Surgical and technological advances in the management of upper limb amputees.

Upper limb amputations, ranging from transhumeral to partial hand, can be devastating for patients, their families, and society. Modern paradigm shifts have focused on reconstructive options after upper extremity limb loss, rather than considering the amputation an ablative procedure. Surgical advancements such as targeted muscle reinnervation and regenerative peripheral nerve interface, in combination with technological development of modern prosthetics, have expanded options for patients after amputation. In the near future, advances such as osseointegration, implantable myoelectric sensors, and implantable nerve cuffs may become more widely used and may expand the options for prosthetic integration, myoelectric signal detection, and restoration of sensation. This review summarizes the current advancements in surgical techniques and prosthetics for upper limb amputees. Cite this article: Bone Joint J 2021;103-B(3):430-439.

Future considerations in prosthetic urology.

Since their popularization, genitourinary prosthetics have remained a gold-standard therapy for the treatment of erectile dysfunction and stress urinary incontinence and in cases of testicular loss or dysfunction. They have also represented an area of significant innovation, which has contributed to excellent long-term outcomes. Given this history, the objective of the current review was to provide a 5-10-year outlook on anticipated trends and developments in the field of genitourinary prosthetics. To accomplish this objective, a PubMed and patent search was performed of topics relating to penile and testicular prostheses and urinary sphincters. In regard to penile prostheses, findings demonstrated several new concepts including temperature-sensitive alloys, automated pumps, devices designed specifically for neophalluses, and improved malleable designs. With artificial urinary sphincters, new concepts include the ability to add or remove fluid from an existing system, two-piece systems, and new mechanisms to occlude the urethra. For testicular prosthetics, future implementations may not only better replicate the feel of a biological testicle but also add endocrinological functions. Beyond device innovation, the future of prosthetics is also one of expanding geographic boundaries, which necessitates variable cost modeling and regulatory considerations. Surgical trends are also changing, with a greater emphasis on nonnarcotic, postoperative pain control, outpatient surgeries, and adjunctive techniques to lengthen the penis and address concomitant stress incontinence, among others. Concomitant with device and surgical changes, future considerations also include a greater need for education and training, particularly given the rapid expansion of sexual medicine into developing nations.

[Future Developments in Retinal Prostheses]. / Zukünftige Entwicklungen bei implantierbaren Netzhautprothesen.

Implantable retinal prostheses for the blind are already in use. In blind subjects suffering from retinitis pigmentosa (RP), these systems are able to induce phosphenes. However, the measurable gain in vision is limited. This is due to degeneration in the retina itself and to the technology, which is used in the currently available systems. Research groups and companies are working on solutions and prototypes to improve the outcome of electrical stimulation in the visual system. One improvement will be to enlarge the electrode array in order to restore a larger visual field. A second approach is to enlarge the number of electrodes and to place them at a higher density to improve the spatial resolution of the system. A third concept is to develop a recording unit within the electrode array to analyse ganglion cell behaviour underneath the electrode. This information can than be used to optimise the stimulation pattern. Not only retinal prostheses are under development but also systems to stimulate the retina from the suprachoroidal space, to directly stimulate the optic nerve or the lateral geniculate body or even the primary visual cortex.

Designing for scale: development of the ReMotion Knee for global emerging markets.

Amputees living in developing countries have a profound need for affordable and reliable lower limb prosthetic devices. The World Health Organization estimates there are approximately 30 million amputees living in low-income countries, with up to 95% lacking access to prosthetic devices. Effective prosthetics can significantly affect the lives of these amputees by increasing opportunity for employment and providing improvements to long-term health and well-being. However, current solutions are inadequate: state-of-the-art solutions from the US and Europe are cost-prohibitive, while low-cost devices have been challenged by poor quality and/or unreliable performance, and have yet to achieve large scale impact. The introduction of new devices is hampered by the lack of a cohesive prosthetics industry in low-income areas; the current network of low-cost prosthetic clinics is informal and loosely organized with significant disparities in geography, patient volume and demographics, device procurement, clinical and logistical infrastructure, and funding. At D-Rev (Design Revolution) we are creating the ReMotion Knee, which is an affordable polycentric prosthetic knee joint that performs on par with devices in more industrialized regions, like the US and Europe. As of September 2012, over 4200 amputees have been fitted with the initial version of the ReMotion Knee through a partnership with the JaipurFoot Organization, with an 79% compliance rate after 2 years. We are currently scaling production of the ReMotion Knee using centralized manufacturing and distribution to serve the existing clinics in low-income countries and increase the availability of devices for amputees without access to appropriate care. At D-Rev, we develop products that target these customers through economically-sustainable models and provide a measurable impact in the lives of the world's amputees.

Current technology: devices available for destination therapy.

Left ventricular assist device therapy as a destination therapy for end-stage heart failure has made a large leap with continuous flow devices. Continuous flow does not seem to have a detrimental effect on end-organ function, at least in the midterm. Various expected and unexpected complications have been reported associated with this technology. More experience and research are warranted.

Future directions in knee replacement.

The use of artificial joints for the treatment of osteoarthritis is expected to expand considerably over the next decade. While newer technologies can offer yet further improvements in total knee systems, implementation will be strongly affected by the need to satisfy apparently competing requirements. Patients expect quicker rehabilitation, improved performance, and lifelong durability; on the other hand, economic constraints require a reduction in cost for each procedure, as well as early intervention and preventative measures, while there is increased pressure from health care systems to use evidence-based medicine as the standard of choice for implants and techniques. The success of a knee replacement depends on the design itself, the surgical technique, the rehabilitation, and, not least, the patient. The major goal of the implant design can be redefined as a restoration of normal knee mechanics, whether by maximum preservation of tissues, or by guiding surfaces that replace their function. Surgical technique needs to be less invasive but achieve optimal patient-specific alignment and soft tissue balancing. Rehabilitation procedures must achieve the expectations of realistic patients. Testing and evaluation methods need to be upgraded for enhanced predictability. This paper discusses current trends and future possibilities to address this expansive scope of design criteria.

[Metal-on-metal hybrid hip resurfacing. Development and current state]. / Der Metall-Metall-Hybridoberflächenersatz des Hüftgelenks. Entwicklung und aktueller Stand.

Worldwide the employment of surface replacements using metal-on-metal components as an option, particularly for the young and active patient, has gained broad acceptance. Part of the attraction for hip resurfacing is its conservative nature as a prosthetic solution for hip arthritis. It is anatomical, replicating the normal hip and limb length, preserving proximal femoral bone, and is a truly minimally bone invasive approach with excellent outcome of joint function. The purpose of this article is to show the data of 1,000 Conserve(c) Plus hybrid metal-on-metal prostheses in a consecutive study of 1,140 patients with a follow-up of 5.6 years. The current Kaplan and Meier survival estimates of the prosthesis, using any conversion to total hip replacement as the end point, were 98.1% at 3 years [95% confidence interval (CI): 96.8-98.9%], 96.7% at 4 years (95% CI: 94.8-97.8%), and 95.2% at 5 years (95% CI: 93.0-96.8%). The mean postoperative Harris hip score was 93.3. The current state of metal-on-metal surface replacement is positive. The new generation of hip resurfacing has a lot of improvements. The purpose of this review of the procedure is to point out the definite improvements from earlier designs using polyethylene as well as to highlight the overall results and durability achieved by one surgeon's extensive experience and to assess the results from other series and centers. We also want to point out the areas where further investigation is needed.

[Present state of retinal prostheses development]. / Zum Stand der Entwicklung retinaler Sehprothesen.

Currently a number of coordinated groups are undertaking experimental research and technological development in order to design implants that may bypass distal degenerative diseases of the retina and in this way provide a restoration of basic orientation in blind people. This paper reviews the present state of these developments.

[Metal/metal coupling in total hip arthroplasty. Progress or setback?]. / Die Metall-Metall-Gleitpaarung in der Hüftendoprothetik. Fortschritt oder Rückschritt?

It was about 1966 that the metal/metal coupling was introduced into clinical use by McKee and Watson-Farrar. The main arguments for the introduction of this hard/hard coupling were the low wear rates compared to polyethylene couplings and the long-term stability of the metal components. The metal/metal couplings of McKee and Watson-Farrar could not meet the requirements of corresponding long-term results (loosening rates of more than 50% in part). The reason was the inadequate manufacturing quality, but also the random combination of components of different manufacturers. Nevertheless, remarkable long-term results could be reported and they were the reason for introducing a modified metal/metal coupling into clinical use in 1999. This metal/metal coupling of the second generation is characterised by modified CoCrMo materials, but also by definitely excellent manufacturing technologies. The clinical results seem to be better due to improved material quality and manufacturing technique. However, the question remains whether the high Co and Cr level, which is often noticed, has any pathological relevance.

Neural machine interfaces for controlling multifunctional powered upper-limb prostheses.

This article investigates various neural machine interfaces for voluntary control of externally powered upper-limb prostheses. Epidemiology of upper limb amputation, as well as prescription and follow-up studies of externally powered upper-limb prostheses are discussed. The use of electromyographic interfaces and peripheral nerve interfaces for prosthetic control, as well as brain machine interfaces suitable for prosthetic control, are examined in detail along with available clinical results. In addition, studies on interfaces using muscle acoustic and mechanical properties and the problem of interfacing sensory information to the nervous system are discussed.

Innovative technologies for the assessment of cardiovascular medical devices: state-of-the-art techniques for artificial heart valve testing.

Prosthetic heart valves (PHVs) are engineered devices used for replacing diseased natural cardiac valves. This article presents several investigational techniques for the evaluation of the performance of these clinical devices, whose implantation is not completely free of drawbacks. The state-of-the-art in the technological approach for PHV testing is addressed. As the fluid dynamics of PHVs are particularly complex, the main focus will be on experimental velocimetric techniques and computational analysis. A methodology for the analysis of the valve's signature, in terms of its characteristic sound in the opening and closing phases, is also presented. The aforementioned techniques are necessary to guarantee an operational life of the implanted device as free as possible from clinical complications. It can be realistically expected that this characterization will help designers in improving PHV performance.