients with DVC-related LSR.

Clinical outcome of biportal endoscopic revisional lumbar discectomy for recurrent lumbar disc herniation

BACKGROUND

Although literature provides evidence regarding the superiority of surgery over conservative treatment in patients with lumbar disc herniation, recurrent lumbar disc herniation (RLDH) was the indication for reoperation in 62% of the cases. The major problem with revisional lumbar discectomy (RLD) is that the epidural scar tissue is not clearly isolated from the boundaries of the dura matter and nerve roots; therefore, unintended durotomy and nerve root injury may occur. The biportal endoscopic (BE) technique is a newly emerging minimally invasive spine surgical modality. However, clinical evidence regarding BE-RLD remains limited. We aimed to compare the clinical outcomes after performing open microscopic (OM)-RLD and BE-RLD to evaluate the feasibility of BE-RLD.

METHODS

This retrospective study included 36 patients who were diagnosed with RLDH and underwent OM-RLD and BE-RLD. RLDH is defined as the presence of herniated disc material at the level previously operated upon in patients who have experienced a pain-free phase for more than 6 months. BE-RLD was performed as follows: two independent surgical ports were made inside the medial pedicular line of the target segment and on the intact upper and lower laminas. Peeling off the soft tissue from the vertebral lamina helps to easily identify the traversing nerve root and the recurrent disc material without dealing with the fibrotic scar tissue. Clinical outcomes were obtained using a visual analog scale (VAS) and the modified Macnab criteria before and at 2 days, 2 and 6 weeks, and 3, 6, and 12 months after surgery.

RESULTS

The data of 20 and 16 patients who underwent OM-RLD and BE-RLD, respectively, were evaluated. The demographic and perioperative data were comparable between the groups. During the year following the surgery, in the BE-RLD group, the VAS scores at each point were significantly improved over the baseline and remained improved up to 2 weeks after surgery (p < 0.05); however, no statistical difference between the two groups was observed after 6 weeks of surgery (p > 0.05). According to the modified Macnab criteria on the follow-up, the excellent or good satisfaction rates reported at 2 weeks, 6 weeks, 6 months, and 12 months after surgery were 81.25%, 81.25%, 75%, and 81.25%, respectively, in the BE-RLD group, and 50%, 75%, 75%, and 80%, respectively, in the OM-RLD group.

CONCLUSION

BE-RLD yielded similar outcomes to OM-RLD, including pain improvement, functional improvement, and patient satisfaction, at 1 year after surgery. However, faster pain relief, earlier functional recovery, and better patient satisfaction were observed when applying BE-LRD.

TRIAL REGISTRATION

Retrospectively registered.

MRI size assessment of cerebral microvasculature using diffusion-time-dependent stimulated-echo acquisition: A feasibility study in rodent

In this study, a stimulated-echo (STE) method was employed to robustify the cerebral vessel size estimation near air-tissue, bone-tissue interfaces, and large vessels. The proposed solution is to replace the relaxation rate change from gradient-echo (GRE) with that from STE with long diffusion time after the injection of an intravascular contrast agent, superparamagnetic iron oxide nanoparticles. The corresponding diffusion length of STE is shorter than the length over which the unwanted macroscopic field inhomogeneities but is still longer than the correlation length of the fields induced by small vessels. Therefore, the unwanted field inhomogeneities are refocused, while preserving microscopic susceptibility contrast from cerebral vessels. The mean vessel diameter (dimensionless) derived from the diffusion-time-varying STE method was compared to the mean vessel diameter obtained by a conventional spin-echo (SE) and GRE combination based on Monte-Carlo proton diffusion simulations and in vivo rat experiments at 7 ​T. The in vivo mean vessel diameter from the MRI experiments was directly compared to available reference mouse brain vasculature obtained by a knife-edge scanning microscope (KESM), which is considered to be the gold standard. Monte-Carlo simulation revealed that SE and GRE-based MR relaxation rate changes (ΔR₂ and ΔR₂∗, respectively) can be enhanced using single STE-based MR relaxation rate change (ΔR_STE) by regulating diffusion time, especially for small vessels. The in vivo mean vessel diameter from the STE method demonstrated a closer agreement with that from the KESM compared to the combined SE and GRE method, especially in the olfactory bulb and cortex. This study demonstrates that STE relaxation rate changes can be used as consistent measures for assessing small cerebral microvasculature, where macroscopic field inhomogeneity is severe and signal contamination from adjacent large vessels is significant.

HLA-A*02:687, a novel allele identified by sequence-based typing in cord blood from a Korean woman

A*02:687 showed one nucleotide difference with A*02:01:01:01 resulting in an amino acid change.

QTL Mapping for Gray Leaf Spot Resistance in a Tropical Maize Population

A tropical gray leaf spot (GLS)-resistant line, YML 32, was crossed to a temperate GLS-susceptible line, Ye 478, to produce an F_2:3 population for the identification of quantitative trait loci (QTL) associated with resistance to GLS. The population was evaluated for GLS disease resistance and flowering time at two locations in Yunnan province. Seven QTL using GLS disease scores and six QTL using flowering time were identified on chromosomes 2, 3, 4, 5, and 8 in the YML 32 × Ye 478 maize population. All QTL, except one identified on chromosome 2 using flowering time, were overlapped with the QTL for GLS disease scores. The results indicated that QTL for flowering time in this population strongly corresponded to QTL for GLS resistance. Among the QTL, qRgls.yaas-8-1/qFt.yaas-8 with the largest genetic effect accounted for 17.9 to 18.1 and 11.0 to 21.42% of variations for GLS disease scores and flowering time, respectively, and these should be very useful for improving resistance to GLS, especially in subtropical maize breeding programs. The QTL effects for resistance to GLS were predominantly additive in nature, with a dominance effect having been found for two QTL on the basis of joint segregation genetic analysis and QTL analysis.

Electrical Characteristics of Ni-CNT-SiO2-SiC Structured 4H-SiC MIS Capacitors

In this study, the electrical characteristics of Ni-CNT-SiO2-SiC structured 4H-SiC MIS capacitors were investigated. The effect of CNTs in the gate/insulator interface have been characterized by C-V measurement at 300 to 500K and J-V have also been measured. The experimental flat-band voltage tends to change with or without CNTs. Current densities of both devices are observed a negligible difference up to 3 V. It has been found that adding CNTs and/or change of temperature can help to control the positive and/or negative flat-band voltage shift.

Reuse of a previously transplanted kidney from a deceased donor using Luminex virtual crossmatching: a case report

Kidney transplantation is the most desired modality of renal replacement therapy for patients with end-stage renal disease (ESRD). We have attempted to expand the organ donor pool through several methods, including the use of expanded donor criteria. Although previously transplanted kidneys are rarely reused, they can be suitable for transplantation into patients in need. We report a case of successful reuse of a previously transplanted kidney from a deceased donor by means of Luminex virtual crossmatching with the first donor and actual crossmatching with the second donor.

Annealing-dependent electrical properties of Ga-doped ZnO film on silicon carbide

The effect of substrate temperature and thermal annealing on the structural, electrical, and optical properties of Ga-doped zinc oxide (GZO) thin films were examined for use as transparent electrodes on silicon carbide (SiC). The variation of these properties is thought to be related to the presence and stability of Ga3+ ions substituted into Zn2+ sites and adsorbed oxygen ions in GZO thin films, as well as the interfacial thickness of GZO/SiC. GZO thin film deposited at 400 degrees C without annealing has the lowest resistivity of - 1.96 x 10(-4) Ω x cm, which increased after annealing. The photosensitivity of GZO/SiC was increased with increased substrate temperature (from 1.51 to 6.87%) and after annealing (from 2.78 to 8.67%). These results were clarified by comparatively analyzing the chemical composition ratio of oxygen in the GZO thin films and the interfacial thickness between GZO/SiC.

Top-down fabrication of 4H-SiC nano-channel field effect transistors

4H-SiC nano-channel field effect transistors (FETs) with various widths of 3 μm-50 nm have been fabricated by "top-down" approach using electron-beam lithography process. It has been demonstrated that the gate controllability of the SiC FETs is improved with decreasing channel width. In the fabricated devices the threshold voltage V(th) for the 50 nm-width nano-channel FETs shows a positive shift (ΔV(th) = 1.4 V) with respect to that of the reference FETs. The on-current degradation of the SiC nano-channel FETs is found to be 1.5 times lower than that of the reference FETs at elevated temperatures up to 450 K. This attributed to the improved heat dissipation of the nano-channel structure with a large surface to volume ratio.

Estimation of size of cord blood inventory based on high-resolution typing of HLAs

Methods for estimating the cord blood (CB) inventory size required vary according to the ethnic diversity of the HLA, degree of HLA matching and HLA-typing resolution. We estimated the CB inventory size required using 7190 stored CB units (CBU) and 2450 patients who were awaiting or underwent allogeneic hematopoietic stem cell transplantation. With high-resolution typing of HLA-A, B and DRB1, 94.6% of Korean patients could find CBUs in 100 000 CBUs with a 5/6 match, and 95.7% could find CBUs in 5000 CBUs with a 4/6 match. With low-resolution typing of HLA-A and B and high-resolution typing of leukocyte antigen-DRB1, 95% of patients could find CBUs in 50 000 CBUs with a 5/6 match, and 96.7% could find CBUs in 3000 CBUs  with a 4/6 match. With additional high-resolution typing for HLA-A and B, which could improve transplantation outcome, the size of the CB inventory would need to increase twofold for Koreans.

The effect of channel width on the performance of AlGaN/GaN nanowire field effect transistors

AIGaN/GaN nanowire (NW) FETs with a channel width down to -300 nm has been fabricated by "top-down" approach by using electron-beam lithography process. The fabricated AIGaN/GaN NW FETs showed the minimum threshold voltage -3 V, the gate leakage current -10(-10) A/mm, and the maximum transconductance -216 mS/mm, respectively. It has also been demonstrated that the gate controllability of the AIGaN/GaN FETs is improved with decreasing channel width. In the fabricated devices the threshold voltage V(th) for the NW FETs with a width of -300 nm shows a positive shift (deltaV(th) = 2.5 V) with respect to that of the reference FETs. This can be attributed the change in carrier density of the two dimensional electron gas generated at the interface of an AlGaN/GaN.

Photosensitive properties of ZnO/p-SiC heterojunction structures

We investigated the effect of the substrate temperature (T(s)) on the photosensitive properties of ZnO/4H-SiC structures. A ZnO thin film layer was grown on p-type 4H-SiC substrate (0001) by pulsed laser deposition (PLD) deposited at different substrate temperatures (T(s)) of 200, 400, and 600 degrees C, respectively. It was shown that the specific contact resistance of ZnO on p-type 4H-SiC, which was increased from -1.92 x10(-4) to -4.4 omega x cm2 as T(s) increases. On the other hand, the rate of oxygen outdiffusion decreases for the temperature T(s) increase, as observed by transmission line method (TLM) and auger electron spectroscopy (AES) profile. In addition, high photoresponsivity was observed for the ZnO (T(s) -200 degrees C) on p-type 4H-SiC hetero-junction diodes at ultraviolet region (wavelength of -250 nm), comparing to visible (wavelength of -550 nm) and infrared (wavelength of -880 nm). These results may suggest that the ZnO/p-SiC may be applied to optical sensor applications.

Passive mode-locking of fiber ring laser at the 337th harmonic using gigahertz acoustic core resonances

We report the experimental demonstration of a passively mode-locked Er-doped fiber ring laser operating at the 337th harmonic (1.80 GHz) of the cavity. The laser makes use of highly efficient Raman-like optoacoustic interactions between the guided light and gigahertz acoustic resonances trapped in the micron-sized solid glass core of a photonic crystal fiber. At sufficient pump power levels the laser output locks to a repetition rate corresponding to the acoustic frequency. A stable optical pulse train with a side-mode suppression ratio higher than 45 dB was obtained at low pump powers (~60 mW).

Optomechanical nonlinearity in dual-nanoweb structure suspended inside capillary fiber

A novel kind of nanostructured optical fiber, displaying an extremely high and optically broadband optomechanical nonlinearity, is presented. It comprises two closely spaced ultrathin glass membranes (webs) suspended in air and attached to the inner walls of a glass fiber capillary. Light guided in this dual-web structure can exert attractive or repulsive pressure on the webs, causing them to be pushed together or pulled apart. The elastic deflection of the webs is, in turn, coupled to the electromagnetic field distribution and results in a change in the effective refractive index within the fiber. Employing a pump-probe technique in an interferometric setup, optomechanically induced refractive index changes more than 10^{4} times larger than the Kerr effect are detected. Theoretical estimates of the optomechanical nonlinearity agree well with the experimental results. The dual-web fiber combines the sensitivity of a microoptomechanical device with the versatility of an optical fiber and could trigger new developments in the fields of nonlinear optics, optical metrology, and sensing.

HLA-B*40:179, a novel allele identified by sequence-based typing in cord blood from a Korean woman

The novel allele B*40:179 showed one nucleotide difference with B*40:01:01 in exon 4.

The embryo lethality of Escherichia coli isolates and its relationship to the presence of virulence-associated genes

The aims of this study were to determine if the chicken embryo lethality assay and the presence of 9 virulence-associated genes of Escherichia coli were correlated and to discover which virulence genes contributed most to embryo lethality. We examined 58 E. coli strains isolated from visceral organs of chickens with colibacillosis for the presence of 9 virulence genes (fimC, tsh, fyuA, irp2, iucD, cvi/cva, iss, astA, and vat) by PCR. The gene FimC (type I fimbriae) was detected with the highest prevalence in 93.1% of the isolates, followed by iucD (67.24%), iss (58.62%), tsh (34.48%), cvi/cva (34.48%), fyuA (32.76%), astA (31.0%), irp2 (27.59%), and vat (17.24%). The embryo mortality ranged from 5 to 100%; however, most of the isolates were moderately or highly virulent. High positive correlations were observed between the presence of virulence genes and chicken embryo lethality. In addition, presence of the iucD (aerobactin) gene was the trait that best contributed to embryo mortality by using the multivariate model. These results suggest that expression frequency of these 9 virulence genes is associated with embryo mortality, and the gene that best predicted embryo mortality was iucD.

Metal work-function-dependent barrier height of Ni contacts with metal-embedded nanoparticles to 4H-SiC

Metal, typically gold [Au], nanoparticles [NPs] embedded in a capping metal contact layer onto silicon carbide [SiC] are considered to have practical applications in changing the barrier height of the original contacts. Here, we demonstrate the use of silver [Ag] NPs to effectively lower the barrier height of the electrical contacts to 4H-SiC. It has been shown that the barrier height of the fabricated SiC diode structures (Ni with embedded Ag-NPs) has significantly reduced by 0.11 eV and 0.18 eV with respect to the samples with Au-NPs and the reference samples, respectively. The experimental results have also been compared with both an analytic model based on Tung's theory and physics-based two-dimensional numerical simulations.

Intraoperative incidence of hallux valgus interphalangeus following basilar first metatarsal osteotomy and distal soft tissue realignment

BACKGROUND

The premise of this study was that after the correction of hallux-metatarsophalangeal pronation, the intraoperative interphalangeal angle (HIA) increases significantly, and that an additional Akin osteotomy (AO) is often needed. Therefore, the purpose of this study was to evaluate whether HIAs in hallux valgus (HV) feet were underestimated, and to assess the need for AO during HV correction.

METHOD

This study was conducted on 54 feet with moderate to severe HV treated from June 2007 to December 2008. HIAs and medial sesamoid subluxations (MSS) were measured initially and intraoperatively after a distal soft tissue procedure (DSTP) and proximal chevron metatarsal osteotomy (PCMO). An intraoperative technique was used to evaluate the incongruency of the metatarsophalangeal joint (MTPJ) to determine the need for additional Akin osteotomy.

RESULTS

After performing DSTP and PCMO, HIAs significantly increased from an average of 9 to 13.3 degrees and MSS reduced from average grade 2.5 to 0.5 (p < 0.05). Akin ostetomy was added in 44 (81%) feet. After an average followup of 13.2 months in Akin group, average VAS pain score decreased from 5.7 to 1.2 and average AOFAS score increased from 57.8 to 90.2 (p < 0.05). Final hallux MTPJ dorsiflexion in the Akin group was significantly larger than in the without-Akin group (p < 0.05).

CONCLUSION

Average HIA significantly increased after DSTP and PCMO for moderate to severe HV necessitating additional Akin osteotomy, to achieve ideal HV correction and, to preserve MTPJ motion.

Characterization of Escherichia coli isolates from laying hens with colibacillosis on 2 commercial egg-producing farms in Korea

The present study reports on layer chickens with colibacillosis in 2 commercial egg-producing farms (referred to as farm A and farm B, which were managed by the same owner and were about 1 km apart) in the middle region of the Korean peninsula. The 2 flocks were infected at the initiation of egg laying. They were characterized by no previous clinical signs but sudden mortality (2.7-4.0%), with severe lesions of septicemia and fibrinous polyserositis. Escherichia coli was isolated from the lesions of the infected birds. Serotyping tests identified isolates that belonged to somatic groups O1 (12/17), O46 (2/17), O78 (1/17), and O84 (1/17) or that were unidentified (1/17). Thirteen of 17 E. coli isolates (76.4%) obtained from 11 birds in the 2 flocks showed similar pulsed-field gel electrophoresis patterns that were arbitrarily designated as pattern A. The isolates had high frequencies of putative virulence genes including 100% [fimC (type 1 fimbriae), iucD (aerobactin synthesis), and iss (increased serum survival)], 94.1% [cva/cvi (structural genes of colicin V operon) and vat (vacuolating autotransporter toxin)], 88.2% [irp2, iron-repressible protein (yersinia bactin) synthesis, and fyuA, ferric yersinia uptake], and 82.3% [tsh (temperature-sensitive hemagglutinin)]; astA (encoding a heat-stable cytotoxin associated with enteroaggregative E. coli) was not associated with the enteric disorder. These data suggest that all chickens with colibacillosis on farms A and B were likely infected by E. coli strains that are highly pathogenic in avian species.

Intraoperative incidence of hallux valgus interphalangeus following basilar first metatarsal osteotomy and distal soft tissue realignment

BACKGROUND

The premise of this study was that after the correction of hallux-metatarsophalangeal pronation, the intraoperative interphalangeal angle (HIA) increases significantly, and that an additional Akin osteotomy (AO) is often needed. Therefore, the purpose of this study was to evaluate whether HIAs in hallux valgus (HV) feet were underestimated, and to assess the need for AO during HV correction.

METHOD

This study was conducted on 54 feet with moderate to severe HV treated from June 2007 to December 2008. HIAs and medial sesamoid subluxations (MSS) were measured initially and intraoperatively after a distal soft tissue procedure (DSTP) and proximal chevron metatarsal osteotomy (PCMO). An intraoperative technique was used to evaluate the incongruency of the metatarsophalangeal joint (MTPJ) to determine the need for additional AO.

RESULTS

After performing DSTP and PCMO, HIAs significantly increased from an average of 9 to 13.3 degrees and MSS reduced from average grade 2.5 to 0.5 (p < 0.05). AO was added in 44 (81%) feet. After an average followup of 13.2 months in Akin group, average VAS pain score decreased from 5.7 to 1.2 and average AOFAS score increased from 57.8 to 90.2 (p < 0.05). Final hallux MTPJ dorsiflexion in the Akin group was significantly larger than in the without-Akin group (p < 0.05).

CONCLUSION

Average HIA significantly increased after DSTP and PCMO for moderate to severe HV necessitating additional AO, to achieve ideal HV correction and, to preserve MTPJ motion.

Histiocytic necrotizing lymphadenitis in the context of systemic lupus erythematosus (SLE): Is histiocytic necrotizing lymphadenitis in SLE associated with skin lesions?

Histiocytic necrotizing lymphadenitis (HNL), or Kikuchi's disease, is a benign and self-limiting lymphadenopathy that typically affects young Asian females. It presents with lymphadenopathy, usually cervical, accompanied by fever, chills and leukopenia. Although the association between systemic lupus erythematosus (SLE) and HNL is rare, the number of reports of HNL in SLE patients is increasing. We present nine cases of HNL in patients with SLE. Among the seven patients with diverse skin manifestations, three had skin manifestations that were histologically compatible with SLE. A review of previous reports in the literature showed that cutaneous involvement was commonly found in HNL in association with SLE. In the patients who had simultaneous onset of both diseases, lupus flare-ups were commonly observed. We suggest that HNL in SLE patients is associated with cutaneous manifestations. This report contributes to our understanding of the relationship between these diseases.

Structural analysis of photonic crystal fibers by side scattering of laser light

A side-scattering technique for investigating the inner microstructure of photonic crystal fibers (PCFs) is reported. Multiple scattering is reduced by filling the hollow PCF channels with index-matching fluid. The scattered signal is measured for fixed angles of incidence and detection while the fiber is rotated. A pattern of peaks, unique to each PCF, whether solid or hollow core, correlates closely with the symmetry planes of the PCF structure. As an example of the technique, the twist profile of a structural rocking filter is directly measured.

Anti-reflective nano- and micro-structures on 4H-SiC for photodiodes

In this study, nano-scale honeycomb-shaped structures with anti-reflection properties were successfully formed on SiC. The surface of 4H-SiC wafer after a conventional photolithography process was etched by inductively coupled plasma. We demonstrate that the reflection characteristic of the fabricated photodiodes has significantly reduced by 55% compared with the reference devices. As a result, the optical response Iillumination/Idark of the 4H-SiC photodiodes were enhanced up to 178%, which can be ascribed primarily to the improved light trapping in the proposed nano-scale texturing.