Pre-sliding of femoral neck system improves fixation stability in pauwels type III femoral neck fracture: a finite element analysis.

BACKGROUND: Femoral neck fractures are a common injury in older adults and their management presents a significant challenge for orthopedic surgeons. The Femoral Neck System (FNS) was recently introduced for the fixation of femur neck fractures. Although neck shortening was reduced with the FNS, the complication rates were not reduced. Thus, improvements to enhance fixation stability should be made for the FNS. We hypothesized that (1) the pre-sliding technique and (2) the use of longer anti-rotation screw would increase fracture stability. This study aimed to determine the change in fracture stability using the pre-sliding technique and long anti-rotation screw in the FNS for fixation of Pauwels type III femoral neck fractures. METHODS: Finite element models of Pauwels type III femoral neck fracture fixed with pre-sliding FNS and 5-mm longer anti-rotation screw were established. The models were subjected to normal walking load. The material properties of the elements belonging to the bone were mapped by assigning the formulation with the computed tomography Hounsfield unit. RESULTS: Pauwels type III femoral neck fractures fixed with pre-slided FNS showed better fracture stability, decreasing fracture gap and sliding by 14% and 12%, respectively, under normal walking load. No element of cortical bone in any of the models had an absolute value of principal strain that exceeded 1%. The peak von Mises stress (VMS) of the implants ranged from 260 to 289 MPa, and the highest peak VMS value was 50% lower than the yield strength of the titanium alloy (800 MPa). The longer anti-rotation screw did not affect fracture stability. CONCLUSIONS: The pre-sliding technique using the FNS showed higher fracture stability than the standard fixation technique for a Pauwels type III femoral neck fracture. The longer anti-rotation screw did not contribute significantly to fixation stability. As this finite element analysis considered the inhomogeneous mechanical property of the bone, it offered equivalent mechanical conditions to investigate the components of interest.

Trajectory of bolt and length of plate in femoral neck system determine the stability of femur neck fracture and risk of subsequent subtrochanteric fracture : a finite element analysis.

BACKGROUND: This study aimed to analyze the differences in the stability of fractures, stress distribution around the distal-most screw according to the length of the plate and the trajectory of the bolt in Pauwels type III femoral neck fracture using the femoral neck system (FNS). METHODS: Finite element models of Pauwels type III femoral neck fractures were established with surgical variations in the trajectory of the bolt (central, inferior, valgus, and varus) and length of the lateral plate (1- and 2-hole plate). The models were subsequently subjected to normal walking and stair-climbing loads. RESULTS: The screw-holding cortical bone in subtrochanter in the model with a 2-hole plate and the bolt in the inferior trajectory and the models with 1-hole or 2-hole plate and the bolt in valgus trajectory had shown greater maximum principal strain than the models with central or varus trajectories. The gap and sliding distance on the fracture surface were larger with inferior or varus trajectories of the bolt and smaller with the valgus trajectory of the bolt under both loads, compared to those of the central trajectory. CONCLUSION: For the fixation of Pauwels type III femoral neck fracture, the trajectory of the FNS bolt and the length of the plate affect the mechanical stability of the fracture and the strain of cortical bone around the distal-most screw. The surgical target should stay on the central trajectory of the bolt and the 2-hole plate's mechanical benefits did not exceed the risk.

Ultrasonic fatigue analysis of 3D-printed carbon fiber reinforced plastic.

The development of 3D printing technologies using composite materials has revolutionized additive manufacturing. Using these technologies, various products can be fabricated with strengths beyond the limits of the strength of the polymer used. However, although parts manufactured using carbon fiber reinforced plastic (CFRP) 3D printing have excellent characteristics, research on their durability is lacking, making their application difficult in the real industry. In this study, an ultrasonic fatigue test was conducted on a CFRP material manufactured by 3D printing to evaluate fatigue performance. Because of the characteristics of CFRP, the strength varies depending on the orientation angle of the carbon fiber, and the durability also varies. Therefore, an experiment on three types of specimens mixed in the bi-direction and uni-direction of 0° and 90° was conducted. For the ultrasonic fatigue test, a specimen design with a special shape is required according to the resonance frequency and dynamic modulus of the material. To this end, a specimen was designed based on measurements of the physical properties of the material according to the angle of the fiber, which were verified by Finite element method (FEM) modal analysis, and the fatigue life was estimated through an actual experiment. The fatigue failure life was simulated by FEM fatigue analysis considering the measured fatigue test results and the derived anisotropic properties simultaneously. Additionally, based on the advantages of CFRP 3D printing, which adjusts the fiber pattern, we fabricated a specimen with a concentric pattern to derive the fatigue life and calculate the actual life improvement. Based on the results of this study, the specific rigidity of the CFRP parts can be optimized by adjusting the fiber pattern. Additionally, the results of this study can aid in the analysis of the fatigue characteristics of 3D-printed CFRP materials.

Mechanical effects of surgical variations in the femoral neck system on Pauwels type III femoral neck fracture : a finite element analysis.

AIMS: In this study, we aimed to explore surgical variations in the Femoral Neck System (FNS) used for stable fixation of Pauwels type III femoral neck fractures. METHODS: Finite element models were established with surgical variations in the distance between the implant tip and subchondral bone, the gap between the plate and lateral femoral cortex, and inferior implant positioning. The models were subjected to physiological load. RESULTS: Under a load of single-leg stance, Pauwels type III femoral neck fractures fixed with 10 mm shorter bolts revealed a 7% increase of the interfragmentary gap. The interfragmentary sliding, compressive, and shear stress remained similar to models with bolt tips positioned close to the subchondral bone. Inferior positioning of FNS provided a similar interfragmentary distance, but with 6% increase of the interfragmentary sliding distance compared to central positioning of bolts. Inferior positioning resulted in a one-third increase in interfragmentary compressive and shear stress. A 5 mm gap placed between the diaphysis and plate provided stability comparable to standard fixation, with a 7% decrease of interfragmentary gap and sliding distance, but similar compressive and shear stress. CONCLUSION: Finite element analysis with FNS on Pauwels type III femoral neck fractures revealed that placement of the bolt tip close to subchondral bone provides increased stability. Inferior positioning of FNS bolt increased interfragmentary sliding distance, compressive, and shear stress. The comparable stability of the fixation model with the standard model suggests that a 5 mm gap placed between the plate and diaphysis could viably adjust the depth of the bolt. Cite this article: Bone Joint Res 2022;11(2):102-111.

Phase Transformations and Subsurface Changes in Three Dental Zirconia Grades after Sandblasting with Various Al2O3 Particle Sizes.

Although sandblasting is mainly used to improve bonding between dental zirconia and resin cement, the details on the in-depth damages are limited. The aim of this study was to evaluate phase transformations and subsurface changes after sandblasting in three different dental zirconia (3, 4, and 5 mol% yttria-stabilized zirconia; 3Y-TZP, 4Y-PSZ, and 5Y-PSZ). Zirconia specimens (14.0 × 14.0 × 1.0 mm3) were sandblasted using different alumina particle sizes (25, 50, 90, 110, and 125 µm) under 0.2 MPa for 10 s/cm2. Phase transformations and residual stresses were investigated using X-ray diffraction and the Williamson-Hall method. Subsurface damages were evaluated with cross-sections by a focused ion beam. Stress field during sandblasting was simulated by the finite element method. The subsurface changes after sandblasting were the emergence of a rhombohedral phase, micro/macro cracks, and compressive/tensile stresses depending on the interactions between blasting particles and zirconia substrates. 3Y-TZP blasted with 110-µm particles induced the deepest transformed layer with the largest compressive stress. The cracks propagated parallel to the surface with larger particles, being located up to 4.5 µm under the surface in 4Y- or 5Y-PSZ subgroups. The recommended sandblasting particles were 110 µm for 3Y-TZP and 50 µm for 4Y-PSZ or 5Y-PSZ for compressive stress-induced phase transformations without significant subsurface damages.

High-Performance Nonfullerene Organic Photovoltaics Applicable for Both Outdoor and Indoor Environments through Directional Photon Energy Transfer.

With the advent of the smart factory and the Internet of Things (IoT) sensors, organic photovoltaics (OPVs) gained attention because of their ability to provide indoor power generation as an off-grid power supply. To satisfy these applications, OPVs must be capable of power generation in both outdoor and indoor at the same time for developing environmentally independent devices. For high performances in indoor irradiation, a strategy that maximizes photon utilization is essential. In this study, graphene quantum dots (GQDs), which have unique emitting properties, are introduced into a ZnO layer for efficient photon utilization of nonfullerene-based OPVs under indoor irradiation. GQDs exhibit high absorption properties in the 350-550 nm region and strong emission properties in the visible region due to down-conversion from lattice vibration. Using these properties, GQDs provide directional photon energy transfer to the bulk-heterojunction (BHJ) layer because the optical properties overlap. Additionally, the GQD-doped ZnO layer enhances shunt resistance (RSh) and forms good interfacial contact with the BHJ layer that results in increased carrier dissociation and transportation. Consequently, the fabricated device based on P(Cl-Cl)(BDD = 0.2) and IT-4F introduces GQDs exhibiting a maximum power conversion efficiency (PCE) of 14.0% with a superior enhanced short circuit current density (JSC) and fill factor (FF). Furthermore, the fabricated device exhibited high PCEs of 19.6 and 17.2% under 1000 and 200 lux indoor irradiation of light emitting diode (LED) lamps, respectively.

Mechanical effect of different implant caput-collum-diaphyseal angles on the fracture surface after fixation of an unstable intertrochanteric fracture: A finite element analysis.

BACKGROUND/OBJECTIVE: The choice of implant is one of the most easily controllable factors affecting the outcome of intertrochanteric fractures. While most of the caput-collum-diaphysis (CCD) angles of the femur are within the range of 125° and 130°, there is a shortage of data on whether 125° or 130° implants are preferable. Thus, the present finite element analysis (FEA) aimed to compare the biomechanical effects on the fracture surface when using implants with different CCD angles where the anatomical CCD angle of the femur was between 125° and 130°. METHODS: After establishing a finite element model of an unstable intertrochanteric fracture from the femur with a native CCD angle of 127.3°, proximal femoral nail antirotation (PFNA) models with CCD angles of 125° and 130° were virtually implanted to have the same position of screw tip, respectively. RESULTS: In the one-leg stance during walking, when the implant with 130º CCD angle was used, the magnitude of compressive stress (1.61 and 2.12 MPa in the 130° and 125° model, respectively) was lower and the area of the fracture surface under tensile stress (55% and 5% in 130° and 125° model, respectively), the interfragmentary movements (40.9% more movement in 130° model), and the magnitude of bone deformation (23.5% more deformation in 130° model) were more than those of the 125° model. CONCLUSION: The intertrochanteric fracture fixed with PFNA with a 125º CCD angle revealed less interfragmentary movement on the fracture surface when the native CCD was an in-between angle in the FEA.

Treatment Response and Long-Term Outcome of Peginterferon α and Ribavirin Therapy in Korean Patients with Chronic Hepatitis C.

BACKGROUND/AIMS: Peginterferon plus ribavirin remains a standard therapy for patients with chronic hepatitis C (CHC) in Korea. We investigated the efficacy and long-term outcome of peginterferon and ribavirin therapy in Korean patients with CHC, particularly in relation to the stage of liver fibrosis. METHODS: The incidence of sustained virological response (SVR), hepatic decompensation, hepatocellular carcinoma, and liver-related death was analyzed in 304 patients with CHC; the patients were followed up for a median of 54 months. RESULTS: Among patients with HCV genotype 1, the SVR rate was 36.7% (18/49) and 67% (69/103) for patients with and without cirrhosis, respectively (p<0.001). For patients with non-1 HCV genotypes, the SVR rates were 86.0% (37/43) in cirrhotic patients and 86.2% (94/109) in noncirrhotic patients. SVR significantly reduced the risk of liverrelated death, hepatic decompensation, and hepatocellular carcinoma, which had hazard ratios of 0.27, 0.16, and 0.22, respectively (all p<0.05). However, despite the SVR rate, patients with advanced fibrosis were still at risk of developing liver-related complications. CONCLUSIONS: A relatively high SVR rate was achieved by peginterferon plus ribavirin therapy in Korean patients with CHC, which improved their long-term outcomes. However, all CHC patients with advanced hepatic fibrosis should receive close follow-up observations, even after successful antiviral treatment.

The management and prognosis of patients with hepatocellular carcinoma: what has changed in 20 years?

BACKGROUND & AIMS: There has been remarkable progress in the management of hepatocellular carcinoma (HCC) during the last several decades, but its effect on the prognosis of HCC patient needs clarification. We analysed the changes that affected prognosis of HCC patients diagnosed over two different eras. METHODS: A retrospective study of 1318 patients diagnosed with HCC from 1986 to 2012 was conducted. Analysis was done according to two cohorts, cohort 1 (patients diagnosed with HCC from 1986 to 1992) and cohort 2 (patients diagnosed from 2006 to 2012). RESULTS: Hepatitis B virus was the most common cause of liver disease for both cohorts (66.2% and 66.0%). The proportion of patients with Barcelona Clinic Liver Cancer stage 0/A was significantly lower in cohort 1 than in cohort 2 (14.4% vs. 39.5%, P < 0.001). The proportions of patients diagnosed during surveillance and general health check-up were significantly higher in cohort 2 than in cohort 1 (28.6% vs. 10.6% and 26.3% vs. 7.9%, respectively) while those diagnosed during symptomatic evaluation was significantly higher in cohort 1 than in cohort 2 (45.1 vs. 81.4%, P < 0.001). Surgical resection rate was similar between the two cohorts (26.1% vs 26%) while the transcatheter arterial chemoembolization rate which was the highest in cohort 1 (40.6%) was overtaken by radiofrequency ablation in cohort 2 (55%) at BCLC stage 0/A. Median survival duration in cohort 2 was significantly longer than cohort 1 (65.0 vs. 7.9 months, P < 0.001). CONCLUSIONS: Implementation of national cancer surveillance and the advancement of treatment modalities have likely led to early detection of HCC and improvements in prognosis over the last 20 years.

BCLC stage B is a better designation for single large hepatocellular carcinoma than BCLC stage A.

BACKGROUND AND AIM: Although the Barcelona Clinic Liver Cancer (BCLC) staging system is widely used for hepatocellular carcinoma (HCC) staging, the most appropriate BCLC stage designation for single large HCC (SLHCC, single nodule > 5 cm) remains controversial. This study investigated the prognosis of patients with SLHCC. METHODS: Patients with newly diagnosed HCCs (BCLC stages A or B) were classified according to tumor burden: group 1, a single nodule > 2 and ≤ 5 cm or two or three nodules ≤ 3 cm; group 2, a single nodule > 5 cm; and group 3, two or three nodules > 3 cm or > 3 nodules. Survival analysis was performed according to tumor stage, treatment type, and Child-Pugh grade. RESULTS: A total of 1005 patients were enrolled. Age was 59.3 ± 10.6 years, and 788 patients (78.4%) were men. Groups 1, 2, and 3 consisted of 613 (61.0%), 124 (12.3%), and 268 (26.7%) patients, respectively. HCC treatment included resection in 202 patients (20.1%), radiofrequency ablation ± transarterial chemoembolization in 311 patients (30.9%), and transarterial chemoembolization in 492 patients (49.0%). The median survival time differed significantly according to tumor stage (75.2, 44.9, and 30.3 months in groups 1, 2, and 3, respectively; P < 0.001). Multivariate analysis showed that group 2 had significantly worse survival compared with group 1 and similar survival to group 3. CONCLUSIONS: Patients in group 2 had a worse prognosis than those in group 1 and a similar prognosis to those in group 3. Our results suggest that BCLC stage B is the best stage designation for SLHCC.

Caroli's disease misdiagnosed as intraductal papillary neoplasm of the bile duct.

Caroli's disease is a rare autosomal-recessive disorder caused by malformation of the ductal plate during embryonic development. Although it is present at birth, Caroli's disease is typically not diagnosed until between the second and fourth decades of life, as it was in the present patient. Here we report a rare case of Caroli's disease limited to one liver segment, which was initially misdiagnosed as an intraductal papillary neoplasm of the bile duct. The asymptomatic patient was treated with liver segmentectomy.

Risk Factors for Developing Hyponatremia During Terlipressin Treatment: A Retrospective Analyses in Variceal Bleeding.

GOALS: The aim of this study was to evaluate the risk factors and clinical significance of terlipressin-induced hyponatremia. BACKGROUND: Patients receiving terlipressin treatment frequently develop hyponatremia. However, its clinical significance and risk factors are not fully elucidated. STUDY: Records of patients treated with terlipressin for variceal bleeding were analyzed. Hyponatremia was defined as a decrease in serum sodium (Na) level of >5 mEq/L from the baseline level; severe hyponatremia as a decrease in serum Na level of >10 mEq/L from the baseline level; and rapid severe hyponatremia as a decrease in serum Na level of >10 mEq/L within 3 days of treatment. RESULTS: The study involved 151 patients (mean age, 55.1±11.8 y) with male predominance (80.8%). Baseline serum Na and creatinine levels were 137.2±6.1 mEq/L and 0.9±0.4 mg/dL, respectively. Patients were treated with terlipressin for 4.5±1.9 days. Changes in serum Na levels from baseline were 0.4±4.1, -1.1±4.8, -4.0±7.0, -6.5±9.1, and -6.1±11.2 mEq/L, whereas the frequencies of hyponatremia and severe hyponatremia were 13.6%, 30.4%, 50.8%, 63.5%, and 66.9% and 0%, 8.8%, 23.3%, 33.0%, and 38.8% on days 1, 2, 3, 4, and 5 of treatment, respectively. Younger age, lower Child-Pugh score, higher serum Na level, and longer duration of terlipressin treatment were independent risk factors. Rapid severe hyponatremia developed in 29 patients (19.2%); lower body mass index was an additional risk factor in this group. Mortality was not associated with hyponatremia. CONCLUSIONS: Terlipressin-induced hyponatremia occurred frequently, especially in young patients with good liver function and higher Na level. Caution is required when administering terlipressin to patients with low body mass index.

Acute duodenal ischemia and periampullary intramural hematoma after an uneventful endoscopic retrograde cholangiopancreatography in a patient with primary myelofibrosis.

Acute duodenal ischemia and periampullary intramural hematoma are rare complications after endoscopic retrograde cholangiopancreatography (ERCP). A 77-year-old man with splenomegaly complained of abdominal pain caused by common bile duct (CBD) stone. After successful removal of the CBD stone without immediate complications, the patient developed intramural hematoma around the ampulla of Vater along with diffuse duodenal edema. The findings were compatible with acute intestinal ischemia, and further evaluation revealed that he had underlying primary myelofibrosis. Myeloproliferative diseases are known to be significantly associated with an increased risk of thrombohemorrhagic complications. Therefore, particular attention should be given to this group of patients when a high-risk procedure such as ERCP is performed.

Development of enterohepatic fistula after embolization in ileal gastrointestinal stromal tumor: a case report.

Gastrointestinal stromal tumor (GIST) is a rare mesenchymal tumor of the gastrointestinal tract that has been associated with the formation of fistulas to adjacent organs in few case reports. However, GIST with enterohepatic fistula has not been reported. Here we report the case of an enterohepatic fistula that occurred after embolization of a liver mass originating in the distal ileum. An 87-year-old woman was hospitalized for melena. On initial conventional endoscopy, a bleeding focus in the gastrointestinal tract was not found. Because of massive hematochezia, enteroscopy was performed through the anus. A protruding, ulcerative mass was found in the distal ileum that was suspected to be the source of the bleeding; a biopsy sample was taken. Electrocoagulation was not successful in controlling the bleeding; therefore, embolization was performed. After embolization, the patient developed a high fever and severe abdominal tenderness with rebound tenderness. Follow-up abdominopelvic computed tomography revealed an enterohepatic fistula between the liver and distal ileum. The fistula was treated surgically by segmental resection of the distal ileum and unlooping of the liver mass.