Explant Analysis of Total Disc Replacement

Explant analysis of human disc prostheses allow early evaluation of the host response to the prosthesis and the response of the prosthesis from the host. Furthermore, early predictions of failure and wear can be obtained. Thus far, about 2-3% of disc prostheses have been removed. Observed wear patterns are similar to that of appendicular prostheses including abrasions/scratching, burnishing, surface deformation, fatigue, and embedded debris. Chemically the polymeric components have shown little degradation in short-term implantation. In metal on metal prostheses the histologic responses consist of large numbers of metallic particles with occasional macrophages and giant cells. Only rare cases of significant inflammatory response from polymeric debris have been seen

Recent Approaches for the Manufacturing of Polymeric Cranial Prostheses by Incremental Sheet Forming

This paper presents recent research experiences developed with the aim of manufacturing cranial prostheses in polymeric sheet using Incremental Sheet Forming (ISF) technologies. With this purpose, different approaches have been carried out in Single-Point Incremental Forming (SPIF) and Two-Point Incremental Forming (TPIF) in order to produce customized cranial implants using different polymeric materials. In this context, this research work provides a methodology to design and manufacture polymer customized cranial prostheses using the ISF technologies starting from a patient’s computerized tomography (CT). The results demonstrate the potential of manufacturing polymeric cranial prostheses by ISF in terms of the high formability achievable and show the appropriate geometrical accuracy at affordable manufacturing costs provided by these processes.Ministerio de Economía y Competitividad DPI2015-64047-

An exploratory evaluation of psychological factors in the rejection of upper limb prostheses : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Psychology at Massey University

This study investigated the reactions of arm amputees to their prostheses and explored possible reasons for these reactions. A questionnaire was constructed to determine the use to which the recipients put their prostheses. A preliminary validation study was conducted to determine the final form of the questionnaire. Rather than selecting a sample of prosthesis recipients, a census of the recipient population was attempted with 48.57 per cent responding. Respondents were asked questions measuring their use of the prosthesis, the nature of their prosthesis, the rehabilitation services they had used, and various demographic variables including age, sex, occupation and so on. It was found that up to 55.9% of the respondents could be classified as low-users of their prosthesis. A regression analysis showed that 44 per cent of the variance in the use of the prosthesis was due to the two variables of prosthesis type and prosthesis length. No other variables explained significant amounts of the variance. A lower-user and a high-user were selected to pilot a further study examining psychological factors that may affect prosthesis use. The areas examined were those of training, perceptions of independence and stigma, and perceptions of the prosthesis. A number of modifications were made to the original questions as a result of the pilot study. The results of the pilot study indicated that the areas of training and expectations of the prosthesis' capabilities prior to receiving it would be most likely to prove useful in explaining different levels of prosthesis use. Some issues relating to possible future research, interventions, and the rehabilitation process were also discussed

On the Analysis of the Contact Conditions in Temporomandibular Joint Prostheses

Temporomandibular joint replacement (TMJR) is a complex surgical procedure in which the artificial joints available must assure the anatomical reconstruction and guarantee a good range of the natural temporomandibular joint (TMJ) movements. With this aim, different types of TMJ prostheses, including the stock prosthetic system and custom-made prostheses, are being currently implanted. Although temporomandibular joint replacements (TMJRs) are expected to accomplish their function during a number of years, they might actually fail and need to be replaced. This paper analyzes different design factors affecting the contact stress distributions within the TMJ prosthesis interface, which are consequently involved in their deterioration and final failure of the prosthetic device. With this purpose, a numerical model based on finite elements has been carried out in order to evaluate the stress states attained in different prosthesis configurations corresponding to general types of TMJ prostheses. On the other hand, the actual degradation of resected implants has been evaluated via optical microscopy. The linkage between the numerical simulations performed and experimental evidence allowed the authors to establish the different wear and damage mechanisms involved in the failure of stock TMJ prostheses. Indeed, the results obtained show that the contact stresses at the interface between the mandible and the glenoid fossa components play a key role in the failure process of the TMJR devices

From Disability to Improvement through Prostheses

Статья рассказывает о последних разработках в области биопротезирования. Описаны возможности современных электронных биопротезов, их интерфейсы, а также компании, занимающиеся разработкой таких биопротезов в разных странах

Fifty Years of Innovation in Plastic Surgery

© 2016 The Korean Society of Plastic and Reconstructive Surgeons.Background Innovation has molded the current landscape of plastic surgery. However, documentation of this process only exists scattered throughout the literature as individual articles. The few attempts made to profile innovation in plastic surgery have been narrative, and therefore qualitative and inherently biased. Through the implementation of a novel innovation metric, this work aims to identify and characterise the most prevalent innovations in plastic surgery over the last 50 years. Methods Patents and publications related to plastic surgery (1960 to 2010) were retrieved from patent and MEDLINE databases, respectively. The most active patent codes were identified and grouped into technology areas, which were subsequently plotted graphically against publication data. Expert-derived technologies outside of the top performing patents areas were additionally explored. Results Between 1960 and 2010, 4,651 patents and 43,118 publications related to plastic surgery were identified. The most active patent codes were grouped under reconstructive prostheses, implants, instruments, non-invasive techniques, and tissue engineering. Of these areas and other expert-derived technologies, those currently undergoing growth include surgical instruments, implants, non-invasive practices, transplantation and breast surgery. Innovations related to microvascular surgery, liposuction, tissue engineering, lasers and prostheses have all plateaued. Conclusions The application of a novel metric for evaluating innovation quantitatively outlines the natural history of technologies fundamental to the evolution of plastic surgery. Analysis of current innovation trends provides some insight into which technology domains are the most active

Mechanical Behavior and Failure Analysis of Prosthetic Retaining Screws after Long‐term Use In Vivo. Part 1: Characterization of Adhesive Wear and Structure of Retaining Screws

Purpose: The general aim of this study and those presented in Parts 2–4 of this series was to characterize the structure, properties, wear, and fracture of prosthetic retaining screws in fixed detachable hybrid prostheses after long‐term use in vivo. This part of the overall investigation addresses whether there are differences in thread wear between the screws closest to the fulcrum and those that are farthest from the fulcrum in fixed detachable hybrid prostheses. Materials and Methods: The total number of prosthetic retaining screws used in this study was 100 (10 new and 90 used). New screws (controls) from Nobel Biocare (NB) were divided into Group 1 (slotted) and Group 2 (hexed). Ninety used screws (in service 18–120 months) were retrieved from fixed detachable hybrid prostheses in 18 patients (5 screws from each patient, 60 from NB and 30 from Sterngold). The used screws were divided into 18 groups. Additionally, each group was subdivided into A and B categories. Category A contained the middle three prosthetic screws, which were considered the farthest screws from the fulcrum line. Category B contained the most posterior two screws, which were considered the screws closest to the fulcrum line. All 100 screws were subjected to thorough, nondestructive testing. Results: Light and scanning electron microscopic examination of all used screws for each group revealed surface deterioration of the active profile of the screw threads consistent with adhesive wear. The observed thread profile deterioration ranged from mild to severe. The wear was aggressive enough to cause galling, which led to thinning of the threads and, in severe cases, to knife‐edges at thread crests. In ten groups, the most anterior three screws exhibited more wear than the most posterior two screws. In addition to thread wear, severe plastic deformation was detected on the bottom part of each screw for three groups, and a long external longitudinal crack was detected in one screw of Group 2. Conclusions: The findings of this study and those presented in Parts 2–4 demonstrate that different retaining screws from the same manufacturer and/or from different manufacturers have different geometrical design, microstructures, major alloy constituents, and microhardness, and that these differences influence their preload and fractured load values. In this part of the overall investigation, the occurrence of galling as a result of wear involving prosthetic retaining screws appears to be an inevitable and unavoidable consequence of long‐term use in vivo in fixed detachable hybrid prostheses regardless of the intended/original preload value. The galling rate is greater on the middle three screws compared to the most posterior two screws in fixed detachable hybrid prostheses. The wear pattern is consistent with an adhesive wear mechanism; however, this study does not provide enough data to support a definitive analysis

Within-socket Myoelectric Prediction of Continuous Ankle Kinematics for Control of a Powered Transtibial Prosthesis

Objective. Powered robotic prostheses create a need for natural-feeling user interfaces and robust control schemes. Here, we examined the ability of a nonlinear autoregressive model to continuously map the kinematics of a transtibial prosthesis and electromyographic (EMG) activity recorded within socket to the future estimates of the prosthetic ankle angle in three transtibial amputees. Approach. Model performance was examined across subjects during level treadmill ambulation as a function of the size of the EMG sampling window and the temporal \u27prediction\u27 interval between the EMG/kinematic input and the model\u27s estimate of future ankle angle to characterize the trade-off between model error, sampling window and prediction interval. Main results. Across subjects, deviations in the estimated ankle angle from the actual movement were robust to variations in the EMG sampling window and increased systematically with prediction interval. For prediction intervals up to 150 ms, the average error in the model estimate of ankle angle across the gait cycle was less than 6°. EMG contributions to the model prediction varied across subjects but were consistently localized to the transitions to/from single to double limb support and captured variations from the typical ankle kinematics during level walking. Significance. The use of an autoregressive modeling approach to continuously predict joint kinematics using natural residual muscle activity provides opportunities for direct (transparent) control of a prosthetic joint by the user. The model\u27s predictive capability could prove particularly useful for overcoming delays in signal processing and actuation of the prosthesis, providing a more biomimetic ankle response