Finite element analysis of a new preoperative traction for cervical kyphosis: suspensory traction.

A finite element model of cervical kyphosis was established to analyze the stress of cervical spine under suspensory traction and to explore the mechanism and effect of it. A patient with typical cervical kyphosis (C2-C5) underwent CT scan imaging, and 3D slicer was used to reconstruct the C2 to T2 vertebral bodies. The reconstructed data was imported into Hypermesh 2020 and Abaqus 2017 for meshing and finite element analysis. The changes of the kyphotic angle and the von Mises stress on the annulus fibrosus of each intervertebral disc and ligaments were analyzed under suspensory traction conditions. With the increase of suspensory traction weight, the overall kyphosis of cervical spine showed a decreasing trend. The correction of kyphosis was mainly contributed by the change of kyphotic segments. The kyphotic angle of C2-C5 was corrected from 45° to 13° finally. In cervical intervertebral discs, the stress was concentrated to anterior and posterior part, except for C4-5. The stress of the anterior longitudinal ligament (ALL) decreased from the rostral to the caudal, and the high level von Mises stress of the kyphotic segments appeared at C2-C3, C3-C4, and C4-C5. The roles of the other ligaments were not obvious. The kyphotic angle was significantly reduced by the suspensory traction. Shear effect due to the high von Mises stress in the anterior and posterior parts of annulus fibrosus and the tension on the anterior longitudinal ligament play a role in the correction of cervical kyphosis.

Developing and Validating an Intelligent Mouth-Opening Training Device: A New Solution for Restricted Mouth Opening.

Restricted mouth opening (trismus) is one of the most common complications following head and neck cancer treatment. Early initiation of mouth-opening exercises is crucial for preventing or minimizing trismus. Current methods for these exercises predominantly involve finger exercises and traditional mouth-opening training devices. Our research group successfully designed an intelligent mouth-opening training device (IMOTD) that addresses the limitations of traditional home training methods, including the inability to quantify mouth-opening exercises, a lack of guided training resulting in temporomandibular joint injuries, and poor training continuity leading to poor training effect. For this device, an interactive remote guidance mode is introduced to address these concerns. The device was designed with a focus on the safety and effectiveness of medical devices. The accuracy of the training data was verified through piezoelectric sensor calibration. Through mechanical analysis, the stress points of the structure were identified, and finite element analysis of the connecting rod and the occlusal plate connection structure was conducted to ensure the safety of the device. The findings support the effectiveness of the intelligent device in rehabilitation through preclinical experiments when compared with conventional mouth-opening training methods. This intelligent device facilitates the quantification and visualization of mouth-opening training indicators, ensuring both the comfort and safety of the training process. Additionally, it enables remote supervision and guidance for patient training, thereby enhancing patient compliance and ultimately ensuring the effectiveness of mouth-opening exercises.

Lack of evolutionary convergence in multiple primary lung cancer suggests insufficient specificity of personalized therapy.

Multiple primary lung cancer (MPLC) is an increasingly prevalent subtype of lung cancer. According to recent genomic studies, the different lesions of a single MPLC patient exhibit functional similarities that may reflect evolutionary convergence. We perform whole-exome sequencing for a unique cohort of MPLC patients with multiple samples from each lesion found. Using our own and other relevant public data, evolutionary tree reconstruction reveals that cancer driver gene mutations occurred at the early trunk, indicating evolutionary contingency rather than adaptive convergence. Additionally, tumors from the same MPLC patient are as genetically diverse as those from different patients, while within-tumor genetic heterogeneity is significantly lower. Furthermore, the aberrant molecular functions enriched in mutated genes for a sample show a strong overlap with other samples from the same tumor, but not with samples from other tumors or other patients. Overall, there is no evidence of adaptive convergence during the evolution of MPLC. Most importantly, the similar between-tumor diversity and between-patient diversity suggest that personalized therapies may not adequately account for the genetic diversity among different tumors in an MPLC patient. To fully exploit the strategic value of precision medicine, targeted therapies should be designed and delivered on a per-lesion basis.

Endplate volumetric bone mineral density biomechanically matched interbody cage.

Disc degenerative problems affect the aging population, globally, and interbody fusion is a crucial surgical treatment. The interbody cage is the critical implant in interbody fusion surgery; however, its subsidence risk becomes a remarkable clinical complication. Cage subsidence is caused due to a mismatch of material properties between the bone and implant, specifically, the higher elastic modulus of the cage relative to that of the spinal segments, inducing subsidence. Our recent observation has demonstrated that endplate volumetric bone mineral density (EP-vBMD) measured through the greatest cortex-occupied 1.25-mm height region of interest, using automatic phantomless quantitative computed tomography scanning, could be an independent cage subsidence predictor and a tool for cage selection instruction. Porous design on the metallic cage is a trend in interbody fusion devices as it provides a solution to the subsidence problem. Moreover, the superior osseointegration effect of the metallic cage, like the titanium alloy cage, is retained. Patient-specific customization of porous metallic cages based on the greatest subsidence-related EP-vBMD may be a good modification for the cage design as it can achieve biomechanical matching with the contacting bone tissue. We proposed a novel perspective on porous metallic cages by customizing the elastic modulus of porous metallic cages by modifying its porosity according to endplate elastic modulus calculated from EP-vBMD. A three-grade porosity customization strategy was introduced, and direct porosity-modulus customization was also available depending on the patient's or doctor's discretion.

Patient-specific numerical investigation of the correction of cervical kyphotic deformity based on a retrospective clinical case.

Little research has been reported on evaluating the safety of the fixation construct in cervical kyphosis correction. In this study, we proposed a principal-strain criterion to evaluate the safety of the fixation construct and validated the modeling method against a retrospective case of anterior cervical discectomy fusion (ACDF). From C2 to T2 vertebra bodies, fixation instruments were reconstructed and positioned as per postoperative computed tomography (CT) scans. Head weight (HW) and various moments estimated from isometric strength data were imposed onto the C2. The postoperative stability of non-surgical segments, deformations surrounding the screw trajectories, and contact slipping on zygapophysial joints were analyzed. The model was validated against the reality that the patient had a good fusion and deformity correction. The ACDF restricted the range of motions (ROMs) of cervical segments and lent stability to vertebra fusion, no failure was found in the finite element (FE) model of cervical vertebrae. The deformation surrounding the screw trajectories were concentrated to the lateral sides of trajectories, recommending that the shape of the anterior cervical plate conforming to the curvature of the vertebra and screws fully inserted into vertebrae reduced the deformation concentration around the screw trajectories.

Non-Lethal Blasts can Generate Cavitation in Cerebrospinal Fluid While Severe Helmeted Impacts Cannot: A Novel Mechanism for Blast Brain Injury.

Cerebrospinal fluid (CSF) cavitation is a likely physical mechanism for producing traumatic brain injury (TBI) under mechanical loading. In this study, we investigated CSF cavitation under blasts and helmeted impacts which represented loadings in battlefield and road traffic/sports collisions. We first predicted the human head response under the blasts and impacts using computational modelling and found that the blasts can produce much lower negative pressure at the contrecoup CSF region than the impacts. Further analysis showed that the pressure waves transmitting through the skull and soft tissue are responsible for producing the negative pressure at the contrecoup region. Based on this mechanism, we hypothesised that blast, and not impact, can produce CSF cavitation. To test this hypothesis, we developed a one-dimensional simplified surrogate model of the head and exposed it to both blasts and impacts. The test results confirmed the hypothesis and computational modelling of the tests validated the proposed mechanism. These findings have important implications for prevention and diagnosis of blast TBI.

Learning curve of uniportal video-assisted thoracoscopic lobectomy: an analysis of the proficiency of 538 cases from a single centre.

OBJECTIVES: Uniportal video-assisted thoracoscopic surgery (UniVATS) is widely used as a minimally invasive thoracic operation. The goal of our study was to analyse the effect of long-term experience with the UniVATS lobectomy on the learning curve. METHODS: The learning curves were quantitatively evaluated by the unadjusted cumulative sum, and they were segmented using joinpoint linear regression analysis. The variables were compared between subgroups using trend analysis, and linear regression analysis was applied to correlate clinical characteristics at different stages of the learning curve with the duration of the operation. RESULTS: The learning curve for the UniVATS lobectomy can be divided into 3 phases of proficiency at ∼200-300 procedures, with a fourth phase as the number of procedures increases. The 1st-52nd, 52nd-156th, 156th-244th and 244th-538th procedures comprised the preliminary learning stage, preliminary proficiency stage, proficiency stage and advanced proficiency stage, respectively. Surgical outcomes and their variability between stages improved with increasing case numbers, with the most significant addition of an auxiliary operating port and conversions. In multivariable analysis, as stages progressed, influences other than surgical experience increased the operative time, with male and extensive pleural adhesions in the preliminary proficiency stage; male and incomplete pulmonary fissures in the proficiency stage; and male, extensive pleural adhesions and incomplete pulmonary fissures in the advanced proficiency stage. CONCLUSIONS: As the number of procedures increases, there may be 4 different proficiency stages in the UniVATS lobectomy learning curve. The surgeon enters the fourth stage at approximately the 244th procedure. Moreover, at stage 4, the perioperative indicators tend to stabilize, and influences other than surgical experience become more significant.

Mediastinal lymphadenectomy under laparoscopic assisted single-port inflatable mediastinoscopy through left neck approach.

Minimally invasive esophagectomy (MIE) has been developed for decades. However, conventional MIE requires transthoracic surgery, which can increase the risk of many perioperative cardiopulmonary complications. Therefore, mediastinoscopy-assisted transhiatal esophagectomy has been proposed, but the traditional surgical methods have shortcomings, such as unclear vision, especially during the dissection of mediastinal lymph nodes (LNs). A new approach for mediastinal lymphadenectomy under single-port inflatable mediastinoscopy with one left-neck incision is proposed. There are three difficulties in this procedure. (I) LNs along the left recurrent laryngeal nerve (RLN). After establishing pneumomediastinum, esophagectomy is performed over the aortic arch to the level of the lower edge of the left main bronchus, and lymphadenectomy along the left RLN is also accomplished during this process. (II) LNs along the right RLN. At the level of the lower edge of the right subclavian artery (RSA), between the trachea and the esophagus, instruments are used to access the right RLN. Lymphadenectomy of up to 2 cm can be accomplished at the upper edge of the RSA. (III) Subcarinal LNs. Between the trachea and esophagus, the left and right main bronchi are exposed along the trailing edge of the trachea down to the carina, and lymphadenectomy can be performed here. The surgical procedure described here in detail is the first mediastinal lymphadenectomy under mediastinoscopy with one single left-neck incision.

A meta-analysis of adjuvant EGFR-TKIs for patients with resected non-small cell lung cancer.

OBJECTIVES: We performed this meta-analysis to compare adjuvant EGFR-TKIs with a placebo or adjuvant chemotherapy among patients with resected non-small cell lung cancer (NSCLC). MATERIALS AND METHODS: A literature search was performed using relevant keywords. All randomized controlled trials (RCTs) that compared the survival benefits of adjuvant EGFR-TKIs with those of placebo or adjuvant chemotherapy for resected NSCLC were eligible for inclusion. RESULTS: The literature search yielded five eligible RCTs including three RCTs that compared adjuvant EGFR-TKIs with a placebo, and two RCTs that compared adjuvant EGFR-TKIs with chemotherapy. For unselected intent-to-treat patients who received adjuvant EGFR-TKIs versus a placebo, the hazard ratio (HR) of disease-free survival (DFS) was 0.88 (95% confidence interval (CI): 0.59-1.32; P = 0.54). For patients with an EGFR mutation, the DFS after adjuvant EGFR-TKIs was superior to that after a placebo, with a HR of 0.59 (95% CI: 0.40-0.88; P = 0.009). For patients with an EGFR mutation, the DFS after EGFR-TKIs was greater than that after chemotherapy, with a HR of 0.42 (95% CI: 0.19-0.93; P = 0.03). For patients with wild-type EGFR, the DFS of adjuvant EGFR-TKIs was similar to the placebo, with a RR of 1.00 (95% CI: 0.62-1.60; P = 0.99). Treatment with EGFR-TKIs resulted in more adverse events compared with the placebo, with a risk ratio (RR) of 2.72, (95% CI: 2.23-3.33; P < 0.00001), but fewer adverse events compared with chemotherapy, with an RR of 0.26 (95% CI: 0.18-0.38; P < 0.00001). CONCLUSIONS: For patients with resected NSCLC harboring EGFR mutations, treatment with an adjuvant EGFR-TKI was superior to that of a placebo or chemotherapy in terms of DFS. Treatment with adjuvant EGFR-TKIs were not effective among patients with wild type EGFR NSCLC.

Short-Term Effects and Safety Analysis of Retrograde Autologous Blood Priming for Cardiopulmonary Bypass in Patients with Cardiac Valve Replacement Surgery.

This randomized, double-blind study evaluated the short-term effects and safety of perioperative retrograde autologous priming (RAP) for cardiopulmonary bypass (CPB) in patients with cardiac replacement surgery to determine if this approach is a better substitute for crystal liquids priming in patients with valvular heart disease. We observed that RAP significantly decreased the actual priming volume, preserved the hematocrit and hemoglobin level during CPB to a certain degree, and decreased lactate accumulation in CPB period. Moreover, RAP lowered the volume of transfusion and dosage blood products. Thus, our results showed that RAP approach effectively improved tissue perfusion and lowered intraoperative Lac levels, by reducing the hemodilution, which safely and reliably improve the microcirculation perfusion.