Biomechanical study between percutaneous vertebroplasty combined with cement pedicle plasty improves vertebral biomechanical stability: A finite element analysis.

OBJECTIVE: To investigate the biomechanical effects of percutaneous vertebroplasty combined with cement pedicle plasty (PVCPP) on the unstable osteoporotic vertebral fractures (OVFs) through finite element (FE) analysis. The study compares the biomechanical stability of finite element models between percutaneous vertebroplasty (PVP) and percutaneous vertebroplasty combined with cement pedicle plasty. METHODS: Two patients with unstable OVFs underwent computed tomography (CT) examination at the thoracolumbar vertebral body levels, respectively. The CT images were reconstructed into three-dimensional finite element models to simulate stress conditions across six dimensions and to evaluate the vertebral von Mises stress before and after bone cement reinforcement. RESULTS: The study found that stress distribution differed between groups mainly at the pedicle base. In the surgical vertebral bodies, the maximum stress in the PVP group decreased during flexion and left bending, while it increased in other states. In the PVCPP group, all maximum stresses decreased. In the inferior vertebral bodies, the maximum stress in the PVP group generally increased, while it decreased in the PVCPP group. In the superior vertebral bodies, postoperatively, the maximum stress in the PVP group generally increased, while it almost remained unchanged in the PVCPP group. PVP group had higher cement stress and displacement. CONCLUSION: PVCPP is an effective treatment method for patients with unstable OVFs. It can quickly relieve pain and enhance the stability of the three columns, thereby reducing the risk of some complications.

Finite element analysis of precise puncture vertebral augmentation in the treatment of different types of osteoporotic vertebral compression fractures.

BACKGROUND: Osteoporosis vertebral compression fracture (OVCF) secondary to osteoporosis is a common health problem in the elderly population. Vertebral augmentation (VA) has been widely used as a minimally invasive surgical method. The transpedicle approach is commonly used for VA puncture, but sometimes, it is limited by the anatomy of the vertebral body and can not achieve good surgical results. Therefore, we propose the treatment of OVCF with precise puncture vertebral augmentation (PPVA). This study used finite element analysis to explore the biomechanical properties of PPVA in the treatment of osteoporotic vertebral compression fractures (OVCFs) with wedge, biconcave, and collapse deformities. METHOD: Three-dimensional finite element models of the fractured vertebral body and adjacent superior and inferior vertebral bodies were established using Computed Tomography (CT) data from patients with OVCF, both before and after surgery. Evaluate the stress changes of the wedged deformed vertebral body, biconcave deformed vertebral body, collapsed deformed vertebral body, and adjacent vertebral bodies before and after PPVA. RESULT: In vertebral bodies with wedge deformity and collapsed deformity, PPVA can effectively reduce the stress on the vertebral body but increases the stress on the vertebral body with biconcave deformity. PPVA significantly decreases the stress on the adjacent vertebral bodies of the wedge deformed vertebral body, and decreases the stress on the adjacent superior vertebral body of biconcave deformity and collapsed deformed vertebral bodies, but increases the stress on the adjacent inferior vertebral bodies. PPVA improves the stress distribution of the vertebral body and prevents high-stress areas from being concentrated on one side of the vertebral body. CONCLUSION: PPVA has shown positive surgical outcomes in treating wedge deformed and collapsed deformed vertebral bodies. However, its effectiveness in treating biconcave vertebral body is limited. Furthermore, PPVA has demonstrated favorable results in addressing adjacent superior vertebral body in three types of fractures.

Meta-Modulation: A General Learning Framework for Cross-Task Adaptation.

Building learning systems possessing adaptive flexibility to different tasks is critical and challenging. In this article, we propose a novel and general meta-learning framework, called meta-modulation (MeMo), to foster the adaptation capability of a base learner across different tasks where only a few training data are available per task. For one independent task, MeMo proceeds like a "feedback regulation system", which achieves an adaptive modulation on the so-called definitive embeddings of query data to maximize the corresponding task objective. Specifically, we devise a type of efficient feedback information, definitive embedding feedback (DEF), to mathematize and quantify the unsuitability between the few training data and the base learner as well as the promising adjustment direction to reduce this unsuitability. The DEFs are encoded into high-level representation and temporarily stored as task-specific modulator templates by a modulation encoder. For coming query data, we develop an attention mechanism acting upon these modulator templates and combine both task/data-level modulation to generate the final data-specific meta-modulator. This meta-modulator is then used to modulate the query's embedding for correct decision-making. Our framework is scalable for various base learner models like multi-layer perceptron (MLP), long short-term memory (LSTM), convolutional neural network (CNN), and transformer, and applicable to different learning problems like language modeling and image recognition. Experimental results on a 2-D point synthetic dataset and various benchmarks in language and vision domains demonstrate the effectiveness and competitiveness of our framework.

Percutaneous kyphoplasty combined with pediculoplasty for the surgical treatment of osteoporotic thoracolumbar burst fractures.

OBJECTIVE: This study introduces a minimally invasive technique for efficient three-column reconstruction, augmentation, and stabilization of osteoporotic thoracolumbar burst fractures (OTLBFs). METHODS: Sixty-eight patients with OTLBFs and no neurological deficits were included from July 2019 to September 2020. The patients were divided into two groups: the simple percutaneous kyphoplasty (PKP) group (n = 32) and the percutaneous kyphoplasty combined with pediculoplasty (PKCPP) group (n = 36). The clinical and radiological outcomes were assessed during a minimum 1-year follow-up period. Clinical outcomes were assessed via the visual analog scale (VAS) and modified MacNab grading criteria. The radiological outcomes included the Cobb angle (CA), anterior wall height (AWH), and posterior wall height (PWH). The surgery duration, postoperative analgesic dosage, length of hospital stay, and complications were recorded. RESULTS: Surgery duration was not significantly different between the two groups (P > 0.05). The PKCPP group had a lower analgesic dosage and shorter hospital stay (P < 0.05). Postoperatively, the PKCPP group exhibited better VAS scores and modified MacNab scale scores (P < 0.05), but the differences at the last follow-up assessment were not significant (P > 0.05). Postoperative CA, AWH, and PWH correction were not significantly different on the first postoperative day (P > 0.05). However, the PKCPP group had significantly less CA and PWH loss of correction at the last follow-up visit (P < 0.05). The PKCPP group had significantly fewer complications (P < 0.05). CONCLUSIONS: The PKCPP technique complements simple PKP for OTLBFs. It quickly relieves pain, maintains the vertebral body height and Cobb angle, ensures cement stabilization, and offers more stable three-column support.

Spinal infection caused by Aspergillus flavus in a diabetic: a case report and literature review.

Spinal infections, notably those induced by Aspergillus flavus (A. flavus), represent a complex and uncommon clinical challenge. In individuals with diabetes mellitus, the risk is exacerbated due to a compromised immune response and a heightened vulnerability to non-standard pathogens. This case report chronicles the intricate diagnostic and treatment journey of a 59-year-old diabetic patient grappling with a spinal infection attributed to A. flavus. The diagnosis was delayed due to non-specific symptoms and unclear radiological signs. The administration of voriconazole, a targeted antifungal treatment, resulted in a significant clinical and radiological improvement, underscoring its effectiveness in treating such unusual fungal spinal infections; meanwhile, we found that terbinafine hydrochloride also has a similar effect in treating fungal spinal infections. This case underscores the importance of considering fungal causes in spinal infections among diabetic patients and highlights prompt diagnosis and individualized targeted antifungal therapy.

Percutaneous kyphoplasty combined with pediculoplasty (PKCPP) augments and internally fixates the severe osteoporotic vertebral fractures: a retrospective comparative study.

A retrospective comparative study revealed that percutaneous kyphoplasty combined with pediculoplasty (PKCPP) offers more benefits in terms of pain relief, spinal stability, and complications compared to simple percutaneous kyphoplasty. Moreover, PKCPP can augment and internally fixate the severe osteoporotic vertebral fractures. PURPOSE: Vertebral augmentation (VA) has emerged as a satisfactory and minimally invasive surgical approach for severe osteoporotic vertebral fractures (OVFs). However, treating severe OVFs with advanced collapse, burst morphology with MC injury, posterior wall retropulsion, high degree of osseous fragmentation, pediculo-somatic junction fracture, and large vacuum cleft presents significant challenges. This study aimed to evaluate the effectiveness of percutaneous kyphoplasty combined with pediculoplasty (PKCPP) in reducing refracture, preventing further collapse and bone cement displacement, reconstructing vertebral body (VB) stability, and providing internal fixation of the anterior column (AC), middle column (MC), and the bilateral pedicles. METHODS: The current study was designed as a retrospective review of clinical and radiologic parameters. From July 2018 to September 2021, ninety-six patients with severe OVFs and without neurological deficit were treated either with simple percutaneous kyphoplasty (simple PKP group, n = 54) or with percutaneous kyphoplasty combined with pediculoplasty (PKCPP group, n = 42). All patients were followed up for at least 1 year, and clinical and radiological outcomes were assessed. Surgery duration and bone cement volume were compared between the two groups, as well as analgesic dosage and hospital stay. Anterior wall height (AWH), posterior wall height (PWH), and Cobb angle (CA) were measured and analyzed before and after surgery. RESULTS: The simple PKP group had significantly shorter surgery duration and lower bone cement volume compared to the PKCPP group (P < 0.05). Conversely, the simple PKP group had significantly higher analgesic dosage and longer hospital stay than the PKCPP group (P < 0.05). Both groups showed significant improvements in AWH, PWH, and CA after surgery (P < 0.05). At the final follow-up, the PWH in the simple PKP group was significantly lower than the preoperative measurement (P < 0.05), and the difference in PWH between the two groups was statistically significant (P > 0.05). Moreover, both groups demonstrated a significant reduction in CA after surgery, with the PKCPP group showing a greater reduction compared to the simple PKP group throughout the postoperative period to the final follow-up (P < 0.05). VAS and ODI scores significantly decreased in both groups after surgery (P < 0.05), with no significant difference between the groups at the final follow-up (P > 0.05). However, the PKCPP group achieved better VAS scores than the simple PKP group at postoperative 1 day, 1 month, and 3 months (P < 0.05), and the ODI in the PKCPP group was lower than the simple PKP group at 1 month after surgery (P < 0.05). Furthermore, the overall complication rate in the PKCPP group was significantly lower than that in the simple PKP group (P < 0.05). CONCLUSION: If performed by appropriately trained surgeons, both PKP and PKCPP are safe and effective treatments for patients with severe OVFs. However, PKCPP offers additional benefits in the setting of bothersome fractures, including rapid pain relief, improved spinal stability, satisfactory restoration of vertebral body height, and better correction of kyphotic deformity. These promising results have been tested in a single center but require further confirmation in multiple centers.

Surgical Strategy for Lumbar Disc Herniation based on the MSU Classification: Percutaneous Endoscopic Lumbar Discectomy versus Transforaminal Lumbar Interbody Fusion: A 5-year Retrospective Study.

OBJECTIVE: Currently, there is no established guideline on whether to opt for percutaneous endoscopic lumbar discectomy (PELD) or traditional transforaminal lumbar interbody fusion (TLIF) surgery based on specific types of lumbar disc herniation (LDH). Based on the Michigan State University (MSU) classification system, this study conducted a medium- to long-term follow-up analysis of two surgical methods over 5 years for the first time, aiming to provide empirical evidence to assist in making more informed decisions before surgery for LDH treatment. METHODS: This was a retrospective study that included 273 patients with single-level LDH who underwent PELD or TLIF treatment at our hospital between January 1, 2016, and December 31, 2018. Detailed metrics included preoperative and postoperative visual analogue scale (VAS) scores and Oswestry disability index (ODI) at 1-day, 1-week, 1-year, and 5-year follow-ups. Complications, recurrences, and 5-year postoperative modified MacNab criteria scores were also recorded. Statistical methods included independent sample t-tests, repeated measures analysis of variance (ANOVA), and χ2 tests. RESULTS: Classified into seven groups according to the MSU classification, it was found that there was an improvement in the VAS and ODI scores at four postoperative follow-ups (p < 0.001). PELD showed better results than TLIF in reducing pain and improving the ODI scores in the classifications of 3B, 2B, and 2C (p < 0.05). TLIF demonstrated consistent superiority over PELD in 2A, 2AB, 3A, and 3AB classifications (p < 0.05). The total recurrence rate in the PELD group (11.05%) within 5 years after surgery was higher (p < 0.05) than that in the TLIF group (3.96%). These were mainly concentrated in the 2A, 2AB, 3A, and 3AB types. Moreover, the rate of excellent and good outcomes in the PELD was higher than in the TLIF but no significant difference (χ2 = 1.0568, p = 0.5895). CONCLUSION: This study suggests that PELD and TLIF may relieve LDH, but have advantages under different MSU classifications. The MSU classification has specific guiding significance and could aid in the surgical selection of PELD or TLIF to achieve optimal treatment outcomes for patients with lumbar disc herniation.

Risk factors for infection in patients undergoing knee arthroscopy: A Systematic Review and Meta-analysis.

PURPOSE: The primary aim was to determine the risk of infection after knee arthroscopy and to evaluate the risk factors for surgical site infection (SSI). METHODS: The PubMed/Medline, Embase and Cochrane Library databases were systematically searched, as were the reference lists of previous systematic reviews and meta-analysis manual studies. A random-effects model was used to calculate the estimated pooled odds ratio (OR). RESULTS: A total of 38,321 potential articles met the initial inclusion criteria. After a review of the titles, abstracts and full texts, the remaining 41 articles were included in the final analysis. We identified 9,089,578 patients who underwent knee arthroscopy in 41 articles. High-quality (class I) evidence showed that autografts (cruciate ligament reconstruction) (OR, 2.66% CI, 1.84-3.86) or high procedure complexity (OR, 2.02;95% CI, 1.69-2.43) had a higher risk of infection, while medium-quality (class II or class III) evidence showed that obesity (BMI ≥ 30 kg/m2) (OR, 1.27; 95% CI, 1.08-1.49) or male (OR, 1.52; 95% CI, 1.32-1.75) or diabetes (OR, 1.71; 95% CI, 1.36-2.14) or tobacco use (OR, 1.65; 95% CI, 1.38-1.97) or preoperative steroid use (OR, 3.41; 95% CI, 2.10-5.54) had a higher risk of infection. The meta-analysis showed that there was no association between age or antibiotic prophylaxis and infection incidence. CONCLUSIONS: The meta-analysis showed that significant risk factors for infection after knee arthroscopy included obesity, male sex, diabetes, tobacco use, high procedure complexity, graft type, and preoperative steroid use. LEVEL OF EVIDENCE: Level IV, systematic review of Level III and Level IV studies.

Role of the mechanosensitive piezo1 channel in intervertebral disc degeneration.

Intervertebral disc degeneration (IDD) is a multifactorial skeletal disease involving mechanical, genetic, systemic, and biological factors, and it is characterized by apoptosis of the nucleus pulposus cells and breakdown of the extracellular matrix (ECM), which will impair the structure and function of the intervertebral disc (IVD), and cause low back pain. Recently, the piezo1 is recognized as a critical mechanically activated ion channel of IDD. Numerous studies have reported that the piezo1 ion channel was aberrantly activated in the degenerated disc tissues and deeply participated in the pathogenesis of IDD. Inactivating or interfering with the piezo1 channel could effectively prevent the progression of IDD under the experimental conditions. It may be a promising target for the prevention and treatment of the disabling disease. Therefore, we have to make a comprehensive investigation and understanding of the mechanisms and functions of the piezo1 in the biomechanics of the spine. This study mainly elucidates the role of the piezo1 channel in IDD, which may facilitate the development of therapeutic targets for this disease.

Identification of genes contributing to cisplatin resistance in osteosarcoma cells.

Osteosarcomas are prevalent in children and young adults and have a high recurrence rate. Cisplatin, doxorubicin, and methotrexate are common adjuvant chemotherapy drugs for treatment of osteosarcoma, but multidrug resistance is a growing problem. Therefore, understanding the molecular mechanisms of chemotherapy resistance in osteosarcoma cells is crucial for developing new therapeutic approaches and ultimately improving the prognosis of osteosarcoma patients. To identify genes associated with cisplatin resistance in osteosarcoma, we screened a large-scale mutant library generated by transfecting human osteosarcoma cells with a piggyBac (PB) transposon-based gene activation vector. Several candidate genes were identified by using Splinkerette-PCR paired with Next Generation Sequencing. We created a disease-free survival predictor model, which includes ZNF720, REEP3, CNNM2, and CGREF1, using TARGET (Therapeutically Applicable Research to Generate Effective Treatments) datasets. Additionally, the results of our enrichment analysis between the Four_genes_high group and Low_group suggested that these four genes may participate in cisplatin resistance in osteosarcoma through cross talk between various signaling pathways, especially the signaling pathway related to bone formation. These data may help guide future studies into chemotherapy for osteosarcoma.

The mechanisms and functions of IL-1ß in intervertebral disc degeneration.

Intervertebral disc degeneration (IDD) is the leading cause of low back pain (LBP) and disability in the elderly, imposing significant public health and economic burden worldwide. Meanwhile, the pathological mechanisms of IDD remain complicated, and treatment strategy to reverse IDD is primarily due to the unclear specific mechanisms of IDD and the lack of particular effective targets. Interleukin-1ß (IL-1ß), one of the most important members of the IL-1 family, can induce solid pro-inflammatory activity by stimulating the secretion of various pro-inflammatory mediators and is considered the key to IDD mediator. However, in recent years, IL-1ß is considered to be able to regulate IVD cell death in many ways, such as apoptosis, pyroptosis, ferroptosis, and so on. At the same time, numerous studies on IL-1ß inhibitors suggest that inhibition of IL-1ß may be a promising biological therapy for IDD. Many IL-1ß inhibitors have been investigated through various pathogenic biological mechanisms, including inhibiting inflammatory processes, regulating ECM degradation, and more. Therefore, anti-IL-1ß therapy may have the effect of alleviating disc degeneration. This article mainly reviews the mechanisms and functions of IL-1ß in IDD and investigates advances in IL-1ß inhibition as a promising biotherapeutic approach for disc degeneration.

IL-1ß-mediated inflammatory responses in intervertebral disc degeneration: Mechanisms, signaling pathways, and therapeutic potential.

Intervertebral disc degeneration (IDD) has been widely recognized as the primary cause of low back pain and is one of the major chronic diseases imposing a severe socioeconomic burden worldwide. IDD is a degenerative process characterized by inflammatory responses, and its underlying pathological mechanisms remain complex. Genetic, developmental, biochemical, and biomechanical factors contribute to the development of IDD. There is a pressing need for an effective non-surgical treatment, mainly due to the lack of comprehensive understanding of the specific mechanisms involved and the effective therapeutic targets for IDD. Recently, interleukin (IL)-1ß has been recognized as an essential inflammatory factor and a key mediator of the inflammatory process in IDD. Current studies have found that IL-1ß is mainly involved in IDD by affecting the metabolism of the extracellular matrix and regulating cell death (RCD), such as apoptosis, pyroptosis, and ferroptosis (a new form of RCD). Although analysis of clinical samples from different laboratories confirmed how IL-1ß is induced in IDD, its specific signal transduction pathway, and the inflammatory role mediated in IDD remains unclear. This review describes the molecules and mechanisms involved in IL-1ß-mediated inflammatory responses, and their roles in resolving the inflammatory process in IDD. Understanding the signaling pathways involved in IL-1ß may lead to a new class of targets that promote remission for IDD patients. This review aims to provide a framework for the treatment of IDD by analyzing the signaling mechanism and function related to IL-1ß, especially in terms of inflammation, matrix metabolism, and cell death regulation.

Exosomes: A promising therapeutic strategy for intervertebral disc degeneration.

As a common problem all over the world, low back pain (LBP) places a huge social and economic burden on people. Intervertebral disc degeneration (IDD) is often considered to be the main cause of low back pain. The current methods of treating disc degenerative diseases mainly focus on relieving symptoms, including surgery and conservative treatment, but none of them can be treated with the etiology, which means that the normal structure of the intervertebral disc cannot be fundamentally restored. With the development of tissue engineering and regenerative medicine, exosomes from different sources, especially mesenchymal stem cell-derived exosomes (MSC-exos) as active biological substances for intercellular communication have made rapid progress due to their potency in promoting tissue regeneration. The study of exosomes in the field of treatment of IDD has yielded many surprising results. This paper mainly reviews the mechanism and function of exosomes in the study of delaying or reversing IDD, as well as gives the prospects and challenges of exosomes.

The Mechanisms and Functions of GDF-5 in Intervertebral Disc Degeneration.

Intervertebral disc degeneration (IDD) is widely recognized as the main cause of low back pain, which leads to disability in aging populations and induces great losses both socially and economically worldwide. Unfortunately, current treatments for IDD are aimed at relieving symptoms instead of preserving disc structure and function. Researchers are forged to find new promising biological therapeutics to stop, and even reverse, IVD degeneration. Recently, the injection of growth factors has been shown to be a promising biological therapy for IDD. A number of growth factors have been investigated to modulate the synthesis of the extracellular matrix (ECM) through a variety of pathogenetic biological mechanisms, including suppressing inflammatory process and down-regulating degrading enzymes. However, growth factors, including Transforming Growth Factor-ß (TGF-ß), Fibroblast Growth Factor (FGF), and Insulin-like Growth Factor-1 (IGF-1), may induce unwanted blood vessel in-growth, which accelerates the process of IDD. On the contrary, studies have demonstrated that injection of GDF-5 into the intervertebral disc of mice can effectively alleviate the degeneration of the intervertebral disc, which elicits their response via BMPRII and will not induce blood vessel in-growth. This finding suggests that GDF-5 is more suitable for use in IDD treatment compared with the three other growth factors. Substantial evidence has suggested that GDF-5 may maintain the structure and function of the intervertebral disc (IVD). GDF-5 plays an important role in IDD and is a very promising therapeutic agent for IDD. This review is focused on the mechanisms and functions of GDF-5 in IDD.

Posterior Percutaneous Transpedicular Endoscopic Approach for Treating Single-Segment Cervical Myelopathy.

BACKGROUND: Standard posterior percutaneous endoscopic cervical discectomy (PECD) is considered an effective minimally invasive surgery. Although standard PECD can be used to treat radiculopathy with relatively minimal trauma, it is still a challenge to use this approach for treating myelopathy. OBJECTIVE: This report is aimed at first describing a posterior transpedicular approach under endoscopy for myelopathy and evaluating the feasibility and short-term clinical effects of this approach. METHODS: In our retrospective analysis between Feb. 2016 to Mar. 2017, 16 patients managed with PECD using the posterior transpedicular approach for symptomatic single-segment myelopathy. Surgery involved drilling 1/2 to 2/3 of the medial portion of the pedicle under endoscopy to provide sufficient space and an appropriate angle for inserting the endoscope into the spinal canal, followed by ventral decompression of the spinal cord. Computed tomography and magnetic resonance imaging were used to evaluate pedicle healing and spinal cord decompression. The primary outcomes included a visual analog scale (VAS) scores of axial neck pain and Japanese Orthopaedic Association (JOA) scores of neurological conditions. RESULTS: All patients completed a 1-year follow-up examination. The mean duration of surgery was 95.44 ± 19.44 min (52-130 min). The fluoroscopy duration was 5.88 ± 1.05 (4-7). The VAS scores of axial pain significantly improved from 6.94 ± 0.75 preoperatively to 2.88 ± 1.22 postoperatively (P < 0.05). The mean JOA scores improved from 8.50 ± 1.12 preoperatively to 14.50 ± 1.46 at the final follow-up (P < 0.05). The effects were excellent in 8 cases, good in 6 cases, and fair in 2 cases. After partial pedicle excision, the width of the remaining pedicle was 1.70 ± 0.22 mm postoperatively and significantly recovered to 3.38 ± 0.49 mm at the 1-year follow-up. There were no surgery-related complications, such as dural tearing, spinal cord injury, nerve root injury, pedicle fracture, and cervical hematocele or infection. CONCLUSIONS: The posterior transpedicular approach is an effective method for the treatment of myelopathy in select patients and is a supplement to the described surgical approach for PECD.

Modified K-Hole Percutaneous Endoscopic Surgery for Cervical Foraminal Stenosis: Partial Pediculectomy Approach.

BACKGROUND: Percutaneous endoscopic cervical discectomy has evolved as an efficient, minimally invasive spine surgery for radiculopathy caused by soft and/or osseous foraminal stenosis. Although interlaminar access can be used to resect lateral herniated lesions or osteophytes located in the foramina, with limited operative space, nerve retraction may be unavoidable. This procedure may injure the nerve root and cause postoperative arm pain, numbness, and muscle weakness, especially when the herniation is located in the ventral nerve root or when there is a massive osteophyte in the foramina. However, posterior partial cervical pediculectomy under endoscopy provides a new approach to effectively reduce or even avoid nerve retraction and reduce the potential risk of nerve injury. OBJECTIVES: This report presents a partial pediculectomy approach and compares the clinical outcomes of different surgical methods, including posterior percutaneous endoscopic cervical discectomy (P-PECD) and P-PECD combined with partial pediculectomySTUDY DESIGN: This study used a retrospective comparative study design. SETTING: This study took place at the Second Affiliated Hospital of Chongqing Medical University. METHODS: From February 2015 to March 2017, 84 patients with single-level and unilateral soft and/or osseous cervical foraminal stenosis were recruited. Patients were treated with P-PECD (40 patients) and P-PECD combined with partial pediculectomy (44 patients). Postoperative clinical outcomes were assessed using the modified MacNab grading criteria and the Visual Analog Scale (VAS) at different times after surgery. The surgery duration, dosage of postoperative analgesic medication, duration of hospital stay, and postoperative complications were recorded. RESULTS: The mean duration of the conventional P-PECD surgery was 74.48 ± 7.08 minutes, which was significantly longer (P = 0.002) than that observed for the P-PECD with partial pediculectomy (66.00 ± 9.62 minutes). The analgesic dosage in the conventional P-PECD group was significantly higher than that in the partial pediculectomy group (9.14 ± 3.07 units vs. 5.71 ± 3.41 units; P = 0.001). The hospital stay in the conventional P-PECD group was significantly longer than that in the partial pediculectomy group (3.86 ± 0.85 days vs. 3.24 ± 0.83 days; P = 0.022). The VAS scores at 1 day, 3 days, and 7 days after surgery in the conventional P-PECD group were significantly higher than those in the partial pediculectomy group (all P < 0.001). The modified MacNab grading criteria showed no significant difference at each follow-up (P = 1). The incidence of complications in the P-PECD with partial pediculectomy group (2/44, 4.55%) was significantly lower than that in the conventional P-PECD group (4/40, 10.0%), including complications of increased pain, increased numbness, and worsening of muscle weakness. LIMITATIONS: This study is limited by being a retrospective study, and by having a small sample size and a short follow-up period. CONCLUSIONS: As an alternative to the P-PECD surgical technique, P-PECD with partial pediculectomy effectively reduced the postoperative complications and may be preferable when considering the surgery duration, postoperative hospital stay, analgesic dosage, and postoperative VAS score. KEY WORDS: Cervical disc herniation, foraminal stenosis, percutaneous endoscopic cervical discectomy, PECD, P-PECD, partial pediculectomy.

Geometrical confinements and depletion interactions.

In the system with two large spheres confined between two parallel plates, there are depletion interactions between the two large spheres and between one large sphere and the closely placed plate. Obviously, the depletion interactions exerted on one large sphere will be strongly affected by the presence of the closely placed plate or the other large sphere. This prediction is confirmed by the numerical results obtained through the acceptance ratio method (ARM) or density integration method (DIM), i.e., they are strengthened when two large spheres are contacted. Furthermore, it is found that the influences on the depletion forces are also sensitive to the angle of the centers' connection line between the two large spheres and the confining walls. In addition, the numerical results show that the total depletion force exerted on one large sphere from both the other large sphere and the closely placed plate can be determined through ARM or DIM from the interactions between the two large spheres or between one large sphere and the corresponding closely placed plate.