Teleflex (Ireland)

There are over 3 million bone fractures in the United States annually; over 30% of which require internal mechanical fixation devices to aid in the healing process. The current standard material used is a metal plate that is implanted onto the bone. However, metal fixation devices have many disadvantages, namely stress shielding and metal ion leaching. This study aims to fix these problems of metal implants by making a completely biodegradable material that will have a high modulus and exhibit great toughness. To accomplish this, long-fiber poly-l-lactic acid (PLLA) was utilized in combination with a matrix composed of polycaprolactone (PCL) and hydroxyapatite (HA) nano-rods. Through single fibril tensile tests, it was found that the PLLA fibers have a Young's modulus of 8.09 GPa. Synthesized HA nanorods have dimensions in the nanometer range with an aspect ratio over 6. By dip coating PLLA fibers in a suspension of PCL and HA and hot pressing the resulting coated fibers, dense fiber-reinforced samples were made having a flexural modulus up to 9.2 GPa and a flexural strength up to 187 MPa. The flexural modulus of cortical bone ranges from 7 to 25 GPa, so the modulus of the composite material falls into the range of bone. The typical flextural strength of bone is 130 MPa, and the samples here greatly exceed that with a strength of 187 MPa. After mechanical testing to failure the samples retained their shape, showing toughness with no catastrophic failure, indicating the possibility for use as a fixation material. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1963-1971, 2017.

AIM: To develop a novel in vitro urethra model and use it to determine if insertion of an intermittent urinary catheter (IC) displaces pathogenic bacteria from the urethral meatus along the urethra. METHODS: Displacement of microbial growth after catheter insertion was assessed using a novel in vitro urethra model. The in vitro urethra model utilized chromogenic agar and was inoculated with bacteria at one side of the artificial urethra channel, to act as a contaminated urethral meatus, before an IC was inserted into the channel. Three ICs types were used to validate the in vitro urethra model and methodology. RESULTS: When compared to the bacterial growth control, a significant difference in bacterial growth was found after insertion of the uncoated (P ≤ 0·001) and hydrophilic coated (P ≤ 0·009) catheters; no significant difference when a prototype catheter was inserted into the in vitro urethra model with either bacterial species tested (P ≥ 0·423). CONCLUSION: The results presented support the hypothesis that a single catheter insertion can initiate a catheter-associated urinary tract infection. SIGNIFICANCE AND IMPACT OF THE STUDY: The in vitro urethra model and associated methodology were found to be reliable and reproducible (P ≥ 0·265) providing new research tool for the development and validation of emerging technologies in urological healthcare.

The development paths of interventional medical devices are long and involve a significant numbers of iterative design steps. Composite interventional catheters deliver implants, facilitate the deployment of delicate therapeutic instruments, measure pressures and temperatures and can remove clots and foreign bodies. This paper summarizes the history of composite interventional catheters and the key evolutions in terms of materials and reinforcement structures. The current design practices, performance standards and general guidance available to assist composite interventional catheter design are reviewed. The environmental factors that affect the companies in which many of the leading edge interventional composite catheter designs are developed are also examined. A Predictive Modelling Framework is proposed to guide the design of composite interventional catheters to meet the key user needs. Two distinct but compatible methodologies are selected: The first method involves use of a DOE (Design of Experiments) approach to understand the influence of key variables on final catheter properties; The second involves the creation of customizable Finite Element models of the various potential catheter structures. The results of the predictive model constructed based on the DOE approach for braided composite catheters are presented and compared with experimental data. The DOE shows good alignment with experimental data in most cases. The sources of noise and error in the initial model are examined and potential improvements and learnings are discussed, with special focus on the results with poorer alignment.

Currently there are limited predictive modeling tools available for composite interventional catheter design. Most interventional catheter development involves iteration based design. Composite interventional catheters typically consist of a PTFE inner layer wrapped with a fine strand, metal reinforcement layer covered with a TPE (thermoplastic elastomer) outer layer. Fast reliable computational based techniques for early stage catheter design would limit the number of prototypes required to get to concept or design freeze stage therefore reducing development time. This paper’s goal is to examine how effective FEA is as a technique for predicting the performance of a composite catheter shaft. The steps taken and challenges overcome in creating a configurable FE model for a spirally reinforced composite catheter are outlined. The paper presents Finite Element (FE) generated data for tensile yield. This is a fundamental performance parameter in interventional catheter design. Catheters are designed to operate below their yield point. Models developed for simulating tensile yield can likely be adapted to simulate other performance characteristics such as flexural properties and torsion characteristics as part of future work. Data from FEA analysis is compared with data from physically testing catheters built to the same specification as that used in the FE model configuration.

The Medical Device industry lags other industries such as automotive and aerospace in terms of the use of predictive modeling as a design tool. This has started to change with growing experience being established with metal scaffold type structures (stents, Transcatheter aortic valve structures etc.). However, these computational methods are generally used with structures that are composed of a single material type as with Finite Element Analysis (FEA). Composite interventional catheters generally features 3-layer composite structures (polymer layer A/Metal reinforcement layer B/polymer layer C) which offer different challenges than single material structures in terms of predictive modeling. The results achieved with two different Experimental Design or Design of Experiments (DOE) based predictive modeling methodologies will be compared. The Classic DOE approach is based on a full factorial DOE with center points. The Custom DOE approach is based on the full factorial approach but is augmented with a series of experiments to fill the internal design space more completely rather than rely on just taking sample points predominantly around the boundaries of the design space as in classic DOE. Results generated from both approaches relate to catheter performance criteria of value in early stage composite catheter design. Strengths and drawbacks of both modeling approaches are discussed.

Scientific moulding, also known as decoupled injection moulding, is a production methodology used to develop and determine robust moulding processes resilient to fluctuations caused by variation in temperature and viscosity. Scientific moulding relies on the meticulous collection of data from the manufacturing process, especially inputs of time (fill, pack/hold), temperature (melt, barrel, tool), and pressure (injection, hold, etc.). This publication presents a use case where scientific moulding was used to enable the transfer and optimisation of an injection moulding process from an Arburg 221M injection moulding machine to an Arburg 375 V model. The part was an endovascular aneurysm repair dilator device where a polypropylene hub was moulded over a high-density polyethylene dilator insert. Upon transfer, multiple studies were carried out, including material rheology study during injection, gate freeze study, cavity balance of the moulding tool, and pressure loss analysis. A design of experiments was developed and carried out on the process with a variety of effects and responses. The developed process cycle time was compared to that achieved theoretically using mathematical modelling and the original process cycle time. The studies resulted in the identification of optimum parameters for injection speed, holding time, holding pressure, cooling time, and mould temperature. The process was verified by completing a 32-shot study and recording part weights and dimensional measurements to confirm repeatability and consistency of the process. The output from the study was a reduction in cycle time by 12.05 s from the original process. A cycle time of 47.28 s was theoretically calculated for the process, which is within 6.6% of the practical experiment results (44.15 s).

Teleflex take this issue very seriously, and undertook a comprehensive evaluation of this fault. Review of the returned device confirmed the reported issue of a deformed connection of the device indicating a probable root cause as manufacturing-related. Corrective measures have been implemented for the reported issue under Teleflex's quality systems.

Background: There is currently no standard established in vitro model to test the efficacy of intermittent catheters to prevent or control introduction/movement of bacteria into the urethra during device insertion. This study aimed to address this issue by developing a reproducible agar based in vitro urethral model. Method: A novel in vitro model and testing method was developed to quantify the displacement of bacterial growth after intermittent catheter insertion.The urethral model consists primarily of a preformed channel within a specifically formulated agar based matrix. The urethra model was inoculated at one side of the channel to act as the urethral meatus, a catheter was then inserted. After incubation the bacteria within the urethra channel was quantified. Results: Once optimised, the model produced reliable and reproducible results with both E. coli and S. aureus (P≥0.265). The model was used to test three different intermittent catheter types. When compared to the growth control there was a significant difference in bacterial distribution when inserting an uncoated (P≤0.001) or hydrophilic coated (P≤0.009) catheter; there was no significant difference when a prototype catheter was inserted with either bacterial species used (P≥0.423). Conclusion: These findings support the hypothesis that a single catheter insertion can initiate a catheter-associated urinary tract infection. The in vitro urethra model and associated methodology provide a new research tool for the development and validation of emerging technologies in urological healthcare.

The aim of this study was to develop a novel biomimetic in vitro extraluminal migration model to observe the migration of bacteria along indwelling urinary catheters within the urethra and assess the efficacy of a prototype chlorhexidine diacetate (CHX) coating to prevent this migration. The in vitro urethra model utilised chromogenic agar. A catheter was inserted into each in vitro urethra. One side of the urethra was then inoculated with bacteria to replicate a contaminated urethral meatus. The models were then incubated for 30 days (d), with the migration distance recorded each day. Four indwelling catheter types were used to validate the in vitro urethra model and methodology. Using the biomimetic in vitro urethra model, E. coli and S. aureus migrated the entire length of a control catheter within 24–48 h (h). In the presence of a prototype CHX coating, full migration of the channel was prevented for 30 d. The results of this study support the hypothesis that catheter-associated urinary tract infections (CAUTIs) could be prevented by targeting catheter-mediated extraluminal microbial migration from outside of the urinary tract into the bladder.