Avulsion Forces Research Articles

Development of implantable electrode based on bioresorbable Mg alloy for tissue welding application

An implantable electrode based on bioresorbable Mg-Nd-Zn-Zr alloy was developed for next-generation radiofrequency (RF) tissue welding application, aiming to reduce thermal damage and enhance anastomotic strength. The Mg alloy electrode was designed with different structural features of cylindrical surface (CS) and continuous long ring (LR) in the welding area, and the electrothermal simulations were studied by finite element analysis (FEA). Meanwhile, the temperature variation during tissue welding was monitored and the anastomotic strength of welded tissue was assessed by measuring the avulsion force and burst pressure. FEA results showed that the mean temperature in the welding area and the proportion of necrotic tissue were significantly reduced when applying an alternating current of 110 V for 10 s to the LR electrode. In the experiment of tissue welding ex vivo, the maximum and mean temperatures of tissues welded by the LR electrode were also significantly reduced and the anastomotic strength of welded tissue could be obviously improved. Overall, an ideal welding temperature and anastomotic strength which meet the clinical requirement can be obtained after applying the LR electrode, suggesting that Mg-Nd-Zn-Zr alloy with optimal structure design shows great potential to develop implantable electrode for next-generation RF tissue welding application.

Traumatic lung laceration secondary to avulsed lung adhesion - A case report

Pulmonary lacerations caused by an avulsion force on an adhesion between the lung and chest wall following blunt thoracic injury are very rare. They may result in pneumothorax and/or hemothorax and may not be immediately apparent clinically or radiologically.We present the case of a healthy 34-year-old male who sustained blunt thoracic injury. He was clinically stable, and his initial routine images were unremarkable. The patient was discharged home on the same day. He presented a week later with a massive hemothorax requiring surgical intervention which revealed bleeding from an avulsed adhesion between the lung and chest wall. Bleeding was successfully controlled by hemostatic agent, and the patient had an uneventful recovery.Hemothorax requiring intervention from an avulsed adhesion may occur following blunt thoracic trauma. Initial imaging and clinical finding may be misleading. Close follow up and adequate patient education should be ensured prior to discharge following seemingly trivial trauma.

3D-Printed Porous Tantalum Scaffold Improves Muscle Attachment via Integrin-β1-Activated AKT/MAPK Signaling Pathway.

3D-printed porous titanium (Ti) alloy scaffolds have been reported for facilitating muscle attachment in our previous study. However, the anti-avulsion ability needs to be improved. In this study, we used 3D-printed porous tantalum (Ta) scaffolds to improve muscle attachment. The differences in chemical and physical characteristics and muscle adhesion between the two scaffolds were tested and compared in the gene and protein level both in vitro and in vivo. The possible molecular mechanism was analyzed and further proved. The results showed that compared with the porous Ti alloy, porous Ta had better cell proliferation, differentiation, migration, and adhesion via the integrin-β1 (Itgb1)-activated AKT/MAPK signaling pathway in L6 rat myoblasts. When artificially down-regulated the expression of Itgb1, cell adhesion and myogenesis differentiation were affected and the phosphorylation of the AKT/MAPK signaling pathway was suppressed. In rat intramuscular implantation, porous Ta had a significantly higher muscle ingrowth rate (85.63% ± 4.97 vs 65.98% ± 4.52, p < 0.01) and larger avulsion force (0.972 vs 0.823 N/mm2, p < 0.05) than the porous Ti alloy. These findings demonstrate that the 3D-printed porous Ta scaffold is beneficial for further clinical application of muscle attachment.

Biomechanical comparison of screw vs. cerclage refixation in orthogeriatric lesser trochanteric fractures: a cadaveric study

PurposeOsteoporosis-related proximal femur fractures continue to increase significantly due to demographic change. This study was designed to evaluate the biomechanical stability of two different fixation methods (cerclage vs. screw) for refixation of a trochanter minor fragment in the pertrochanteric fractures in cadaveric bones.MethodsArtificial bones (n = 14) and human bones (n = 16) were treated with a DHS and the trochanter minor fragment was reduced by cerclage wiring or direct screw fixation. After preloading the simulated iliopsoas with 10 N, a tensile test was performed, ending with either a 70% loss of strength or avulsion of the fragment. The mean values of the avulsion force and the surface strain were recorded.ResultsAll tensile tests showed no significant differences between refixation using a direct screw or wire cerclage, for both artificial bones and human specimens. Absolute values showed higher avulsion forces after direct screw fixation than refixation with a wire cerclage. The surface tension of specimens treated with direct screw fixation was lower than that of specimens treated with wire cerclage. An opposite effect was seen in artificial bones. Both effects were not statistically significant.ConclusionBased on the equal stability after lag screw placement compared to cerclage wiring, we promote the placement of a lag screw into the lesser trochanter fragment in pertrochanteric femur fractures when using a dynamic hip screw.Level of evidenceLevel III.

A Novel Design of Temporomandibular Joint Prosthesis for Lateral Pterygoid Muscle Attachment: A Preliminary Study.

Introduction: In temporomandibular joint (TMJ) replacement operation, due to the condylectomy, the lateral pterygoid muscle (LPM) lost attachment and had impact on the mandible kinematic function. This study aimed to design a novel TMJ replacement prosthesis for LPM attachment and to verify its feasibility by preliminary in vitro and in vivo experiments.Materials and Methods: An artificial TMJ prosthesis designed with a porous structure on the condylar neck region for LPM attachment was fabricated by a 3D printed titanium (Ti) alloy. A rat myoblast cell line (L6) was tested for adhesion and biocompatibility with porous titanium scaffolds in vitro by cell counting Kit-8 (CCK-8), scanning electron microscope (SEM), flow cytometry (FCM), real-time quantitative polymerase chain reaction (RT-qPCR), immunocytofluorescense, western blotting, etc. The porous titanium scaffolds were further embedded in the rat intervertebral muscle to analyze muscle growth and biomechanical strength in vivo. The novel artificial TMJ prosthesis was implanted to reconstruct the goat's condyle and LPM reattachment was analyzed by hard tissue section and avulsion force test.Results: L6 muscle cells showed good proliferation potential on the porous Ti scaffold under SEM scanning and FCM test. In RT-qPCR, immunocytofluorescense and western blotting tests, the L6 cell lines had good myogenic capacity when cultured on the scaffold with high expression of factors such as Myod1 and myoglobin, etc. In the in vivo experiment, muscles penetrated into the porous scaffold in both rats and goats. In rat's intervertebral muscle implantation, the avulsion force was 0.716 N/mm2 in 4 weeks after operation and was significantly increased to 0.801 N/mm2 at 8 weeks (p < 0.05). In goat condylar reconstruction with the porous scaffold prosthesis, muscles attached to the prosthesis with the avulsion force of 0.436 N/mm2 at 8 weeks, but was smaller than the biological muscle-bone attachment force.Conclusion: The novel designed TMJ prosthesis can help LPM attach to its porous titanium scaffold structure area for future function.

Anatomic study of fibrous structures attached to the volar ulnar corner of the radius: implications in the volar rim fracture

This study aimed to clarify the bone and soft tissue morphological features at the volar ulnar corner of the radius. Micro-computed tomography, macroscopic and histological analyses were conducted using 12 cadaveric wrists, and invivo MRI studies of the wrist were evaluated in five healthy volunteers. The volar ulnar corner of the distal radius has a protrusion volar to the sigmoid notch. The capsule elements of the radiolunate and radioulnar joints merge and this conjoined capsule attaches to the radius at the ulnar protrusion. Histologically, this capsule attaches to the radius via fibrocartilage, with fibres running in the radioulnar direction. In-vivo MRI studies showed that the capsule attaching to the volar ulnar corner could be traced to the dorsal side of the ulnar styloid. Our findings indicate that, given the direction of the fibres, an avulsion force in the radioulnar direction could be a cause for volar rim fractures.

Assessment of Ablative Therapies in Swine: Response of Respiratory Diaphragm to Varying Doses.

Ablation is a common procedure for treating patients with cancer, cardiac arrhythmia, and other conditions, yet it can cause collateral injury to the respiratory diaphragm. Collateral injury can alter the diaphragm's properties and/or lead to respiratory dysfunction. Thus, it is important to understand the diaphragm's physiologic and biomechanical properties in response to ablation therapies, in order to better understand ablative modalities, minimize complications, and maximize the safety and efficacy of ablative procedures. In this study, we analyzed physiologic and biomechanical properties of swine respiratory diaphragm muscle bundles when exposed to 5 ablative modalities. To assess physiologic properties, we performed in vitro tissue bath studies and measured changes in peak force and baseline force. To assess biomechanical properties, we performed uniaxial stress tests, measuring force-displacement responses, stress-strain characteristics, and avulsion forces. After treating the muscle bundles with all 5 ablative modalities, we observed dose-dependent sustained reductions in peak force and transient increases in baseline force-but no consistent dose-dependent biomechanical responses. These data provide novel insights into the effects of various ablative modalities on the respiratory diaphragm, insights that could enable improvements in ablative techniques and therapies.

Significance of Extraction Forces in Kidney Stone Basketing.

Ureteroscopic stone extraction devices are effective tools in the management of urolithiasis, but on occasion, their improper use can cause injury to the ureter. Avulsion and perforation of the ureter as a result of excessive forces on the extraction device are some of the more serious complications of this treatment. In this article, avulsion and perforation forces were measured by two different test setups. Eleven clinicians were asked to apply three ranges of forces (safe, cautious, and dangerous). The output force measurements were recorded and plotted for further analysis. The maximal average perforation forces were 7.13±2.36 N in the benchtop tests and 7.07±2.20 N in the ex-vivo porcine tests (P=0.54). The maximal average avulsion forces were measured to be 10.14±2.01 N in the benchtop tests. Although the average forces were similar in the proximal and distal parts of the ureter (P=0.27), higher values were recorded for the distal part. The operative time was noted to be significantly different in the safe and cautious force regions (P=0.006). The average forces were higher in the benchtop tests compared with the porcine ureter tests. The extraction forces were measured and were noted to be significantly different for attending physicians and residents. The results suggest the need for force feedback training for residents. The findings can be used to design a "smart device" that can provide visual force feedback to clinicians while they are operating, leading to improved patient outcome.

PD42-10 A SMART KIDNEY STONE BASKET WITH FORCE FEEDBACK

You have accessJournal of UrologyStone Disease: New Technology1 Apr 2015PD42-10 A SMART KIDNEY STONE BASKET WITH FORCE FEEDBACK Zahra Najafi, Thomas Tieu, Ajay M. Mahajan, and Bradley F. Schwartz Zahra NajafiZahra Najafi More articles by this author , Thomas TieuThomas Tieu More articles by this author , Ajay M. MahajanAjay M. Mahajan More articles by this author , and Bradley F. SchwartzBradley F. Schwartz More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2015.02.2595AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Ureteroscopy with stone extraction devices has become an effective treatment in the management of urolithiasis. Perforation and avulsion of the ureter wall, due to excessive force on the extraction device, are serious complications of basketing. In this paper, we design a prototype that provides instantaneous extraction forces. The proposed prototype will aid in reducing the risk of ureter wall perforation and avulsion by highlighting the safe and hazardous extraction forces. Additionally, it can be used to improve the skills of surgeons during professional training. METHODS The mechanical sensor prototype is shown in Fig.1. The basket is connected to a spring that is located inside a tube. Three regions, safe (green), cautious (yellow), and dangerous (red), are defined by the amount of perforation and avulsion forces reported by Pedro RN et al. (2007). The prototype was calibrated and bench top testing was performed by preparing a model of the ureter (polyurethane tubing). A stricture was created on the tube and a metal bead simulating the stone was placed in the tube (Fig.1). The entire system was withdrawn from the ureter model by first sweeping the stone down to the stricture and then increasing the force up to the perforation and avulsion forces. The movement of the indicator was monitored and recorded. RESULTS The spring was calibrated and used to define the different force regions. Table 1 illustrates the results of the device calibration after five repetitions. Bench top testing on the ureter model shows that the results obtained by the proposed smart device prototype are consistent with the perforation and avulsion values reported by Pedro RN et al. (2007). CONCLUSIONS A smart device was designed to feedback the instantaneous forces during basketing. Safe and hazardous regions were defined and the device was calibrated and tested on a ureter model. The same prototype can also be calibrated to be used on human ureter (we undertake this in our future work). The feedback forces provided by the prototype will lead to less complication and aid in reducing the procedure cost. Table 1. Calibration of the prototype by increasing the mass (based on forces reported by Pedro RN et al. (2007) for porcine ureter) and reading the spring extension. Region Mass (g) Extension run 1 (mm) Extension run 2 (mm) Extension run 3 (mm) Extension run 4 (mm) Extension run 5 (mm) Average Extension (mm) Green (safe) Min: 0 Max: 550 Min: 0 Max: 10.80 Min: 0 Max: 10.82 Min: 0 Max: 10.81 Min: 0 Max: 10.82 Min: 0 Max: 10.82 Min: 0 Max: 10.814 Yellow (cautious)* Min: 550 Max: 1000 Min: 10.80 Max: 20.25 Min: 10.82 Max: 20.26 Min: 10.81 Max: 20.24 Min: 10.82 Max: 20.26 Min: 10.82 Max: 20.26 Min: 10.814 Max: 20.254 Red (dangerous)** > 1000 > 20.25 > 20.26 > 20.24 > 20.26 > 20.26 > 20.254 *May lead to perforation, **Avulsion will occur © 2015 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 193Issue 4SApril 2015Page: e889-e890 Advertisement Copyright & Permissions© 2015 by American Urological Association Education and Research, Inc.MetricsAuthor Information Zahra Najafi More articles by this author Thomas Tieu More articles by this author Ajay M. Mahajan More articles by this author Bradley F. Schwartz More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

An innovative external fixator for the management of trochanteric fractures of the femur. Surgical technique and outcomes of 200 patients with 24 month follow up

An innovative external fixator for the management of trochanteric fractures of the femur. Surgical technique and outcomes of 200 patients with 24 month follow up

In Vitro Evaluation of Ureteral Perforation Forces

Objectives Ureteroscopy has become a very effective treatment option for ureteral and upper tract abnormalities. The reported complication rates have ranged from 1.5% to 13% for perforations and have been less than 1% for avulsions. We present a study that quantified the ureteral avulsion force in porcine ureters and ureteral perforation forces in human and porcine ureters. Methods The avulsion force was measured in six porcine kidneys. A 2.4F stainless steel flat-wire basket was advanced through an incision made in the renal pelvis, and a 10-mm stone was placed in the extraction basket. The external end of the basket (handle) was attached to a miniature, low-force load cell and slowly pulled with increasing force until the ureter avulsed. The ureteral perforation forces were measured in 10 fresh porcine and 9 human ureters. Perpendicular perforation with either the blunt end of a CT-1 needle (0.038 in.) or the back end of a stiff guidewire (0.035 in.) was measured using the miniature, low-force load cell. Results The average maximal force to avulse the pig ureter was 2.21 ± 0.43 pound-mass (lb m). The force required to perforate the porcine ureter was significantly greater than that required to perforate the human ureter, irrespective of whether a needle (1.70 ± 0.26 lb m versus 1.05 ± 0.29 lb m, P = 0.019) or guidewire (1.30 ± 0.25 lb m versus 0.79 ± 0.25 lb m, P = 0.013) was used. Greater force was required to perforate with the needle than with the guidewire in both the porcine ( P = 0.037) and the human ( P = 0.26) ureter. Conclusions Quantifying the ureteral perforation forces will facilitate the design of endourologic devices, open the door for “smart devices” that sense forces and provide feedback, provide information critical to the design of endourologic and suturing simulators, and, finally, establish competency parameters for professionals in training.

Thrombosis and Altered Expression of Intercellular Adhesion Molecule-1 (ICAM-1) after Avulsion Injury in Rat Vessels

This study was undertaken to characterize the relative degrees of arterial and venous trauma after graded avulsion injuries. Rat femoral arteries and veins were subjected to reproducible avulsion injuries using forces of between 60 and 220 g. Thrombotic occlusion occurred at lower avulsion forces in veins than in arteries. Histologic and scanning electron microscopic analysis indicated increased endothelial disruption and exposed elastic lamina with increasing avulsion force in both vessels, but more prominently in arteries. Intercellular adhesion molecule-1 (ICAM-1) mRNA expression was evident at 3 and 6 hours after avulsion injury in veins, but only with higher avulsion-force injuries in arteries. ICAM-1 mRNA expression was not found in either vessel before or after this 3 to 6 hour post-injury interval. These results indicate that the amount of avulsion force to which traumatized extremity vessels are subjected has a direct effect on the degree of intimal injury and subsequent thrombosis.

Sports injuries in children

Sports injuries in children affect both growing bone and soft tissues, and can result in damage of growth mechanisms with subsequent lifelong growth disturbance. During growth, there are significant changes in the biomechanical properties of bone. In young athletes, as bone stiffness increases and resistance to impact diminishes, sudden overload may cause bones to bow or buckle. Epiphyseal injuries are usually due to shearing and avulsion forces, although compression also plays a significant role. Given the remarkable healing potential of bone in childhood, fractures that initially united with some deformity can completely remodel, and the bone may appear totally normal in later life. Most injuries in children’s sports are minor and self-limiting, suggesting that children and youth sports are safe. However, as the risk of injuries sustained by young athletes can be significant, training programmes should take into account their physical and psychological immaturity, so that growing athletes can adjust to their own body’s changes.

Injuries in young athletes.

Most injuries in children's sports are minor and self-limiting, suggesting that children and youth sports are safe. A child's skeletal system shows pronounced adaptive changes to intensive sports training. Sports injuries affect both growing bone and soft tissues and could result in damage of the growth mechanisms with subsequent life-lasting damage. During growth there are significant changes in the biomechanical properties of bone. In young athletes, as bone stiffness increases and resistance to impact diminishes, sudden overload may cause bones to bow or buckle. Epiphyseal injuries are usually due to shearing and avulsion forces, although compression also plays a significant role. Given the remarkable healing potential of bone in youngsters, fractures that initially united with some deformity can completely remodel and appear totally normal in later life. As the risk of injuries sustained by young athletes can be significant, it is essential that training programmes take into account their physical and psychological immaturity, so that growing athletes can adjust to their own body changes.

Common Skeletal Injuries in Young Athletes

The increasing frequency of injury in young athletes over the last 2 decades reflects the increases in sports participation of children of a young age. Physical injury is an inherent risk in sports participation at any age. In general, the factors causing sports injuries can be grouped in 2 separate broad categories: extrinsic and intrinsic factors. However, the great majority of injuries which are sustained are minor and self-limiting, suggesting that children and youth sports are safe. However, a increasing number of children undergo treatment because of the effects that injuries may have on their developing bodies. A child's skeletal system shows pronounced adaptive changes to intensive sports training. Sports injuries affect both growing bone and soft tissues, and could result in damage of the growth mechanisms with subsequent life-lasting damage. Adolescents are particularly vulnerable to injuries, at least partially due to an imbalance in strength and flexibility. During growth there are significant changes in the biomechanical properties of bone. In young athletes, as bone stiffness increases and resistance to impact diminishes, sudden overload may cause bones to bow or buckle. Epiphyseal injuries occur at the epiphyseal growth plates. They are usually due to shearing and avulsion forces, although compression also plays a significant role. Given the remarkable healing potential of bone in youngsters, fractures that initially united with some deformity can completely remodel and appear totally normal in later life. As the risk of injuries sustained by young athletes can be significant, it is essential that training programmes take into account their physical and psychological immaturity, so that the growing athlete can adjust to their own body changes.

肩鎖関節脱臼を伴う烏口突起骨折の３例

We report three cases of coracoid fracture with acromioclavicular dislocation. One case was a 14-year-old with an epiphyseal lesion of the coracoid process. As this fracture is not readily visualized by anteroposterior x-ray, both an axillary and anteroposterior cephalic tilt view of 30 degrees are needed. Operative therapy was performed in all cases and the coracoclavicular ligament was intact.We believe this fracture with acromioclavicular dislocation occurs with an avulsion force of the coracoclavicular ligament.