Current Diagnosis and Treatment of Acute Pancreatitis in Korea: A Nationwide Survey.

Background/Aims: : Acute pancreatitis (AP) is a leading cause of emergency hospitalization. We present the current diagnostic and therapeutic status of AP as revealed by analysis of a large multicenter dataset. Methods: : The medical records of patients diagnosed with AP between 2018 and 2019 in 12 tertiary medical centers in Korea were retrospectively reviewed. Results: : In total, 676 patients were included; of these, were 388 (57.4%) males, and the mean age of all patients was 58.6 years. There were 355 (52.5%), 301 (44.5%), and 20 (3.0%) patients with mild, moderate, and severe AP, respectively, as assessed by the revised Atlanta classification. The most common etiologies of AP were biliary issues (41.6%) and alcohol consumption (24.6%), followed by hypertriglyceridemia (6.8%). The etiology was not identified in 111 (16.4%) patients at the time of initial admission. The overall mortality rate was 3.3%, increasing up to 45.0% among patients with severe AP. Notably, 70.0% (14/20) of patients with severe AP and 81.5% (154/189) of patients with systemic inflammatory response syndrome had received <4 L per day during the initial 24 hours of admission. Only 23.8% (67/281) of acute biliary pancreatitis patients underwent cholecystectomy during their initial admission. In total, 17.8% of patients experienced recurrent attacks during follow-up. However, none of the patients with acute biliary pancreatitis experienced recurrent attacks if they had undergone cholecystectomy during their initial admission. Conclusions: : This study provides insights into the current status of AP in Korea, including its etiology, severity, and management. Results: reveal disparities between clinical guidelines and their practical implementation for AP treatment.

Biomechanical Characteristics of Glenosphere Orientation Based on Tilting Angle and Overhang Changes in Reverse Shoulder Arthroplasty.

Background: Glenoid position and inclination are important factors in protecting against scapular notching, which is the most common complication that directly affects the longevity of reverse shoulder arthroplasty (RSA). This study aimed to investigate the biomechanical characteristics of glenosphere orientation, comparing neutral tilt, inferior overhang with an eccentric glenosphere at the same placement of baseplate, and inferior tilt after 10° inferior reaming in the lower part of the glenoid in RSA. Methods: Nine cadaveric shoulders were tested with 5 combinations of customized glenoid components: a centric glenosphere was combined with a standard baseplate (group A); an eccentric glenosphere to provide 4-mm inferior overhang than the centric glenosphere was combined with a standard baseplate (group B); a centric glenosphere was combined with a wedge-shaped baseplate tilted inferiorly by 10° with the same center of rotation (group C); an eccentric glenosphere was attached to a wedge-shaped baseplate (group D); and 10° inferior reaming was performed on the lower part of the glenoid to apply 10° inferior tilt, with a centric glenosphere secured to the standard baseplate for simulation of clinical tilt (group E). Impingement-free angles for adduction, abduction, forward flexion, external rotation, and internal rotation were measured. The capability of the deltoid moment arm for abduction and forward flexion, deltoid length, and geometric analysis for adduction engagement were evaluated. Results: Compared with neutral tilt, inferior tilt at the same position showed no significant difference in impingement-free angle, moment arm capability, and deltoid length. However, group D resulted in better biomechanical properties than a central position, regardless of inferior tilt. Group E demonstrated a greater range of adduction, internal and external rotation, and higher abduction and forward flexion capability with distalization, compared to corresponding parameters for inferior tilt with a customized wedge-shaped baseplate. Conclusions: A 10° inferior tilt of the glenosphere, without changing the position of the baseplate, had no benefit in terms of the impingement-free angle and deltoid moment arm. However, an eccentric glenosphere had a significant advantage, regardless of inferior tilt. Inferior tilt through 10° inferior reaming showed better biomechanical results than neutral tilt due to the distalization effect.

Practice guidelines for managing extrahepatic biliary tract cancers.

Backgrounds/Aims: Reported incidence of extrahepatic bile duct cancer is higher in Asians than in Western populations. Korea, in particular, is one of the countries with the highest incidence rates of extrahepatic bile duct cancer in the world. Although research and innovative therapeutic modalities for extrahepatic bile duct cancer are emerging, clinical guidelines are currently unavailable in Korea. The Korean Society of Hepato-Biliary-Pancreatic Surgery in collaboration with related societies (Korean Pancreatic and Biliary Surgery Society, Korean Society of Abdominal Radiology, Korean Society of Medical Oncology, Korean Society of Radiation Oncology, Korean Society of Pathologists, and Korean Society of Nuclear Medicine) decided to establish clinical guideline for extrahepatic bile duct cancer in June 2021. Methods: Contents of the guidelines were developed through subgroup meetings for each key question and a preliminary draft was finalized through a Clinical Guidelines Committee workshop. Results: In November 2021, the finalized draft was presented for public scrutiny during a formal hearing. Conclusions: The extrahepatic guideline committee believed that this guideline could be helpful in the treatment of patients.

Comparison of long-term outcomes of endoscopic ultrasound-guided hepaticogastrostomy and choledochoduodenostomy for distal malignant biliary obstruction: a multicenter retrospective study.

Background: Endoscopic ultrasound-guided biliary drainage (EUS-BD), classified as choledochoduodenostomy (CDS) and hepaticogastrostomy (HGS), is a feasible and effective alternative for distal malignant biliary obstruction (MBO) in failed endoscopic retrograde cholangiopancreatography. However, the preferred technique for better outcomes has not yet been evaluated. Objectives: We compared the long-term outcomes between the techniques. Design: Retrospective comparative study. Methods: We reviewed consecutive patients who underwent EUS-CDS or EUS-HGS with transmural stent placement for distal MBO between 2009 and 2022. The primary outcome was the stent patency. The secondary outcomes were technical and clinical success, adverse events (AEs) of each technique, and independent risk factors for stent dysfunction. Results: In all, 115 patients were divided into EUS-CDS (n = 56) and EUS-HGS (n = 59) groups. Among them, technical success was achieved in 98.2% of EUS-CDS and 96.6% of EUS-HGS groups. Furthermore, clinical success was 96.4% in EUS-CDS and 88.1% in EUS-HGS groups, without significant difference (p = 0.200). The mean duration of stent patency for EUS-CDS was 770.3 days while that for EUS-HGS was 164.9 days (p = 0.010). In addition, the only independent risk factor for stent dysfunction was systematic treatment after EUS-BD [hazard ratio and 95% confidence interval 0.238 (0.066-0.863), p = 0.029]. The incidence of stent dysfunction of EUS-HGS was higher than EUS-CDS (35.1% versus 18.2%, 0.071), despite no significant differences even in late AEs. Conclusion: In distal MBO, EUS-CDS may be better than EUS-HGS with longer stent patency and fewer AEs. Furthermore, systematic treatment after EUS-BD is recommended for the improvement of stent patency.

Comparison between Anatomic Total Shoulder Arthroplasty and Reverse Shoulder Arthroplasty for Older Adults with Osteoarthritis without Rotator Cuff Tears.

Background: Many older adults with glenohumeral osteoarthritis without rotator cuff tears experience muscle atrophy and fatty degeneration. In these cases, range of motion (ROM) recovery and clinical results after total shoulder arthroplasty (TSA) could be poor, with low subjective satisfaction after surgery. The purpose of this study was to compare the clinical outcomes of anatomic TSA and reverse shoulder arthroplasty (RSA) in patients aged over 70 years with primary glenohumeral osteoarthritis without rotator cuff tears. We hypothesized that the clinical outcomes of anatomical TSA would be better than those of RSA. Methods: This single-center, retrospective comparative study involved patients who underwent TSA or RSA from 2013 to 2020. Clinical outcomes were assessed using the American Shoulder and Elbow Surgeons (ASES) score, Constant-Murley score, and active ROM preoperatively and at the follow-up. Walch classification and glenoid version angle were measured using preoperative computed tomography, and fatty infiltration of supraspinatus and infraspinatus muscles were checked through preoperative magnetic resonance imaging. Results: Of the 67 patients included in this study, TSA was performed in 41 patients (TSA group), and RSA was performed in 26 patients (RSA group). The two groups had no clinical differences in the patients' preoperative demographic and radiographic data. At the final follow-up, both groups showed improved pain, ROM, and functional outcomes. Moreover, the TSA group demonstrated significantly better postoperative ASES (86.8 ± 6.3 vs. 81.6 ± 5.5, p = 0.001) and Constant-Murley (80.4 ± 5.7 vs. 73.4 ± 6.2, p < 0.001) scores than the RSA group. The TSA group showed a significantly better postoperative active ROM than the RSA group regarding forward flexion as well as external and internal rotations (p < 0.001). All patients in the RSA and TSA groups exceeded the minimal clinically important difference. Conclusions: In older adult patients with degenerative glenohumeral osteoarthritis wherein the rotator cuff is preserved without excessive bone loss, anatomic TSA and RSA can improve pain, ROM, and clinical outcomes. However, clinical results and ROM were better with TSA than with RSA during the short- and mid-term follow-up periods.

Diagnosis and Treatment of Perihilar Cholangiocarcinoma: A National Survey from the Korean Pancreatobiliary Association.

Background/Aims: Based on their anatomy, cholangiocarcinomas (CCAs) are classified into intrahepatic, hilar, and distal CCAs. Although the diagnosis and treatment of each type of CCA are thought to be different, real-world data studies on the current practice are limited. Therefore, this study was designed to capture the current practice of diagnosing and treating perihilar CCA in Korea. Methods: We conducted a survey using an online platform. The questionnaire consisted of 18 questions designed to evaluate the current practice of diagnosing and treating perihilar CCA in Korea. The targets of this survey were biliary endoscopists who are members of the Korean Pancreatobiliary Association. Results: In total, 119 biliary endoscopists completed the survey. Of the respondents, 89.9% thought that the use of the International Classification of Diseases, 11th Revision (ICD-11) system is necessary to classify CCA. Approximately half of the respondents would recommend surgery or chemotherapy until patients were 80 years of age. For the pathological diagnosis of CCA, endoscopic retrograde cholangiopancreatography with biopsy was the most preferred modality. Routine preoperative biliary drainage was performed by 44.5% of the respondents. For operable CCAs, 64.7% of the respondents preferred endoscopic biliary drainage using plastic stents. For palliative biliary drainage, 69.7% of the respondents used plastic stents. For palliative endoscopic biliary drainage using metal stents, 63% of the respondents preferred the stent-in-stent method. Conclusions: A new coding system using the ICD-11 is needed for classifying CCAs. Guidelines for diagnosing and treating CCA based on the clinical situation in Korea are needed.

No Difference In Clinical Outcomes Following Repair of Large Retracted Anterior Rotator Cuff Tears Using Patch Augmentation With Human Dermal Allograft Versus Anterior Cable Reconstruction With Biceps Tendon Autograft.

PURPOSE: To compare the clinical outcomes and tendon integrity after rotator cuff repair combined with anterior cable reconstruction (ACR) using the proximal biceps tendon and patch augmentation (PA) using a human dermal allograft (HDA) in a large retracted anterior rotator cuff tear. METHODS: Patients who underwent arthroscopic rotator cuff repair with 2 different augmentation procedures between January 2017 and December 2020 were enrolled. The inclusion criteria were patients who were treated by arthroscopic rotator cuff repair with ACR using the proximal biceps tendon (ACR group) or patch augmentation using a an HDA (PA group) and follow-up for at least 2 years. Clinical outcomes were assessed using American Shoulder and Elbow Surgeons (ASES) score, Constant score, and the number of patients who achieved minimal clinically important differences (MCID). Magnetic resonance imaging was performed to evaluate tendon integrity after surgery. RESULTS: A total of 92 patients were enrolled (ACR group = 55 patients and PA group = 37 patients). The mean ASES and Constant scores significantly improved in the ACR group (68.8 ± 15.3 and 58.4 ± 16.9 before surgery vs 91.4 ± 6.3 and 87.8 ± 6.0 after surgery, P < .001) and in the PA group (63.7 ± 16.7 and 57.9 ± 15.4 before surgery vs 93.1 ± 6.3 and 88.3 ± 6.2 after surgery, P < .001). Overall, 78 patients (84.8%) achieved the MCID with 81.8% in the ACR group and 89.2% in the PA group, with no significant differences between the 2 groups (P = .638). Ten patients (18.2%) had retear in the ACR group, and three patients (8.1%) had retear in the PA group (P = .174). CONCLUSIONS: In large retracted anterior rotator cuff tears, both augmentation techniques using biceps tendon autograft and HDA provided satisfactory clinical outcomes that achieved the MCID in 84.8%, range of motion restoration, and lower retear rates with no significant differences between the two groups. LEVEL OF EVIDENCE: Level III, retrospective case-control study.

Quality indicators of endoscopic ultrasound in the pancreatobiliary system: a brief review of current guidelines.

Since its development, the use of endoscopic ultrasonography (EUS) in the pancreas and the biliary tract has become increasingly important. The accuracy of EUS varies depending on the experience of the endoscopist. Hence, quality control measures using appropriate indicators are required to reduce these variations. American Society for Gastrointestinal Endoscopy and European Society of Gastrointestinal Endoscopy have announced the EUS quality indicators. Here, we reviewed the quality indicators of the EUS procedure in the current published guidelines.

Endoscopic Gallbladder Drainage Conversion versus Conservative Treatment Following Percutaneous Gallbladder Drainage in High-Risk Surgical Patients.

Background/Aims: There are no consensus guidelines for patients with acute cholecystitis undergoing percutaneous cholecystostomy who are unfit for interval cholecystectomy. The current study aimed to compare the clinical outcomes of endoscopic gallbladder drainage, i.e. conversion from percutaneous cholecystostomy (including endoscopic transpapillary gallbladder stenting and endoscopic ultrasound-guided gallbladder drainage), and conservative treatment after percutaneous cholecystostomy tube removal. Methods: This retrospective review included patients who underwent percutaneous cholecystostomy for acute cholecystitis between January 2017 and December 2020. Consecutive patients who underwent endoscopic gallbladder drainage or percutaneous cholecystostomy tube removal without interval cholecystectomy were included. Outcome measures included recurrent acute cholecystitis and unplanned readmission due to gallstone-related diseases. Results: During the study period, 238 patients were selected (63 underwent endoscopic gallbladder drainage conversion and 175 underwent conservative treatment). Patients who underwent endoscopic gallbladder drainage conversion had lower rates of recurrent acute cholecystitis (3 [4.76%] vs 31 [17.71%], p=0.012) and unplanned readmission due to gallstone-related diseases (6 [9.52%] vs 40 [22.86%], p=0.022) than those who underwent conservative treatment following percutaneous cholecystostomy tube removal. In the univariate and multivariate analyses, calculus cholecystitis (odds ratio, 13.75; 95% confidence interval, 1.83 to 102.83; p=0.011) and conversion of endoscopic gallbladder drainage (odds ratio, 0.23; 95% confidence interval, 0.06 to 0.78; p=0.019) were significant predictive factors for recurrent acute cholecystitis. Conclusions: Endoscopic gallbladder drainage conversion led to more favorable outcomes than conservative treatment after percutaneous cholecystostomy tube removal. Therefore, endoscopic gallbladder drainage conversion may be considered a promising treatment option for patients undergoing percutaneous cholecystostomy who are at a high surgical risk.

Index Finger Flexor Digitorum Profundus Function Deficit after Shoulder Arthroscopy Treated by Neurolysis: A Case Report.

A 60-year-old woman presented functional deficit of the index finger flexor digitorum profundus (FDP) tendon after shoulder arthroscopic rotator cuff repair. As no recovery was observed for 10 months, we conducted an operative exploration of the median nerve and the anterior interosseous nerve, followed by an external neurolysis. The patient recovered FDP function 4.5 months after the second operation. In a patient with persistent isolated FDP dysfunction after shoulder arthroscopy, operative exploration and external neurolysis could facilitate functional recovery. Level of Evidence: Level V (Therapeutic).

Miniscrews position for a tissue bone borne palatal C-expander affects the displacement pattern of nasomaxillary complex: a finite element study.

This study aimed to evaluate the difference in expansion patterns based on the position of miniscrews for a tissue-bone-borne palatal C-expander using a finite element method. Ten expansion models were examined, each representing a different position of miniscrews on the palate. Models A and B had miniscrews symmetrically placed 7 mm and 15 mm below the cementoenamel junction (CEJ), respectively. Models C to J had miniscrews positioned in a triangular manner at 7 mm and 15 mm below CEJ. Stress, displacement, angular changes of the bone and teeth, and changes in the nasomaxillary complex were measured using elastoplastic behavior models through static-nonlinear simulation employing an implicit method. The anterior and posterior parts of paramidpalatal suture area were identified as ANT, TPS-M, and TPS-L, and their ratio was assessed. Model A, which featured three miniscrews located 7 mm below the CEJ, exhibited the least molar inclination and the smallest amount of skeletal expansion. Model I, with two miniscrews placed between the first and second molars, demonstrated the greatest lateral displacement at point N on the nasal cavity wall, along with the smallest ratio of ANT to TPS-M or TPS-L. This finding suggests that the posterior expansion of the palate in relation to the anterior expansion was maximized. The results of this study indicate that strategic positioning of miniscrews is effective in achieving various expansion patterns based on the targeted correction areas within the nasomaxillary complex.

Comparing zero-profile and conventional cage and plate in anterior cervical discectomy and fusion using finite-element modeling.

Conventional cage and plate (CCP) implants usually used in ACDF surgery, do have limitations such as the development of postoperative dysphagia, adjacent segment degeneration, and soft tissue injury. To reduce the risk of these complications, zero-profile stand-alone cage were developed. We used finite-element modeling to compare the total von Mises stress applied to the bone, disc, endplate, cage and screw when using CCP and ZPSC implants. A 3-dimensional FE (Finite element) analysis was performed to investigate the effects of the CCP implant and ZPSC on the C3 ~ T1 vertebrae. We confirmed that the maximum von Mises stress applied with ZPSC implants was more than 2 times greater in the endplate than that applied with CCP implants. The 3D analysis of the ZPSC model von Mises stress measurements of screw shows areas of higher stress in red. Although using ZPSC implants in ACDF reduces CCP implant-related sequalae such as dysphagia, we have shown that greater von Mises stress is applied to the endplate, and screw when using ZPSC implants. This may explain the higher subsidence rate associated with ZPSC implant use in ACDF. When selecting an implant in ACDF, surgeons should consider patient characteristics and the advantages and disadvantages of each implant type.

Shape memory polyurethanes crosslinked with castor oil-based multifunctional polyols.

As both the industry and academia become more focused on biomass-based smart materials, they are attracting a lot of attention. There has been a significant effort in the field of polyurethane (PU) synthesis to replace polyols used in synthesis with bio-derived polyols. Bio-derived polyols have limited application potential for bio-based PU due to their low functionality. Here, we reported castor oil (CO) based multifunctional polyols prepared by grafting thiols such as 1-mercaptoethanol or α-thioglycerol via a facile thiol-ene click reaction method (coded as COM and COT, respectively). Subsequently, bio-based shape memory polyurethanes (SMPU) crosslinked with prepared polyols were synthesized using a 2-step prepolymer method. By confirming the functionality of the synthesized polyols, it was determined that COT has an OH value of 380 mg KOH/g, which is approximately three times that of CO. The successful synthesis of SMPUs was confirmed through chemical structural analysis. It was also proved that the phase separation between the soft and hard segments was limited due to the increase in crosslinking density. As compared to SMPU crosslinked with CO, the mechanical strength of SMPU crosslinked with COT was improved by 80%, while the elongation was decreased by about 26%. As a result of shape memory behavior analysis, it was confirmed that the outstanding SMPU can be synthesized using CO-based multifunctional polyols.

Prevalence, natural progression, and clinical practices of upper gastrointestinal subepithelial lesions in Korea: a multicenter study.

BACKGROUND/AIMS: This study aimed to evaluate the prevalence and natural progression of subepithelial lesions (SELs) in the upper gastrointestinal (UGI) tract. METHODS: The medical records of patients with UGI SELs who underwent endoscopic screening at eight university hospitals between January and December 2010 were retrospectively investigated. The follow-up evaluations were performed until December 2016. RESULTS: UGI SELs were found in 1,044 of the 65,233 participants screened (endoscopic prevalence, 1.60%; the total number of lesions, 1,062; mean age, 55.1±11.2 years; men, 53.6%). The median follow-up period was 48 (range, 8-74) months. SELs were most frequently found in the stomach (63.8%) and had a mean size of 9.9±6.1 mm. Endoscopic ultrasonography (EUS) was performed in 293 patients (28.1%). The most common lesions were leiomyomas, followed by gastrointestinal stromal tumors (GISTs), and ectopic pancreas. The proportions of SELs with malignant potential according to size were 3% (<1 cm), 22% (1-2 cm), 27% (2-3 cm), and 38% (≥3 cm). In gastric SELs larger than 1 cm, resections were performed in 20 patients because of an increase in size, of which 12 were found to be GISTs. CONCLUSION: The prevalence of UGI SELs was 1.60%. Further, 23% of gastric SELs ≥1 cm were precancerous lesions, most followed by EUS and clinical decisions without initial pathological confirmation.

Internal marketing analysis for improving the internal consumer satisfaction and customer orientation of employees in private-owned sports center.

With the concept of "healthy lifestyle" deeply rooted in people's minds, the sports service industry is thriving, which has resulted in intense competition. The sports service industry must improve its service quality to be competitive. Customer orientation is the key factor for enterprises to gain competitive advantage. With the in-depth understanding of internal marketing in the service industry. Managers have realized that treating employees as internal consumer is a good way to improve their satisfaction and gain customer orientation. However, what internal marketing strategies will have a positive effect on internal consumer satisfaction and customer orientation of private-owned sports center employees are still unclear. In this investigation, a total of 326 employees from the private-owned sports center were used to investigate the effects of internal marketing strategies on internal consumer satisfaction and customer orientation. All employees were asked to complete a questionnaire on 5-point scale. A path model was used to investigate the direct and indirect effects of hypothetical measurements on internal consumer satisfaction and customer orientation. The findings suggested that internal communication, administrative support, and educational training were important factors affecting internal consumer satisfaction and customer orientation. We concluded that the implementation of internal marketing strategies could improve internal consumer satisfaction and customer orientation, and higher levels of internal consumer satisfaction will encourage employees to have higher degrees of customer orientation. Therefore, the implementation of internal marketing strategy was beneficial to the development of private-owned sports centers.

Enhanced Electrical and Thermal Conductivities of Polymer Composites with a Segregated Network of Graphene Nanoplatelets.

Introducing a segregated network constructed through the selective localization of small amounts of fillers can be a solution to overcome the limitations of the practical use of graphene-based conductive composites due to the high cost of fillers. In this study, polypropylene composites filled with randomly dispersed GNPs and a segregated GNP network were prepared, and their conductive properties were investigated according to the formation of the segregated structure. Due to the GNP clusters induced by the segregated structure, the electrical percolation threshold was 2.9 wt% lower than that of the composite incorporating randomly dispersed GNPs. The fully interconnected GNP cluster network inside the composite contributed to achieving the thermal conductivity of 4.05 W/m∙K at 10 wt% filler content. Therefore, the introduction of a segregated filler network was suitable to simultaneously achieve excellent electrical and thermal conductivities at a low content of GNPs.

Annotation-Efficient Deep Learning Model for Pancreatic Cancer Diagnosis and Classification Using CT Images: A Retrospective Diagnostic Study.

The aim of this study was to develop a novel deep learning (DL) model without requiring large-annotated training datasets for detecting pancreatic cancer (PC) using computed tomography (CT) images. This retrospective diagnostic study was conducted using CT images collected from 2004 and 2019 from 4287 patients diagnosed with PC. We proposed a self-supervised learning algorithm (pseudo-lesion segmentation (PS)) for PC classification, which was trained with and without PS and validated on randomly divided training and validation sets. We further performed cross-racial external validation using open-access CT images from 361 patients. For internal validation, the accuracy and sensitivity for PC classification were 94.3% (92.8-95.4%) and 92.5% (90.0-94.4%), and 95.7% (94.5-96.7%) and 99.3 (98.4-99.7%) for the convolutional neural network (CNN) and transformer-based DL models (both with PS), respectively. Implementing PS on a small-sized training dataset (randomly sampled 10%) increased accuracy by 20.5% and sensitivity by 37.0%. For external validation, the accuracy and sensitivity were 82.5% (78.3-86.1%) and 81.7% (77.3-85.4%) and 87.8% (84.0-90.8%) and 86.5% (82.3-89.8%) for the CNN and transformer-based DL models (both with PS), respectively. PS self-supervised learning can increase DL-based PC classification performance, reliability, and robustness of the model for unseen, and even small, datasets. The proposed DL model is potentially useful for PC diagnosis.

Impact fracture mechanism and heat deflection temperature of PLA/PEICT blends reinforced by glass fiber.

To enhance the crack propagation and initiation properties and heat deflection temperature of poly(lactic acid) (PLA), PLA/poly(1,4-cyclohexanedimethylene isosorbide terephthalate) (PEICT) blend systems were prepared and glass fibers (GF) were incorporated as reinforcements. Due to high shear force during extrusion and injection molding the length of GF was reduced and was oriented towards the flow direction. Although the reinforcing effect of the GF deviated from the theoretical values calculated by the Halpin-Tsai equation, both tensile and flexural properties were greatly enhanced with increasing GF content. Dynamic mechanical and thermal testing showed improved storage modulus throughout the entire temperature range showing outstanding reinforcing ability. By incorporating GF into the PLA/PEICT blend, the crack propagation and initiation properties were enhanced compared to pristine PLA. Such an increase in crack propagation properties was the result of enhanced modulus with the added GF. Moreover, because of the increased modulus, the heat deflection temperatures of the GF reinforced blends were drastically increased showing a value of 91.4 °C at 20 wt% GF loading. The high performance reached by the biomass-based composites developed in this research shows great possibility of replacing these conventional petroleum-based polymer systems.

The biomechanical effects of acromial fracture angulation in reverse total shoulder arthroplasty.

BACKGROUND: The biomechanical changes and treatment guidelines on acromial fracture after reverse shoulder arthroplasty (RSA) are still not well understood. The purpose of our study was to analyze the biomechanical changes with respect to acromial fracture angulation in RSA. METHODS: RSA was performed on 9 fresh-frozen cadaveric shoulders. An acromial osteotomy was performed on the plane extending from the glenoid surface to simulate an acromion fracture. Four conditions of acromial fracture inferior angulation were evaluated (0°, 10°, 20°, and 30° angulation). The middle deltoid muscle loading origin position was adjusted based on the position of each acromial fracture. The impingement-free angle and capability of the deltoid to produce movement in the abduction and forward flexion planes were measured. The length of the anterior, middle, and posterior deltoid was also analyzed for each acromial fracture angulation. RESULTS: There was no significant difference in the abduction impingement angle between 0° (61.8° ± 2.9°) and 10° angulation (55.9° ± 2.8°); however, the abduction impingement angle of 20° (49.3° ± 2.9°) significantly decreased from 0° and 30° angulation (44.2° ± 4.6°), and 30° angulation significantly differed from 0° and 10° (P < .01). On forward flexion, 10° (75.6° ± 2.7°), 20° (67.9° ± 3.2°), and 30° angulation (59.8° ± 4.0°) had a significantly decreased impingement-free angle than 0° (84.2° ± 4.3°; P < .01), and 30° angulation had a significantly decreased impingement-free angle than 10°. On analysis of glenohumeral abduction capability, 0° significantly differed (at 12.5, 15.0, 17.5, and 20.0N) from 20° and 30°. For forward flexion capability, 30° angulation showed a significantly smaller value than 0° (15N vs. 20N). As acromial fracture angulation increased, the middle and posterior deltoid muscles of 10°, 20°, and 30° became shorter than those of 0°; however, no significant change was found in the anterior deltoid length. CONCLUSIONS: In acromial fractures at the plane of glenoid surface, 10° inferior angulation of the acromion did not interfere with abduction and abduction capability. However, 20° and 30° of inferior angulation caused prominent impingement in abduction and forward flexion and reduced abduction capability. In addition, there was a significant difference between 20° and 30°, suggesting that not only the location of the acromion fracture after RSA but also the degree of angulation are important factors for shoulder biomechanics.