Failure Force Research Articles

Comprehensive Analysis of Ferrocement-Strengthened Reinforced Concrete Beam

Starting with the premise that the choice of the optimal method for strengthening reinforced concrete (RC) structures is a complex task and that ferrocement strengthening is comparable to other advanced strengthening technologies due to its cost-effectiveness, ease of construction, and durability, this paper presents a comparative study of the flexural bearing capacity of RC beams strengthened with ferrocement strips applied by gluing. An overview of the life cycle assessment (LCA) based on embodied energy or CO2 is presented in the introduction, based on the existing literature review. The research includes tests of 15 RC beams of identical cross-sections (150/250 mm) and a span of 3000 mm. Strengthening was conducted by applying four types of ferrocement strips (different widths and wire mesh layers). Two factors were examined: the verification of the comprehensive FEM numerical model against the experimental results and the applicability of existing simplified calculation methods for sufficiently accurate results which could be used in regular practice. The results show that the failure forces obtained from numerical models and experimental models differ by no more than 3.94%. The increase in the bearing capacity of the strengthened models is up to 21.4%. The transformed area method for the cracked section showed good results when compared to the FEM and experimental models. The analytically calculated failure force is contingent upon the partial factor for variable action, which was explored within the 1.5–1.7 range.

A critical review of wheel/rail high frequency vibration-induced vibration fatigue of railway bogie in China

PurposeThis review aims to give a critical view of the wheel/rail high frequency vibration-induced vibration fatigue in railway bogie.Design/methodology/approachVibration fatigue of railway bogie arising from the wheel/rail high frequency vibration has become the main concern of railway operators. Previous reviews usually focused on the formation mechanism of wheel/rail high frequency vibration. This paper thus gives a critical review of the vibration fatigue of railway bogie owing to the short-pitch irregularities-induced high frequency vibration, including a brief introduction of short-pitch irregularities, associated high frequency vibration in railway bogie, typical vibration fatigue failure cases of railway bogie and methodologies used for the assessment of vibration fatigue and research gaps.FindingsThe results showed that the resulting excitation frequencies of short-pitch irregularity vary substantially due to different track types and formation mechanisms. The axle box-mounted components are much more vulnerable to vibration fatigue compared with other components. The wheel polygonal wear and rail corrugation-induced high frequency vibration is the main driving force of fatigue failure, and the fatigue crack usually initiates from the defect of the weld seam. Vibration spectrum for attachments of railway bogie defined in the standard underestimates the vibration level arising from the short-pitch irregularities. The current investigations on vibration fatigue mainly focus on the methods to improve the accuracy of fatigue damage assessment, and a systematical design method for vibration fatigue remains a huge gap to improve the survival probability when the rail vehicle is subjected to vibration fatigue.Originality/valueThe research can facilitate the development of a new methodology to improve the fatigue life of railway vehicles when subjected to wheel/rail high frequency vibration.

Pull‐Out Testing of Electrochemically Etched NiTi Shape Memory Alloy Wires in Shape Memory Alloy Hybrid Composites

This study presents an experimental characterization of the interface strength of the shape memory alloy hybrid composite (SMAHC) consisting of the two‐way effect NiTi shape memory alloy (SMA) wire structured by electrochemical etching and the surrounding thermoset matrix. Mechanically induced, in situ thermally induced, and cyclic load‐increase pull‐out tests consistently reveal that SMAHC with structured SMA wires outperforms those with as‐delivered SMA wires by a substantial factor of 2.6–2.7 in interfacial strength — the critical factor governing the overall performance and functionality of the composite. Analyzing the force–displacement curves from mechanically induced pull‐out tests demonstrates that structuring the SMA wire surface leads to a significantly increased elastic energy to initiate a crack and achieve complete failure. SMA wires with structured surfaces continue transferring load even after the initial interfacial failure due to the presence of intact mechanical interlocking sites. The cyclic load‐increase pull‐out test confirms that SMA wires with structured surfaces exhibit a significantly higher load‐bearing capacity, withstanding more load levels and demonstrating greater force of the first failure. Furthermore, in thermally induced pull‐out tests with structured SMA wires, a re‐initiation of failure from the lower side follows an initial failure progression at the SMA wire entry point.

Evaluation of Different Fixation Methods Combinations After L-Shaped Osteotomy Reduction Malarplasty: An In Vitro Biomechanical Study.

This in vitro study compared the stability of different fixation method combinations for the zygomatic complex after simulated L-shaped osteotomy reduction malarplasty, a common facial contouring surgery in East Asia with high postoperative complications due to poor fixation methods. The study used 108 zygoma replicas with various fixation methods combinations in the zygomatic body (L-shaped plate with short wing on zygoma and on the maxilla, two bicortical screws, one bicortical screw with L-shaped plate, square plate, and rectangular plate) and zygomatic arch (Mortise-Tenon structure, 3-hole plate, and Mortise-Tenon structure plus short screw). The failure force under incremental load was applied through the Instron tensile machine to a well-stabilized model using a rubber band simulating the masseter muscle and recorded the increasing force digitally. ANOVA test was used for comparison between recorded values (P < 0.05). The results showed that the most stable combination was a six-hole rectangular plate and a Mortise-Tenon structure plus one short screw (358.55 ± 51.64 N/mm2). The results also indicated that the placement vector of the fixation methods around the L-shaped osteotomy and the use of the two-bridge fixation method were important factors in enhancing the stability of the zygomatic complex. The study suggested that surgeons should choose appropriate fixation methods based on these factors to reduce postoperative complications and improve surgical outcomes. This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews, and manuscripts that concern Basic Science, Animal Studies, Cadaver Studies, and Experimental Studies. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Experimental investigation of transition composite connections in historic style buildings

Historic timber buildings possess immense historical, artistic, and scientific value, but a few of them have survived after thousands of years of natural disasters and wars. Historic style buildings with modern construction material, imitating historic timber buildings forms, have emerged to inherit and promote traditional culture. To investigate the seismic performance of transition columns commonly used in historic style buildings, two full-scaled composite column transition (CCT) connections between steel reinforced concrete (SRC) square column and reinforced concrete (RC) circular column were designed and tested under invariable axial load and cyclic lateral load. Both failure patterns and force mechanism were studied based on the test process of the CCT connections. Then, the influence of axial compressive ratio on the mechanical behaviour of the CCT connections was assessed by looking at the hysteretic curves, backbone curves, characteristic loads, ductility, energy dissipation capacity and strength degradation. The results demonstrated that the failure patterns of the CCT connections were typical flexural failure, with the failure zone occurring at the upper column-root. The CCT connections exhibited excellent capacities of deformation and energy dissipation. As axial compression ratio increases, the failure of the CCT connection becomes more severe, leading to enhanced energy dissipation capacity. However, the strength and ductility of the CCT connection decrease. Based on the experimental results, an equation for calculating the lateral stiffness of CCT connections between SRC square column and RC circular column in historic style buildings was proposed, and verified to be accurate. The findings can provide necessary basis for the rational design and widespread application of historic style buildings.

An investigation of high-frequency vibration of bogie frame due to wheel/rail short-pitch irregularities and its control methodologies

High frequency impacts arising from wheel/rail short pitch irregularities have been widely reported as main casual factor of high frequency vibration of bogie frames recent years. This study aims at exploring characteristics of high frequency vibration of a metro bogie frame and its control methodologies. Firstly, the measurements obtained from a field test were employed to demonstrate the elastic vibration of bogie frame due to rail corrugation-induced impacts. Secondly, a rigid/flexible coupled dynamic model neglecting the wheel/rail contact model was established to simulate the vibration of bogie frame. Subsequently, the control methodologies were proposed to suppress the high frequency vibration of bogie frame. The results showed that the end of bogie frame is predominated by the localized bending vibration mode at 220 Hz, which is close to the passing frequency of rail corrugation at the rubber booted short sleeper track. The structural resonance serves as the main driving force of fatigue failure for the end of bogie frame. The structural improvement through installing a stiffener at end of bogie frame can effectively suppress the local bending of end of bogie frame. The piezoelectric-based actuator could serve as an alternative method to reduce the vibration level for considered frequency range.

An anti-infection and biodegradable TFRD-loaded porous scaffold promotes bone regeneration in segmental bone defects -experimental studies.

Addressing segmental bone defects remains a complex task in orthopedics, and recent advancements have led to the development of novel drugs to enhance the bone regeneration. However, long-term oral administration can lead to malnutrition and poor patient compliance. Scaffolds loaded with medication are extensively employed to facilitate the restoration of bone defects. Inspired by the local use of total flavonoids of Rhizoma Drynariae (TFRD) in the treatment of fracture, a novel 3D-printed HA/CMCS/PDA/TFRD scaffold with anti-infection, biodegradable and induced angiogenesis was designed, and to explore its preclinical value in segmental bone defect of tibia. The scaffold exhibited good degradation and drug release performance. In vitro, the scaffold extract promoted osteogenesis by enhancing bone-related gene/protein expression and mineral deposition in BMSCs. It also stimulated endothelial cell migration and promoted angiogenesis through the upregulation of specific genes and proteins associated with cell migration and tube formation. This may be attributed to the activation of the PI3k/AKT/HIF-1α pathway, facilitating the processes of osteogenesis and angiogenesis. Furthermore, the HA/CMCS/PDA/TFRD scaffold was demonstrated to alleviate infection, enhance angiogenesis, promote bone regeneration, and increase the maximum failure force of new formed bone in a rat model of segmental bone defects. Porous scaffolds loaded with TFRD can reduce infection, be biodegradable, and induce angiogenesis, presenting a novel approach for addressing tibial segmental bone defects.

Optimization of S2-alar-iliac screw (S2AI) fixation in adult spine deformity using a comprehensive genetic algorithm and finite element model personalized to patient geometry and bone mechanical properties.

To optimize the biomechanical performance of S2AI screw fixation using a genetic algorithm (GA) and patient-specific finite element analysis integrating bone mechanical properties. Patient-specific pelvic finite element models (FEM), including one normal and one osteoporotic model, were created from bi-planar multi-energy X-rays (BMEXs). The genetic algorithm (GA) optimized screw parameters based on bone mass quality (BM method) while a comparative optimization method maximized the screw corridor radius (GEO method). Biomechanical performance was evaluated through simulations, comparing both methods using pullout and toggle tests. The optimal screw trajectory using the BM method was more lateral and caudal with insertion angles ranging from 49° to 66° (sagittal plane) and 29° to 35° (transverse plane). In comparison, the GEO method had ranges of 44° to 54° and 24° to 30° respectively. Pullout forces (PF) using the BM method ranged from 5 to 18.4kN, which were 2.4 times higher than the GEO method (2.1-7.7kN). Toggle loading generated failure forces between 0.8 and 10.1kN (BM method) and 0.9-2.9kN (GEO method). The bone mass surrounding the screw representing the fitness score and PF of the osteoporotic case were correlated (R2 > 0.8). Our study proposed a patient-specific FEM to optimize the S2AI screw size and trajectory using a robust BM approach with GA. This approach considers surgical constraints and consistently improves fixation performance.

The Influence of Flame Exposure and Solid Particle Erosion on Tensile Strength of CFRP Substrate with Manufactured Protective Coating.

This paper presents the results of laboratory tests for new materials made of a carbon fibre-reinforced polymer (CFRP) composite with a single-sided protective coating. The protective coatings were made of five different powders-Al2O3, aluminium, quartz sand, crystalline silica and copper-laminated in a single process during curing of the prepreg substrate with an epoxy matrix. The specimens were subjected to flame exposure and solid particle erosion tests, followed by uniaxial tensile tests. A digital image correlation (DIC) system was used to observe the damage location and deformation of the specimens. All coatings subjected to solid particle erosion allowed an increase in tensile failure force ranging from 5% to 31% compared to reference specimens made of purely CFRP. When exposed to flame, only three of the five materials tested, Al2O3, aluminium, quartz sand, could be used to protect the surface, which allowed an increase in tensile failure force of 5.6%.

Critical loss of primary implant stability in osteosynthesis locking screws under cyclic overloading

Primary implant stability, which refers to the stability of the implant during the initial healing period is a crucial factor in determining the long-term success of the implant and lays the foundation for secondary implant stability achieved through osseointegration. Factors affecting primary stability include implant design, surgical technique, and patient-specific factors like bone quality and morphology. In vivo, the cyclic nature of anatomical loading puts osteosynthesis locking screws under dynamic loads, which can lead to the formation of micro cracks and defects that slowly degrade the mechanical connection between the bone and screw, thus compromising the initial stability and secondary stability of the implant. Monotonic quasi-static loading used for testing the holding capacity of implanted screws is not well suited to capture this behavior since it cannot capture the progressive deterioration of peri‑implant bone at small displacements. In order to address this issue, this study aims to determine a critical point of loss of primary implant stability in osteosynthesis locking screws under cyclic overloading by investigating the evolution of damage, dissipated energy, and permanent deformation. A custom-made test setup was used to test implanted 2.5 mm locking screws under cyclic overloading test. For each loading cycle, maximum forces and displacement were recorded as well as initial and final cycle displacements and used to calculate damage and energy dissipation evolution. The results of this study demonstrate that for axial, shear, and mixed loading significant damage and energy dissipation can be observed at approximately 20 % of the failure force. Additionally, at this load level, permanent deformations on the screw-bone interface were found to be in the range of 50 to 150 mm which promotes osseointegration and secondary implant stability. This research can assist surgeons in making informed preoperative decisions by providing a better understanding of the critical point of loss of primary implant stability, thus improving the long-term success of the implant and overall patient satisfaction.

Fascia lata autografts achieve interface healing with the supraspinatus muscle histologically and mechanically in a rat supraspinatus tendon reconstruction model for massive irreparable rotator cuff tears

PurposeTo evaluate the histologic healing process and mechanical characteristics of the interface between a fascia lata autograft and supraspinatus muscle by establishing a supraspinatus tendon reconstruction model for chronic massive, irreparable rotator cuff tears (MIRCTs). MethodsA total of 40 rats were studied. Eight rats were sacrificed to establish an intact control group, and the other rats were first established as the chronic MIRCTs model and then developed as the supraspinatus tendon reconstruction model. Histology, fatty infiltration, mechanics and the open field test for the interface between the fascia lata autograft and muscle were assessed at 2, 4, 8 and 16 weeks postoperatively. ResultsHistologically, the interface between the fascia lata autograft and muscle gradually regenerated structural similarities to the normal muscle-tendon interface by 16 weeks postoperatively. The amounts of collagen I and III were both increased significantly during the healing time and stabilized at 8 weeks postoperatively. Fatty infiltration was obvious in the supraspinatus muscle 4 weeks after the MIRCTs model. However, the degree of fatty infiltration in the supraspinatus muscle gradually decreased after supraspinatus tendon reconstruction and stabilized at 8 weeks postoperatively. The ultimate failure force and the ultimate stress gradually increased from 2 to 16 weeks and reached the level of the intact control tendon at 16 weeks postoperatively (P=0.086). The movability of the forepaw returned to normal in the open field test (P=0.907). ConclusionsIn this rat supraspinatus tendon reconstruction model, fascia lata autografts showed good interface healing with the supraspinatus muscle, and fatty infiltration in the supraspinatus muscle was histologically decreased. The interface between the fascia lata autograft and muscle can sustain mechanical strength similar to the anatomical muscle–tendon interface. Clinical RelevanceThe supraspinatus tendon reconstruction technique using fascia lata autografts might be a good histological and biomechanical option for treating MIRCTs.

Plastic and elastic biomechanical properties of anterior cruciate ligament autografts

BackgroundAnterior cruciate ligament (ACL) rupture is a common orthopedic injury, occurring in roughly 68.6 per 100,000 persons annually, with the primary treatment option being ACL reconstruction. However, debate remains about the appropriate graft type for restoring the native biomechanical properties of the knee. Furthermore, plastic graft elongation may promote increased knee laxity and instability without rupture. This study aims to investigate the plastic properties of common ACL-R graft options.MethodsPatellar tendon (PT), hamstring tendon (HT), and quadriceps tendon (QT) grafts were harvested from 11 cadaveric knees (6 male and 5 female) with a mean age of 71(range 55–81). All grafts were mechanically tested under uniaxial tension until failure to determine each graft’s elastic and plastic biomechanical properties.ResultsMechanically, the QT graft was the weakest, exhibiting the lowest failure force and the lowest failure stress (QT < HT, p = 0.032). The PT was the stiffest of the grafts, having a significantly higher stiffness (PT > QT, p = 0.0002) and Young’s modulus (PT > QT, p = 0.001; PT > HT, p = 0.041). The HT graft had the highest plastic elongation at 4.01 ± 1.32 mm (HT > PT, p = 0.002). The post-yield behavior of the HT tendon shows increased energy storage capabilities with the highest plastic energy storage (HT > QT, p = 0.012) and the highest toughness (HT > QT, p = 0.032).ConclusionOur study agrees with prior studies indicating that the failure load of all grafts is above the requirements for everyday activities. However, grafts may be susceptible to yielding before failure during daily activities. This may result in the eventual loss of functionality for the neo-ACL, resulting in increased knee laxity and instability.

Rapidly Dissolving Trans-scleral Microneedles for Intraocular Delivery of Cyclosporine A

Cyclosporine A (CsA) is a cyclic peptide immunosuppressant drug that is beneficial in the treatment of various ocular diseases. However, its ocular bioavailability in the posterior eye is limited due to its poor aqueous solubility. Conventional CsA formulations such as a solution or emulsion permeate poorly across the eye due to various static and dynamic barriers of the eye. Dissolvable microneedle (MN)-based patches can be used to overcome barrier properties and, thus, enhance the ocular bioavailability of CsA in the posterior eye. CsA-loaded dissolvable MN patches were fabricated using polyvinylpyrrolidone (PVP) and characterized for MN uniformity and sharpness using SEM. Further characterization for its failure force, penetration force, and depth of penetration were analyzed using a texture analyzer. Finally, the dissolution time, ex vivo permeation, and ocular distribution of cyclosporine were determined in isolated porcine eyes. PVP MNs were sharp, uniform with good mechanical properties, and dissolved within 5 min. Ocular distribution of CsA in a whole porcine eye perfusion model showed a significant increase of CsA levels in various posterior segment ocular tissues as compared to a topically applied ophthalmic emulsion (Restasis®) (P < 0.001). Dissolving MNs of CsA were prepared, and the MN arrays can deliver CsA to the back of the eye offering potential for treating various inflammatory diseases.

A novel and efficient murine model for investigating tendon-to-bone healing

BackgroundTendon-to-bone healing is a critical challenge in sports medicine, with its cellular and molecular mechanisms yet to be explored. An efficient murine model could significantly advance our understanding of this process. However, most existing murine animal models face limitations, including a propensity for bleeding, restricted operational space, and a steep learning curve. Thus, the need for a novel and efficient murine animal model to investigate the cellular and molecular mechanisms of tendon-to-bone healing is becoming increasingly evident.MethodsIn our study, forty-four 9-week-old male C57/BL6 mice underwent transection and reattachment of the Achilles tendon insertion to investigate tendon-to-bone healing. At 2 and 4 weeks postoperatively, mice were killed for histological, Micro-CT, biomechanical, and real-time polymerase chain reaction tests.ResultsHistological staining revealed that the original tissue structure was disrupted and replaced by a fibrovascular scar. Although glycosaminoglycan deposition was present in the cartilage area, the native structure had been destroyed. Biomechanical tests showed that the failure force constituted approximately 44.2% and 77.5% of that in intact tissues, and the ultimate tensile strength increased from 2 to 4 weeks postoperatively. Micro-CT imaging demonstrated a gradual healing process in the bone tunnel from 2 to 4 weeks postoperatively. The expression levels of ACAN, SOX9, Collagen I, and MMPs were detected, with all genes being overexpressed compared to the control group and maintaining high levels at 2 and 4 weeks postoperatively.ConclusionsOur results demonstrate that the healing process in our model is aligned with the natural healing process, suggesting the potential for creating a new, efficient, and reproducible mouse animal model to investigate the cellular and molecular mechanisms of tendon-to-bone healing.Graphical abstract

Optimisation and study of a welding process for aluminium and galvanised steel based on resistance welding

In this study, taking six-series aluminium alloy and DC06 galvanised steel resistance spot welding as the object of study, the impacts of the electrode cap shape and process parameters on the joint welding performance were analysed, and the electrode cap was optimised. The optimised process parameters involved the use of spherical asymmetric electrodes and a pre-welding preheating step for zinc extrusion treatment, followed by a double pulse for welding. The optimal parameters resulted in an aluminium/steel spot welding head average pull shear failure load of 2858.7 N and aluminium/aluminium spot welding head failure force of 2436 N, reaching 117.3% of its original value. The minimum force value (2253.4 N) was greater than 92.5%, and the failure section was all from the aluminium side in parent material button failure, achieving good final results.

Comparative study of locking neutralization plate construct versus tension band wiring with a cannulated screw for patella fractures: experimental and finite element analysis

Transverse patella fractures, accounting for approximately 1% of Orthopedic injuries, pose intricate challenges due to their vital role in knee mechanics. This study aimed to compare the biomechanical performance of a construct, integrating cannulated screws and an anterior locking neutralization plate, with the conventional tension band wiring technique for treating these fractures. Experimental testing and Finite Element Analysis were employed to evaluate the constructs and gain profound insights into their mechanical behavior. Sixteen cadaveric knees were prepared, and transverse patella fractures were induced at the midpoints using a saw. The plate construct and tension band wire fixation were randomly assigned to the specimens. A cyclic test evaluated the implants' durability and stability, simulating knee movement during extension and flexion. Tensile testing assessed the implants' maximum failure force after cyclic testing, while Finite Element Analysis provided detailed insights into stress distribution and deformation patterns. Statistical analysis was exclusively performed for the experimental data. Results showed the plate enhanced stability with significantly lower deformation (0.09 ± 0.12 mm) compared to wire fixation (0.77 ± 0.54 mm) after 500 cycles (p = 0.004). In tensile testing, the construct also demonstrated higher failure resistance (1359 ± 21.53 N) than wire fixation (780.1 ± 22.62N) (p = 0.007). Finite Element Analysis highlighted distinct stress patterns, validating the construct's superiority. This research presents a promising treatment approach for transverse patella fractures with potential clinical impact and future research prospects. This study presents a promising advancement in addressing the intricate challenges of transverse patella fractures, with implications for refining clinical practice. The construct's improved stability and resistance to failure offer potential benefits in postoperative management and patient outcomes.

[Effect of a 10-Methacryloyloxydecyl Dihydrogen Phosphate- treated Bioceramic Sealer on the Bond Strength of an Endodontic Fiber Post: Multilayer Composite Disk Models and Ultra-highspeed Imaging Analysis].

Multiple materials are found in the root canal after fiber-post cementation. The layer of a bioceramic-based (BC) sealer may affect the bond strength (σBS) of the fiber post in the root canal. The purpose of this study was to employ multilayer compos-ite-disk models in diametral compression to investigate whether the bond strength between a fiber post and root dentin can be in-creased by the application of a primer on the BC sealer. The multilayers of materials in the root canal required 3D finite-element (FE) stress analyses (FEA) to pro-vide precise σBS values. First, BC sealer was characterized using x-ray powder diffraction (XRD) to determine when the sealer com-pletely set and the types of crystals formed to select which primer to apply to the sealer. We selected a 10-methacryloyloxydecyl dihydrogen phosphate (10-MDP)-based primer to treat the BC sealer before post cementation. Ultra-highspeed (UHS) imaging was utilized to analyze the crack initiation interface. The obtained failure force was used in FE analysis to calculate σBS. UHS imaging validated the fracture interface at the post-dentin junction as FEA simulations predicted. σBS values of the fiber posts placed with various material combinations in the root canal were 21.1 ± 3.4 (only cement/ post), 22.2 ± 3.4 (BC sealer/cement/post) and 28.6 ± 4.3 MPa (10-MDP primer treated BC sealer/cement/post). The 10-MDP-treated BC sealer exhibited the highest σBS (p < 0.05). The multilayer composite disk model proved reliable with diametral compression testing. The presence of BC sealer in the root canal does not reduce σBS of the fiber post. Conditioning the BC sealer layer with 10-MDP primer before fiber-post cemen-tation increases σBS.

Mechanical response of human thoracic spine ligaments under quasi-static loading: An experimental study

PurposeThis study aimed to investigate the geometrical and mechanical properties of human thoracic spine ligaments subjected to uniaxial quasi-static tensile test. MethodsFour human thoracic spines, obtained through a body donation program, were utilized for the study. The anterior longitudinal ligament (ALL), posterior longitudinal ligament (PLL), capsular ligament (CL), ligamenta flava (LF), and the interspinous ligament and supraspinous ligament complex (ISL + SSL), were investigated. The samples underwent specimen preparation, including dissection, cleaning, and reinforcement, before being immersed in epoxy resin. Uniaxial tensile tests were performed using a custom-designed mechanical testing machine equipped with an environmental chamber (T = 36.6 °C; humidity 95%). Then, the obtained tensile curves were averaged preserving the characteristic regions of typical ligaments response. ResultsGeometrical and mechanical properties, such as initial length and width, failure load, and failure elongation, were measured. Analysis of variance (ANOVA) revealed significant differences among the ligaments for all investigated parameters. Pairwise comparisons using Tukey's post-hoc test indicated differences in initial length and width. ALL and PLL exhibited higher failure forces compared to CL and LF. ALL and ISL + SSL demonstrated biggest failure elongation. Comparisons with other studies showed variations in initial length, failure force, and failure elongation across different ligaments. The subsystem (Th1 – Th6 and Th7 – Th12) analysis revealed increases in initial length, width, failure force, and elongation for certain ligaments. ConclusionsVariations of both the geometric and mechanical properties of the ligaments were noticed, highlighting their unique characteristics and response to tensile force. Presented results extend very limited experimental data base of thoracic spine ligaments existing in the literature. The obtained geometrical and mechanical properties can help in the development of more precise human body models (HBMs).

Strength of small-bites abdominal wall closure using different suturing methods and materials in an experimental animal model.

Using small instead of large bites for laparotomy closure results in lower incidence of incisional hernia, but no consensus exists on which suture material to use. This study aimed to compare five different closure strategies in a standardized experimental setting. Fifty porcine abdominal walls were arranged into 5 groups: (A) running 2/0 polydioxanone; (B) interlocking 2/0 polydioxanone; (C) running size 0 barbed polydioxanone; (D) running size 0 barbed glycolic acid and trimethylene carbonate; (E) running size 0 suturable polypropylene mesh. The small-bites technique was used for linea alba closure in all. The abdominal walls were divided into a supra- and infra-umbilical half, resulting in 20 specimens per group that were pulled apart in a tensile testing machine. Maximum tensile force and types of suture failure were registered. The highest tensile force was measured when using barbed polydioxanone (334.8N ± 157.0), but differencesdid not reach statisticalsignificance. Infra-umbilical abdominal walls endured a significantly higher maximum tensile force compared to supra-umbilical (397N vs 271N, p < 0.001). Barbed glycolic acid and trimethylene carbonate failed significantly more often (25% vs 0%, p = 0.008). Based on tensile force, both interlocking and running suture techniques using polydioxanone, and running sutures using barbed polydioxanone or suturable mesh, seem to be suitable for abdominal wall closure. Tensile strength was significantly higher in infra-umbilical abdominal walls compared to supra-umbilical. Barbed glycolic acid and trimethylene carbonate should probably be discouraged for fascial closure, because of increased risk of suture failure.

Biomechanical Comparison of Suture Bridge Rotator Cuff Repair With and Without Dermal Allograft Pledgets

BackgroundOne method to augment rotator cuff repair is to pass dermal allograft pledgets along the sutures that bridge from the medial to the lateral row. It remains unclear whether this augmentation method alters repair biomechanics. MethodsThis was a controlled laboratory study. After an a priori power analysis, nine pairs of rotator cuffs underwent double row suture bridge rotator cuff repair, half randomized to augmentation with dermal allograft pledgets passed along the suture bridge sutures. Repairs were then mounted on a material testing system and loaded cyclically 500 cycles to mesure applied force and displacement. Repairs then underwent ultimate failure testing and stiffness, ultimate failure force, and ultimate failure displacement were measured. Paired t-tests were performed to compare between groups. ResultsThere were no differences between groups in construct gapping with cyclic loading after 500 cycles (p = 0.885). There no differences between the augmented and control groups in yield force (103.5 ± 5.0 vs. 101.4 ± 5.9 N, respectively, p=0.183), stiffness (94.2 ± 13.9 vs. 90.9 ± 13.8, p=0.585), or ultimate failure force (255.3 ± 65.8 vs. 285.3 ± 83.2, p=0.315). There were no differences between groups in failure modes, with most specimens failing by cuff tissue tearing within or medial to the construct. ConclusionThe addition of dermal allograft pledgets does not positively or negatively influence the time-zero biomechanical characteristics of double-row suture bridge rotator cuff repair.