Fabrication and assessment of partial finger prostheses made using 3D-printed molds: A case study.

3D printing for custom prosthetic finger fabrication can have better fit and comfort than non-custom off-the-shelf ones while reducing fabrication labor time. The purpose of this case study was (1) to design and fabricate custom prosthetic fingers using 3D-printed molds for the treatment of partial finger amputation; (2) to evaluate patient satisfaction of the custom prosthetic fingers fabricated using 3D-printed molds and compare them to the custom prosthetic fingers fabricated through a conventional method of molding using plaster casts. The method to develop the custom prosthetic finger are as follows: (1) The shapes of the residual digits and contralateral fingers were acquired using a high-resolution 3D optical scanner. (2) Prosthetic fingers were designed by modifying the model of the residual digits and the contralateral fingers. (3) Molds of the prosthetic fingers were designed using computer-aided design software and fabricated by 3D printing. The study compared hand function tests and rehabilitation outcome surveys to evaluate the performance of the prosthetic fingers fabricated using 3D-printed molds and plaster casts. This case suggests that the prosthetic fingers fabricated using 3D-printed molds had comparable performance to the prosthetic fingers fabricated using plaster casts. The aesthetics and transparency of the prosthetic fingers contributed highly to the low satisfaction of the prosthetic fingers fabricated using 3D-printed molds.

Tandem use of gastroesophageal resuscitative occlusion of the aorta followed by resuscitative endovascular balloon occlusion of the aorta in a lethal liver laceration model.

BACKGROUND: Gastroesophageal resuscitative occlusion of the aorta (GROA) has been shown effective in creating zone II aortic occlusion capable of temporarily improving survival in animal models of lethal noncompressible torso hemorrhage. In this study, tandem application of GROA transitioning to resuscitative endovascular balloon occlusion of the aorta (REBOA) is explored to demonstrate feasibility as a potential point-of-injury bridge to more advanced care, using a swine model of lethal abdominal hemorrhage. METHODS: Swine (n = 19) were anesthetized, instrumented, and subjected to a combination of controlled and uncontrolled hemorrhage from a grade-V liver laceration. Animals were designated as intervention (n = 9; GROA to REBOA) or control (n = 10), for 60 minutes. Following intervention, devices were deactivated, and animals received blood and crystalloid resuscitation. Animals were monitored for 4 hours. RESULTS: Injury resulted in onset of class IV shock in all animals with a mean arterial pressure (SD) of 24.5 (4.11) mm Hg at the start of intervention. Nine of 10 controls died during the intervention period with a median (interquartile) survival time of 8.5 (9.25) minutes. All animals receiving the intervention survived both the 60-minute intervention period demonstrating a significant survival improvement ( p = 0.0007). Transition from GROA to REBOA was successful in all animals with a transition time ranging from 30 to 90 seconds. Mean arterial pressure significantly improved in animals receiving GROA to REBOA for the duration of intervention, regardless of the method of aortic occlusion, with a range of 70.9 (16.04) mm Hg to 101.1 (15.3) mm Hg. Additional hemodynamics, metrics of shock, and oxygenation remained stable during intervention. CONCLUSION: Less invasive technologies such as GROA may present an opportunity to control noncompressible torso hemorrhage more rapidly, with a subsequent transition to more advanced care such as REBOA.

Mosquito proboscis-inspired needle insertion to reduce tissue deformation and organ displacement.

This study investigates mosquito proboscis-inspired (MPI) insertion applied to the clinically used biopsy needle to reduce tissue deformation and organ displacement. Advanced medical imagining has enabled early-stage identification of cancerous lesions that require needle biopsy for minimally invasive tissue sampling and pathological analysis. Accurate cancer diagnosis depends on the accuracy of needle deployment to the targeted cancerous lesion site. However, currently available needle delivery systems deform and move soft tissue and organs, leading to a non-diagnostic biopsy or undersampling of the target. Two features inspired by the mosquito proboscis were adopted for MPI insertion in prostate biopsy: (1) the harpoon-shape notches at the needle tip and (2) reciprocating needle-cannula motions for incremental insertion. The local tissue deformation and global prostate displacement during the MPI vs. traditional direct insertions were quantified by optically tracking the displacement of particle-embedded tissue-mimicking phantoms. Results show that the MPI needle insertion reduced both local tissue deformation and global prostate displacement because of the opposite needle-cannula motions and notches which stabilized and reduced the tissue deformation during insertion. Findings provide proof of concept for MPI insertion in the clinical biopsy procedures as well as insights of needle-tissue interaction for future biopsy technology development.

Biaxial test and hyperelastic material models of silicone elastomer fabricated by extrusion-based additive manufacturing for wearable biomedical devices.

Biaxial tensile testing of the silicone elastomer fabricated by additive manufacturing (AM) for wearable biomedical devices is presented. Silicone elastomer has unique mechanical properties ideal for stretchable parts in wearable biomedical devices. Biaxial tensile testing, in comparison to the uniaxial tensile and compression tests, is more representative for materials with large, multidirectional stretch. This study investigates the experimental setup and methods to measure and characterize mechanical properties of AM solid and porous silicone elastomer sheets on equi-biaxial stretch (with the stretch ratio up to 2). Four hyperelastic material models were applied to characterize the AM silicone sheet and evaluated through the finite element analysis (FEA) to quantify the fit to biaxial tensile test results. The Yeoh model with C10 = 80.7 kPa, C20 = -2.11 kPa, and C30 = 0.22 kPa has the best match to the experimentally measured stress-strain curve as well as the force and strain in FEA. This study demonstrates that the effects of raster angle and thickness are insignificant in the stress-strain curve of an AM silicone elastomer with solid cross-section. This study also demonstrates that AM can fabricate anisotropic porous silicone elastomer parts with different stiffness in x- and y-directions.