Narrow Results

This paper shows experimental results on electromyography (EMG)-based system control applied to motorized orthoses. Biceps and triceps EMG signals are captured through two biometrical sensors, which are then filtered and processed by an acquisition system. Finally an output/control signal is produced and sent to the actuators, which will then perform the actual movement, using algorithms based on autoregressive (AR) models and neural networks, among others. The research goal is to predict the desired movement of the lower arm through the analysis of EMG signals, so that the movement can be reproduced by an arm orthosis, powered by two linear actuators. In this experiment, best accuracy has achieved values up to 91%, using a fourth-order AR-model and 100ms block length.

This paper reviews the use of the Swanson finger prosthesis, concentrating on clinical results from the metacarpophalangeal (MCP) joint and modes of prosthetic "failure". While "failure" is generally associated with fracture, it is recognised that fracture does not always necessitate replacement of the Swanson prosthesis. Fracture tends to occur at the junction of the distal stem and hinge of the prosthesis. Initial improvements in ulnar deviation and range of motion (ROM) tend to be gradually reduced over the duration of implantation, and there is little evidence to suggest any long-term improvement in hand strength. Bone erosion and silicone synovitis have been seen but at a much lesser incidence than in other joints implanted with silicone spacers. An evaluation of retrieved Swanson prostheses, tied in with patient history and hand measurements might provide additional information to improve the design of the Swanson prosthesis itself and of other finger prostheses.

This article describes the development of a proximal interphalangeal (PIP) joint prosthesis based on the principles of replicating anatomical surface components, the use of macrolocking intramedullary stem and the use of a cobalt-chrome alloy material. The design features are intended to obtain an optimal range of motion while retaining stability and longevity. The final prototype, for which a patent has been filed, is described.

Trapezium components from two uncemented total joint replacements were compared in a three-dimensional finite element model. A 100 N axial and angular load was applied in a normal and an osteoporotic bone model. The axial deformation and maximum periprosthetic stress are greater for the Elektra^TM than the Motec CMC^® cup. The Motec CMC^® design is less sensitive to changing bone quality. The Elektra^TM cup transmits more stress to the cortical bone rim in all load conditions, but under angular loading the proportionate increase in stress is lower. The Motec CMC^® design distributes the stress and contact pressure more evenly, whereas the Elektra^TM transfers most of the load to the cortical bone rim and the screw hole base. The design features that are believed to be of greatest significance for the differences are the raised centre of rotation of the Motec CMC^® cup and the collar acting as a lever arm.

While in revision hip surgery it has been described cold welding of the femoral component in titanium implants, no previous reports have been published in TMC prosthesis. We present a case report of a patient who sustained a TMC ARPE® dislocation 11 months after surgery and during revision surgery, cold welding of the neck with the metacarpal stem was observed. This may represent a problem when revising this prosthesis and alternative procedures should be advised and discussed with the patient when revising these implants.

A numerical procedure was implemented for the three-dimensional shape optimization of femoral component of total hip replacements. An algorithm was developed for defining the component geometry in terms of longitudinal and cross-sectional shape variables. The three-dimensional design model was combined with a non-linear 3-D finite element analysis and a numerical optimization procedure. An idealized femoral geometry and a frictional contact were used for bone-implant interfaces. The design objective was to reduce the shear stresses and the relative motion between implant and the surrounding bone along the interface region. The general trend in all design optimization was to produce a somewhat bulky implant with a more rectangular cross section. The outcome was more strongly affected by interface condition than choice of objective function.

Considering effects of physiological factors in failure of total hip arthroplasty, a numerical procedure was implemented for the three-dimesional (3D) shape optimization of femoral component of total hip replacements on the basis of remodeling objective functions. Design variables are the shape parameters, which define the femoral component geometry. The 3D design model was incorporated with 3D finite element analysis and a numerical optimization procedure. The main optimization goal was to reduce the potential for change of the bone morphology and to keep it close to the normal condition of an intact femur, by changing the geometry of the implant. Both local and global remodeling goals were examined. The results suggest a much more slender implant than is normally used would be required to minimize the remodeling potential. The results also demonstrated that the outcomes are indeed sensitive to whether the remodeling goal is treated as local or global.

Glenoid failure is one of the major indications for revision in total shoulder arthroplasty. Glenoid components should be carefully designed to improve the reliability of the prostheses, and mechanical testing can be a key tool to compare the performances of different designs. The most relevant guidelines for mechanical testing of glenoid prostheses are included in the ASTM F2028-05 Standard. The Standard refers to glenoid subluxation tests, designed to evaluate the intrinsic stability of the prosthesis system, and to glenoid edge displacement tests, which estimate the risk of micro-motions at the bone-glenoid interface. However, some indications given by the Standard are not mandatory, leaving the possibility to choose some parameters of the testing set-up and procedure. The main goal of this study was to investigate how different testing parameters (i.e. loads, velocities and bone-glenoid conformity) may affect the test results. In order to reach this target an experimental apparatus was developed and mechanical tests were performed on a keeled glenoid. The study showed that the applied load and the bone-glenoid conformity have a significant effect on the tests results, because of bone and glenoid deformation. Contrarily, the testing velocity was not found to be an influencing testing parameter.

Recently, there has been an increasing interest in upper limb prosthetic hand control, but most of these studies focused on the detection of exact motion intentions. Few results have been reported on the perturbation resistance of prostheses, which is extremely important for their uses in daily life. Understanding the human upper limb reflexive mechanism would provide an efficient solution to improve the perturbation resistance of prostheses. In this study, upper limb reflexive responses to force perturbation were measured in the conditions as determined from activities of daily living. Specifically, not only muscle activities, but also joint angle changes of the reflexive responses to multi-direction, multi-site perturbation during a reaching motion were recorded and analyzed. Results showed a direction-dependency of the upper limb reflexive mechanism and the different roles of shoulder, elbow, and wrist during the responses. The results could be applied to the control system of prosthetic devices for improving their perturbation resistance.

Accurate identification of intended grip actions using the myoelectric signal recorded from the surface of the residual muscles can facilitate natural control of a prosthetic hand for an amputee. However, this is not trivial due to the complexity of the hand muscles. To overcome these shortcomings, there is the need for determining features of the myoelectric recordings that can be used for accurate identification of the grip actions. This study reports the use of S-transform (ST) of the surface myoelectric recordings for recognizing the intent of the user to generate a set of grip patterns. Surface Electromyogram (sEMG) recorded while performing five different hand/finger grip patterns was analyzed. ST of the signal was computed to analyze the signal in a windowed time–frequency domain. The energy and mean amplitude of the transformed signal were classified using a neural network. The method was tested for able-hand and trans-radial amputee subjects. The results show that ST showed improved sensitivity, specificity and accuracy for both healthy and amputee people.

Individuals with transtibial amputation exhibit altered movement strategy to sustain stability during quiet standing due to reduced proprioception on the amputated limb. The aim of this study is to determine the movement strategies in anterior–posterior and medial–lateral directions in predicting the overall postural stability. In this crossover study, postural stability of ten transtibial amputees was assessed using computed posturography while wearing different prosthetic foot types: solid ankle cushion heel (SACH), single axis (SA) and energy storage and return (ESAR). Three stability indices were measured during four conditions: standing with eyes opened and closed, standing on compliant surface and standing with tilted head. From the standard multiple regression analysis, 63% to 99% of the OSI score in all sensory conditions were explained from the MLSI score, while 11% to 56% from the APSI score. The Pearson’s $r$ indicated significant strong positive relationship between OSI and MLSI $(r=0.82$–$0.99,p\le 0.001)$ during all sensory conditions. The APSI score was significantly lower than OSI during eyes-closed and head extended conditions for all prosthetic feet $(p<0.05)$. Adjustments in postural stability strategies in transtibial amputees mostly occurred in medial–lateral direction regardless of prosthetic feet types and altered sensory conditions.

In 1997, Sony announced AIBO, a fully autonomous small quadruped robot for home entertainment, and in 1999 the company began selling it as a consumer product. Soon after development, two small humanoid robots were announced. One was QRIO by Sony, which is about 60cm height body with dynamical bipedal walking and whole-body cooperative control. The other was PINO by the ERATO Kitano Symbiotic Systems Project, which is about 70cm height body, Open HW/SW with inexpensive off-the-shelf component. In this paper, we revisit the two humanoids and nearly 20-year-old technologies, and discuss what were done 20 years ago, what have been achieved and what challenges are ahead.

This work deals with the nonlinear mechanics of smart bioinspired tensegrity structures. A minimal regular tensegrity prism actuated by shape memory alloy (SMA) elements is investigated to represent a human foot. A formulation considering the force density matrix approach is used to model the equilibrium equations of the tensegrity structure based on node mapping. Lagrange multipliers are employed to represent constraints. The SMA thermomechanical behavior is described by considering a modified polynomial constitutive model. Numerical simulations are developed from an optimization procedure employing the Levenberg–Marquardt method. An investigation of the tensegrity capability to model a human foot is carried out analyzing either mechanical or physiological aspects of the tensegrity prosthesis. The mechanical performance is compared with high performance prostheses available on the market, showing that it is an interesting alternative with respect to mechanical resistance. Regarding physiology, foot movements are properly mimicked from SMA actuation.

The total hip replacement is the only approved procedure for restoring a degenerated hip joint through operation. The life span of a prosthesis could depend on the geometry and material properties of the implant. This study aims to analyze the biomechanics of the carbon/polyetheretherketone (PEEK) composite prosthesis having three different fiber ply configurations compared to traditional stainless steel (SS) ones. The implant-bone system was established and subjected to a load from the head of the femur and abductor muscle sides. The stresses and strains in the implant-bone systems were calculated and compared. The results revealed lower stresses and strains in composite prostheses compared to SS ones. The fiber ply orientation of the carbon/PEEK composite prosthesis is shown to be a key asset in stress and strain distribution of the 13 implant-bone systems. The fiber plies which orientated multidirectionally with −45 and +45 degrees exhibited uniform stress and strain distributions. The results suggested the advantage of using composite prostheses in implant designs as they not only invoke lower stresses and strains in the implant-bone system but also amplify the life span of implants in the body.

Growth arrest following paediatric distal radius and ulnar fractures infrequently results in a symptomatic deformity. The distal radioulnar joint (DRUJ) plays a complex role in the motion of the wrist, allowing for forearm rotation, and acceptable reconstruction options are limited when severe deformity does occur. We present a case of symptomatic severe post traumatic growth arrest of the distal radioulnar joint which was treated by osteotomy and Scheker total distal radioulnar joint arthroplasty.

Background: Literature investigating the long-term outcomes of prosthesis options for proximal interphalangeal (PIP) joint arthroplasty is scarce, with most reports combining indications and underlying pathologies in analyses. In this study, we aim to compare silicone, pyrocarbon and metal prostheses in PIP joint arthroplasty for primary degenerative osteoarthritis (OA).

Methods: A review of scientific literature published between 1990 and 2021 was conducted. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed. Relevant studies were screened and the appropriate data was extracted. An evaluation of clinical outcomes (range of motion [ROM] and pain), complications (reoperation) and survival rates for each prosthesis was performed.

Results: Twelve studies were included for analysis with a total of 412 PIP joints. ROM was 66.6°, 55.8° and 46.4° for metal, silicone and pyrocarbon implants, respectively. Silicone implants had the best pain score on the visual analogue scale (1.2) followed by the pyrocarbon (2.6) and metal (3.9) groups. Complication rates were lowest in silicone implants (11.3%) compared to 18.5% in pyrocarbon and 22.4% in metal prostheses. Survival did not differ significantly amongst the three groups.

Conclusions: Our findings suggest that for patients with primary degenerative OA, PIP joint arthroplasty using a silicone prosthesis can provide greater pain relief with lower complication rates compared to other implant options.

Level of Evidence: Level III (Therapeutic)

Background: This retrospective study compares the outcomes of trapeziectomy and Weilby suspensionplasty procedure versus implant arthroplasty using the TOUCH^® prosthesis for basilar thumb arthritis in an Asian population.

Methods: A total of 15 consecutive thumbs in 13 patients were included in this study. Six patients (2 male, 4 female, mean age of 62 years old) underwent trapeziectomy and Weilby suspensionplasty procedure. Seven patients (4 male, 3 female, mean age 63 years old) underwent implant CMCJ arthroplasty using the TOUCH^® prosthesis. Data collected include demographics, severity of arthritis on plain radiographs of the thumb basilar joint, length of follow-up, pre- and postoperative pain levels, Kapandji thumb opposition score, grip and pinch strength and the time taken to return to work.

Results: Patients in the trapeziectomy and Weilby suspensionplasty group had a mean follow-up of 4.5 months, while those in the TOUCH^® implant arthroplasty group had a mean follow-up of 14 months. TOUCH^® implant arthroplasty patients showed significantly higher grip strengths at 3 months post-surgery and a shorter return to work. There were no differences in pinch strength at 3 months, pinch or grip strength at 6 months or pain scores. Complications included prolonged scar hypersensitivity in two patients who underwent the Weilby suspensionplasty and a dislocated TOUCH^® implant cup in one patient.

Conclusions: Our study suggests that in the short term, CMCJ implant arthroplasty with the TOUCH^® prosthesis produces results comparable to trapeziectomy and Weilby suspensionplasty.

Level of Evidence: Level III (Therapeutic)

A duplicated mold of the residual limb of an amputee is usually needed to make the socket of prosthesis for the patient. However, traditional means to duplicate a positive mold is time-consuming, patient suffering and intensive manual-efforts required. The study has developed a prototype system that allows a prosthetist to construct the computer-aided design(CAD) model of residual limb easily using it's digitized points based on the concept of reverse engineering. First of all, the topographic data of a residual limb is captured using a non-intrusive scanning machine. The scanned data is then used as the input of a self-developed system that is based on the theories of B-spline curve and lofted surface to process the digitized points. The CAD model can then be built and transferred to a computer-aided manufacturing(CAM) system to generate the code for a computer numerical control(CNC) machine to make the duplicated mold of the residual limb.

No abstract received.

Motion analysis is a fundamental instrument for the quantification of joint function during daily living activities. Several devices can be used for this purpose. An overview of some of these methods is here presented, focusing mainly on (i) stereophotogrammetry (flexible and widespread), (ii) 3D fluoroscopy (accurate but invasive), and (iii) inertial sensors (economic though not very accurate). The main advantages and limitations of these methods are outlined, paying particular attention to the errors which can affect the estimated kinematic variables. Finally, some applications are described in the field of error compensation, joint modeling, and upper limb motion analysis.