Publications by authors named "David Forrestal"

4 Publications

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3D Printing Improved Testicular Prostheses: Using Lattice Infill Structure to Modify Mechanical Properties.

Front Surg 2021 20;8:626143. Epub 2021 Apr 20.

Engineering Faculty, Queensland University of Technology, Brisbane, QLD, Australia.

Patients often opt for implantation of testicular prostheses following orchidectomy for cancer or torsion. Recipients of testicular prostheses report issues regarding firmness, shape, size, and position, aspects of which relate to current limitations of silicone materials used and manufacturing methods for soft prostheses. We aim to create a 3D printable testicular prosthesis which mimics the natural shape and stiffness of a human testicle using a lattice infill structure. Porous testicular prostheses were engineered with relative densities from 0.1 to 0.9 using a repeating cubic unit cell lattice inside an anatomically accurate testicle 3D model. These models were printed using a multi-jetting process with an elastomeric material and compared with current market prostheses using shore hardness tests. Additionally, standard sized porous specimens were printed for compression testing to verify and match the stiffness to human testicle elastic modulus (E-modulus) values from literature. The resulting 3D printed testicular prosthesis of relative density between 0.3 and 0.4 successfully achieved a reduction of its bulk compressive E-modulus from 360 KPa to a human testicle at 28 Kpa. Additionally, this is the first study to quantitatively show that current commercial testicular prostheses are too firm compared to native tissue. 3D printing allows us to create metamaterials that match the properties of human tissue to create customisable patient specific prostheses. This method expands the use cases for existing biomaterials by tuning their properties and could be applied to other implants mimicking native tissues.
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http://dx.doi.org/10.3389/fsurg.2021.626143DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8093764PMC
April 2021

Interobserver and intraobserver agreement of three-dimensionally printed models for the classification of proximal humeral fractures.

JSES Int 2021 Mar 15;5(2):198-204. Epub 2020 Dec 15.

James Cook University, Mackay Clinical School, Mackay, QLD, Australia.

Hypothesis: This study aimed to examine whether three-dimensionally printed models (3D models) could improve interobserver and intraobserver agreement when classifying proximal humeral fractures (PHFs) using the Neer system. We hypothesized that 3D models would improve interobserver and intraobserver agreement compared with x-ray, two-dimensional (2D) and three-dimensional (3D) computed tomography (CT) and that agreement using 3D models would be higher for registrars than for consultants.

Methods: Thirty consecutive PHF images were selected from a state-wide database and classified by fourteen observers. Each imaging modality (x-ray, 2D CT, 3D CT, 3D models) was grouped and presented in a randomly allocated sequence on two separate occasions. Interobserver and intraobserver agreements were quantified with kappa values (κ), percentage agreement, and 95% confidence intervals (CIs).

Results: Seven orthopedic registrars and seven orthopedic consultants classified 30 fractures on one occasion (interobserver). Four registrars and three consultants additionally completed classification on a second occasion (intraobserver). Interobserver agreement was greater with 3D models than with x-ray (κ = 0.47, CI: 0.44-0.50, 66.5%, CI: 64.6-68.4% and κ = 0.29, CI: 0.26-0.31, 57.2%, CI: 55.1-59.3%, respectively), 2D CT (κ = 0.30, CI: 0.27-0.33, 57.8%, CI: 55.5-60.2%), and 3D CT (κ = 0.35, CI: 0.33-0.38, 58.8%, CI: 56.7-60.9%). Intraobserver agreement appeared higher for 3D models than for other modalities; however, results were not significant. There were no differences in interobserver or intraobserver agreement between registrars and consultants.

Conclusion: Three-dimensionally printed models improved interobserver agreement in the classification of PHFs using the Neer system. This has potential implications for using 3D models for surgical planning and teaching.
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http://dx.doi.org/10.1016/j.jseint.2020.10.019DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7910723PMC
March 2021

Spectral changes associated with transmission of OLED emission through human skin.

Sci Rep 2019 07 8;9(1):9875. Epub 2019 Jul 8.

School of Chemistry Physics and Mechanical Engineering, Science and Engineering Faculty, Queensland University of Technology (QUT), Brisbane, QLD, 4000, Australia.

A recent and emerging application of organic light emitting diodes (OLEDs) is in wearable technologies as they are flexible, stretchable and have uniform illumination over a large area. In such applications, transmission of OLED emission through skin is an important part and therefore, understanding spectral changes associated with transmission of OLED emission through human skin is crucial. Here, we report results on transmission of OLED emission through human skin samples for yellow and red emitting OLEDs. We found that the intensity of transmitted light varies depending on the site from where the skin samples are taken. Additionally, we show that the amount of transmitted light reduces by ~ 35-40% when edge emissions from the OLEDs are blocked by a mask exposing only the light emitting area of the OLED. Further, the emission/electroluminescence spectra of the OLEDs widen significantly upon passing through skin and the full width at half maximum increases by >20 nm and >15 nm for yellow and red OLEDs, respectively. For comparison, emission profile and intensities of transmitted light for yellow and red inorganic LEDs are also presented. Our results are highly relevant for the rapidly expanding area of non-invasive wearable technologies that use organic optoelectronic devices for sensing.
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http://dx.doi.org/10.1038/s41598-019-45867-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6614498PMC
July 2019

Challenges in engineering large customized bone constructs.

Biotechnol Bioeng 2017 06 9;114(6):1129-1139. Epub 2017 Feb 9.

Institute of Health and Biomedical Innovation, Queensland University of Technology (QUT), 60 Musk Ave, Kelvin Grove, Brisbane, QLD 4059, Australia.

The ability to treat large tissue defects with customized, patient-specific scaffolds is one of the most exciting applications in the tissue engineering field. While an increasing number of modestly sized tissue engineering solutions are making the transition to clinical use, successfully scaling up to large scaffolds with customized geometry is proving to be a considerable challenge. Managing often conflicting requirements of cell placement, structural integrity, and a hydrodynamic environment supportive of cell culture throughout the entire thickness of the scaffold has driven the continued development of many techniques used in the production, culturing, and characterization of these scaffolds. This review explores a range of technologies and methods relevant to the design and manufacture of large, anatomically accurate tissue-engineered scaffolds with a focus on the interaction of manufactured scaffolds with the dynamic tissue culture fluid environment. Biotechnol. Bioeng. 2017;114: 1129-1139. © 2016 Wiley Periodicals, Inc.
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http://dx.doi.org/10.1002/bit.26222DOI Listing
June 2017