Residual Limb Research Articles

Bioinspired Design of 3D-Printed Cellular Metamaterial Prosthetic Liners for Enhanced Comfort and Stability.

Traditional prosthetic liners are often limited in customization due to constraints in manufacturing processes and materials. Typically made from non-compressible elastomers, these liners can cause discomfort through uneven contact pressures and inadequate adaptation to the complex shape of the residual limb. This study explores the development of bioinspired cellular metamaterial prosthetic liners, designed using additive manufacturing techniques to improve comfort by reducing contact pressure and redistributing deformation at the limb-prosthesis interface. The gyroid unit cell was selected due to its favorable isotropic properties, ease of manufacturing, and ability to distribute loads efficiently. Following the initial unit cell identification analysis, the results from the uniaxial compression test on the metamaterial cellular samples were used to develop a multilinear material model, approximating the response of the metamaterial structure. Finite Element Analysis (FEA) using a previously developed generic limb-liner-socket model was employed to simulate and compare the biomechanical behavior of these novel liners against conventional silicone liners, focusing on key parameters such as peak contact pressure and liner deformation during donning, heel strike, and the push-off phase of the gait cycle. The results showed that while silicone liners provide good overall contact pressure reduction, cellular liners offer superior customization and performance optimization. The soft cellular liner significantly reduced peak contact pressure during donning compared to silicone liners but exhibited higher deformation, making it more suitable for sedentary individuals. In contrast, medium and hard cellular liners outperformed silicone liners for active individuals by reducing both contact pressure and deformation during dynamic gait phases, thereby enhancing stability. Specifically, a medium-density liner (10% infill) balanced contact pressure reduction with low deformation, offering a balance of comfort and stability. The hard cellular liner, ideal for high-impact activities, provided superior shape retention and support with lower liner deformation and comparable contact pressures to silicone liners. The results show that customizable stiffness in cellular metamaterial liners enables personalized design to address individual needs, whether focusing on comfort, stability, or both. These findings suggest that 3D-printed metamaterial liners could be a promising alternative to traditional prosthetic materials, warranting further research and clinical validation.

Digital technologies and strategies in amputation medicine

Surgical techniques in amputation medicine did not change for a long time, while prosthesis technology underwent rapid development. The focus shifted to optimising the residual limb for prostheses use. At the same time, digital technologies such as gamification, virtual and mixed reality revolutionised rehabilitation. The use of gamification elements increases motivation and adherence to therapy, while immersive technologies enable realistic and interactive therapy experiences. This is particularly useful in the context of controlling modern prostheses and treating phantom pain. In addition, digital applications contribute to optimised documentation of symptoms and therapy successes. Overall, these technologies open up new, effective and personalised therapeutic approaches that can significantly improve the quality of life of amputation patients.

52769 Microwave Thermoablation of Eccrine Glands to Treat Residual Limb Hyperhidrosis

52769 Microwave Thermoablation of Eccrine Glands to Treat Residual Limb Hyperhidrosis

Innovative noninvasive gait-synchronized vibrotactile feedback system : "I can feel myself walking again"

Despite intensive research and development of systems for restoration of sensory information, these have so far only been the subject of study protocols. Anew noninvasive feedback system translates pressure loads on the forefoot and hindfoot into gait-synchronized vibrotactile stimulation of adefined skin area. To increase the authenticity, this treatment can be supplemented by a surgical procedure. Targeted sensory reinnervation (TSR) describes amicrosurgical procedure in which adefined skin area on the amputated stump of the residual limb is first denervated and then reinnervated by aspecific, transposed sensory nerve harvested from the amputated part of the limb. This creates asensory interface at the residual stump. This article presents the clinical and orthopedic technical treatment pathway with this innovative vibrotactile feedback system and explains in detail the surgical procedure of TSR after amputation of the lower limb.

New insights into muscle activity associated with phantom hand movements in transhumeral amputees.

Muscle activity patterns in the residual arm are systematically present during phantom hand movements (PHM) in transhumeral amputees. However, their characteristics have not been directly investigated yet, leaving their neurophysiological origin poorly understood. This study pioneers a neurophysiological perspective in examining PHM-related muscle activity patterns by characterizing and comparing them with those in the arm, forearm, and hand muscles of control participants executing intact hand movements (IHM) of similar types. To enable rigorous comparison, we developed meta-variables independent of electrode placement, quantifying the phasic profile of recorded surface EMG signals and the specificity of their patterns across electrode sites and movement types. Similar to the forearm and hand muscles during IHM, each signal recorded from the residual upper arm during PHM displays a phasic profile, synchronized with the onset and offset of each movement repetition. Furthermore, the PHM-related patterns of phasic muscle activity are specific not only to the type of movement but also to the electrode site, even within the same upper arm muscle, while these muscles exhibit homogeneous activities in intact arms. Our results suggest the existence of peripheral reorganization, eventually leading to the emergence of independently controlled muscular sub-volumes. This reorganization potentially occurs through the sprouting of severed axons and the recapture of muscle fibers in the residual limb. Further research is imperative to comprehend this mechanism and its relationship with PHM, holding significant implications for the rehabilitation process and myoelectric prosthesis control.

ARTIFICIAL INTELLIGENCE–BASED AUTONOMOUS SOCKET PROPOSAL PROGRAM: A PRELIMINARY STUDY FOR CLINICAL DECISION SUPPORT SYSTEM

Purpose: The aim of this study is to develop artificial intelligence-based interfaces that can be used by professionals (clinicians and/or academics) working with disabled individuals who need prosthetics and to create a sample data set for professionals working in this field. Methods: 101 patients who had undergone amputation were enrolled. The residual limbs of all patients were scanned using a three-dimensional (3D) scanner and saved on the computer. The prosthetic sockets, fabricated using traditional methods, were also scanned with the same scanner and saved as a 3D model. Residual limb–prosthetic socket matches were obtained using data points and a deep neural network (DNN)-based decision support system was developed. Results: Simulation studies conducted with the point cloud data sets of 101 patients yielded a training success rate of 86%. The DNN model exhibited a generalization success rate of 78%. Conclusion: The artificial intelligence–based software interface has potential and could assist professionals by suggesting a suitable 3D socket model for patients in need of a prosthesis. Further studies will benefit from additional sample data to enhance the accuracy of the model.

Enhanced orthopedic implant design for transfemoral amputation incorporating a honeycomb structure technology

After lower limb amputation, the primary challenge is to facilitate the patient’s adoption of a prosthetic limb seamlessly, without encountering complications or discomfort. Elevated stress levels within the residual limb, experienced when wearing the socket and while standing or walking, contribute to patient discomfort. As an initial step in this study, we developed a finite element model of above-knee amputation. Additionally, we designed a prototype orthopedic implant composed of several parts, with the lower section featuring a honeycomb structure aimed at absorbing and diminishing stresses at the interface of the residual limb and prosthetic. In this study, finite element models with and without orthopedic implants were analyzed to assess the feasibility and impact of incorporating a honeycomb structure within the implants on stress distribution, particularly at the stump-prosthetic interface. Models with honeycomb-structured implants, at varying densities, showed a reduction in interface stress to approximately 2.15e-2 MPa and 2.01e-2 MPa, compared to 4.5e-2 MPa in model without honeycomb structure in the implant and 7.97e-2 MPa in models without any implants.

The relationship of hip strength to walking and balance performance in unilateral lower limb prosthesis users differs by amputation level.

Safe and efficient locomotion is a frequently stated goal of lower limb prosthesis users, for which hip strength may play a central yet poorly understood role. Additional research to identify associations between hip strength, balance, and mobility among transtibial and transfemoral prosthesis users is required. To test whether residual and/or intact limb isometric hip strength was associated with lower limb prosthesis users' walking speed, endurance, and balance. Cross-sectional study. Research laboratory. Convivence sample of 14 transtibial and 14 transfemoral prosthesis users. Multiple linear regression was used to evaluate the relationship between isometric measures of residual and intact limb hip strength and walking and balance performance. Measures of isometric hip muscle strength, including peak torque, average torque, torque impulse, and torque steadiness (i.e. consistency with which an isometric torque can be sustained) were derived from maximum voluntary hip flexion, extension, abduction and adduction torque signals collected with a motor-driven dynamometer. Walking speed, endurance, and balance were assessed by administering the 10-meter walk test, 2-minute walk test, Four Square Step Test, and Narrowing Beam Walking Test, respectively. Residual limb hip extensor max torque and abductor torque steadiness explained between 51% and 69% of the variance in transtibial prosthesis users' walking speed, endurance, and balance. In contrast, intact limb hip abductor torque impulse explained between 33% and 48% of the variance in transfemoral prosthesis users' walking speed, endurance, and balance. Our results suggest that unilateral transtibial and transfemoral prosthesis users' walking and balance performance may depend on different hip muscles, and different facets of hip strength. Amputation level-specific hip strength interventions may therefore be required to improve walking and balance performance in unilateral transtibial and transfemoral prosthesis users. The "intact leg strategy" adopted by transfemoral prosthesis users may be due to a variety of prosthesis and biomechanical factors that limit the efficiency with which transfemoral prosthesis users can exploit the strength of their residual limb hip muscles while walking.

Reversible cerebral vasoconstriction syndrome post-cardiac transplantation: a therapeutic dilemma: case report

BackgroundReversible cerebral vasoconstriction syndrome (RCVS) is characterized by diffuse, multifocal segmental narrowing of cerebral arteries and can result in ischaemic stroke. Causal factors, identified in 60% of cases, include immunosuppressant pharmacotherapy. The few reports following heart transplantation are almost all in Asian recipients. We report on a Caucasian Australian patient with immunotherapy induced RCVS post heart transplantation to highlight the state of knowledge of the condition and the treatment dilemma it poses.Case presentationA 51-year-old female underwent orthotopic heart transplantation at our institution. Induction immunotherapy comprised basiliximab, mycophenolate mofetil and methylprednisolone. On day 6 post-transplantation the patient was transitioned to oral prednisolone and tacrolimus. On day 7 the patient began to experience bilateral, severe, transient occipital and temporal headaches. On day 9 tacrolimus dose was up-titrated. A non-contrast computed tomography brain (CTB) was normal. Endomyocardial biopsy on day 12 demonstrated moderate Acute Cellular Rejection (ACR), which was treated with intravenous methylprednisolone. That evening the patient experienced a 15-minute episode of expressive dysphasia. The following morning she became confused, aphasic, and demonstrated right sided neglect and right hemianopia. A CT cerebral perfusion scan demonstrated hypoperfusion in the left middle cerebral artery (MCA) territory and cerebral angiography revealed widespread, focal multi-segmental narrowing of the anterior and posterior circulations. A diagnosis of RCVS was made, and nimodipine was commenced. As both steroids and tacrolimus are potential triggers of RCVS, cyclosporin replaced tacrolimus and methylprednisolone dose was reduced. A further CTB demonstrated a large left MCA territory infarct with left M2 MCA occlusion. The patient made steady neurological improvement. She was discharged 34 days post-transplantation with mild residual right lower limb weakness and persistent visual field defect on verapamil, cyclosporine, everolimus, mycophenolate mofetil and prednisolone.ConclusionReversible cerebral vasoconstriction syndrome is rare after orthotopic heart transplantation. Until now, RCVS has been almost exclusively described in Asian recipients, and is typically caused by immunotherapy. The condition may lead to permanent neurological deficits, and in the absence of definitive treatments, early recognition and imaging based diagnosis is essential to provide the opportunity to remove the causal agent(s). Co-existent ACR, can pose unique treatment difficulties.

Robotic-Enhanced Prosthetic Liners for Vibration Therapy: Reducing Phantom Limb Pain in Transfemoral Amputees.

Phantom limb pain, a common challenge for amputees, lacks effective treatment options. Vibration therapy is a promising non-pharmacologic intervention for reducing pain intensity, but its efficacy in alleviating phantom limb pain requires further investigation. This study focused on developing prosthesis liners with integrated vibration motors to administer vibration therapy for phantom limb pain. The prototypes developed for this study addressed previous issues with wiring the electronic components. Two transfemoral amputees participated in a four-week at-home trial, during which they used the vibration liner and rated their initial and final pain intensity on a numeric rating scale each time they had phantom pain. Semi-structured interviews were conducted to gather feedback following the at-home trial. Both participants described relaxing and soothing sensations in their residual limb and phantom limb while using vibration therapy. One participant reported a relaxation of his phantom limb sensations, while both participants noted a decrease in the intensity of their phantom limb pain. Participants said the vibration liners were comfortable but suggested that the vibration could be stronger and that aligning the contacts could be easier. The results of this study highlight the potential effectiveness of using vibration therapy to reduce the intensity of phantom limb pain and suggest a vibration liner may be a feasible mode of administering the therapy. Future research should address optimizing the performance of the vibration liners to maximize their therapeutic benefits.

Designing a personalized thermo-mechanically optimized liner for transfemoral prosthetics

Elastomeric interphases (liners) protect the residual limb and distribute mass bearing to the prosthetic socket. However, discomfort due to excessive sweat and heat in the residual limb is the most relevant factor that negatively affects the quality of life in transfemoral prosthetics users. Additionally, a warm and humid environment and the non-uniform mass distribution can compromise blood flow in the residual limb; these factors favor the development of skin lesions, the dropout rate of prosthetic use, and subsequent amputations. Previous mathematical models that predict skin temperature distribution based on Pennes' model and explain the Fourier and non-Fourier thermic response are available. However, these models require knowledge of difficult parameters to obtain in conditions that lead to amputation. Therefore, the current study aims to propose an experimentally based method to design a personalized liner with areas of different diffusivity rates by using perforations according to thermal needs, preserving the mechanical properties of the liner. After thermal and mechanical characterization, we elaborated a personalized plane liner according to the thermal expression of the anterior thigh using infrared analysis. We tested the liner to probe its ability to dissipate heat.

A preliminary study exploring the effects of transcutaneous spinal cord stimulation on spinal excitability and phantom limb pain in people with a transtibial amputation

Objective. Phantom limb pain (PLP) is debilitating and affects over 70% of people with lower-limb amputation. Other neuropathic pain conditions correspond with increased spinal excitability, which can be measured using reflexes andF-waves. Spinal cord neuromodulation can be used to reduce neuropathic pain in a variety of conditions and may affect spinal excitability, but has not been extensively used for treating PLP. Here, we propose using a non-invasive neuromodulation method, transcutaneous spinal cord stimulation (tSCS), to reduce PLP and modulate spinal excitability after transtibial amputation.Approach. We recruited three participants, two males (5- and 9-years post-amputation, traumatic and alcohol-induced neuropathy) and one female (3 months post-amputation, diabetic neuropathy) for this 5 d study. We measured pain using the McGill Pain Questionnaire (MPQ), visual analog scale (VAS), and pain pressure threshold (PPT) test. We measured spinal reflex and motoneuron excitability using posterior root-muscle (PRM) reflexes andF-waves, respectively. We delivered tSCS for 30 min d-1for 5 d.Main Results. After 5 d of tSCS, MPQ scores decreased by clinically-meaningful amounts for all participants from 34.0 ± 7.0-18.3 ± 6.8; however, there were no clinically-significant decreases in VAS scores. Two participants had increased PPTs across the residual limb (Day 1: 5.4 ± 1.6 lbf; Day 5: 11.4 ± 1.0 lbf).F-waves had normal latencies but small amplitudes. PRM reflexes had high thresholds (59.5 ± 6.1μC) and low amplitudes, suggesting that in PLP, the spinal cord is hypoexcitable. After 5 d of tSCS, reflex thresholds decreased significantly (38.6 ± 12.2μC;p< 0.001).Significance. These preliminary results in this non-placebo-controlled study suggest that, overall, limb amputation and PLP may be associated with reduced spinal excitability and tSCS can increase spinal excitability and reduce PLP.

Does Terminology Matter? Perspectives From People With Limb Difference, Clinicians, and Researchers

ObjectiveTo elicit the preferred terminology among people with limb difference as well as health care and/or research professionals. DesignCross-sectional survey. SettingOnline. ParticipantsA convenience sample of N=122 individuals (people with limb difference, n=65; health care and/or research professionals, n=57) completed an online survey. People were included if they (1) were aged ≥18 years; (2) self-identified as having limb difference (regardless of etiology) or as a health care or research professional (with experience working with people with limb difference); and (3) lived in the United States for most of the time in their selected role. InterventionsNot applicable. Main Outcome MeasuresImportance of terminology, preference toward person-first or identity-first terms, preferred terms, and individual perspectives on terminology preferences. ResultsMost participants identified as White (92.6%). Age significantly differed between groups (people with limb difference, 49.9±15.4y; professionals, 41.0±14.3y; P=.001). Approximately 50% of people with limb difference stated terminology was very or extremely important, compared to 70% of professionals (χ2=16.6, P=.002). While 73.7% of professionals reported a preference for person-first terminology, the sample of people with limb difference were more evenly split, as 42.9% reported a preference for identity-first terminology and 50.8% reported a preference for person-first terminology. The most frequently selected limb and population terms, respectively, were residual limb and individual/person with limb difference; however, many people with limb difference indicated they preferred “amputee” when speaking about a population. ConclusionsMost of the participants indicated terminology was very or extremely important, and both groups tended to prefer the terms residual limb (limb term) and individual/person with limb difference (population term). However, this study was not intended to recommend terminology, but rather help inform terminology choices that are centered around people with limb difference. Individuality and context should be considered when deciding terminology. Future studies should include more participants from racially/ethnically minoritized groups and people with limb difference who have dysvascular and/or congenital etiologies.

Clinical Outcomes of Transradial vs Nontransradial Aortoiliac Endovascular Therapy

BackgroundThe introduction of radial-specific equipment has made transradial (TR) aortoiliac (AI) endovascular therapy (EVT) more convenient. ObjectivesThe authors aimed to investigate the perioperative outcomes of the TR approach in patients undergoing AI EVT for symptomatic peripheral artery disease. MethodsThe COMFORT (Contemporary Strategy for Aortoiliac Intervention) registry was a prospective, multicenter, observational study enrolling patients with symptomatic peripheral artery disease undergoing AI EVT between January 2021 and June 2023. The primary outcome was perioperative complications, whereas the secondary outcomes included core laboratory–evaluated residual stenosis >30%, time to hemostasis, time to ambulation, 30-day patency, and 30-day limb symptoms. These outcomes were compared between TR and non-TR AI EVT after propensity score matching. ResultsThe TR approach was selected for 231 of the 947 patients (24.3%). The TR approach was chosen more in patients with a higher ankle-brachial index, chronic total occlusion, aortic lesion, bare nitinol stent implantation, and plain angioplasty, whereas it was chosen less in patients with dialysis, a history of AI EVT, chronic limb-threatening ischemia, bilateral calcification, and simultaneous infrainguinal EVT (all P < 0.05). After propensity score matching, the incidence of perioperative complications did not differ significantly between the groups (TR group: 6.0% vs non-TR group: 5.1%; P = 0.69). The proportions of residual stenosis, 30-day patency, and 30-day limb symptoms were not significantly different (all P > 0.05); however, the time to hemostasis and the time to ambulation were shorter in the TR group (both P < 0.05). ConclusionsNon-TR AI EVT and TR AI EVT using radial-specific equipment were associated with a similar risk of perioperative complications. The TR approach helps shorten the time required for hemostasis and ambulation.

Bone Bridge Transtibial Amputation by an Innovative Technique.

We present a case report of synostosis after transtibial amputation because of distraction regenerate formation after decortication of the lateral surfaces of the tibia and fibula, sequential compression, and distraction using the Ilizarov apparatus. Its advantage is that there is no need to shorten bone. The establishment of distal tibia-fibula synostosis (Ertl) in patients with transtibial amputation has been advocated to improve function and prosthetic wear. There are a variety of techniques to create a bone block. This case reports the successful use of an innovative technique to establish bone block. A patient with transtibial amputation underwent revision of residual limb by decorticating the lateral aspect of the distal tibia and the medial aspect of the distal fibula and acutely compressing the distal ends of the 2 bones with the Ilizarov apparatus. The distal fibula is then slowly and progressively distracted laterally, and the bone is formed in the space between the distal fibula and tibia, creating synostosis with an increased distal bone cross-sectional surface area for improved function and prosthetic wear. The follow-up period was 24 months. Within 3 months, synostosis was formed, which increased the area of the supporting surface and allowed temporary and then permanent prosthetics. After 24 months, synostosis did not differ from the structure of tibial stump bones.

A review of reliability and geometrical precision for residual limb contour acquisition by different scanners

A review of reliability and geometrical precision for residual limb contour acquisition by different scanners

Management of different types of postamputation residual limb pain amid full scale war

Management of different types of postamputation residual limb pain amid full scale war

The Overlay, a New Solution for Volume Variations in the Residual Limb for Individuals with a Transtibial Amputation.

The company Ethnocare has developed the Overlay, a new pneumatic solution for managing volumetric variations (VVs) of the residual limb (RL) in transtibial amputees (TTAs), which improves socket fitting. However, the impact of the Overlay during functional tasks and on the comfort and pain felt in the RL is unknown. 8 TTAs participated in two evaluations, separated by two weeks. We measured compensatory strategies (CS) using spatio-temporal parameters and three-dimensional lower limb kinematics and kinetics during gait and sit-to-stand (STS) tasks. During each visit, the participant carried out our protocol while wearing the Overlay and prosthetic folds (PFs), the most common solution to VV. Between each task, comfort and pain felt were assessed using visual analog scales. While walking, the cadence with the Overlay was 105 steps/min, while it was 101 steps/min with PFs (p = 0.021). During 35% and 55% of the STS cycle, less hip flexion was observed while wearing the Overlay compared to PFs (p = 0.004). We found asymmetry coefficients of 13.9% with the Overlay and 17% with PFs during the STS (p = 0.016) task. Pain (p = 0.031), comfort (p = 0.017), and satisfaction (p = 0.041) were better with the Overlay during the second visit. The Overlay's impact is similar to PFs' but provides less pain and better comfort.

The physical experiences of women with lower limb absence during pregnancy and postpartum: symptoms, prosthesis management & mobility

Purpose Little information is available to women with lower limb absence (LLA) and their health care providers regarding the impacts they may experience during the perinatal period. This study explores the physical impacts of pregnancy on women with LLA, including mobility, prosthesis fit and prosthesis use. Methods We conducted semi-structured interviews with 19 women with LLA who had experienced pregnancy in the last 10 years. Interviews were analyzed using thematic analysis. Results Substantial variation exists in the experience of women’s physical symptoms, prosthesis management and mobility. Physical symptoms were similar to any pregnant individual, but the impacts were more substantial. As volume change in the residual limb can impact prosthesis fit, self-management techniques and prosthetist adjustments were used to manage it. Pregnancy impacted the way in which women were mobile and the activities they chose to participate in. A wide variety of creative mobility solutions were utilized to complete activities including prosthesis use, assistive equipment and adaptive movement. Conclusions Women with LLA and their health care providers must be aware of the wide range of experiences women face during pregnancy and treat each pregnancy uniquely. Planning ahead and working with a health care team can mitigate many of these challenges.

Identifying discriminant factors between phantom limb pain, residual limb pain, and both in people with lower limb amputations: a cross-sectional study.

Postamputation pain is a common condition in patients with lower limb amputation (LLA), which compromises amputees' rehabilitation, use of the prosthesis, and quality of life. The aim of our study was to investigate the prevalence of phantom limb pain (PLP), residual limb pain (RLP), or both types of pain among individuals with LLA, and to identify the factors associated with the presence of one type of pain versus the other. Patients who underwent amputation for traumatic or vascular reasons and who reported on RLP or PLP were analyzed and divided into three groups: PLP, RLP, or a group of subjects that presented both pains. We searched for factors that affect the occurrence of limb pain using univariate analyses, followed by multinomial logistic regression. Among the 282 participants with transtibial and transfemoral amputations, 192 participants (150 male and 42 female) presented PLP, RLP, or both types of pain, while 90 participants declared to perceive no pain. The estimated prevalence of any type of pain after transfemoral and transtibial amputation was therefore 68% (27% PLP, 10% RLP, and 31% both). Among the studied characteristics, only amputation level was associated with the type of pain ( P = 0.001). Multinomial logistic regression identified transfemoral amputation as the only statistically significant predictor for PLP (odds ratio = 2.8; P = 0.002). Hence, it was estimated that individuals with transfemoral amputation have nearly three times higher odds of experiencing PLP compared with those with transtibial amputation.