Mechanical Stapling Devices for Soft Tissue Repair: A Review of Commercially Available Linear, Linear Cutting, and Circular Staplers.
Stapling devices have emerged as a widespread and effective option for soft tissue surgery, offering promising outcomes for patients by
reducing complication rates and surgery time. This review aims to provide an exhaustive analysis of commercially available alternatives in the market, incorporating insights from market analysis, patent landscape, and the existing literature. The main focus lies in identifying and evaluating the
most widely adopted and innovative stapling devices, including linear, linear cutting, circular, and powered staplers.
In addition, this review delves into the realm of bioabsorbable staples, exploring the materials utilized and the surgical fields where these advanced staples find applications. To facilitate easy comprehension, the gathered information is presented in tables, highlighting the essential parameters for each stapling device.
This comprehensive research about stapling devices is intended to aid healthcare practitioners and researchers in making informed decisions when choosing the most appropriate instrument for specific surgical procedures.
Mechanical Properties of Animal Ligaments: A Review and Comparative Study for the Identification of the Most Suitable Human Ligament Surrogates.
The interest in the properties of animal soft tissues is often related to the desire to find an animal model to replace human counterparts due to the unsteady availability of human tissues for experimental purposes. Once the most appropriate animal model is identified, it is possible to carry out ex-vivo and in-vivo studies for the repair of ligamentous tissues and performance testing of replacement and support healing devices. This work aims to present a systematic review of the mechanical properties of ligaments reported in the scientific literature by considering different anatomical regions in humans and several animal species. This study was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) method. Moreover, considering the lack of a standard protocol for preconditioning of tissues, this aspect is also addressed. Ninety-six studies were selected for the systematic review and analysed. The mechanical properties of different animal species are reported and summarised in tables. Only results from studies reporting the strain rate parameter were considered for comparison with human ligaments, as they were deemed more reliable. Elastic modulus, ultimate tensile stress, and ultimate strain properties are graphically reported identifying the range of values for each animal species and to facilitate comparison between values reported in the scientific literature in animal and human ligaments. Useful similarities between the mechanical properties of swine, cow, and rat and human ligaments have been found.
Analysis of a Motocross Knee Brace: From the Real Model to the Numerical Finite Element Model via 3D Scanning and Reverse Engineering
Musculoskeletal injuries often occur when performing motocross; almost half of the overall ligamentous injuries (42%) are knee ligaments injuries. Lesions can be greatly reduced with knee braces. Commercial knee braces are expected to oppose and limit unwanted and potentially harmful movements such as hyperextension and excessive rotation of the knee joint. However, this aspect has not been fully investigated from a biomechanical point of view. This would require proper Finite Element Modelling (FEM) and Analysis (FEA). However, to perform FEA and evaluate the efficacy of the brace simulating sportive conditions, numerical models need to be built. It requires a dedicated setup and several preprocessing steps, for which no industrial standard or widely accepted better practise is available as of today. Firstly, the brace and the lower limb are scanned using a 3D scanner. The geometry is reconstructed using reverse engineering techniques. These allow us to obtain a smooth, reliable 3D model starting from the points cloud acquired during scanning. A lower limb model was created using a mixed approach, combining MRI data and 3D scanning. Finally, a simulation of the impact condition after a jump using the developed model was carried out.
Worldwide Incidence and Surgical Costs of Tendon Injuries: A Systematic Review and Meta-Analysis.
Tendon injuries represent a broad and economically expensive problem in clinical reality, however, there is no systematic review or meta-analysis in the literature that delves into this topic. The aim of this work is to investigate the incidence and clinical costs of tendon rupture on a global, continental and national scale.
Methods. PubMed, Google Scholar, PICO (Politecnico di Torino’s bibliographic search engine) were the online databases interrogated for research purposes, while the Minister of Health was the institution contacted to obtain data regarding hospitalization rates. FHM (Federal Health Monitoring) and HES (Hospital Episode Statistics) were the national databases interrogated respectively for German and England data. We looked for the most recent and specific data possible, so papers too outdated or too general were excluded.
The total number of tendon ruptures in the world ranges from 80 to 90 cases per 100,000 inhabitants, i.e., 6 to 7 million per year. There is a linear relationship between the incidence of cases and the population, whilst it seems to be no correlation between surgical costs and inhabitants, as it likely depends on the populousness and economical power of a country.
Conclusions. This research may serve physicians and healthcare policymakers to make more informed decisions. It will also provide valuable information to industries and researchers involved in tendon repair solutions, to better understand the extent of the phenomenon worldwide.
Implantable Medical Devices for Tendon and Ligament Repair: A Review of Patents and Commercial Products.
Tendon and ligament injuries are a frequent and debilitating issue that affects many patients worldwide. The predominant solution is the suture thread, which is not without potential side effects and limitations. Implantable medical devices have gained more attention as an alternative approach. However, due to the many challenges of the inner body environment (limited available space, chemically aggressive environment, etc), the development of suitable devices is not exempt from practical and technical difficulties. Areas covered: Here, implantable medical devices for tendon and ligaments injuries are reviewed and discussed. Commercially-available products and registered patents are all considered as long as they fit the standard definitions of ‘implantable medical devices’ (reported in the Introduction). The research was then narrowed down to five commercial products, deemed as the most representative of the whole market. Their effectiveness and performance are analysed, as well as the possible areas of improvement and development. Expert opinion: Commercially available products present overall superior mechanical performances than suture techniques. Nevertheless, these latter ones might be still preferred for their wider range of customization. This aspect, and many others, could represent an area of improvement for implantable medical devices, to further explore their potential for tendon and ligament repair.
Design and Mechanical Characterization Using Digital Image Correlation of Soft Tissue-Mimicking Polymers.
Present and future anatomical models for biomedical applications will need bio-mimicking three-dimensional (3D)-printed tissues. These would enable, for example, the evaluation of the quality-performance of novel devices at an intermediate step between ex-vivo and in-vivo trials. Nowadays, PolyJet technology produces anatomical models with varying levels of realism and fidelity to replicate organic tissues. These include anatomical presets set with combinations of multiple materials, transitions, and colors that vary in hardness, flexibility, and density. This study aims to mechanically characterize multi-material specimens designed and fabricated to mimic various bio-inspired hierarchical structures targeted to mimic tendons and ligaments. A Stratasys® J750™ 3D Printer was used, combining the Agilus30™ material at different hardness levels in the bio-mimicking configurations. Then, the mechanical properties of these different options were tested to evaluate their behavior under uni-axial tensile tests. Digital Image Correlation (DIC) was used to accurately quantify the specimens’ large strains in a non-contact fashion. A difference in the mechanical properties according to pattern type, proposed hardness combinations, and matrix-to-fiber ratio were evidenced. The specimens V, J1, A1, and C were selected as the best for every type of pattern. Specimens V were chosen as the leading combination since they exhibited the best balance of mechanical properties with the higher values of Modulus of elasticity (2.21 ± 0.17 MPa), maximum strain (1.86 ± 0.05 mm/mm), and tensile strength at break (2.11 ± 0.13 MPa). The approach demonstrates the versatility of PolyJet technology that enables core materials to be tailored based on specific needs. These findings will allow the development of more accurate and realistic computational and 3D printed soft tissue anatomical solutions mimicking something much closer to real tissues.
Mechanical Properties of Animal Tendons: A Review and Comparative Study for the Identification of the Most Suitable Human Tendon Surrogates.
The mechanical response of a tendon to load is strictly related to its complex and highly organized hierarchical structure, which ranges from the nano- to macroscale. In a broader context, the mechanical properties of tendons during tensile tests are affected by several distinct factors, due in part to tendon nature (anatomical site, age, training, injury, etc.) but also depending on the experimental setup and settings. This work aimed to present a systematic review of the mechanical properties of tendons reported in the scientific literature by considering different anatomical regions in humans and several animal species (horse, cow, swine, sheep, rabbit, dog, rat, mouse, and foal). This study was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) method. The literature research was conducted via Google Scholar, PubMed, PicoPolito (Politecnico di Torino’s online catalogue), and Science Direct. Sixty studies were selected and analyzed. The structural and mechanical properties described in different animal species were reported and summarized in tables. Only the results from studies reporting the strain rate parameter were considered for the comparison with human tendons, as they were deemed more reliable. Our findings showed similarities between animal and human tendons that should be considered in biomechanical evaluation. An additional analysis of the effects of different strain rates showed the influence of this parameter.
3D Printing and Testing of Rose Thorns or Limpet Teeth Inspired Anchor Device for Tendon Tissue Repair.
Advancements in medical technology have enabled medical specialists to resolve significant problems concerning tendon injuries. However, despite the latest improvements, surgical tendon repair remains challenging. This study aimed to explore the capabilities of the current state-of-the-art technologies for implantable devices.
Methods: After performing extensive patent landscaping and literature review, an anchored tissue fixation device was deemed the most suitable candidate. This design was firstly investigated numerically, realizing a Finite Element Model of the device anchored to two swine tendons stumps, to simulate its application on a severed tendon. Two different hook designs, both bio-inspired, were tested while retaining the same device geometry and anchoring strategy. Then, the applicability of a 3D-printed prototype was tested on swine tendons. Finally, the device-tendon stumps ensemble was subjected to uniaxial tensile tests.
Results: The results show that the investigated device enables a better load distribution during the immobilized limb period in comparison to standard suture-based approaches, yet it still presents several design flaws.
The current implantable solutions do not ensure an optimal result in terms of strength recovery. This and other weak points of the currently available proposals will serve as a starting point for future works on bio-inspired implantable devices for tendon repair.
Effects of the Manufacturing Methods on the Mechanical Properties of a Medical-Grade Copolymer Poly (L-Lactide-co-D,L-Lactide) and Poly (L-Lactide-co-ε-Caprolactone) Blend.
Biocompatible and biodegradable polymers represent the future in the manufacturing of medical implantable solutions. As of today, these are generally manufactured with metallic components which cannot be naturally absorbed within the human body. This requires performing an additional surgical procedure to remove the remnants after complete rehabilitation or to leave the devices in situ indefinitely. Nevertheless, the biomaterials used for this purpose must satisfy well-defined mechanical requirements. These are difficult to ascertain at the design phase since they depend not only on their physicochemical properties but also on the specific manufacturing methods used for the target application. Therefore, this research was focused on establishing the effects of the manufacturing methods on both the mechanical properties and the thermal behavior of a medical-grade copolymer blend. Specifically, Injection and Compression Molding were considered. A Poly(L-lactide-co-D,L-lactide)/Poly(L-lactide-co-ε-caprolactone) blend was considered for this investigation, with a ratio of 50/50 (w/w), aimed at the manufacturing of implantable devices for tendon repair. Interesting results were obtained.
Effects of Curing on Photosensitive Resins in SLA Additive Manufacturing.
Different mechanical properties characterise the materials of 3D printed components, depending on the specific additive manufacturing (AM) process, its parameters, and the post-treatment adopted. Specifically, stereolithography (SLA) uses a photopolymerisation technique that creates solid components through selective solidification. In this study, 72 specimens were 3D printed using 12 commercial-grade methacrylate resins and tested under uniaxial tensile loads. The resin specimens were evaluated before and after curing. The recommended cure temperature and time were followed for all materials. The stress-strain curves measured during the testing campaign were evaluated in terms of maximum tensile strength, Young’s modulus, ductility, resilience, and toughness. The results reveal that the curing process increases the material stiffness and resistance to tensile loads. However, it was found that the curing process generally reduces the plasticity of the resins, causing a more or less marked brittle behaviour. This represents a potential limitation to the use of SLA 3D printing for structural elements which require some plasticity to avoid dangerous sudden failures.
Non-linear tendon fatigue life under uncertainties.
Tendons play a pivotal role in facilitating joint movement by transmitting muscular forces to bones. The intricate hierarchical structure and diverse material composition of tendons contribute to their non-linear mechanical response. However, comprehensively grasping their mechanical properties poses a challenge due to inherent variability in biological tissues. This necessitates a thorough examination of uncertainties associated with properties measurements, particularly under diverse loading conditions. Given the cyclic loading experienced by tendons throughout an individual’s lifespan, understanding their mechanical behaviour under such circumstances becomes crucial.
This study addresses this need by introducing a generalised Paris Erdogan Law tailored for non-linear materials. To examine uncertainties within this proposed framework, Monte Carlo Analysis is employed. This approach allows for a thorough exploration of the uncertainties associated with tendon mechanics, contributing to a more robust comprehension of their behaviour under cyclic loading conditions.
Finally, self-healing has been integrated into the fatigue law of tendons through the proposal of a healing function, formulated as a polynomial function of the maximum stress. This approach allows to account for an increase in the number of cycles for each stress value due to self-repair after the damage event generated by long-term cycling load over the individual’s life span.