Search Results (107)

Background/Objective: The most effective strategy for addressing users’ prosthetic needs is a comprehensive clinical assessment that provides a holistic understanding of the individual’s symptoms, health, function, and environmental barriers and facilitators. A standardized evaluation form would provide guidance for a structured approach to comprehensive clinical assessments of people with LLA. The objective of this study was to determine a list of relevant elements to be included in prosthetic evaluation for adults with lower limb amputation. Methods: Three independent focus group discussions were conducted with prosthetists (n = 15), prosthesis users (n = 11), and decision makers (n = 4) to identify all relevant elements that should be included in the clinical assessment of prosthetic services. The final content was then determined using the Delphi technique, with 35 panelists (18 prosthetists and decision makers, and 17 prosthesis users) voting in each round. Results: A total of 91 elements were identified through the focus group, of which 78 were included through the Delphi process. The identified elements are mostly related to the physical health of the prosthesis user (e.g., mobility, pain, and medical information), while others address personal or psychosocial aspects (e.g., activities of daily living, goals, and motivation) or technical aspects (prosthesis-related). Conclusions: Through a Delphi consensus, a list of relevant elements to be included in a prosthetic evaluation was generated. These results will inform the development of a standardized clinical prosthetic assessment form. This form has the potential to improve the quality of clinical evaluations, guide interventions, and enhance the well-being of prosthetic users. Full article

Background: This study compared performance-based function and self-report function in lower-limb prosthesis users. Methods: Twenty-two lower-limb prosthesis users (aged 52.1 ± 14.2) were administered the Orthotic Prosthetic User Survey (OPUS) Lower Extremity Functional Status (LEF), Satisfaction With Devices (SWD), alongside the Godin Leisure-Time Exercise Questionnaire (GLTQ), Timed Up and Go (TUG) test, two-minute walk test (2MWT), and six-minute walk test (6MWT). Body composition and standing postural sway displacement and velocity were also measured. Pearson’s Product Moment coefficients were used to assess relationships between the OPUS and other outcome variables. ANOVAs were used to identify differences in all outcome variables between lower unilateral (LU) and all other (AO) amputees. Results: There was a moderate correlation between LEF and center of pressure (CoP) path length with eyes open (r₍₁₉₎ = −0.43, p = 0.048) and eyes closed (r₍₁₉₎ = −0.43, p = 0.049). While the relationship between LEF and TUG was significant (r₍₂₀₎ = −0.49, p = 0.021), this was not so with SWD and TUG (r₍₂₀₎ = −0.17, p = 0.456). Both the 2MWT (r₍₂₀₎ = 0.48, p = 0.023) and 6MWT (r₍₂₀₎ = 0.47, p = 0.028) were moderately correlated with LEF. GLTQ was significantly correlated with LEF (r₍₂₀₎ = 0.70, p = 0.001). The LU group outperformed the AP group during the TUG and 6MWT (p < 0.05). LU group scored significantly higher on LEF compared to the AO group (p < 0.05). The reliability of LEF between the measurement on day 1 (54.3 ± 12.0) and day 2 (53.6 ± 12.8) was high (α = 0.94). Conclusions: This study provides an insight into associations of balance and self-reported function in lower limb prosthesis users. Future work can target rehabilitation strategies to address challenges faced by multiple limb prosthesis users. Full article

Background/Objectives: Peripheral prosthetic vascular graft infection represents a very serious complication after lower limb revascularization, with amputation and mortality rates up to 70% and 30%, respectively. This study was designed to determine the incidence of prosthetic graft infection, amputation, and mortality rate in our institution, analyzing different types of treatment. Methods: A retrospective cohort single institution review of peripheral prosthetic bypass grafts evaluated patient demographics, comorbidities, indications, location of bypass, type of prosthetic material, and case urgency and evaluated the incidence of graft infections, amputations, and mortality. Results: Between January 2016 and December 2021, a total of 516 bypasses were recorded (318 male, 198 female, mean age 74.2): 320 bypasses in venous material and 196 prosthetic bypasses using Dacron or PTFE. Among patients with a prosthetic bypass, 16 (8.2%) presented a graft infection at a mean follow-up of 39 months. Thirteen other patients who submitted to prosthetic peripheral bypass in other centers presented to our institution with a graft infection, so a total of 29 infected grafts were treated. Infected grafts were removed in 20 patients (68.9%), while a conservative treatment was helpful in nine cases (31.1%). The germs involved were Gram-negative in 27.6% and Gram-positive in 41.4%. During follow-up, we recorded five deaths (17.2%) and six amputations (20.7%) directly after bypass excision; another two amputations (6.9%) occurred after failure of the new bypass replacing the prosthesis removed. Conclusions: Redo-bypass, active infection at the time of bypass, and advanced gangrene were associated with a higher risk for prosthetic graft infection and major extremity amputation. Complete graft removal and replacement by venous material or Omniflow II represents the typical treatment. However, aggressive local treatment including drainage, debridement, vacuum-assisted closure therapy application, and muscle transposition seem to be a better solution in selected patients without the need for graft removal and with rates of limb salvage superior to those obtained with excisional therapy. Full article

Lower limb prosthesis abandonment is a significant challenge, leading to reliance on walking aids, such as wheelchairs, which frequently do not match the patient’s needs and lead to increased morbidity. Prosthesis abandonment is driven by a lack of embodiment, the latter defined as the integration of a prosthetic device into one’s body schema. This review evaluates interventions enhancing embodiment through three dimensions: ownership, agency, and co-location. The aim of this narrative review is to ask what interventions are available to improve embodiment, and what dimensions of embodiment should be included in the standard of care for lower-limb amputation surgery and componentry development. This narrative is constructed through a thorough literature search on how the aforementioned dimensions of embodiment can be optimized. In the studies reviewed, standardization of embodiment metrics and longitudinal data are lacking, hindering clinical translation. Future work must prioritize patient-centered design, integrate multidimensional assessments, and address practical issues to expand eligibility for advanced interventions. Full article

Lower limb motion recognition using surface electromyography (EMG) enhances human-computer interaction for intelligent prostheses. This study proposes a surface electromyography (EMG)-based scheme for lower limb motion recognition to enhance human-computer interaction in intelligent prostheses. Addressing the loss of phase information in existing methods, the approach combines S-transform energy concentration and multi-channel fusion analysis. EMG signals from six lower limb muscles of 10 subjects performing four movements (level walk, stair ascent, stair descent, and obstacle crossing) were analyzed. Correlation analysis identified the most relevant and least correlated muscles, optimizing signal quality. Using support vector machines (SVM), motion recognition accuracy was evaluated for single-channel and multi-channel signals. Results indicated that the semi-tendon and rectus femoris muscles achieved 80.71% accuracy with simple time-frequency features, while the medial gastrocnemius and rectus femoris reached 93.70% accuracy with S-transform energy concentration. Multi-channel fusion (rectus femoris, biceps femoris, and medial gastrocnemius) based on S-transform achieved over 96% accuracy, demonstrating superior recognition performance and potential for improving adaptive human-robot interaction in prosthetic control. Full article

As the field of prosthetic engineering advances, questions around whether these new prosthetics hold the ability to outperform biological limbs become more relevant. To further clarify such a debate and discover gaps in our understanding, a narrative review of the present literature on this topic is needed. The purpose of the present review was to explore whether prosthetic legs grant amputee athletes an unfair advantage over traditional athletes by reviewing 11 articles pertaining to the running performance and potential among athletes with transtibial amputations. The findings of the included articles were categorized into three domains of running performance, chosen due to their precedence in the current literature: propulsion forward, limb repositioning, and physiological limitations. Our review indicated that the present literature alludes to transtibial amputee runners having a potential competitive advantage over able-bodied runners, with the caveat that some performance domains appear not to be differentiated. The present findings offer a unique perspective on understanding the impact of prosthetics on the running performance among para-athletes and suggest future research directions. As the depth of this area of literature increases, future systematic reviews and meta-analyses may be able to answer with greater certainty whether transtibial prosthetics allow for supra-biological running performances. Full article

Background: Transtibial prosthetic sockets are critical components in the complete assembly of a prosthetic, as they form the major load-bearing parts by housing the residual limb of a prosthesis user. Conventional procedures for manufacturing these sockets require repeated iterations and manual casting, baking, and drying, which often lead to longer processing and waiting times. Additive Manufacturing (AM) enables the creation of bespoke designs with meticulous control over the socket’s shape, thickness, and material composition. Method: To design and propose an optimal socket design to a lower-limb prosthetic user based on their preference of activity such as walking, running, and jumping, we investigated seven materials—Polypropylene (PP) standard material for conventional socket fabrication, Polylactic-acid-plus (PLA+), Polyamide (PA) Natural, Polyamide-6-Glass-Fiber (PA6-GF), Polyamide-copolymer (CoPA), Polyamide-6-Carbon-Fiber (PA6-CF), and Polyamide-12-Carbon-Fiber (PA12-CF)—that have AM compatibility by subjecting them to heavy external loading and evaluating their von Mises stress–strain behavior. Result: Using Finite Element Analysis (FEA), we evaluated a single-material design and a combination design with two materials—one major (low cost) and one minor (higher cost)—to optimize a composition that would bear heavy external loads without yielding. A maximum load-bearing capacity of 3650 N was achieved with the combination of PLA+ and 31.54 vol% PA6-CF (30.23 weight%, 99.13 g), costing about USD 14 for the total socket material. Similarly, a combination of PLA+ with 31.54 vol% PA6-GF (30.76 weight%, 101.67 g) exhibited a maximum load-bearing capacity of 2528.91 N. Conclusions: The presence of high-strength CF and GF in minor compositions and at critical locations within the transtibial socket are the suggested reasons for these enhanced load-bearing capacities, due to which these sockets could be used for undertaking a wider range of activities by the prosthesis users. Full article

Background/Objectives: A cam-driven hydraulic prosthetic ankle was designed to overcome the weaknesses of commercial prostheses and research prototypes, which largely fail to mimic the energy-recycling behaviour of an intact ankle, resulting in poor walking performance for lower-limb prosthesis users. Methods: This novel device exploits miniature hydraulics to capture the negative work performed during stance, prior to push-off, in a hydraulic accumulator, and return positive work during push-off for forward body propulsion. Two cams are used to replicate intact ankle torque profiles based on experimental data. The design process for the new prosthesis used a design programme, implemented in MATLAB, based on a simulation of the main components of the prosthetic ankle. Results: In this paper, we present the design programme and explain how it is used to determine the cam profiles required to replicate intact ankle torque, as well as to size the cam follower return springs. Moreover, a constraint-based preliminary design investigation is described, which was conducted to size other key components affecting the device’s size, performance, and energy efficiency. Finally, the feasible design alternatives are compared in terms of their energy losses to determine the best design with regard to minimising both energy losses and device size. Conclusions: Such a design approach not only documents the design of a particular novel prosthetic ankle, but can also provide a systematic framework for decomposing complex design challenges into a series of sub-problems, providing a more effective alternative to heuristic approaches in prosthetic design. Full article

Arterial cystic disease (ACD) affecting the popliteal artery (PA) is a rare form of non-atherosclerotic vascular disease. This cystic tumor is defined by the accumulation of a mucinous substance in the adventitia. Treatment options include percutaneous cyst aspiration, percutaneous transluminal balloon angioplasty, the evacuation of the cyst through a surgical approach, and resection of the affected artery segment followed by arterial reconstruction using autologous venous or prosthetic grafting. Our hospital received a 36-year-old man who had an intermittent claudication and periodically nocturnal rest pain in the left lower limb. Duplex scanning and CTA showed an entrapment of the left PA by a structure related to the arterial wall with an approximate 80% stenosis. The pedal and posterior tibial pulses faded when the knee was flexed. The ACD of the PA was diagnosed. An excision of an affected arterial segment and revascularization of the PA with great saphenous vein procedures were performed. We were unable to locate any instances in the literature of ACD accompanied by nocturnal rest pain that resembled the case we have presented. At a seventeen-year follow-up, the patient’s condition was reported as normal with no intermittent claudication or rest pain in the left lower limb. Full article

Background: Prostheses are becoming more advanced and biomimetic with time, providing additional capabilities to their users. However, prosthetic sensation lags far behind its natural limb counterpart, limiting the use of sensory feedback in prosthetic motion planning and execution. Without actionable sensation, prostheses may never meet the functional requirements to match biological performance. Methods: We propose an approach for upper limb prosthetic grasp security feedback, delivered to the wearer through direct nerve stimulation proportional to the likelihood of objects slipping from grasp. This proportional feedback is based on a linear regression of the sensors embedded in a prosthetic hand to predict slip before it occurs. Four participants with transhumeral amputation performed pulling tasks with their prosthetic hand grasping an object at predetermined grip forces, attempting to pull the object with as much force as possible without slip. These trials were performed with two different prediction notification paradigms. Results: At lower grasp forces, where slip was more likely, a strong, single impulse notification of impending slip reduced the incidence of object slip by a median of 32%, but the maximum achieved pull forces did not change. At higher grasp forces, where slip was less likely, the maximum achieved pull forces increased by a median of 19% across participants when provided with a stimulation strength inversely proportional to the grasp security, but slip incidence was unchanged. Conclusions: These results suggest that this approach may be effective in recreating a lost sense of grip stability in the missing limb that can be incorporated into motor planning and ultimately prevent unanticipated object slips. Full article

(1) Background: The use of tumor megaprostheses faces challenges, but the published series are typically small and offer limited solutions. Our aim was to compile a large series; describe patient profiles and surgical techniques; analyze prosthetic survival identifying factors affecting survival; and provide a basis for future subanalyses. (2) Methods: This is a retrospective observational multicenter study that included patients with a tumor megaprosthesis in any anatomical location. Demographic, etiologic, and surgical variables were analyzed. Data on complications and survival were also collected. (3) Results: Our series includes a total of 816 prostheses (585 primary, 181 revision, and 50 second revision). The patients’ mean age was 44.2 ± 20.8 years. Primary surgeries were performed on the femur (n = 404; 69.1%), tibia (n = 79; 13.5%), humerus (n = 74; 12.6%), pelvis (n = 20; 3.4%), and scapula (n = 4; 0.7%). Survival following primary surgery was 73.3% at 10 years. No statistically significant differences were found with respect to survival from primary surgery between males and females (p = 0.194), between the different etiologies (p = 0.540), or between the lower and the upper limb (p = 0.618). In contrast, statistically significant survival differences were found when the type of fixation was analyzed (p < 0.001). (4) Conclusions: This study analyzed one of the largest series of patients treated with tumor megaprostheses, demonstrating their acceptable survival and validating them as a treatment option for bone tumors. Full article

Polymethyl methacrylate (PMMA) bone cement has been a transformative material in orthopedics since its introduction in the mid-20th century. Originally used in dental medicine, PMMA was adopted for orthopedic applications by Sir John Charnley in the 1950s, significantly enhancing joint replacement surgeries. The primary appeal of PMMA lies in its biocompatibility, mechanical strength, and ease of handling, making it a favored choice for various orthopedic procedures, including arthroplasties and limb-salvage surgeries. However, the exothermic polymerization process of PMMA poses a risk of thermal necrosis in the surrounding bone tissue, as local temperatures can exceed 70 °C, causing damage to osteocytes. Research has sought to mitigate these risks by optimizing mixing techniques, reducing cement mantle thickness, and incorporating cooling methods. Recent advancements, such as the use of phase-change materials (PCMs) and alternative monomers, have shown promise in lowering the exothermic peak during polymerization. Other strategies include pre-cooling the cement and prosthetic components and using composite cement. Despite these innovations, managing the balance between minimizing heat generation and maintaining mechanical properties remains a challenge. The impact of thermal necrosis is significant, compromising implant stability and osseointegration. Understanding the complex interactions between PMMA’s thermal properties and its clinical outcomes is essential for improving orthopedic surgical practices and patient recovery. Full article

The volitional control of powered assistive devices is commonly performed by mapping the electromyographic (EMG) activity of the lower limb to joints’ angular kinematics, which are then used as the input for regulation. However, during walking, the ground reaction force (GRF) plays a central role in the modulation of the gait, providing dynamic stability and propulsion during the stance phase. Including this information within the control loop of prosthetic devices can improve the quality of the final output, providing more physiological walking dynamics that enhances the usability and patient comfort. In this work, we explored the feasibility of the estimation of the ground reaction force vertical component (VGRF) by using only the EMG activities of the thigh and shank muscles. We compared two deep learning models in three experiments that involved different muscular configurations. Overall, the outcomes show that the EMG signals could be leveraged to obtain a reliable estimation of the VGRF during walking, and the shank muscles alone represent a viable solution if a reduced recording setup is needed. On the other hand, the thigh muscles failed in providing performance enhancements, either when used alone or together with the shank muscles. The results outline the feasibility of including GRF information within an EMG-driven control scheme for prosthetic and assistive devices. Full article

Background: Research on sensory feedback systems for prosthetic devices aims to enhance sensory capabilities to better meet user needs. Feedback systems for lower limb amputees (LLA) have been shown to reduce cognitive efforts, metabolic cost and phantom limb pain. This study evaluated the effect of a non-invasive, gait-synchronized, vibrotactile feedback system (VTFS) on the gait parameters of LLA. Methods: Four stimulators applied vibrotactile stimulation to the thigh of LLA during walking, corresponding to four pressure sensors located at the fore- and hindfoot embedded in a sock worn on the prosthetic foot. Standardized gait tests, such as the Timed “Up and Go” Test (TUG), the Four Square Step Test (FSST), the 10 Meter Walk Test (10 MWT) and the 2 Minute Walk Test (2 MWT), were performed to assess the risk of falling, coordination, walking speed and endurance before and after intervention. Results: After an average of 61.5 days using the VTFS, gait stability (TUG) improved significantly. Coordination (FSST) improved in 36% of subjects, while 45% showed a clinically relevant increase in gait speed (10 MWT). Conclusions: The results suggest an improved gait performance in the cohort. Though FSST lacked statistical significance, a p-value near 0.05 indicates a trend toward meaningful improvement. Notably, the participant with Targeted Sensory Reinnervation demonstrated the most favorable outcomes. Full article

Friction and wear characteristics play a critical role in the functionality and durability of prosthetic sockets, which are essential components in lower-limb prostheses. Traditionally, these sockets are manufactured from bulk polymers or composite materials reinforced with advanced carbon, glass, and Kevlar fibres. However, issues of accessibility, affordability, and sustainability remain, particularly in less-resourced regions. This study investigates the potential of self-reinforced polymer composites (SRPCs), including poly-lactic acid (PLA), polyethylene terephthalate (PET), glass fibre (GF), and carbon fibre (CF), as sustainable alternatives for socket manufacturing. The tribological behaviour of these self-reinforced polymers (SrPs) was evaluated through experimental friction tests, comparing their performance to commonly used materials like high-density polyethylene (HDPE) and polypropylene (PP). Under varying loads and rotational speeds, HDPE and PP exhibited lower coefficients of friction (COF) compared to SrPLA, SrPET, SrGF, and SrCF. SrPLA recorded the highest average COF of 0.45 at 5 N and 240 rpm, while SrPET demonstrated the lowest COF of 0.15 under the same conditions. Microscopic analysis revealed significant variations in wear depth, with SrPLA showing the most profound wear, followed by SrCF, SrGF, and SrPET. In all cases, debris from the reinforcement adhered to the steel ball surface, influencing the COF. While these findings are based on friction tests against steel, they provide valuable insights into the durability and wear resistance of SRPCs, a crucial consideration for socket applications. This study highlights the importance of tribological analysis for optimising prosthetic socket design, contributing to enhanced functionality and comfort for amputees. Further research, including friction testing with skin-contact scenarios, is necessary to fully understand the implications of these materials in real-world prosthetic applications. Full article