Effect of compressive and tensile forces on glucose concentration and cell viability within the intervertebral disc: A finite element study.

Understanding the role of mechanical force on tissue nutrient transport is essential, as sustained force may affect nutrient levels within the disc and initiate disc degeneration. This study aims to evaluate the time-dependent effects of different compressive force amplitudes as well as tensile force on glucose concentration and cell viability within the disc. Based on the mechano-electrochemical mixture theory, a multiphasic finite element model of the lumbar intervertebral disc was developed. The minimum glucose concentration and minimum cell density in both normal and degenerated discs were predicted for different compressive force amplitudes, tensile force, and corresponding creep time. Under high compressive force, the minimum glucose concentration exhibited an increasing and then decreasing trend with creep time in the normal disc, whereas that of the degenerated disc increased, then decreased, and finally increased again. At steady state, a higher compressive force was accompanied by a lower glucose concentration distribution. In the degenerated disc, the minimum cell density was negatively correlated with creep time, with a greater range of affected tissue under a higher compressive force. For tensile force, the minimum glucose concentration of the degenerated disc raised over time. This study highlighted the importance of creep time, force magnitude, and force type in affecting nutrient concentration and cell viability. Sustained weight-bearing activities could deteriorate the nutrient environment of the degenerated disc, while tensile force might have a nonnegligible role in effectively improving nutrient levels within the degenerated disc.

A nomogram to predict conversion of laparoscopic surgery to laparotomy for Choledocholithiasis.

BACKGROUND: Laparoscopic surgery is effective for treating common bile duct (CBD) stones. However, it has high requirements for surgeons and the risk of conversion to laparotomy cannot be ignored. However, when conditions during surgery are not favorable, persisting with laparoscopic procedures blindly can lead to serious complications. Our study aimed to establish a nomogram model for predicting conversion of laparoscopic to laparotomy for choledocholithiasis. MATERIALS AND METHODS: A total of 867 patients who were diagnosed with choledocholithiasis and underwent laparoscopic surgery were randomly divided into a training group (70%, n = 607) and a validation group (30%, n = 260). A nomogram was constructed based on the results of logistic regression analysis. The area under the receiver operating characteristic curve (AUC), calibration curve, and decision curve analysis (DCA) were used to assess the predictive performance of the nomogram. RESULTS: Previous upper abdominal surgery, maximum diameter of stone ≥12 mm, medial wall of the duodenum stone, thickening of the gallbladder wall, thickening of CBD wall, stone size/CBD size ≥0.75, and simultaneous laparoscopic hepatectomy were included in the nomogram. The AUC values were 0.813 (95% CI: 0.766-0.861) and 0.804 (95% CI: 0.737-0.871) in the training and validation groups, respectively. The calibration curve showed excellent consistency between the nomogram predictions and actual observations. DCA showed a positive net benefit for the nomogram. CONCLUSIONS: We constructed a nomogram with a good ability to predict conversion to open surgery in laparoscopic surgery for choledocholithiasis, which can help surgeons to make a reasonable operation plan before surgery and timely convert to laparotomy during operation to reduce potential harm to the patient.

A scoring system for gallbladder polyps based on the cross-sectional area and patient characteristics.

BACKGROUND: Current management guidelines for gallbladder polyps (GBPs) focus on a diameter more than 1 cm as an indication for cholecystectomy. Since most GBPs are not malignant, unnecessary cholecystectomies can lead to unnecessary complications and costs. We developed a score to identify true polyps focusing on their cross-sectional area (CSA). METHODS: We retrospectively analyzed the demographic, clinical, laboratory, and sonographic characteristics of 522 patients with GBPs who had undergone cholecystectomy at our hospital between January 2010 and July 2020 (reference group). We used univariate analysis to compare these parameters between 88 true polyps and 434 pseudopolyps and multivariate logistic regression analysis to identify parameters to include in our scoring model. Receiver operating characteristics and area under the curve were used to identify cut-off values. The model was tested on a validation group of 98 patients. RESULTS: In the multivariate analysis, a CSA >123 mm2, positive blood flow signal, age >55.5 years, alanine aminotransferase (ALT) levels > 50 U/L, and an ALT/aspartate aminotransferase ratio > 0.77 were significantly associated with true polyps (odds ratio 6.528, 2.377, 2.617, 2.445, and -0.372, respectively). A prediction model based on cut-off values was used to distinguish a low-risk and high-risk GBP group; true polyps accounted for 6.54% and 58.72%, respectively (p < 0.001). In the low-risk and high-risk validation groups, true polyps comprised 12.35% and 82.35%, respectively (p < 0.001). CONCLUSIONS: Our scoring system shows high accuracy and specificity in identifying true polyps and helps determine the need for surgical resection.