3D-Printing and upper-limb prosthetic sockets: promises and pitfalls

Modernising the way upper-limb prosthetic sockets are made has seen limited progress. The casting techniques that are employed in clinics today resemble those developed over 50 years ago and there is still a heavy reliance on manual labour. Modern manufacturing methods such as 3D scanning and printing are often presented as ready-to-use solutions for producing low-cost functional devices, with public perceptions being largely shaped by the superficial media representation and advertising. The promise is that modern socket manufacturing methods can improve patient satisfaction, decrease manufacturing times and reduce the workload in the clinic. However, the perception in the clinical community is that total conversion to digital methods in a clinical environment is not straightforward. Anecdotally, there is currently a disconnect between those developing technology to produce prosthetic devices and the actual needs of clinicians and people with limb difference. In this paper, we demonstrate strengths and drawbacks of a fully digitised, low-cost trans-radial diagnostic socket making process, informed by clinical principles. We present volunteer feedback on the digitally created sockets and provide expert commentary on the use of digital tools in upper-limb socket manufacturing. We show that it is possible to utilise 3D scanning and printing, but only if the process is informed by expert knowledge. We bring examples to demonstrate how and why the process may go wrong. Finally, we provide discussion on why progress in modernising the manufacturing of upper-limb sockets has been slow yet it is still too early to rule out digital methods

Influence of Alveolar Ridge Morphology and Guide-hole Design on the Accuracy of Static Computer-Assisted Implant Surgery with two Implant Macro-designs: An in Vitro Study.

OBJECTIVES The primary aim of this in vitro study was to evaluate the influence of alveolar ridge morphologies on the accuracy of static Computer-Assisted Implant Surgery (sCAIS). The secondary aims were to evaluate the influence of guide-hole design and implant macro-design on the accuracy of the final implant position. METHODS Eighteen standardized partially edentulous maxillary models with two different types of alveolar ridge morphologies were used. Each model was scanned via cone beam computer tomography prior to implant placement and scanned with a laboratory scanner prior to and following implant placement using sCAIS. The postsurgical scans were superimposed on the initial treatment planning position to measure the deviations between planned and postsurgical implant positions. RESULTS Seventy-two implants were equally distributed to the study groups. Implants placed in healed alveolar ridges showed significantly lower mean deviations at the crest (0.36 ± 0.17 mm), apex (0.69 ± 0.36 mm), and angular deviation (1.86 ± 0.99°), compared to implants placed in fresh extraction sites (0.80 ± 0.29 mm, 1.61 ± 0.59 mm, and 4.33 ± 1.87°; all p<0.0001). Implants placed with a sleeveless guide-hole design demonstrated significantly lower apical (1.02 ± 0.66 mm) and angular (2.72 ± 1.93°) deviations compared to those placed with manufacturer's sleeves (1.27 ± 0.67 mm; p=0.01, and 3.46 ± 1.9°; p=0.02). Deep-threaded tapered bone level implants exhibited significantly lower deviations at the crest (0.49 ± 0.28 mm), apex (0.97 ± 0.63 mm), and angular deviations (2.63 ± 1.85°) compared to shallow-threaded parallel-walled bone level implants (0.67 ± 0.34 mm; p=0.0005, 1.32 ± 0.67 mm; p=0.003, and 3.56 ± 1.93°; p=0.01). CONCLUSIONS The accuracy of the final implant position with sCAIS is determined by the morphology of the alveolar ridge, the design of the guide holes, and the macrodesign of the implant. CLINICAL SIGNIFICANCE Higher accuracy in the final implant position was observed with implants placed in healed alveolar ridge morphologies, in implants with deep-threaded tapered macro-design, and when sleeveless surgical guide holes were used

A personalised prosthetic liner with embedded sensor technology:a case study

BACKGROUND: Numerous sensing techniques have been investigated in an effort to monitor the main parameters influencing the residual limb/prosthesis interface, fundamental to the optimum design of prosthetic socket solutions. Sensing integration within sockets is notoriously complex and can cause user discomfort. A personalised prosthetic liner with embedded sensors could offer a solution. However, to allow for a functional and comfortable instrumented liner, highly customised designs are needed. The aim of this paper is to presents a novel approach to manufacture fully personalised liners using scanned three-dimensional image data of the patient's residual limb, combined with designs that allow for sensor integration. To demonstrate the feasibility of the proposed approach, a personalised liner with embedded temperature and humidity sensors was realised and tested on a transtibial amputee, presented here as a case study. METHODS: The residual limb of a below knee amputee was first scanned and a three-dimensional digital image created. The output was used to produce a personalised prosthesis. The liner was manufactured using a cryogenic Computer Numeric Control (CNC) machining approach. This method enables fast, direct and precise manufacture of soft elastomer products. Twelve Hygrochron Data Loggers, able to measure both temperature and humidity, were embedded in specific liner locations, ensuring direct sensor-skin contact. The sensor locations were machined directly into the liner, during the manufacturing process. The sensors outputs were assessed on the below amputee who took part in the study, during resting (50 min) and walking activities (30 min). To better describe the relative thermal properties of new liner, the same tests were repeated with the amputee wearing his existing liner. Quantitative comparisons of the thermal properties of the new liner solution with that currently used in clinical practice are, therefore, reported. RESULTS: The liner machining process took approximately 4 h. Fifteen minutes after donning the prosthesis, the skin temperature reached a plateau. Physical activity rapidly increased residuum skin temperatures, while cessation of activity caused a moderate decrease. Humidity increased throughout the observation period. In addition, the new liner showed better thermal properties with respect to the current liner solution (4% reduction in skin temperature). CONCLUSIONS: This work describes a personalised liner solution, with embedded temperature and humidity sensors, developed through an innovative approach. This new method allows for a range of sensors to be smoothly embedded into a liner, which is capable of measuring changes in intra-socket microclimate conditions, resulting in the design of advanced socket solutions personalised specifically for individual requirements. In future, this method will not only provide a personalised liner but will also enable dynamic assessment of how a residual limb behaves within the socket during daily activities.</p

Applications of three-dimensional printing in ophthalmology

Three-dimensional (3D) printing is increasingly used to produce customised objects and is a promising alternative to traditional manufacturing methods in diverse fields, such as dentistry and orthopaedics. Already in use in other medical specialities, adoption in ophthalmology has been limited to date. This review aims to provide an overview of 3D printing technology with respect to current and potential applications in ophthalmic practice. Medline, Embase and internet search were performed with "3D printing", "ophthalmology", "dentistry", "orthopaedics" and their synonyms used as main search terms. In addition, search terms related to clinical applications such as "surgery" and "implant" were employed. 3D printing has multiple applications in ophthalmology, including in diagnosis, surgery, prosthetics, medications and medical education. Within the past decade, researchers have produced 3D printed models of objects such as implants, prostheses, anatomical models and surgical simulators. Further development is necessary to generate optimal biomaterials for various applications, and the quality and long-term performance of 3D models needs to be validated

Development and evaluation of custom prosthetic devices for a companion animal utilizing additive manufacturing.

BACKGROUND AND SIGINIFICANCE: Few options exist for companion animals in need of prosthetic devices. With the rise of rapid prototyping technology, the availability and customization of prosthetic devices for individual companion animals is now a viable and cost effective alternative to the current options of a peg leg prosthetic, or wheel-assisted prosthetic device. The goals of this study were to describe the (1) specific needs and (2) biomechanics of a feline with bilateral thoracic limb amputation, (3) develop custom prosthetic devices utilizing rapid prototyping technology, and (4) describe the biomechanics of a feline with bilateral thoracic limb amputation using the custom prosthetic devices. The feline being studied in this project is a 2 year old Maine Coon feline weighing 9 lbs. She was a stray that was found with severe frostbite on her thoracic limbs. These sections of her thoracic limbs were amputated to remove the necrotic tissue. SPECIFIC AIMS: The goals of this study is to describe the (1) specific needs and (2) biomechanics of feline with bilateral thoracic limb amputation, (3) develop custom prosthetic devices utilizing rapid prototyping technology, and (4) describe the biomechanics of a feline with bilateral thoracic limb amputation with the use of the custom prosthetic devices. MATERIALS & METHODS: Fused Deposition Modeling (FDM) technology was utilized to fabricate the prosthetic devices that were designed and put through a Finite Element Analysis to simulate static loading and fatigue testing during various stages of the gait cycle. The devices were mechanically tested to ensure device failure did not occur during static loading, as well as fatigue tested to resemble continued use. vii Kinematic gait analysis was performed prior to and after use of the prosthetic devices, and outcomes were compared between the scenarios. Gait data was also compared to published feline gait data to determine any effects to the feline’s gait resulting from the amputation, and if this effect was corrected through the use of the prosthetic devices. RESULTS: FDM was a cost effective way to fabricate strong, durable prosthetic devices designed specifically for a companion animal with dual thoracic limb amputation. Mechanical testing ensured that the prosthetic devices can survive over 10,000 loading cycles at 6 N, and 3000 N of vertical force. The gait analysis performed without the use of the prosthetic devices show increased flexion of the elbows, stifle, and tarsus joint during ambulation. Gait analysis during the use of the prosthetic devices removes this additional flexion. CONCLUSION: Use of prosthetic devices can have a positive influence in the gait of companion animals with amputations. The comparison between the two data sets shows removal of the additional flexion found in the thoracic limbs when the prosthetic devices are used. This project showcases the feasibility of using additive manufacturing to create cost effect and durable prosthetic devices for use in companion animals

Evolution of Dental Implant Shapes and Today’s Custom Root Analogue Implants

Native tooth has a unique design to serve perfect stomatognathic function and esthetics which could never be replaced with another material or apparatus if it is lost. Over the past few decades, screw-type endosseous implants have been considered to be as the gold standard for the rehabilitation of edentulism owing to the similarity with the anatomical root shape and location inside the alveolar bone. They have been widely investigated so as to find out the ideal characteristics. Further researches have focused on the cervical region of the dental implant because the maximum stress is pronounced around the implant neck. The ideal characteristics indicate that a wide implant neck for better stress distribution, and a large surface area with a minimal thread geometry for a better long term crestal bone stability. Along with the growing clinical knowledge and digital technology, an innovative and noteworthy approach for implant dentistry, custom root analogue implant (RAI), has evolved. With the computer aided design and manufacturing (CAD/CAM) methods, original and optimized characteristics could be transferred to the custom dental implants just as performing an original root replacement

A scoping review of digital fabrication techniques applied to prosthetics and orthotics: Part 1 of 2—Prosthetics

Background: Traditionally, the manufacture of prostheses is time-consuming and labor-intensive. One possible route to improving access and quality of these devices is the digitalizing of the fabrication process, which may reduce the burden of manual labor and bring the potential for automation that could help unblock access to assistive technologies globally. Objectives: To identify where there are gaps in the literature that are creating barriers to decision-making on either appropriate uptake by clinical teams or on the needed next steps in research that mean these technologies can continue on a pathway to maturity. Study design: Scoping literature review. Methods: A comprehensive search was completed in the following databases: Allied and Complementary Medicine Database, MEDLINE, Embase, Global Health Archive, CINAHL Plus, Cochrane Library, Web of Science, Association for Computing Machinery, Institute of Electrical and Electronics Engineers, and Engineering Village, resulting in 3487 articles to be screened. Results: After screening, 130 lower limb prosthetic articles and 117 upper limb prosthetic articles were included in this review. Multiple limitations in the literature were identified, particularly a lack of long-term, larger-scale studies; research into the training requirements for these technologies and the necessary rectification processes; and a high range of variance of production workflows and materials which makes drawing conclusions difficult. Conclusions: These limitations create a barrier to adequate evidence-based decision-making for clinicians, technology developers, and wider policymakers. Increased collaboration between academia, industry, and clinical teams across more of the pathway to market for new technologies could be a route to addressing these gaps