Lower Limb Amputation Research Articles

Clinical Characteristics of the Patient With Unmeasurable Ankle-Brachial Index in Endovascular Treatment.

Introduction Ankle-brachial index (ABI) is an important indicator to diagnose lower extremity arterial disease (LEAD). However, patients with unmeasurable ABI are sometimes excluded from the analysis and their clinical characteristics are poorly understood. Methods One hundred twenty-two consecutive Japanese subjects (mean age, 72 years), who underwent successful endovascular treatment (EVT) for lower extremity arteries at our hospital were retrospectively studied. Results Of the 122 patients, 23 (19%) patients presented an unmeasurable ABI before EVT. Five of 23 (22%) had still an unmeasurable ABI one day after EVT. Comorbidities including hypertension, diabetes, dyslipidemia, hemodialysis, smoking, ischemic heart disease, atrial fibrillation, and past-EVT history were not different between ABI measurable and unmeasurable patients. However, patients with unmeasurable ABI presented a significantly higher degree of Rutherford category and a smaller number of tibial vessel runoff than patients with measurable ABI before EVT (p<0.05 and p<0.01, respectively). There was no difference in the lesion site between the two groups. The event rate including all-cause mortality, re-EVT, lower limb amputation, and bypass surgery did not differ between two groups four years after EVT. ABI after four years of initial EVT did not differ between pre-EVT measurable and unmeasurable patients (0.96 vs. 0.84, p=0.48). Conclusions Patients with unmeasurable ABI before EVT were characterized by higher degree of Rutherford categorization and a small number of tibial vessel runoff, but there was no significant difference in outcomes during the follow-up period.

Comparing Patient and Provider Priorities Around Amputation Level Outcomes Using Multiple Criteria Decision Analysis

Patients with chronic limb threatening ischemia may require a transmetatarsal amputation (TMA) or a transtibial amputation. When making an amputation-level decision, these patients face a tradeoff-a TMA preserves more limb and may provide better mobility but has a lower probability of primary wound healing and may therefore result in additional same or higher level amputation surgeries with an associated negative impact on function. Understanding differences in how patients and providers prioritize these tradeoffs and other outcomes may enhance shared decision-making. Compare patient priorities with provider perceptions of patient priorities using Multiple Criteria Decision Analysis (MCDA). The MCDA Analytic Hierarchy Process was chosen due to its low cognitive burden and ease of implementation. We included 5 criteria (outcomes): ability to walk, healing after amputation surgery, rehabilitation program intensity, limb length, and ease of use of prosthetic/orthotic device. A national sample of dysvascular lower-limb amputees and providers were recruited from the Veterans Health Administration with the MCDA administered online to providers and telephonically to patients. Twenty-six dysvascular amputees and 38 providers participated. Fifty percent of patients had undergone a TMA; 50%, a transtibial amputation. When compared to providers, patients placed higher value on TMA (72% vs. 63%). Patient versus provider priorities were ability to walk (47% vs. 42%), healing (18% vs. 28%), ease of prosthesis use (17% vs. 13%), limb length (11% vs. 13%), and then rehabilitation intensity (7% vs. 6%). Our sample may not generalize to other populations. Provider perceptions aligned with patient values on amputation level but varied around the importance of each outcome. These findings illuminate some differences between patients' values and provider perceptions of patient values, suggesting a role for shared decision-making. Embedding this MCDA framework into a future decision aid may facilitate these discussions.

Morbidity and mortality of patients with diabetic neuropathy treated with pathogenetically oriented alpha-lipoic acid versus symptomatic pharmacotherapies – A nationwide database analysis from Hungary

AimsDiabetic neuropathy is associated with increased risk of morbidity and all-cause mortality. It is unclear whether these outcomes differ in patients with diabetic neuropathy treated with pathogenetically oriented vs symptomatic pharmacotherapies. MethodsWe performed a retrospective (2009–2019) database analysis of patients treated with pathogenetically oriented alpha-lipoic acid (ALA) or symptomatic pharmacotherapies for diabetic neuropathy. We investigated clinical outcomes in propensity score matched patients in Hungary. Changes in hazard ratios and annualized event rates were assessed and sensitivity analyses performed. ResultsHazard ratios favored treatment with ALA vs symptomatic pharmacotherapies regarding acute myocardial infarction (HR 0.73, 95% CI: 0.60–0.89, p = 0.0016), stroke (HR 0.71, 95% CI: 0.62–0.82, p < 0.0001), hospitalization for heart failure (HR 0.72, 95% CI: 0.66–0.78, p < 0.0001), cancer events (HR 0.83, 95% CI: 0.76–0.92, p = 0.0002) and all-cause mortality (HR 0.55, 95% CI: 0.49–0.61, p < 0.0001), but not for lower limb amputation (HR 1.05, 95% CI: 0.89–1.25, p = 0.5455). This association was supported by results of evaluating annual event rates and sensitivity analyses. ConclusionsThis retrospective database analysis revealed a lower occurrence of cardio- and cerebrovascular morbidity, cancer events and all-cause mortality in patients with diabetic neuropathy treated with pathogenetically oriented ALA vs symptomatic pharmacotherapies. This hypothesis-generating result requires further investigations.

Outcome predictors of patients who underwent limb amputation/s following trauma at a level I trauma center in North India.

Limb amputation is one of the oldest medical operations, dating back over 2500years to Hippocrates' time. In developing countries like India, most of the patients are young, and trauma is the primary cause of limb amputation. The objectives of this study were to investigate the factors that can predict the outcome of patients who underwent upper or lower limb amputations. This was a retrospective analysis of the prospectively collected data of patients who underwent limb amputations from January 2015 to December 2019. From January 2015 to December 2019, 547patients underwent limb amputations. Males predominated (86%). Road traffic injuries (RTI) were the most common (323, 59%) mechanism of injury. Hemorrhagic shock was present in 125 (22.9%) patients. Above-knee amputation was the most common (33%) amputation procedure performed. Thecorrelation of hemodynamic status at presentationwith the outcome was statistically significant (p-0.001). Outcome measures like delayed presentation, hemorrhagic shock, Injury severity scores (ISS), and the new injury severity scores (NISS) were statistically significant (p-0.001) when compared to the outcome. There were 47 (8.6%) mortalities during the study period. Factors that affected the outcome were delayed presentation, hemorrhagic shock, higher ISS, NISS, MESS scores, surgical-site infection, and associated injuries. Overall mortality during the study was 8.6%.

Droperidol in the Management of Phantom Limb Pain: Case Report.

Phantom limb pain (PLP) is a poorly understood phenomenon experienced by amputees. The pain is typically classified as neuropathic, and there is no established first-line therapy. Droperidol is an antipsychotic with a wide array of pharmacologic activity including gamma-aminobutyric acid-A channel modulation, μ opioid receptor potentiation, dopamine-2-receptor blockade, and alpha-2-receptor agonism. Due to this broad therapeutic activity, droperidol is used for many off-label indications. Our patient was a 25-year-old male with a history of lower limb amputation who presented for evaluation and management of an acute exacerbation of PLP. On arrival, the patient was in 10/10 pain (numeric pain rating scale) described as cramping and burning. He had been previously successfully managed with subdissociative ketamine. However, during a recent exacerbation he experienced an emergence reaction to ketamine. Literature guiding pharmacotherapy in the management of PLP is sparse and of low quality. Based on the prior emergence reaction to subdissociative ketamine we explored other pharmacotherapy options. Droperidol has a wide array of pharmacologic activity and is used off label for the management of some pain syndromes. Therefore, we administered an intravenous dose of droperidol 5 milligrams. Approximately 15 minutes after receiving droperidol the patient's pain was visibly improved, and 30 minutes later he rated his pain at 3/10. The success in treating this patient provides encouragement for future research and bolsters confidence that droperidol could be another tool in the management of complex pain syndromes.

Adults with lower-limb amputation: Reduced multifidi muscle activity and extensor muscle endurance is associated with worse physical performance.

Trunk muscles may be an overlooked region of deficits following lower-limb amputation (LLA). This study sought to determine the extent that trunk muscle deficits are associated with physical function following amputation. Sedentary adults with a unilateral transtibial- (n = 25) or transfemoral-level (n = 14) amputation were recruited for this cross-sectional research study. Participants underwent a clinical examination that included ultrasound imaging of the lumbar multifidi muscles, the modified Biering-Sorensen Endurance Test (mBSET), and performance-based measures, that is, the Timed Up and Go (TUG), Berg Balance Scale (BBS), and 10-m Walk Test (10mWT). Associations between trunk muscle metrics and performance were explored with regression modeling, while considering covariates known to impact performance postamputation (p ≤ 0.100). Average ultrasound-obtained, lumbar multifidi activity was 14% and 16% for transfemoral- and transtibial-level amputations, respectively, while extensor endurance was 37.34 and 12.61 s, respectively. For TUG, nonamputated-side multifidi activity and an interaction term (level x non-amputated-side multifidi activity) explained 9.4% and 6.2% of the total variance, respectively. For 10mWT, beyond covariates, non-amputated-side multifidi activity and the interaction term explained 6.1% and 5.8% of the total variance, respectively. For TUG, extensor endurance and an interaction term (level x mBSET) explained 11.9% and 8.3% of the total variance beyond covariates; for BBS and 10mWT, extensor endurance explained 11.2% and 17.2% of the total variance, respectively. Findings highlight deficits in lumbar multifidi activity and extensor muscle endurance among sedentary adults with a LLA; reduced muscle activity and endurance may be important factors to target during rehabilitation to enhance mobility-related outcomes.

A Workflow for Studying the Stump-Socket Interface in Persons with Transtibial Amputation through 3D Thermographic Mapping.

The design and fitting of prosthetic sockets can significantly affect the acceptance of an artificial limb by persons with lower limb amputations. Clinical fitting is typically an iterative process, which requires patients' feedback and professional assessment. When feedback is unreliable due to the patient's physical or psychological conditions, quantitative measures can support decision-making. Specifically, monitoring the skin temperature of the residual limb can provide valuable information regarding unwanted mechanical stresses and reduced vascularization, which can lead to inflammation, skin sores and ulcerations. Multiple 2D images to examine a real-life 3D limb can be cumbersome and might only offer a partial assessment of critical areas. To overcome these issues, we developed a workflow for integrating thermographic information on the 3D scan of a residual limb, with intrinsic reconstruction quality measures. Specifically, workflow allows us to calculate a 3D thermal map of the skin of the stump at rest and after walking, and summarize this information with a single 3D differential map. The workflow was tested on a person with transtibial amputation, with a reconstruction accuracy lower than 3 mm, which is adequate for socket adaptation. We expect the workflow to improve socket acceptance and patients' quality of life.

Anesthesia Management of the Lower Limb Amputation in an Adult Patient with Recessive Dystrophic Epidermolysis Bullosa

Anesthesia Management of the Lower Limb Amputation in an Adult Patient with Recessive Dystrophic Epidermolysis Bullosa

Outcomes after minor lower limb amputation for peripheral arterial disease and diabetes: population-based cohort study.

Patients with diabetes and peripheral arterial disease are at increased risk of minor amputation. The aim of study was to assess the rate of re-amputations and death after an initial minor amputation, and to identify associated risk factors. Data on all patients aged 40 years and over with diabetes and/or peripheral arterial disease, who underwent minor amputation between January 2014 and December 2018, were extracted from Hospital Episode Statistics. Patients who had bilateral index procedures or an amputation in the 3 years before the study were excluded. Primary outcomes were ipsilateral major amputation and death after the index minor amputation. Secondary outcomes were ipsilateral minor re-amputations, and contralateral minor and major amputations. In this study of 22 118 patients, 16 808 (76.0 per cent) were men and 18 473 (83.5 per cent) had diabetes. At 1 year after minor amputation, the estimated ipsilateral major amputation rate was 10.7 (95 per cent c.i. 10.3 to 11.1) per cent. Factors associated with a higher risk of ipsilateral major amputation included male sex, severe frailty, diagnosis of gangrene, emergency admission, foot amputation (compared with toe amputation), and previous or concurrent revascularization. The estimated mortality rate was 17.2 (16.7 to 17.7) per cent at 1 year and 49.4 (48.6 to 50.1) per cent at 5 years after minor amputation. Older age, severe frailty, comorbidity, gangrene, and emergency admission were associated with a significantly higher mortality risk. Minor amputations were associated with a high risk of major amputation and death. One in 10 patients had an ipsilateral major amputation within the first year after minor amputation and half had died by 5 years.

Pre-operative sciatic nerve block vs postoperative surgeon-placed perineural stump catheter for prevention of phantom limb pain after below-knee amputation.

Pre-operative sciatic nerve block vs postoperative surgeon-placed perineural stump catheter for prevention of phantom limb pain after below-knee amputation.

Frontiers in diagnostic and therapeutic approaches in diabetic sensorimotor neuropathy (DSPN).

Diabetes sensory polyneuropathy (DSPN) is a significant complication of diabetes affecting up to 50% of patients in their lifetime and approximately 20% of patients suffer from painful diabetes neuropathic pain. DSPN - both painless and painful - leads to considerable morbidity including reduction of quality of life, increased lower limb amputations and is associated with worsening mortality. Significant progress has been made in the understanding of pathogenesis of DSPN and the last decade has seen newer techniques aimed at its earlier diagnosis. The management of painful DSPN remains a challenge despite advances made in the unravelling the pathogenesis of pain and its transmission. This article discusses the heterogenous clinical presentation of DSPN and the need to exclude key differential diagnoses. Furthermore, it reviews in detail the current diagnostic techniques involving both large and small neural fibres, their limitations and advantages and current place in the diagnosis of DSPN. Finally, the management of DSPN including newer pharmacotherapies are also discussed.

Creating Adjusted Scores Targeting mobiLity Empowerment (CASTLE 1): determination of normative mobility scores after lower limb amputation for each year of adulthood

Purpose As United States healthcare transitions from traditional fee-for-service models to value-based care, there is increased need to demonstrate quality care through clinical outcomes. Therefore, the purpose of this study was to create equations to calculate an expected mobility score for lower limb prosthesis users specific to their age, etiology, and amputation level to provide benchmarks to qualify good outcomes. Materials and Methods A retrospective cross-sectional analysis of outcomes collected during clinical care was performed. Individuals were grouped based on amputation level (unilateral above-knee (AKA) or below-knee (BKA)) and etiology (trauma or diabetes/dysvascular (DV)). The mean mobility score (PLUS-M® T-score) for each year of age was calculated. AKAs were further stratified into having a microprocessor knee (MPK) or non-microprocessor (nMPK) for secondary analysis. Results As expected, average prosthetic mobility declined with age. Overall, BKAs had higher PLUS-M T-scores compared to AKAs and trauma etiologies had higher scores compared to DV. For AKAs, those with a MPK had higher T-scores compared to those with a nMPK. Conclusions Results from this study provide average mobility for adult patients across every year of life. This can be leveraged to create a mobility adjustment factor to qualify good outcomes in lower limb prosthetic care. IMPLICATIONS FOR REHABILITATION Normative values of mobility are needed to qualify good outcomes in prosthetic care as healthcare shifts towards value-based care. Understanding where an individual is relative to others with similar characteristics (e.g., age, etiology, gender, amputation level, and device type) can provide clinicians with better benchmarks for individual goal-setting. The ability to generate predicted mobility scores specific to each individual can create a mobility adjustment factor to better qualify good outcomes.

Association Between Combat-Related Traumatic Injury and Skeletal Health: Bone Mineral Density Loss Is Localized and Correlates With Altered Loading in Amputees: the Armed Services Trauma Rehabilitation Outcome (ADVANCE) Study.

The association between combat-related traumatic injury (CRTI) and bone health is uncertain. A disproportionate number of lower limb amputees from the Iraq and Afghanistan conflicts are diagnosed with osteopenia/osteoporosis, increasing lifetime risk of fragility fracture and challenging traditional osteoporosis treatment paradigms. The aim of this study is to test the hypotheses that CRTI results in a systemic reduction in bone mineral density (BMD) and that active traumatic lower limb amputees have localized BMD reduction, which is more prominent with higher level amputations. This is a cross-sectional analysis of the first phase of a cohort study comprising 575 male adult UK military personnel with CRTI (UK-Afghanistan War 2003 to 2014; including 153 lower limb amputees) who were frequency-matched to 562 uninjured men by age, service, rank, regiment, deployment period, and role-in-theatre. BMD was assessed using dual-energy X-ray absorptiometry (DXA) scanning of the hips and lumbar spine. Femoral neck BMD was lower in the CRTI than the uninjured group (T-score -0.08 versus -0.42 p=.000). Subgroup analysis revealed this reduction was significant only at the femoral neck of the amputated limb of amputees (p=0.000), where the reduction was greater for above knee amputees than below knee amputees (p < 0.001). There were no differences in spine BMD or activity levels between amputees and controls. Changes in bone health in CRTI appear to be mechanically driven rather than systemic and are only evident in those with lower limb amputation. This may arise from altered joint and muscle loading creating a reduced mechanical stimulus to the femur resulting in localized unloading osteopenia. This suggests that interventions to stimulate bone may provide an effective management strategy. © 2023 Crown copyright and The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR). This article is published with the permission of the Controller of HMSO and the King's Printer for Scotland.

Diabetic foot and lower limb amputations at central, provincial and tertiary hospitals-underscores the need for organised foot health services at primary healthcare level

BackgroundDiabetic foot amputations are a devastating outcome for any diabetic patient. They are associated with various risk factors, including failure to risk stratify the diabetic foot. Early risk stratification could lower foot complications risk at the primary healthcare level (PHC). In the Republic of South Africa (RSA), PHC clinics are the first entry point to the public healthcare system. Failure to correctly identify, risk categorise, and refer diabetic foot complications at this level may lead to poor clinical outcomes for diabetic patients. This study looks at the incidence of diabetic-related amputations at central and tertiary hospitals in Gauteng to highlight the case of the needed foot health services at the PHC level. MethodsA cross-sectional retrospective study that reviewed prospectively collected theatre records database of all patients who underwent a diabetic-related foot and lower limb amputation between January 2017 and June 2019. Inferential and descriptive statistics were performed, and patient demographics, risk factors and type of amputation were reviewed. ResultsThere were 1862 diabetic-related amputations in the period under review. Most patients (98 %) came from a poor socioeconomic background earning ZAR 0.00–70 000.00 (USD 0.00–4754.41) per annum. Most amputations, 62 % were in males, and the majority, 71 % of amputations, were in patients younger than 65. The first amputation was major in 73 % of the cases, and an infected foot ulcer was a primary amputation cause in 75 % of patients. ConclusionAmputations are a sign of poor clinical outcomes for diabetic patients. Due to the hierarchal nature of healthcare delivery in RSA, diabetic-related foot amputations could imply inadequate care of or access to diabetic foot complications at the PHC level in RSA. A lack of access to structured foot health services at PHC levels impedes early identification of foot complication identification and appropriate referral resulting in amputation in some of the patients.

Penetrating Vascular Injuries of the Lower Limbs after Stab Wounds: Predictive Factors of Limb Loss and Mortality.

Penetrating vascular injuries (PVIs) of the lower limbs due to stab wounds are associated with high mortality and limb loss rates. We analyzed the outcomes of a series of patients who underwent surgical treatment of these lesions, assessing the presence of any factor associated with limb loss and mortality; (2) Methods: Data of patients admitted from 01/2008 to 12/2018 were retrospectively analyzed. Primary outcomes were the limb loss and the mortality rate at 30 days postoperatively. Univariate and multivariate analyses were performed as appropriate. p values < 0.05 were considered significant; (3) Results: Data of 67 male patients were analyzed. Two died (3%) and three (4.5%) had a lower limb amputation after failed revascularization. In the univariate analysis, the clinical presentation significantly affected the risk of postoperative mortality and limb loss. The location of the lesion at the superficial femoral artery (OR 4.32, p = 0.001) or at the popliteal artery (OR 4.89, p = 0.0015) also increased the risk. In the multivariate analysis, the need for a vein graft bypass was the only significant predictor of limb loss and mortality (OR 4.58, p < 0.0001); (4) Conclusions: PVIs of lower limbs due to stab wounds were lethal in 3% of cases and lead to a secondary major amputation in 4.5% more cases. The need for a vein bypass grafting was the strongest predictor of postoperative limb loss and mortality.

Life Expectancy and Mortality After Lower Extremity Amputation: Overview and Analysis of Literature.

Lower limb amputation (LLA) is a major surgical procedure with a significant impact on quality of life and mortality rates as well. Previous studies have shown that mortality rates following LLA can range from 9-17% within 30 days in the UK. This study systematically evaluates and reviews the published literature on life expectancy, mortality, and survival rates following lower extremity amputation (LEA). We have conducted a comprehensive search on Medline, CINAHL, and Cochrane Central databases resulting in 87 full-text articles. After a thorough review, only 45 (52.9%) articles met the minimum inclusion criteria for the study. Our analysis indicated 30-day mortality rates following LEA ranged from 7.1% to 51.4%, with an average mortality rate of 16.45% (SD 14.35) per study. Furthermore, 30-day mortality rates following below-knee amputation (BKA) and above-knee amputation (AKA) were found to be between 6.2% to 51.4%, X= 17.16% ± 19.46 SD and 12.7 to 21.7%, X= 16.15% ± 4.17 SD, respectively. Our review provides a comprehensive insight into the life expectancy, mortality, and survival rates following LEA. These findings highlight the importance of considering various factors, including patient age, presence of comorbidities such as diabetes, heart failure, and renal failure, and lifestyle factors such as smoking, in determining prognosis following LLA. Further research is necessary to determine strategies for improving outcomes and reducing mortality in this patient population.

Using embedded prosthesis sensors for clinical gait analyses in people with lower limb amputation: A feasibility study

BackgroundBiomechanical gait analyses are typically performed in laboratory settings, and are associated with limitations due to space, marker placement, and tasks that are not representative of the real-world usage of lower limb prostheses. Therefore, the purpose of this study was to investigate the possibility of accurately measuring gait parameters using embedded sensors in a microprocessor-controlled knee joint. MethodsTen participants were recruited for this study and equipped with a Genium X3 prosthetic knee joint. They performed level walking, stair/ramp descent, and ascent. During these tasks, kinematics and kinetics (sagittal knee and thigh segment angle, and knee moment) were recorded using an optical motion capture system and force plates (gold standard), as well as the prosthesis-embedded sensors. Root mean square errors, relative errors, correlation coefficients, and discrete outcome variables of clinical relevance were calculated and compared between the gold standard and the embedded sensors. FindingsThe average root mean square errors were found to be 0.6°, 5.3°, and 0.08 Nm/kg, for the knee angle, thigh angle, and knee moment, respectively. The average relative errors were 0.75% for the knee angle, 11.67% for the thigh angle, and 9.66%, for the knee moment. The discrete outcome variables showed small but significant differences between the two measurement systems for a number of tasks (higher differences only at the thigh). InterpretationThe findings highlight the potential of prosthesis-embedded sensors to accurately measure gait parameters across a wide range of tasks. This paves the way for assessing prosthesis performance in realistic environments outside the lab.

Percutaneous decannulation of venoarterial extracorporeal membrane oxygenation using the Manta vascular closure device: A systematic review and meta-analysis.

To perform a systematic review and meta-analysis of the techniques and outcomes associated with percutaneous decannulation of venoarterial extracorporeal membrane oxygenation (VA-ECMO) using the Manta vascular closure device. Peripheral VA-ECMO can be used to treat critically ill patients with conditions such as refractory cardiogenic shock. After percutaneous implantation of VA-ECMO, VA-ECMO can also be decannulated completely percutaneously by using a vascular closure device. The Manta vascular closure device is a dedicated device used in the closure of large-bore arteriotomies by sandwiching the arteriotomy with an intra-arterial toggle and an extraluminal collagen plug. We performed a thorough literature search using various electronic databases. We included studies that reported outcomes after peripheral femorofemoral VA-ECMO decannulation with the Manta vascular closure device. We performed a meta-analysis of proportions on outcome measures, including technical success, bleeding complications, vascular complications, wound complications, major amputation, and procedural-related deaths. We included seven studies with a total of 116 patients. The overall technical success of percutaneous decannulation of VA-ECMO with the Manta vascular closure device was 93.7%. The overall incidence of bleeding, vascular and wound complications was 1.7%, 13.8%, and 3.4%, respectively. No patient required lower limb amputation or died due to VA-ECMO decannulation. Percutaneous decannulation with the Manta vascular closure device is an effective and safe procedure that should be considered in suitable patients on VA-ECMO.

Biomechanical responses of individuals with transtibial amputation stepping on a coronally uneven and unpredictable surface

Coronally uneven surfaces are prevalent in natural and man-made terrain, such as holes or bumps in the ground, curbs, sidewalks, and driveways. These surfaces can be challenging to navigate, especially for individuals with lower limb amputations. This study examined the biomechanical response of individuals with unilateral transtibial amputation (TTA) taking a step on a coronally uneven surface while wearing their clinically prescribed prosthesis, compared to individuals without mobility impairments (controls). An instrumented walkway was used with the middle force plate positioned either flush or rotated ± 15˚ in the coronal plane and concealed (blinded). TTAs used greater hip abduction compared to controls across all conditions, but especially during blinded inversion. The recovery step width of TTAs was wider after blinded eversion and narrower after blinded inversion, but unchanged for controls. These results suggest TTAs may have decreased balance control on unexpected, uneven surfaces. Additionally, TTAs generated less positive prosthetic ankle joint work during blinded inversion and eversion, and less negative coronal hip joint work during blinded inversion compared to controls. These biomechanical responses could lead to increased energy expenditure on uneven terrain. Surface condition had no effect on the vertical center of mass for either group of participants. Finally, the TTAs and the control group generated similar vertical GRF impulses, suggesting the TTAs had sufficient body support despite differences in surface conditions. These results are important to consider for future prosthetic foot designs and rehabilitation strategies.

Uneven Terrain Recognition Using Neuromorphic Haptic Feedback.

Recent years have witnessed relevant advancements in the quality of life of persons with lower limb amputations thanks to the technological developments in prosthetics. However, prostheses that provide information about the foot-ground interaction, and in particular about terrain irregularities, are still missing on the market. The lack of tactile feedback from the foot sole might lead subjects to step on uneven terrains, causing an increase in the risk of falling. To address this issue, a biomimetic vibrotactile feedback system that conveys information about gait and terrain features sensed by a dedicated insole has been assessed with intact subjects. After having shortly experienced both even and uneven terrains, the recruited subjects discriminated them with an accuracy of 87.5%, solely relying on the replay of the vibrotactile feedback. With the objective of exploring the human decoding mechanism of the feedback startegy, a KNN classifier was trained to recognize the uneven terrains. The outcome suggested that the subjects achieved such performance with a temporal dynamics of 45 ms. This work is a leap forward to assist lower-limb amputees to appreciate the floor conditions while walking, adapt their gait and promote a more confident use of their artificial limb.