Does Ipsilateral Remapping Following Hand Loss Impact Motor Control of the Intact Hand?

What happens once a cortical territory becomes functionally redundant? We studied changes in brain function and behavior for the remaining hand in humans (male and female) with either a missing hand from birth (one-handers) or due to amputation. Previous studies reported that amputees, but not one-handers, show increased ipsilateral activity in the somatosensory territory of the missing hand (i.e., remapping). We used a complex finger task to explore whether this observed remapping in amputees involves recruiting more neural resources to support the intact hand to meet greater motor control demands. Using basic fMRI analysis, we found that only amputees had more ipsilateral activity when motor demand increased; however, this did not match any noticeable improvement in their behavioral task performance. More advanced multivariate fMRI analyses showed that amputees had stronger and more typical representation-relative to controls' contralateral hand representation-compared with one-handers. This suggests that in amputees, both hand areas work together more collaboratively, potentially reflecting the intact hand's efference copy. One-handers struggled to learn difficult finger configurations, but this did not translate to differences in univariate or multivariate activity relative to controls. Additional white matter analysis provided conclusive evidence that the structural connectivity between the two hand areas did not vary across groups. Together, our results suggest that enhanced activity in the missing hand territory may not reflect intact hand function. Instead, we suggest that plasticity is more restricted than generally assumed and may depend on the availability of homologous pathways acquired early in life.

Integrating Upper-Limb Prostheses with the Human Body: Technology Advances, Readiness, and Roles in Human-Prosthesis Interaction.

Significant advances in bionic prosthetics have occurred in the past two decades. The field's rapid expansion has yielded many exciting technologies that can enhance the physical, functional, and cognitive integration of a prosthetic limb with a human. We review advances in the engineering of prosthetic devices and their interfaces with the human nervous system, as well as various surgical techniques for altering human neuromusculoskeletal systems for seamless human-prosthesis integration. We discuss significant advancements in research and clinical translation, focusing on upper limbprosthetics since they heavily rely on user intent for daily operation, although many discussed technologies have been extended to lower limb prostheses as well. In addition, our review emphasizes the roles of advanced prosthetics technologies in complex interactions with humans and the technology readiness levels (TRLs) of individual research advances. Finally, we discuss current gaps and controversies in the field and point out future research directions, guided by TRLs.

Modulations in high-density EEG during the suppression of phantom-limb pain with neurostimulation in upper limb amputees.

Phantom limb pain (PLP) is a distressing and persistent sensation that occurs after the amputation of a limb. While medication-based treatments have limitations and adverse effects, neurostimulation is a promising alternative approach whose mechanism of action needs research, including electroencephalographic (EEG) recordings for the assessment of cortical manifestation of PLP relieving effects. Here we collected and analyzed high-density EEG data in 3 patients (P01, P02, and P03). Peripheral nerve stimulation suppressed PLP in P01 but was ineffective in P02. In contrast, transcutaneous electrical nerve stimulation was effective in P02. In P03, spinal cord stimulation was used to suppress PLP. Changes in EEG oscillatory components were analyzed using spectral analysis and Petrosian fractal dimension. With these methods, changes in EEG spatio-spectral components were found in the theta, alpha, and beta bands in all patients, with these effects being specific to each individual. The changes in the EEG patterns were found for both the periods when PLP level was stationary and the periods when PLP was gradually changing after neurostimulation was turned on or off. Overall, our findings align with the proposed roles of brain rhythms in thalamocortical dysrhythmia or disruption of cortical excitation and inhibition which has been linked to neuropathic pain. The individual differences in the observed effects could be related to the specifics of each patient's treatment and the unique spectral characteristics in each of them. These findings pave the way to the closed-loop systems for PLP management where neurostimulation parameters are adjusted based on EEG-derived markers.

Prosthetic outcomes after amputation and the impact of mobility level on survival.

OBJECTIVE: Lower extremity amputation continues to be necessary in a significant number of patients with peripheral vascular disease. The 5-year survival following lower limb loss is markedly reduced. Many of these patients are never fitted with a prosthesis, and there is a dearth of knowledge regarding the barriers to prosthetic attainment. The goal of this study was to identify the risk factors for not receiving a prosthesis and the effect of mobility level on survival following major amputation. METHODS: This was a retrospective analysis of all patients that underwent lower extremity amputation by surgeons in our practice from January 1, 2010, to December 31, 2019. Abstracted data included: age, sex, race, body mass index, comorbidities, American Society of Anesthesiologists score, statin use, level of amputation, stump revision, fitting for prosthesis, type of prosthesis, and the United States' Medicare Functional Classification Level, also called K level. Survival was determined using a combination of sources, including the Social Security Death Master File, searches of multiple genealogic registries, and general internet searches. Multivariable logistic regression was used to determine risk factors associated with prosthesis attainment. Multivariable Cox proportional hazard regression with time-dependent covariates was performed to assess risk factors associated with 5-year mortality. RESULTS: A total of 464 patients were included in this study. The mean age was 65 years, and mean body mass index was 27 kg/m2. The majority of patients were male (68%), White (56%), diabetic (62%), and hypertensive (76%), and underwent below-the-knee amputation (69%). Prosthetic attainment occurred in 185 (40%). On multivariable analysis, age >81 years and current tobacco use were associated with no prosthetic fitting. Overall 5-year survival was 41.9% (95% confidence interval [CI], 37.6%-46.6%) (below-the-knee amputation, 47.7% [95% CI, 42.5%-53.5%]; above-the-knee amputation, 28.7% [95% CI, 22.1%-37.2%]). On multivariable analysis, age >60 years, congestive heart failure, above-the-knee amputation, and no prosthetic attainment were associated with decreased survival. Increasing K level was incrementally associated with improved survival. CONCLUSIONS: This study has identified several patient factors associated with prosthetic attainment, as well as multiple factors predictive of reduced survival after amputation. Being referred for prosthetic fitting was associated with improved survival not explained by patient characteristics and comorbidities. The Medicare Functional Classification Level K level predicts survival. More research is needed to determine the barriers to prosthetic attainment and if improving a patients K level will improve survival.

Prosthetic fitting and mortality after major lower extremity amputation.

BACKGROUND: Studies suggest that ambulation after major lower extremity amputation (LEA) is low and mortality after LEA is high. Successful prosthetic fitting after LEA has a significant quality of life benefit; however, it is unclear if there are benefits in post-LEA mortality. Our objective was to examine a contemporary cohort of patients who underwent LEA and determine if there is an association between fitting for a prosthetic and mortality. METHODS: We reviewed all patients who underwent LEA between 2015 and 2022 at two academic health care systems in a large metropolitan city. The exposure of interest was prosthetic fitting after LEA. The primary outcomes were mortality within 1 and 3 years of follow-up. Ambulation after LEA was defined as being ambulatory with or without an assistive device. Patients with prior LEA were excluded. Extended Cox models with time-dependent exposure were used to evaluate the association between prosthetic fitting and mortality at 1 and 3 years of follow-up. RESULTS: Among 702 patients who underwent LEA, the mean (SD) age was 64.3 (12.6) years and 329 (46.6%) were fitted for prosthetic. The study population was mostly male (n = 488, 69.5%), predominantly non-Hispanic Black (n = 410, 58.4%), and nearly one-fifth were non-ambulatory before LEA (n = 139 [19.8%]). Of note, 14.3% of all subjects who were nonambulatory at some point after LEA, and 28.5% of patients not ambulatory preoperatively were eventually ambulatory after LEA. The rate of death among those fitted for a prosthetic was 12.0/100 person-years at 1 year and 5.8/100 person-years at 3 years of follow-up; among those not fitted for a prosthetic, the rate of death was 55.7/100 person-years and 50.7/100 person-years at 1 and 3 years of follow-up, respectively. After adjusting for several sociodemographic data points, comorbidities, pre- or post- coronavirus disease 2019 pandemic timeframe, and procedural factors, prosthetic fitting is associated with decreased likelihood of mortality within 1 year of follow-up (adjusted hazard ratio, 0.24; 95% confidence interval, 0.14-0.40) as well as within 3 years (adjusted hazard ratio, 0.40; 95% confidence interval, 0.29-0.55). CONCLUSIONS: Prosthetic fitting is associated with improved survival, and preoperative functional status does not always predict postoperative functional status. Characterizing patient, surgical, and rehabilitation factors associated with receipt of prosthetic after LEA may improve long-term survival in these patients. Process measures employed by the Department of Veterans Affairs, such as prosthetic department evaluation of all amputees, may represent a best practice.

Health Care Utilization After Major Limb Loss in Adults (18-64) Receiving Care in the Military Health System From 2001 to 2017.

OBJECTIVE: To characterize and quantify health care utilization of Military Health System beneficiaries with major limb loss. DESIGN: Retrospective cohort study. SETTING: Military treatment facilities and civilian health care facilities that accept TRICARE insurance across the United States. PARTICIPANTS: A total 5950 adult Military Health System beneficiaries with major limb amputation(s) acquired between January 1st, 2001, and September 30th, 2017 (N=5950). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: This study was an exploratory analysis designed to identify common care specialties, services, and devices utilized by Military Health System beneficiaries with major limb loss. RESULTS: Most beneficiaries were retirees/dependents (63.3%), men (73.1%), and had a single amputation (88.7%), with a mean age of 42 years. Differences between beneficiary categories were found. Active-duty service members used a larger proportion of inpatient, emergency, primary care, physical and occupational therapy, prosthetics and orthotics, physical medicine and rehabilitation, and psychiatry services than retirees/dependents. Most common procedures included "revision of amputation stump" (57.2%) for the active-duty population and "other amputation below knee" (24.3%) for the retirees/dependents. CONCLUSIONS: These findings highlight the rehabilitation trajectories of beneficiaries receiving treatment for major limb loss in military and civilian care settings. The results could inform staffing decisions and training programs for military treatment facilities, American trauma centers, rehabilitation hospitals, and outpatient health care providers treating individuals with amputation.

Prognosticating Prosthetic Ambulation Ability in People With Lower Limb Amputation in Early Post-operative Phase.

OBJECTIVE: To formulate a prognostication model in the early post-operation phase of lower limb amputation to predict patient's ability to ambulate with a prosthesis post rehabilitation. DESIGN: Retrospective cohort study, using data collected from electronic medical records. Predictive factors and prosthetic ambulation outcomes post rehabilitation were used to develop prognostic models via machine learning techniques. SETTING: Regional hospital's ambulatory rehabilitation clinic. PARTICIPANTS: Patients with major lower limb amputation (N=329). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: The outcome of prosthetic ambulation ability post rehabilitation collected was categorized in 3 groups: non-ambulant with prosthesis, homebound ambulant with prosthesis (AP), and community AP. RESULTS: In a 2-class model of non-ambulant and AP (homebound and community), the model with highest accuracy of prediction included ethnicity, total Functional Comorbidity Index (FCI), level of amputation, being community ambulant prior to amputation, and age. The f1-score and area under receiver operator curve (AUROC) of the model is 0.78 and 0.82. In a 3-class model consisting of all 3 groups of outcomes, the model with highest accuracy of prediction required 10 factors. The additional factors from the 2-class model include presence of caregiver, history of congestive heart failure, diabetes, visual impairment, and stroke. The 3-class model has a moderate accuracy with a f1-score and AUROC of 0.60 and 0.79. CONCLUSION: The 2-class prognostication model has a high accuracy which can be used early post-amputation to predict if patient would be ambulant with a prosthesis post rehabilitation. The 3-class prognostication model has moderate accuracy and is able to further differentiate the walking ability to either homebound or community ambulation with a prosthesis, which can assist in prosthetic prescription and setting realistic rehabilitation goals.

Utilization and Perception of Peer-Support After Lower Limb Loss in the United States: Potential Benefits on Mobility Outcomes.

OBJECTIVE: To examine participants' experiences with peer-support after lower limb loss (LLL) and the associations between the peer-support experience (perceived benefits and barriers) and mobility outcomes. DESIGN: Quantitative and qualitative descriptive study with a cross-sectional design. SETTING: National survey (distributed to 169 peer-support groups in 44 states in the US). PARTICIPANTS: The survey was completed by 82 individuals with a major lower limb amputation (53% female, 54% over 55 years of age; N=82). MAIN OUTCOME MEASURES: A 32-item survey to examine respondents' experiences in peer-support activities. Prosthetic mobility was measured using the Prosthetic Limb Users Survey of Mobility (PLUS-M). RESULTS: Two out of 3 respondents received some forms of peer-support after amputation. Among them 75% reported peer-support having a positive effect on their outlook on life, and 78% reported that information gained from peer-support was helpful. Companionship, altruistic acts, and gaining information on how to cope with amputation were the top themes of why respondents enjoyed the peer-support experience. Nearly all (94%) respondents would recommend peer-support to other people with LLL. Individuals who received peer-support exhibited a trend of greater mobility (55th vs 36th percentile on PLUS-M; P=.055). CONCLUSION: Individuals with LLL reported generally positive experiences regarding their engagement in peer-support activities. Peer-support groups are viewed as a helpful source for both information and emotional support, potentially benefiting functional and psychological recovery after amputation. Individuals who have received peer-support also exhibited greater mobility.

Association of Race, Ethnicity, and Gender to Disparities in Functional Recovery and Social Health After Major Lower Limb Amputation: A Cross-sectional Pilot Study.

OBJECTIVE: To assess if evidence of disparities exists in functional recovery and social health post-lower limb amputation. DESIGN: Race-ethnicity, gender, and income-based group comparisons of functioning and social health in a convenience sample of lower limb prosthetic users. SETTING: Prosthetic clinics in 4 states. PARTICIPANTS: A geographically diverse cohort of 56 English and Spanish speaking community-dwelling individuals with dysvascular lower limb amputation, between 18-80 years old. INTERVENTIONS: None. MAIN OUTCOMES MEASURES: Primary outcomes included 2 physical performance measures, the Timed Up and Go test and 2-minute walk test, and thirdly, the Prosthetic Limb Users Survey of Mobility. The PROMIS Ability to Participate in Social Roles and Activities survey measured social health. RESULTS: Of the study participants, 45% identified as persons of color, and 39% were women (mean ± SD age, 61.6 (9.8) years). People identifying as non-Hispanic White men exhibited better physical performance than men of color, White women, and women of color by -7.86 (95% CI, -16.26 to 0.53, P=.07), -10.34 (95% CI, -19.23 to -1.45, P=.02), and -11.63 (95% CI, -21.61 to -1.66, P=.02) seconds, respectively, on the TUG, and by 22.6 (95% CI, -2.31 to 47.50, P=.09), 38.92 (95% CI, 12.53 to 65.30, P<.01), 47.53 (95% CI, 17.93 to 77.13, P<.01) meters, respectively, on the 2-minute walk test. Income level explained 14% and 11% of the variance in perceived mobility and social health measures, respectively. CONCLUSIONS: Study results suggest that sociodemographic factors of race-ethnicity, gender, and income level are associated with functioning and social health post-lower limb amputation. The clinical effect of this new knowledge lies in what it offers to health care practitioners who treat this patient population, in recognizing potential barriers to optimal recovery and quality of life. More work is required to assess lived experiences after amputation and provide better understanding of amputation-related health disparities.

The Effect of Prosthetic Limb Sophistication and Amputation Level on Self-reported Mobility and Satisfaction With Mobility.

OBJECTIVE: To determine if lower limb prosthesis (LLP) sophistication is associated with patient-reported mobility and/or mobility satisfaction, and if these associations differ by amputation level. DESIGN: Cohort study that identified participants through a large national database and prospectively collected self-reported patient outcomes. SETTING: The Veterans Administration (VA) Corporate Data Warehouse, the National Prosthetics Patient Database, participant mailings, and phone calls. PARTICIPANTS: 347 Veterans who underwent an incident transtibial (TT) or transfemoral (TF) amputation due to diabetes and/or peripheral artery disease and received a qualifying LLP between March 1, 2018, and November 30, 2020. INTERVENTIONS: Basic, intermediate, and advanced prosthesis sophistication was measured by the accurate and reliable PROClass system. MAIN OUTCOME MEASURE: Patient-reported mobility using the advanced mobility subscale of the Locomotor Capabilities Index-5; mobility satisfaction using a 0-10-point Likert scale. RESULTS: Lower limb amputees who received intermediate or advanced prostheses were more likely to achieve advanced mobility than those who received basic prostheses, with intermediate nearing statistical significance at nearly twice the odds (adjusted odds ratio (aOR)=1.8, 95% confidence interval (CI), .98-3.3; P=.06). The association was strongest in TF amputees with over 10 times the odds (aOR=10.2, 95% CI, 1.1-96.8; P=.04). The use of an intermediate sophistication prosthesis relative to a basic prosthesis was significantly associated with mobility satisfaction (adjusted ß coefficient (aß)=.77, 95% CI, .11-1.4; P=.02). A statistically significant association was only observed in those who underwent a TT amputation (aß=.79, 95% CI, .09-1.5; P=.03). CONCLUSIONS: Prosthesis sophistication was not associated with achieving advanced mobility in TT amputees but was associated with greater mobility satisfaction. In contrast, prosthesis sophistication was associated with achieving advanced mobility in TF amputees but was not associated with an increase in mobility satisfaction.

Patients Experience Significant Long-Term Social and Health Challenges After Major Lower Extremity Amputation.

BACKGROUND: Major lower extremity amputation is a significant life-changing event that can have long-term implications. The goal of this study was to assess long-term medical outcomes and social determinants of health (SDH) challenges in this population. METHODS: A retrospective review of major lower extremity (previously mentioned ankle) amputations (2018-2022) was performed at a safety-net tertiary care center. Patients who participated in an SDH survey between 6 months and 1.5 years postoperatively were included for survey analysis. Patient demographics, comorbidities, and perioperative and long-term outcomes were analyzed. RESULTS: There were 100 patients included. Mean age was 61.5 years and 23% were of female gender. The majority (57%) were Black race, 20% White race, and 21% Hispanic ethnicity. Comorbidities included diabetes (78%), chronic kidney disease (51%), coronary artery disease (31%), congestive heart failure (23%), previous cerebrovascular events (19%), and 37% used opioids preadmission. At baseline, the majority (62%) lived at home. Guillotine amputation was performed in 24%, with definitive amputation in the following and previously mentioned knee in 67% and 33%, respectively. Median length of stay was 7 days. Readmission at 30 days, 90 days, and 1 year was 13%, 30%, and 43% respectively. The average follow up was 839 days. At long-term follow up, 55% lived at home, 25% used opioids, and only 25% were independently ambulatory. In the SDH survey at follow up, 32% identified at least one SDH challenge, with younger patients more often affected (58 vs. 63 years, P = 0.031). SDH challenges consisted of food insecurity (17%), housing insecurity (13%), transportation challenges (13%), seeking employment (8%), difficulty paying for utilities (5%) and medications (4%), seeking further education (5%), and difficulty caring for family/friends (4%). On multivariable analysis, having at least one SDH challenge was independently associated with 1-year readmission (odds ratio 6.7, 95% confidence interval 1.3-35.8, P < 0.001). Older age was associated with lower long-term independent ambulation (odds ratio 0.92, 95% confidence interval 0.85-0.99, P = 0.025). CONCLUSIONS: After major lower extremity amputation, patients have significant medical and social challenges with fewer living at home, the majority were not independently ambulatory, and one-third having at least one SDH challenge. Improvements in long-term support including medical, social, and rehabilitation services are required for this vulnerable population.

Mobility Rates After Lower-Limb Amputation for Patients Treated with Physician-Led Collaborative Care Model.

BACKGROUND: Clinical outcomes after major lower-limb amputation have been historically poor. The current care provided to most amputees is often disorganized and without physician supervision. The primary purpose of this study is to examine rates of postamputation mobility achieved with a prosthesis by patients with chronic limb-threatening ischemia and/or diabetes who required major lower-limb amputation and were treated under an established physician-led collaborative care pathway. The secondary purpose is to describe the structure and utilization of the care pathway by multiple independent vascular surgery practices in the United States to enable future exploration of its impact on key clinical outcomes within this patient population. METHODS: Clinical records of 2,475 patients from 6 vascular practices that adopted this collaborative care pathway between 2017 and 2020 were retrospectively reviewed. Only records with sufficient documented histories of amputation surgeries, prosthetic services, and mobility status were included. RESULTS: Of 2,475 patient records reviewed, 1,787 patients (2,157 major amputations) were eligible for analysis. Sixty-two-point 2 percent (n = 1,111) of patients achieved mobility with the collaborative care pathway. Mobility rate varied by amputation level in the study. Prosthetic mobility was achieved in 73.5% of transtibial amputations, 40.4% of transfemoral amputations, and 35.7% of through-knee amputations, regardless of patient laterality, which is superior or equivalent to the best published rates of mobility. CONCLUSIONS: The study describes the structure and utilization of a physician-led collaborative care pathway for treating patients who require lower-limb amputation that meets 5 of the 7 recommendations from the 2019 Global Vascular Guidelines on the Management of Chronic Limb Threatening Ischemia. Internal data analysis results suggest that patients treated via this care pathway can potentially achieve improved mobility rates with a prosthesis following amputation. This collaborative care pathway should be further evaluated for its ability to directly improve mobility and other clinically relevant amputation outcomes.

Care Priorities for Individuals with Lower Extremity Amputations: A Patient Delphi Study.

OBJECTIVE: To gather preliminary evidence on short- and long-term care priorities for people with lower extremity amputations. DESIGN: A three-round modified Delphi study using semi-structured interviews. PARTICIPANTS: A convenience sample of 20 adult participants who had undergone lower extremity amputations at a tertiary public hospital. MAIN MEASURE: Consensus on each care priority was defined a priori as an agreement of more than 50%. Semi-structured interviews were conducted to understand the rationales for endorsing the care priorities. RESULTS: Consensus was reached on 24 short-term care priorities and 12 long-term care priorities in the biomedical, practical and psychological and spiritual domains. The rationales for endorsing each of the care priorities generated three themes: preparedness; mental health, psychological and spiritual well-being; and participating in life, with respect and dignity. CONCLUSIONS: Our results highlight the substantial need to improve patient access to education and planning support prior to undergoing limb amputation, and optimising post-amputation rehabilitation programmes, enabling people with amputations to participate in meaningful life roles that provide them with purpose, dignity, and self-respect. The knowledge of care priorities revealed in this study may promote effective patient-centred care and improve clinical outcomes.

Graded motor imagery and its phases for individuals with phantom limb pain following amputation: A scoping review.

OBJECTIVE: Three-phase graded motor imagery (limb laterality, explicit motor imagery, and mirror therapy) has been successful in chronic pain populations. However, when applied to phantom limb pain, an amputation-related pain, investigations often use mirror therapy alone. We aimed to explore evidence for graded motor imagery and its phases to treat phantom limb pain. DATA SOURCES: A scoping review was conducted following the JBI Manual of Synthesis and Preferred Reporting Items for Systematic Review and Meta-Analyses extension for Scoping Reviews. Thirteen databases, registers, and websites were searched. REVIEW METHODS: Published works on any date prior to the search (August 2023) were included that involved one or more graded motor imagery phases for participants ages 18+ with amputation and phantom limb pain. Extracted data included study characteristics, participant demographics, treatment characteristics, and outcomes. RESULTS: Sixty-one works were included representing 19 countries. Most were uncontrolled studies (31%). Many participants were male (75%) and had unilateral amputations (90%) of varying levels, causes, and duration. Most works examined one treatment phase (92%), most often mirror therapy (84%). Few works (3%) reported three-phase intervention. Dosing was inconsistent across studies. The most measured outcome was pain intensity (95%). CONCLUSION: Despite the success of three-phase graded motor imagery in other pain populations, phantom limb pain research focuses on mirror therapy, largely ignoring other phases. Participant demographics varied, making comparisons difficult. Future work should evaluate graded motor imagery effects and indicators of patient success. The represented countries indicate that graded motor imagery phases are implemented internationally, so future work could have a widespread impact.

Hip and knee replacement in lower limb amputees: a scoping review.

BACKGROUND: There are many consequences of lower limb amputation, including altered biomechanics of gait. It has previously been shown that these can lead to increased rates of osteoarthritis (OA). A common and successful treatment for severe OA is joint replacement. However, it is unclear whether amputees undergoing this surgery can expect the same outcomes or complication profile compared with non-amputees. Furthermore, there are key technical challenges associated with hip or knee replacement in lower limb amputees. This scoping review aimed to identify and summarise the existing evidence base. METHODS: This was a systematic scoping review performed according to PRISMA guidelines. An electronic database search of MEDLINE (PubMed), Cochrane Library, EMBASE and CINAHL was completed from the date of inception to 1st April 2023. All peer reviewed literature related to hip or knee replacement among lower limb amputees was included. RESULTS: Of the 931 records identified, 40 studies were included in this study. The available literature consisted primarily of case reports and case series, with generally low level of evidence. In total, there were 265 patients of which 195 received total hip replacement (THR), 51 received total knee replacement (TKR) and 21 received hip hemiarthroplasty. The most common reason for amputation was trauma (34.2%), and the main indication for joint replacement was OA (77.1%), occurring more frequently in the contralateral limb (66.7%). The outcomes reported varied widely between studies, with most suggesting good functional status post-operatively. A variety of technical tips were reported, primarily concerned with intra-operative control of the residual limb. CONCLUSION: There is a need for more observational studies to clearly define the association between amputation and subsequent need for joint replacement. Furthermore, comparative studies are needed to identify whether amputees can be expected to achieve similar functional outcomes after surgery, and if they are at higher risk of certain complications.

Towards efficient motor imagery interventions after lower-limb amputation.

BACKGROUND: The therapeutic benefits of motor imagery (MI) are now well-established in different populations of persons suffering from central nervous system impairments. However, research on similar efficacy of MI interventions after amputation remains scarce, and experimental studies were primarily designed to explore the effects of MI after upper-limb amputations. OBJECTIVES: The present comparative study therefore aimed to assess the effects of MI on locomotion recovery following unilateral lower-limb amputation. METHODS: Nineteen participants were assigned either to a MI group (n = 9) or a control group (n = 10). In addition to the course of physical therapy, they respectively performed 10 min per day of locomotor MI training or neutral cognitive exercises, five days per week. Participants' locomotion functions were assessed through two functional tasks: 10 m walking and the Timed Up and Go Test. Force of the amputated limb and functional level score reflecting the required assistance for walking were also measured. Evaluations were scheduled at the arrival at the rehabilitation center (right after amputation), after prosthesis fitting (three weeks later), and at the end of the rehabilitation program. A retention test was also programed after 6 weeks. RESULTS: While there was no additional effect of MI on pain management, data revealed an early positive impact of MI for the 10 m walking task during the pre-prosthetic phase, and greater performance during the Timed Up and Go Test during the prosthetic phase. Also, a lower proportion of participants still needed a walking aid after MI training. Finally, the force of the amputated limb was greater at the end of rehabilitation for the MI group. CONCLUSION: Taken together, these data support the integration of MI within the course of physical therapy in persons suffering from lower-limb amputations.

The influence of prosthetic suspension on gait and cortical modulations is persons with a transfemoral amputation: socket-suspended versus bone-anchored prosthesis.

BACKGROUND: Persons with a transfemoral amputation (TFA) often experience difficulties in daily-life ambulation, including an asymmetrical and less stable gait pattern and a greater cognitive demand of walking. However, it remains unclear whether this is effected by the prosthetic suspension, as eliminating the non-rigid prosthetic connection may influence stability and cortical activity during walking. Spatiotemporal and stability-related gait parameters, as well as cortical activity during walking, were evaluated between highly active individuals (MFC-level K3-4) with a TFA and able-bodied (AB) persons, and between persons with a bone-anchored prosthesis (BAP) and those with a socket-suspended prosthesis (SSP). METHODS: 18 AB persons and 20 persons with a unilateral TFA (10 BAP-users, 10 SSP-users) walked on a treadmill at their preferred speed. Spatiotemporal and margin of stability parameters were extracted from three-dimensional movement recordings. In addition, 126-channel electroencephalogram (EEG) was recorded. Brain-related activity from several cortical areas was isolated using independent component analysis. Source-level data were divided into gait cycles and subjected to time-frequency analysis to determine gait-cycle dependent modulations of cortical activity. RESULTS: Persons with TFA walked with smaller and wider steps and with greater variability in mediolateral foot placement than AB subjects; no significant differences were found between BAP- and SSP-users. The EEG analysis yielded four cortical clusters in frontal, central (both hemispheres), and parietal areas. No statistically significant between-group differences were found in the mean power over the entire gait cycle. The event-related spectral perturbation maps revealed differences in power modulations (theta, alpha, and beta bands) between TFA and AB groups, and between BAP- and SSP-users, with largest differences observed around heel strike of either leg. CONCLUSIONS: The anticipated differences in gait parameters in persons with TFA were confirmed, however no significant effect of the fixed suspension of a BAP was found. The preliminary EEG findings may indicate more active monitoring and control of stability in persons with TFA, which appeared to be timed differently in SSP than in BAP-users. Future studies may focus on walking tasks that challenge stability to further investigate differences related to prosthetic suspension.

Intelligent ankle-foot prosthesis based on human structure and motion bionics.

The ankle-foot prosthesis aims to compensate for the missing motor functions by fitting the motion characteristics of the human ankle, which contributes to enabling the lower-limb amputees to take care of themselves and improve mobility in daily life. To address the problems of poor bionic motion of the ankle-foot prosthesis and the lack of natural interaction among the patient, prosthesis, and the environment, we developed a complex reverse-rolling conjugate joint based on the human ankle-foot structure and motion characteristics, the rolling joint was used to simulate the rolling-sliding characteristics of the knee joint. Meanwhile, we established a segmental dynamics model of the prosthesis in the stance phase, and the prosthetic structure parameters were obtained with the optimal prosthetic structure dimensions and driving force. In addition, a carbon fiber energy-storage foot was designed based on the human foot profile, and the dynamic response of its elastic strain energy at different thicknesses was simulated and analyzed. Finally, we integrated a bionic ankle-foot prosthesis and experiments were conducted to verify the bionic nature of the prosthetic joint motion and the energy-storage characteristics of the carbon fiber prosthetic foot. The proposed ankle-foot prosthesis provides ambulation support to assist amputees in returning to social life normally and has the potential to help improve clinical viability to reduce medical rehabilitation costs.

Factors leading to falls in transfemoral prosthesis users: a case series of prosthesis-side stumble recovery responses.

BACKGROUND: Falls due to stumbling are prevalent for transfemoral prosthesis users and may lead to increased injury risk. This preliminary case series analyzes the transfemoral prosthesis user stumble recovery response to highlight key deficits in current commercially-available prostheses and proposes potential interventions to improve recovery outcomes. METHODS: Six transfemoral prosthesis users were perturbed on their prosthetic limb at least three times while walking on a treadmill using obstacle perturbations in early, mid and late swing. Kinematic data were collected to characterize the response, while fall rate and key kinematic recovery metrics were used to assess the quality of recovery and highlight functional deficits in current commercially-available prostheses. RESULTS: Across all participants, 13 (54%) of the 24 trials resulted in a fall (defined as > 50% body-weight support) with all but one participant (83%) falling at least once and two participants (33%) falling every time. In contrast, in a previous study of seven young, unimpaired, non-prosthesis users using the same experimental apparatus, no falls occurred across 190 trials. For the transfemoral prosthesis users, early swing had the highest rate of falling at 64%, followed by mid-swing at 57%, and then late swing at 33%. The trend in falls was mirrored by the kinematic recovery metrics (peak trunk angle, peak trunk angular velocity, forward reach of the perturbed limb, and knee angle at ground contact). In early swing all four metrics were deficient compared to non-prosthesis user controls. In mid swing, all but trunk angular velocity were deficient. In late swing only forward reach was deficient. CONCLUSION: Based on the stumble recovery responses, four potential deficiencies were identified in the response of the knee prostheses: (1) insufficient resistance to stance knee flexion upon ground contact; (2) insufficient swing extension after a perturbation; (3) difficulty initiating swing flexion following a perturbation; and (4) excessive impedance against swing flexion in early swing preventing the potential utilization of the elevating strategy. Each of these issues can potentially be addressed by mechanical or mechatronic changes to prosthetic design to improve quality of recovery and reduce the likelihood a fall.