Comparative biomechanical analysis of reconstruction and cephalomedullary nails in the treatment of osteoporotic subtrochanteric fractures.

INTRODUCTION: This study aimed to compare the biomechanical properties of two types of intramedullary nails - reconstruction nails (RCN) and cephalomedullary nails (CMN) - each with different proximal fixations, in a model of an osteoporotic subtrochanteric femoral fracture. This study focused on assessing stiffness and load to failure of RCN and CMN nails to provide insight into their clinical applications in osteoporotic fracture treatments. MATERIALS AND METHODS: Ten synthetic osteoporotic femoral models were used to generate a comminuted subtrochanteric fracture model. Five femurs were fixed using an RCN, and the remaining five were fixed using a CMN. The constructs were subjected to axial compression to measure their structural stiffness, load to failure, and failure modes. RESULTS: The CMN group demonstrated a slightly higher load to failure (mean, 2250 N) than the RCN group (mean, 2100 N), which was statistically significant (p = 0.008). However, the stiffness in both groups was statistically similar (RCN, 250 N/mm; CMN, 255 N/mm; p = 0.69). Both groups showed a load to failure exceeding 1500 N, a typically exerted load on the femoral head by a 75 kg individual. The failure patterns differed, with CMN failures starting at the nail insertion area and RCN failures starting at the reconstruction screw area. CONCLUSION: The RCN offers stiffness comparable to that of the CMN; although its load to failure is slightly lower than that of the CMN, it still exceeds the physiological tolerance limit. These findings suggest that the RCN is a viable alternative for treating osteoporotic subtrochanteric fractures.

A Study on Wheel Member Condition Recognition Using 1D-CNN.

The condition of a railway vehicle's wheels is an essential factor for safe operation. However, the current inspection of railway vehicle wheels is limited to periodic major and minor maintenance, where physical anomalies such as vibrations and noise are visually checked by maintenance personnel and addressed after detection. As a result, there is a need for predictive technology concerning wheel conditions to prevent railway vehicle damage and potential accidents due to wheel defects. Insufficient predictive technology for railway vehicle's wheel conditions forms the background for this study. In this research, a real-time tire wear classification system for light-rail rubber tires was proposed to reduce operational costs, enhance safety, and prevent service delays. To perform real-time condition classification of rubber tires, operational data from railway vehicles, including temperature, pressure, and acceleration, were collected. These data were processed and analyzed to generate training data. A 1D-CNN model was employed to classify tire conditions, and it demonstrated exceptionally high performance with a 99.4% accuracy rate.

A Study on Wheel Member Condition Recognition Using Machine Learning (Support Vector Machine).

The wheels of railway vehicles are of paramount importance in relation to railroad operations and safety. Currently, the management of railway vehicle wheels is restricted to post-event inspections of the wheels whenever physical phenomena, such as abnormal vibrations and noise, occur during the operation of railway vehicles. To address this issue, this paper proposes a method for predicting abnormalities in railway wheels in advance and enhancing the learning and prediction performance of machine learning algorithms. Data were collected during the operation of Line 4 of the Busan Metro in South Korea by directly attaching sensors to the railway vehicles. Through the analysis of key factors in the collected data, factors that can be used for tire condition classification were derived. Additionally, through data distribution analysis and correlation analysis, factors for classifying tire conditions were identified. As a result, it was determined that the z-axis of acceleration has a significant impact, and machine learning techniques such as SVM (Linear Kernel, RBF Kernel) and Random Forest were utilized based on acceleration data to classify tire conditions into in-service and defective states. The SVM (Linear Kernel) yielded the highest recognition rate at 98.70%.

Strain-Insensitive Stretchable Fiber Conductors Based on Highly Conductive Buckled Shells for Wearable Electronics.

Based on their high applicability to wearable electronics, fiber-based stretchable electronics have been developed via different strategies. However, the electrical conductivity of a fiber electrode is severely degraded, following deformation upon stretching. Despite the introduction of conductive buckled structures to resolve this issue, there still exist limitations regarding the simultaneous realizations of high conductivity and stretchability. Here, we exploit the dense distribution of the Ag nanoparticle (AgNP) network in polyurethane (PU) to fabricate a strain-insensitive stretchable fiber conductor comprising highly conductive buckled shells via a facile chemical process. These buckled AgNPs/PU fibers exhibit stable and reliable electrical responses across a wide range (tensile strain = ∼200%), in addition to their high electrical conductivity (26,128 S/m) and quality factor (Q = 2.29). Particularly, the negligible electrical hysteresis and excellent durability (>10,000 stretching-releasing cycles) of the fibers demonstrate their high applicability to wearable electronics. Furthermore, we develop buckled fiber-based pH sensors exhibiting stable, repeatable, and highly distinguishable responses (changing pH is from 4 to 8, response time is 5-6 s) even under 100% tensile strain. The buckled AgNPs/PU fibers represent a facile strategy for maintaining the stable electrical performances of fiber electrodes across the strain range of human motion for wearable applications.

Minimally Invasive Derotational Osteotomy of Long Bones: Smartphone Application Used to Improve the Accuracy of Correction.

Correction of rotational malalignments caused by fractures is essential as it may cause pain and gait disturbances. This study evaluated the intraoperative use of a smartphone application (SP app) to measure the extent of corrective rotation in patients treated using minimally invasive derotational osteotomy. Intraoperatively, two parallel 5 mm Schanz pins were placed above and below the fractured/injured site, and derotation was performed manually after percutaneous osteotomy. A protractor SP app was used intraoperatively to measure the angle between the two Schanz pins (angle-SP). Intramedullary nailing or minimally invasive plate osteosynthesis was performed after derotation, and computerized tomography (CT) scans were used to assess the angle of correction postoperatively (angle-CT). The accuracy of rotational correction was assessed by comparing angle-SP and angle-CT. The mean preoperative rotational difference observed was 22.1°, while the mean angle-SP and angle-CT were 21.6° and 21.3°, respectively. A significant positive correlation between angle-SP and angle-CT was observed, and 18 out of 19 patients exhibited complete healing within 17.7 weeks (1 patient exhibited nonunion). These findings suggest that using an SP app during minimally invasive derotational osteotomy can result in accurate correction of malrotation of long bones in a reproducible manner. Therefore, SP technology with integrated gyroscope function represents a suitable alternative for determination of the magnitude of rotational correction when performing corrective osteotomy.

Prophylactic Femoral Neck Fixation in an Osteoporosis Femur Model: A Novel Surgical Technique with Biomechanical Study.

Intramedullary nailing (IMN) is a popular treatment for elderly patients with femoral shaft fractures. Recently, prophylactic neck fixation has been increasingly used to prevent proximal femoral fractures during IMN. Therefore, this study aimed to investigate the biomechanical strength of prophylactic neck fixation in osteoporotic femoral fractures. An osteoporotic femur model was created to simulate the union of femoral shaft fractures with IMN. Two study groups comprising six specimens each were created for IMN with two standard proximal locking screws (SN group) and IMN with two reconstruction proximal locking screws (RN group). Axial loading was conducted to measure the stiffness, load-to-failure, and failure modes. There were no statistically significant differences in stiffness between the two groups. However, the load-to-failure in the RN group was significantly higher than that in the SN group (p < 0.05). Femoral neck fractures occurred in all specimens in the SN group. Five constructs in the RN group showed subtrochanteric fractures without femoral neck fractures. However, one construct was observed in both subtrochanteric and femoral neck fractures. Therefore, prophylactic neck fixation may be considered an alternative biomechanical solution to prevent proximal femoral fractures when performing IMN for osteoporotic femoral fractures.

The Combination PARP Inhibitor Olaparib With Temozolomide in an Experimental Glioblastoma Model.

BACKGROUND/AIM: Poly (ADP-ribose) polymerase (PARP) inhibition could enhance the efficacy of temozolomide and prolong survival in patients with glioblastoma. The aim of this study was to evaluate the combination of the PARP inhibitor olaparib with temozolomide in the treatment of glioblastoma. MATERIALS AND METHODS: The in vitro and in vivo antitumor effects of the PARP inhibitor olaparib together with temozolomide were evaluated. The in vitro experimental glioblastoma model involved O6-methylguanine methyltransferase (MGMT) promoter-methylated (U87MG, U251MG) and MGMT promoter-unmethylated (T98G) glioblastoma cell lines using In this model cell viability and apoptosis were assessed. For the in vivo studies, nude mice bearing orthotopically xenografted glioblastoma cell lines (U87MG) were randomized to four experimental groups: i) the untreated, ii) temozolomide alone, iii) olaparib alone and iv) olaparib and temozolomide combination groups. Mice were treated daily for 4 weeks and monitored for tumor growth and survival. RESULTS: In vitro we found that the combination of olaparib with temozolomide enhanced temozolomide-induced cytotoxicity in all glioblastoma cell lines regardless of the status of MGMT promoter methylation. In vivo, mice treated with temozolomide alone or in combination with olaparib showed greater survival than those untreated or with the olaparib monotherapy, as well as significantly decreased tumor volume. There was no significant difference in survival and tumor volume between temozolomide alone and the combination treatment. CONCLUSION: The combination of the PARP inhibitor olaparib with temozolomide could be promising candidates for combination therapy of glioblastoma regardless of the MGMT promoter methylation status.

Pullout strength of pedicle screws using cadaveric vertebrae with or without artificial demineralization.

OBJECTIVES: To evaluate the differences in the pullout strength and displacement of pedicle screws in cadaveric thoracolumbar vertebrae with or without artificial demineralization. METHODS: Five human lumbar and five thoracic vertebrae from one cadaver were divided into two hemivertebrae. The left-side specimens were included in the simulated osteopenic model group and the right-side bones in a control group. In the model group, we immersed each specimen in HCl (1 N) solution for 40 minutes. We measured bone mineral density (BMD) using dual-energy X-ray absorptiometry and quantitative computerized tomography. We inserted polyaxial pedicle screws into the 20 pedicles of the cadaveric lumbar and thoracic spine after measuring the BMD of the 2 hemivertebrae of each specimen. We measured the pullout strength and displacement of the screws before failure in each specimen using an Instron system. RESULTS: The average pullout strength of the simulated osteopenic model group was 76% that of the control group. In the control and model groups, the pullout strength was 1678.87±358.96 N and 1283.83±341.97 N, respectively, and the displacement was 2.07±0.34 mm and 2.65±0.50 mm, respectively (p<.05). We detected positive correlations between pullout strength and BMD in the control group and observed a negative correlation between displacement and BMD in the model group. CONCLUSIONS: By providing an anatomically symmetric counterpart, the human cadaveric model with or without demineralization can be used as a test bed for pullout tests of the spine. In the simulated osteopenic model group, pullout strength was significantly decreased compared with the untreated control group. CLINICAL SIGNIFICANCE: Decreased bone mineral density may significantly reduce the pullout strength of a pedicle screw, even though the range is osteopenic rather than osoteoporotic.

Conventional bicortical pin substitution with a novel unicortical pin in external fixation: A biomechanical study.

INTRODUCTION: As most patients with polytrauma or open fractures are converted from temporary external fixation to definite stabilization, the prevention of complications such as infection is especially important. To overcome the high risk of infection associated with the use of the conventional bicortical pin for temporary external fixation, the authors developed a novel unicortical pin and analyzed it in a biomechanical study. METHODS: The unicortical pin consisted of an inner screw, purchasing the cortical bone, and an outer sleeve with 6 spikes. A bicortical pin was used for the purpose of comparison. A fracture gap model was stabilized using a monoplanar configuration. Both the unicortical pins (Uni group) and bicortical pins (Bi group) underwent axial compressive and torsional load testing using a servo-hydraulic testing machine. Stiffness, load to failure, and mode of failure were documented. RESULTS: Stiffness and load to failure of the Uni group (average, 40.5 N/mm and 1098.4 N, respectively) were greater than that of the Bi group (average, 33.7 N/mm and 968.6 N, respectively) in the axial compressive load test (P = 0.008 and 0.032). Stiffness and load to failure of the Uni group (average, 1.2 Nm/degree and 1.7 Nm, respectively) were also significantly higher than those of the Bi group (average, 0.8 Nm/degree and 0.6 Nm, respectively) in the torsional load test (P = 0.008 and 0.016). All pins in the Bi group were bent at the pin-synthetic bone interface without synthetic bone failure. Contrarily, the Uni group did not show any pin bending or failure. However, in the axial compression test, partial cracks in the synthetic bone were found at the interface with spikes in the outer shell. In addition, in the torsion test, incomplete fractures were seen through the inner screws' holes. CONCLUSION: Compared with the conventional bicortical pin, the newly designed unicortical pin significantly increased fracture stability under both axial compressive and torsional loads. The unicortical pin can be considered an alternative biomechanical solution to obtain adequate stability when performing external fixation of fractures.