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"Prosthesis Design"
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Mechanics of biomaterials : fundamental principles for implant design
\"Teaching mechanical and structural biomaterials concepts for successful medical implant design, this self-contained text provides a complete grounding for students and newcomers to the field. Split into three sections: Materials, Mechanics and Case Studies, it begins with a review of sterilization, biocompatibility and foreign body response before presenting the fundamental structures of synthetic biomaterials and natural tissues. Mechanical behavior of materials is then discussed in depth, covering elastic deformation, viscoelasticity and time-dependent behavior, multiaxial loading and complex stress states, yielding and failure theories, and fracture mechanics. The final section on clinical aspects of medical devices provides crucial information on FDA regulatory issues and presents case studies in four key clinical areas: orthopedics, cardiovascular devices, dentistry and soft tissue implants. Each chapter ends with a list of topical questions, making this an ideal course textbook for senior undergraduate and graduate students, and also a self-study tool for engineers, scientists and clinicians\"-- Provided by publisher.
Book
Patient-specific computational simulation of coronary artery bifurcation stenting
Patient-specific and lesion-specific computational simulation of bifurcation stenting is an attractive approach to achieve individualized pre-procedural planning that could improve outcomes. The objectives of this work were to describe and validate a novel platform for fully computational patient-specific coronary bifurcation stenting. Our computational stent simulation platform was trained using n = 4 patient-specific bench bifurcation models (n = 17 simulations), and n = 5 clinical bifurcation cases (training group, n = 23 simulations). The platform was blindly tested in n = 5 clinical bifurcation cases (testing group, n = 29 simulations). A variety of stent platforms and stent techniques with 1- or 2-stents was used. Post-stenting imaging with micro-computed tomography (μCT) for bench group and optical coherence tomography (OCT) for clinical groups were used as reference for the training and testing of computational coronary bifurcation stenting. There was a very high agreement for mean lumen diameter (MLD) between stent simulations and post-stenting μCT in bench cases yielding an overall bias of 0.03 (− 0.28 to 0.34) mm. Similarly, there was a high agreement for MLD between stent simulation and OCT in clinical training group [bias 0.08 (− 0.24 to 0.41) mm], and clinical testing group [bias 0.08 (− 0.29 to 0.46) mm]. Quantitatively and qualitatively stent size and shape in computational stenting was in high agreement with clinical cases, yielding an overall bias of < 0.15 mm. Patient-specific computational stenting of coronary bifurcations is a feasible and accurate approach. Future clinical studies are warranted to investigate the ability of computational stenting simulations to guide decision-making in the cardiac catheterization laboratory and improve clinical outcomes.
Journal Article
Limbo
In the aftermath of an atomic war, a new international movement of pacifism has arisen. Multitudes of young men have chosen to curb their aggressive instincts through voluntary amputation - disarmament in its most literal sense. Those who have undergone this procedure are highly esteemed in the new society. But they have a problem - their prosthetics require a rare metal to function, and international tensions are rising over which countries get the right to mine it ...
Book
Assessing the non-inferiority of prosthesis constructs used in hip replacement using data from the National Joint Registry of England, Wales, Northern Ireland and the Isle of Man: a benchmarking study
ObjectivesTo investigate the relative performance of hip prosthesis constructs as compared with the best performing prosthesis constructs and illustrate the substantial variability in performance of currently used prostheses.DesignA non-inferiority study.SettingThe National Joint Registry for England, Wales, Northern Ireland and the Isle of Man (NJR).ParticipantsAll patients with a primary total hip replacement registered in the NJR between 1 April 2003 and 31 December 2016.Main outcome measuresKaplan-Meier failure function for hip prosthesis constructs. Failure difference between best performing construct and remaining constructs.MethodsUsing a non-inferiority analysis, the performance of hip prosthesis constructs by brand were compared with the best performing contemporary construct. Construct failure was estimated using the 1-Kaplan-Meier survival function method, that is, an estimate of net failure. The difference in failure between the contemporary benchmark and all other constructs was tested.ResultsOf the 4442 constructs used, only 134 had ≥500 procedures at risk at 3 years postprimary, 89 of which were not demonstrated to be inferior to the benchmark by at least 100% relative risk. By 10 years postprimary, there were 26 constructs with ≥500 at risk, 13 of which were not demonstrated to be inferior by at least 20% relative risk.Even fewer constructs were not inferior to the benchmark when analysed by age and gender. At 5 years postprimary, there were 15 constructs in males and 11 in females, aged 55–75 years, not shown to be inferior.ConclusionsThere is great variability in construct performance and the majority of constructs have not been demonstrated to be non-inferior to contemporary benchmarks. These results can help to inform patients, clinicians and commissioners when considering hip replacement surgery.
Journal Article
Implementation of 3D Printing Technology in the Field of Prosthetics: Past, Present, and Future
There is an interesting and long history of prostheses designed for those with upper-limb difference, and yet issues still persist that have not yet been solved. Prosthesis needs for children are particularly complex, due in part to their growth rates. Access to a device can have a significant impact on a child’s psychosocial development. Often, devices supporting both cosmetic form and user function are not accessible to children due to high costs, insurance policies, medical availability, and their perceived durability and complexity of control. These challenges have encouraged a grassroots effort globally to offer a viable solution for the millions of people living with limb difference around the world. The innovative application of 3D printing for customizable and user-specific hardware has led to open-source Do It Yourself “DIY” production of assistive devices, having an incredible impact globally for families with little recourse. This paper examines new research and development of prostheses by the maker community and nonprofit organizations, as well as a novel case study exploring the development of technology and the training methods available. These design efforts are discussed further in the context of the medical regulatory framework in the United States and highlight new associated clinical studies designed to measure the quality of life impact of such devices.
Journal Article
3D printing in dentistry
Key Points
Discusses the latest technologies in 3D imaging and printing that can be applied in dentistry.
Suggests these technologies could be used in daily practice.
3D printing has been hailed as a disruptive technology which will change manufacturing. Used in aerospace, defence, art and design, 3D printing is becoming a subject of great interest in surgery. The technology has a particular resonance with dentistry, and with advances in 3D imaging and modelling technologies such as cone beam computed tomography and intraoral scanning, and with the relatively long history of the use of CAD CAM technologies in dentistry, it will become of increasing importance. Uses of 3D printing include the production of drill guides for dental implants, the production of physical models for prosthodontics, orthodontics and surgery, the manufacture of dental, craniomaxillofacial and orthopaedic implants, and the fabrication of copings and frameworks for implant and dental restorations. This paper reviews the types of 3D printing technologies available and their various applications in dentistry and in maxillofacial surgery.
Journal Article
Ureteral stent-associated complications—where we are and where we are going
Key Points
Ureteral stents are associated with complications including infection, encrustation, haematuria and discomfort that can be caused by tissue irritation
The role of bacterial adhesion and biofilm formation on stents in stent-associated UTIs is unclear and development of UTIs and their treatment might depend on patient immune status
Encrustation and calcification are common problems that can lead to severe complications, which can be prevented by implementing electronic systems to monitor stent dwell times
Metal stents are a good alternative to polymer stents in the treatment of extrinsically caused ureteral obstruction; flexible and drug-eluting metal designs could help ameliorate discomfort and stenosis, respectively
Biodegradable ureteral stents could avoid complications, such as encrustation, but flaws in their biocompatibility still need to be addressed
Future stent design will focus on biodegradable and metal stents that elute drugs to prevent complications and are engineered to treat specific urological conditions
In this Review, Lange
et al
. give an overview of the main complications associated with commonly used ureteral stents and discuss novel stent designs based on metal or biodegradable materials that could help ameliorate patient discomfort and overcome current problems, such as encrustation and stenosis.
Ureteral stents are one of the most commonly used devices in the treatment of benign and malignant urological diseases. However, they are associated with common complications including encrustation, infection, pain and discomfort caused by ureteral tissue irritation and possibly irregular peristalsis. In addition, stent migration and failure due to external compression by malignancies or restenosis occur, albeit less frequently. As these complications restrict optimal stent function, including maintenance of adequate urine drainage and alleviation of hydronephrosis, novel stent materials and designs are required. In recent years, progress has been made in the development of drug-eluting expandable metal stents and biodegradable stents. New engineering technologies are being investigated to provide stents with increased biocompatibility, decreased susceptibility to encrustation and improved drug-elution characteristics. These novel stent characteristics might help eliminate some of the common complications associated with ureteral stenting and will be an important step towards understanding the behaviour of stents within the urinary tract.
Journal Article
Fabrication of low cost soft tissue prostheses with the desktop 3D printer
Soft tissue prostheses such as artificial ear, eye and nose are widely used in the maxillofacial rehabilitation. In this report we demonstrate how to fabricate soft prostheses mold with a low cost desktop 3D printer. The fabrication method used is referred to as Scanning Printing Polishing Casting (SPPC). Firstly the anatomy is scanned with a 3D scanner, then a tissue casting mold is designed on computer and printed with a desktop 3D printer. Subsequently, a chemical polishing method is used to polish the casting mold by removing the staircase effect and acquiring a smooth surface. Finally, the last step is to cast medical grade silicone into the mold. After the silicone is cured, the fine soft prostheses can be removed from the mold. Utilizing the SPPC method, soft prostheses with smooth surface and complicated structure can be fabricated at a low cost. Accordingly, the total cost of fabricating ear prosthesis is about $30, which is much lower than the current soft prostheses fabrication methods.
Journal Article
Fully covered stents are similar to semi-covered stents with regard to migration in palliative treatment of malignant strictures of the esophagus and gastric cardia: results of a randomized controlled trial
Introduction
Stent migration is a significant clinical problem in palliation of malignant strictures in the esophagus and gastro-esophageal junction (GEJ). We have compared a newer design of a fully-covered stent to a widely used semi-covered stent using migration >20 mm as the primary outcome variable. Effects on dysphagia, quality of life (QoL) and re-intervention frequency were also investigated.
Methods
Patients with dysphagia due to non-curable esophagus/GEJ cancer were randomized to receive either a more recent design of a fully-covered stent (n = 48) or a conventional semi-covered stent (n = 47). Chest x-ray, dysphagia and QoL were studied at baseline, one week, four weeks and three months thereafter.
Results
There were no significant differences either in stent migration distance or in the migration frequency. Stent migration during the total study period occurred in 37.2 % in the semi-covered group compared to 20.0 % for the fully-covered group. Dysphagia was measured with Watson and Ogilvie scores and with the dysphagia module in the QoL scale (QLQ-OG25). On average, there was a tendency to better dysphagia relief for the fully-covered design as scored with the two latter dysphagia instruments (p= 0.081 and p= 0.067) at three months and towards more re-interventions in the semi-covered group (p= 0.083).
Conclusion
In spite of its somewhat lower intrinsic radial force, the fully-covered stent was comparable to the conventional semi-covered stent with regard to stent migration. The data further suggest a potential benefit of the fully-covered stent in improving dysphagia in patients with longer life expectancy.
Journal Article
Smoking and Risk of Prosthesis-Related Complications after Total Hip Arthroplasty: A Meta-Analysis of Cohort Studies
Increasing evidence suggests that smoking may increase the incidence of prosthesis-related complications after total hip arthroplasty (THA). We performed a meta-analysis of cohort studies to quantitatively evaluate the association between smoking and the risk of prosthesis-related complications after THA.
Relevant articles published before August 15, 2014, were identified by searching the PubMed, EMBASE and Cochrane library databases. Pooled risk ratios (RRs) or weighted mean differences (WMDs) with 95% confidence intervals (CIs) were calculated with either a fixed- or random-effects model.
Six cohort studies, involving a total of 8181 participants, were included in the meta-analysis. Compared with the patients who never smoked, smokers had a significantly increased risk of aseptic loosening of prosthesis (summary RR=3.05, 95% CI: 1.42-6.58), deep infection (summary RR=3.71, 95% CI: 1.86-7.41) and all-cause revisions (summary RR=2.58, 95% CI: 1.27-5.22). However, no significant difference in the risk of implant dislocation (summary RR= 1.27, 95% CI: 0.77-2.10) or length of hospital stay (WMD=0.03, 95% CI: -0.65-0.72) was found between smokers and nonsmokers.
Smoking is associated with a significantly increased risk of aseptic loosening of prosthesis, deep infection and all-cause revisions after THA, but smoking is not correlated with a risk of implant dislocation or the length of hospital stay after surgery.
Journal Article