Exploration and demonstration of explainable machine learning models in prosthetic rehabilitation-based gait analysis.

Quantitative gait analysis is important for understanding the non-typical walking patterns associated with mobility impairments. Conventional linear statistical methods and machine learning (ML) models are commonly used to assess gait performance and related changes in the gait parameters. Nonetheless, explainable machine learning provides an alternative technique for distinguishing the significant and influential gait changes stemming from a given intervention. The goal of this work was to demonstrate the use of explainable ML models in gait analysis for prosthetic rehabilitation in both population- and sample-based interpretability analyses. Models were developed to classify amputee gait with two types of prosthetic knee joints. Sagittal plane gait patterns of 21 individuals with unilateral transfemoral amputations were video-recorded and 19 spatiotemporal and kinematic gait parameters were extracted and included in the models. Four ML models-logistic regression, support vector machine, random forest, and LightGBM-were assessed and tested for accuracy and precision. The Shapley Additive exPlanations (SHAP) framework was applied to examine global and local interpretability. Random Forest yielded the highest classification accuracy (98.3%). The SHAP framework quantified the level of influence of each gait parameter in the models where knee flexion-related parameters were found the most influential factors in yielding the outcomes of the models. The sample-based explainable ML provided additional insights over the population-based analyses, including an understanding of the effect of the knee type on the walking style of a specific sample, and whether or not it agreed with global interpretations. It was concluded that explainable ML models can be powerful tools for the assessment of gait-related clinical interventions, revealing important parameters that may be overlooked using conventional statistical methods.

Preliminary characterization of rectification for transradial prosthetic sockets.

Achieving proper socket fit is crucial for the effective use of a prosthesis. However, digital socket design lacks standardization and presents a steep learning curve for prosthetists. While research has focused on digital socket design for the lower-limb population, there is a research gap in upper-limb socket design. This study aimed to characterize the design (rectification) process for the transradial socket, specifically the three-quarter Northwestern-style design, towards the development of a more systematic, data-driven socket design approach. Fourteen (n = 14) pairs of unrectified and rectified plaster models were compared. Six common rectification zones were identified through shape analysis, with zones of plaster addition being the most prominent in terms of volume and surface area. A novel 3D vector mapping technique was employed, which revealed that most of the shape changes occurred in the anterior-posterior and proximal-distal directions. Overall, the interquartile range of each rectification zone demonstrated reasonable consistency in terms of volume, surface deviation, and 3D vector representation. The initial findings from this study support the potential for quantitively modelling the transradial socket design process. This opens the door for developing tools for categorizing and predicting socket designs across diverse populations through the application of techniques such as machine learning.

Measuring functional hand use in children with unilateral cerebral palsy using accelerometry and machine learning.

AIM: To investigate wearable sensors for measuring functional hand use in children with unilateral cerebral palsy (CP). METHOD: Dual wrist-worn accelerometry data were collected from three females and seven males with unilateral CP (mean age = 10 years 2 months [SD 3 years]) while performing hand tasks during video-recorded play sessions. Video observers labelled instances of functional and non-functional hand use. Machine learning was compared to the conventional activity count approach for identifying unilateral hand movements as functional or non-functional. Correlation and agreement analyses compared the functional usage metrics derived from each method. RESULTS: The best-performing machine learning approach had high precision and recall when trained on an individual basis (F1 = 0.896 [SD 0.043]). On an individual basis, the best-performing classifier showed a significant correlation (r = 0.990, p < 0.001) and strong agreement (bias = 0.57%, 95% confidence interval = -4.98 to 6.13) with video observations. When validated in a leave-one-subject-out scenario, performance decreased significantly (F1 = 0.584 [SD 0.076]). The activity count approach failed to detect significant differences in non-functional or functional hand activity and showed no significant correlation or agreement with the video observations. INTERPRETATION: With further development, wearable accelerometry combined with machine learning may enable quantitative monitoring of everyday functional hand use in children with unilateral CP.

The Development of a Wearable Biofeedback System to Elicit Temporal Gait Asymmetry using Rhythmic Auditory Stimulation and an Assessment of Immediate Effects.

Temporal gait asymmetry (TGA) is commonly observed in individuals facing mobility challenges. Rhythmic auditory stimulation (RAS) can improve temporal gait parameters by promoting synchronization with external cues. While biofeedback for gait training, providing real-time feedback based on specific gait parameters measured, has been proven to successfully elicit changes in gait patterns, RAS-based biofeedback as a treatment for TGA has not been explored. In this study, a wearable RAS-based biofeedback gait training system was developed to measure temporal gait symmetry in real time and deliver RAS accordingly. Three different RAS-based biofeedback strategies were compared: open- and closed-loop RAS at constant and variable target levels. The main objective was to assess the ability of the system to induce TGA with able-bodied (AB) participants and evaluate and compare each strategy. With all three strategies, temporal symmetry was significantly altered compared to the baseline, with the closed-loop strategy yielding the most significant changes when comparing at different target levels. Speed and cadence remained largely unchanged during RAS-based biofeedback gait training. Setting the metronome to a target beyond the intended target may potentially bring the individual closer to their symmetry target. These findings hold promise for developing personalized and effective gait training interventions to address TGA in patient populations with mobility limitations using RAS.

Convolutional Neural Network for Estimating Spatiotemporal and Kinematic Gait Parameters using a Single Inertial Sensor.

Lower limb disability severely impacts gait, thus requiring clinical interventions. Inertial sensor systems offer the potential for objective monitoring and assessment of gait in and out of the clinic. However, it is imperative such systems are capable of measuring important gait parameters while being minimally obtrusive (requiring few sensors). This work used convolutional neural networks to estimate a set of six spatiotemporal and kinematic gait parameters based on raw inertial sensor data. This differs from previous work which either was limited to spatiotemporal parameters or required conventional strap-down integration techniques to estimate kinematic parameters. Additionally, we investigated a data segmentation method which does not rely on gait event detection, further supporting its applicability in real-world settings.Preliminary results demonstrate our model achieved high accuracy on a mix of spatiotemporal and kinematic gait parameters, either meeting or exceeding benchmarks based on literature. We achieved 0.04 ± 0.03 mean absolute error for stance-time symmetry ratio and an absolute error of 4.78 ± 4.78, 4.50 ± 4.33, and 6.47 ± 7.37cm for right and left step length and stride length, respectively. Lastly, errors for knee and hip ranges of motion were 2.31 ± 4.20 and 1.73 ± 1.93°, respectively. The results suggest that machine learning can be a useful tool for long-term monitoring of gait using a single inertial sensor to estimate measures of gait quality.

Classifying Changes in Amputee Gait following Physiotherapy Using Machine Learning and Continuous Inertial Sensor Signals.

Wearable sensors allow for the objective analysis of gait and motion both in and outside the clinical setting. However, it remains a challenge to apply such systems to highly diverse patient populations, including individuals with lower-limb amputations (LLA) that present with unique gait deviations and rehabilitation goals. This paper presents the development of a novel method using continuous gyroscope data from a single inertial sensor for person-specific classification of gait changes from a physiotherapist-led gait training session. Gyroscope data at the thigh were collected using a wearable gait analysis system for five LLA before, during, and after completing a gait training session. Data from able-bodied participants receiving no intervention were also collected. Models using dynamic time warping (DTW) and Euclidean distance in combination with the nearest neighbor classifier were applied to the gyroscope data to classify the pre- and post-training gait. The model achieved an accuracy of 98.65% ± 0.69 (Euclidean) and 98.98% ± 0.83 (DTW) on pre-training and 95.45% ± 6.20 (Euclidean) and 94.18% ± 5.77 (DTW) on post-training data across the participants whose gait changed significantly during their session. This study provides preliminary evidence that continuous angular velocity data from a single gyroscope could be used to assess changes in amputee gait. This supports future research and the development of wearable gait analysis and feedback systems that are adaptable to a broad range of mobility impairments.

Rules-Based Real-Time Gait Event Detection Algorithm for Lower-Limb Prosthesis Users during Level-Ground and Ramp Walking.

Real-time gait event detection (GED) using inertial sensors is important for applications such as remote gait assessments, intelligent assistive devices including microprocessor-based prostheses or exoskeletons, and gait training systems. GED algorithms using acceleration and/or angular velocity signals achieve reasonable performance; however, most are not suited for real-time applications involving clinical populations walking in free-living environments. The aim of this study was to develop and evaluate a real-time rules-based GED algorithm with low latency and high accuracy and sensitivity across different walking states and participant groups. The algorithm was evaluated using gait data collected from seven able-bodied (AB) and seven lower-limb prosthesis user (LLPU) participants for three walking states (level-ground walking (LGW), ramp ascent (RA), ramp descent (RD)). The performance (sensitivity and temporal error) was compared to a validated motion capture system. The overall sensitivity was 98.87% for AB and 97.05% and 93.51% for LLPU intact and prosthetic sides, respectively, across all walking states (LGW, RA, RD). The overall temporal error (in milliseconds) for both FS and FO was 10 (0, 20) for AB and 10 (0, 25) and 10 (0, 20) for the LLPU intact and prosthetic sides, respectively, across all walking states. Finally, the overall error (as a percentage of gait cycle) was 0.96 (0, 1.92) for AB and 0.83 (0, 2.08) and 0.83 (0, 1.66) for the LLPU intact and prosthetic sides, respectively, across all walking states. Compared to other studies and algorithms, the herein-developed algorithm concurrently achieves high sensitivity and low temporal error with near real-time detection of gait in both typical and clinical populations walking over a variety of terrains.

Evaluating the Reliability of a Shape Capturing Process for Transradial Residual Limb Using a Non-Contact Scanner.

Advancements in digital imaging technologies hold the potential to transform prosthetic and orthotic practices. Non-contact optical scanners can capture the shape of the residual limb quickly, accurately, and reliably. However, their suitability in clinical practice, particularly for the transradial (below-elbow) residual limb, is unknown. This project aimed to evaluate the reliability of an optical scanner-based shape capture process for transradial residual limbs related to volumetric measurements and shape assessment in a clinical setting. A dedicated setup for digitally shape capturing transradial residual limbs was developed, addressing challenges with scanning of small residual limb size and aspects such as positioning and patient movement. Two observers performed three measurements each on 15 participants with transradial-level limb absence. Overall, the developed shape capture process was found to be highly repeatable, with excellent intra- and inter-rater reliability that was comparable to the scanning of residual limb cast models. Future work in this area should compare the differences between residual limb shapes captured through digital and manual methods.

Cost-effectiveness analysis of prosthesis provision for patients with transfemoral amputation in Tanzania.

BACKGROUND: Limb loss leads to significant disability. Prostheses may mitigate this disability but are not readily accessible in low- and middle-income countries (LMICs). Cost-effectiveness data related to prosthesis provision in resource-constrained environments such as Tanzania is greatly limited. OBJECTIVES: This study aimed to compare the cost-effectiveness of a prosthesis intervention compared with that of no prosthesis for persons with transfemoral amputations in an LMIC. STUDY DESIGN: This is a prospective cohort study. METHODS: Thirty-eight patients were prospectively followed up. Clinical improvement with prosthesis provision was measured using EuroQuol-5D, represented as quality-adjusted life years gained. Direct and indirect costs were measured. The primary outcome was incremental cost per quality-adjusted life year, measured at 1 year and projected over a lifetime using a Markov model. Reference case was set as a single prosthesis provided without replacement from a payer perspective. Additional scenarios included the societal perspective and replacement of the prosthesis. Uncertainty was measured with one-way probabilistic sensitivity analysis. RESULTS: From the payer perspective, the incremental cost-effectiveness ratio (ICER) was $242 for those without prosthetic replacement over a lifetime, and the ICER was $390 for those with prosthetic replacement over a lifeime. From the societal perspective, prosthesis provision was both less expensive and more effective. One-way sensitivity analysis demonstrated the ICER remained below the willingness to pay threshold up to prosthesis costs of $763. CONCLUSIONS: These findings suggest prosthesis provision in an LMIC may be cost-effective, but further studies with long-term follow up are needed to validate the results.

Understanding the adoption of digital workflows in orthotic & prosthetic practice from practitioner perspectives: a qualitative descriptive study.

BACKGROUND: The implementation of digital technology (DT) in orthotics and prosthetics (O&P) has been slow despite recent research suggesting that the use of DT will continue to grow and become more prevalent within the industry. There is a need to further investigate DT in O&P practice and the current state of its use in the field. OBJECTIVE: This study aimed to explore the views and experiences of practitioners using DT workflows in their O&P practice. METHODS: In this qualitative descriptive study, 10 in-depth, semistructured interviews with O&P practitioners were conducted. A content analysis was performed to analyze the transcripts and identify key themes from the data. RESULTS: The study examined the experiences of practitioners using or trying to use DT in their practices, and three key themes were identified on the implementation of digital practice: 1) technological advancement and scientific evidence; 2) marketplace, economic, and operational factors; and 3) industry mindset shift in embracing DT practice. CONCLUSION: A collaborative effort involving academia, healthcare institutions, vendors, and individual practitioners will be required to facilitate the widespread adoption of DT in O&P. More work is required to overcome challenges from the technical, logistical, and cultural aspects.

'It's more than just a running leg': a qualitative study of running-specific prosthesis use by children and youth with lower limb absence.

PURPOSE: The purpose of this study was to investigate the use of running-specific prostheses (RSPs) by children with lower limb absence (LLA) along with the benefits and challenges of RSPs. MATERIALS AND METHODS: In this descriptive qualitative study, eight children (ages 8-20 years) and their parents participated in semi-structured interviews. The interviews were audio-recorded and transcribed. Coded data were the foundation for central theme development. RESULTS: Three main themes were generated. "Run faster, jump higher, do more" (the benefits of RSP use), "Every leg serves its purpose" (comparing functionality between daily use prostheses and RSPs), and "A lot more to think about" (additional considerations with RSP use). CONCLUSIONS: RSPs have a positive impact in promoting children's engagement in sports and physical activities. While some children used their RSP primarily for running, others wore it for a broader range of physical activities. Issues with balance and discomfort caused by leg length discrepancies and/or ill-fitting sockets limited daily wear time. Limitations related to current RSP designs and clinical implementation should be addressed to optimize the functional potential of children with unilateral or bilateral LLA.Implications for rehabilitationRunning-specific prostheses (RSPs) positively impacted children's ability to participate in some sports with peers promoting their physical and social well-being.The main issues that children faced were discomfort, difficulty balancing, and inability to use RSPs for certain sports, while parents' issues focused on supporting prosthesis use and transport, and adjustments of different prostheses to keep up with their child's growth.Clinicians should be aware of the challenges of RSP use to best support children and their families.Designers should focus on addressing limitations with current RSPs to facilitate the diverse needs of pediatric users.

Biomechanical factors affecting individuals with lower limb amputations running using running-specific prostheses: A systematic review.

BACKGROUND: Running-specific prostheses (RSPs) are biomechanically designed to enable individuals with lower limb amputations to engage in high level sports. RESEARCH QUESTION: What is the influence of RSP use on the running biomechanics of individuals with lower limb amputations? METHODS: An article search was conducted in six databases since their inception to July 2021. Two independent reviewers assessed the title, abstract and full texts in the review process. The quality of the papers was appraised. The review included a total of 35 articles. RESULTS: Main findings indicate force production is a limitation of RSPs. Individuals with lower limb absence employ a variety of compensatory strategies such as adjusting their step frequency, contact length and joint kinetics to improve their running performance. Leg stiffness modulation and external factors relating to the RSP design and fitting play important roles in RSP biomechanics. For individuals with unilateral amputations, the increased loading of the intact limb could increase the risk of acute injury or chronic joint degradation. SIGNIFICANCE: To improve their running performance, runners with lower limb amputations employ various compensatory strategies, such as altering the spatiotemporal and kinetic parameters. Factors relating to RSP height, stiffness, shape, and alignment also play an important role in terms of running biomechanics and should be considered in RSP design and fitting. Future studies should focus on the use of RSPs for recreation, in pediatric populations, with certain amputation levels, as well as the impact of training and running techniques.

Impact of prostheses on quality of life and functional status of transfemoral amputees in Tanzania.

BACKGROUND: The rise of diabetes and traumatic injury has increased limb loss-related morbidity in low- and middle-income countries (LMICs). Despite this, the majority of amputees in LMICs have no access to prosthetic devices, and the magnitude of prosthesis impact on quality of life (QOL ) and function has not been quantified. OBJECTIVES: Quantify the impact of prostheses on QOL and function in Tanzanian transfemoral amputees. METHOD: A prospective cohort study was conducted. Transfemoral amputees at Muhimbili Orthopaedic Institute were assessed twice before and three times after prosthetic fitting using EuroQol-5D-3L (EQ-5D-3L), Prosthetic Limb Users Survey of Mobility (PLUS-M), 2-minute walk test (2MWT) and Physiologic Cost Index (PCI). Data were analysed for change over time. Subgroup analysis was performed for amputation aetiology (vascular or non-vascular) and prosthesis use. RESULTS: Amongst 30 patients, EQ-5D, PLUS-M and 2MWT improved after prosthesis provision (p < 0.001). EuroQol-5D increased from 0.48 to 0.85 at 1 year (p < 0.001). EuroQol-5D and 2MWT were higher in non-vascular subgroup (p < 0.030). At 1-year, 84% of non-vascular and 44% of vascular subgroups reported using their prosthesis (p = 0.068). CONCLUSION: Prosthesis provision to transfemoral amputees in an LMIC improved QOL and function. This benefit was greater for non-vascular amputation aetiologies. Quality of life and function returned to pre-prosthesis levels with discontinued use of prosthesis.

Functional outcomes and user preferences of individuals with transfemoral amputations using two types of knee joints in under-resourced settings.

BACKGROUND: Information relating to prosthetic performance can inform clinical practice and improve patient outcomes in under-resourced countries. OBJECTIVES: The main goal of this study was to compare functional outcomes and user preferences of individuals with transfemoral amputations using common types of knee joints in an under-resourced country. STUDY DESIGN: Prospective, longitudinal, before and after trial. METHODS: Twenty individuals with unilateral transfemoral amputations from a center in Cambodia transitioned from a commonly used single-axis manually locking knee International Committee of the Red Cross (ICRC) to a more advanced multiaxis knee joint with stance control All-Terrain Knee (ATK). Data were collected for the ICRC knee joint and the ATK immediately after fitting, after acclimation, and as part of a long-term follow-up. A timed walk test assessed walking distance and efficiency. Mobility and user-preferences were evaluated through questionnaires. RESULTS: Distance during the timed walk test was significantly higher for the ATK compared with ICRC (P < 0.001), with functional gains retained at follow-up. No differences were found for gait efficiency and the mobility questionnaires. All participants, except one, preferred the ATK prosthesis. Benefits included greater knee stability and fewer perceived knee collapses; however, some disliked the appearance of the ATK. CONCLUSIONS: The findings suggest positive outcomes with prosthetic services in under-resourced regions and the ICRC system, as well as the potential for improved functional outcomes with more advanced multiaxis knee components.

Identifying priorities and developing strategies for building capacity in amputation research in Canada.

BACKGROUND: Compared to other patient population groups, the field of amputation research in Canada lacks cohesion largely due to limited funding sources, lack of connection among research scientists, and loose ties among geographically dispersed healthcare centres, research institutes and advocacy groups. As a result, advances in clinical care are hampered and ultimately negatively influence outcomes of persons living with limb loss. OBJECTIVE: To stimulate a national strategy on advancing amputation research in Canada, a consensus-workshop was organized with an expert panel of stakeholders to identify key research priorities and potential strategies to build researcher and funding capacity in the field. METHODS: A modified Delphi approach was used to gain consensus on identifying and selecting an initial set of priorities for building research capacity in the field of amputation. This included an anonymous pre-meeting survey (N = 31 respondents) followed by an in-person consensus-workshop meeting that hosted 38 stakeholders (researchers, physiatrists, surgeons, prosthetists, occupational and physical therapists, community advocates, and people with limb loss). RESULTS: The top three identified research priorities were: (1) developing a national dataset; (2) obtaining health economic data to illustrate the burden of amputation to the healthcare system and to patients; and (3) improving strategies related to outcome measurement in patients with limb loss (e.g. identifying, validating, and/or developing outcome measures). Strategies for moving these priorities into action were also developed. CONCLUSIONS: The consensus-workshop provided an initial roadmap for limb loss research in Canada, and the event served as an important catalyst for stakeholders to initiate collaborations for moving identified priorities into action. Given the increasing number of people undergoing an amputation, there needs to be a stronger Canadian collaborative approach to generate the necessary research to enhance evidence-based clinical care and policy decision-making.IMPLICATIONS FOR REHABILITATIONLimb loss is a growing concern across North America, with lower-extremity amputations occurring due to complications arising from diabetes being a major cause.To advance knowledge about limb loss and to improve clinical care for this population, stronger connections are needed across the continuum of care (acute, rehabilitation, community) and across sectors (clinical, advocacy, industry and research).There are new surgical techniques, technologies, and rehabilitation approaches being explored to improve the health, mobility and community participation of people with limb loss, but further research evidence is needed to demonstrate efficacy and to better integrate them into standard clinical care.

A Wearable Vibrotactile Biofeedback System Targeting Gait Symmetry of Lower-limb Prosthetic Users.

Lower limb prosthetic users exhibit gait deviations, which include asymmetrical stance time (ST), leading to secondary musculoskeletal problems. Biofeedback (BFB) systems have the potential to provide gait training to correct gait deviations. In this work, we describe a wearable BFB system that delivers vibrotactile feedback via two tactors (located at the anterior and posterior side of the residual limb of prosthetic users) to correct asymmetrical ST (%) using two strategies - single threshold feedback (SF) and bandwidth threshold feedback (BF). Validation of the system involved a sample of five lower limb amputees to examine the effectiveness of each strategy when compared to no feedback (NF) gait trials. Significant differences were found between no feedback and feedback trials. Although no significant differences were found between SF and BF, there are small but evident trends indicating that BF encourages ST (%) that is closest to the target with less error.

Derivative Based Gait Event Detection Algorithm Using Unfiltered Accelerometer Signals.

Wearable sensors have been investigated for the purpose of gait analysis, namely gait event detection. Many types of algorithms have been developed specifically using inertial sensor data for detecting gait events. Though much attention has turned toward machine learning algorithms, most of these approaches suffer from large computational requirements and are not yet suitable for real-time applications such as in prostheses or for feedback control. Current rules-based algorithms for real-time use often require fusion of multiple sensor signals to achieve high accuracy, thus increasing complexity and decreasing usability of the instrument. We present our results of a novel, rules-based algorithm using a single accelerometer signal from the foot to reliably detect heel-strike and toe-off events. Using the derivative of the raw accelerometer signal and applying an optimizer and windowing approach, high performance was achieved with a sensitivity and specificity of 94.32% and 94.70% respectively, and a timing error of 6.52 ± 22.37 ms, including trials involving multiple speed transitions. This would enable development of a compact wearable system for robust gait analysis in real-world settings, providing key insights into gait quality with the capability for real-time system control.

Two-dimensional video gait analysis: A systematic review of reliability, validity, and best practice considerations.

BACKGROUND: Motion capture systems are widely used to quantify human gait. Two-dimensional (2D) video systems are simple to use, easily accessible, and affordable. However, their performance as compared to other systems (i.e. three-dimensional (3D) gait analysis) is not well established. OBJECTIVES: This work provides a comprehensive review of design specifications and performance characteristics (validity and reliability) of two-dimensional motion capture systems. STUDY DESIGN: Systematic review. METHODS: A systematic literature search was conducted in three databases from 1990 to 2019 and identified 30 research articles that met the inclusion/exclusion criteria. RESULTS: Reliability of measurements of two-dimensional video motion capture was found to vary greatly from poor to excellent. Results relating to validity were also highly variable. Comparisons between the studies were challenging due to differences in protocols, instrumentation, parameters assessed, and analyses performed. CONCLUSIONS: Variability in performance could be attributed to study design, gait parameters being measured, and technical aspects. The latter includes camera specifications (i.e. resolution and frame rate), setup (i.e. camera position), and analysis software. Given the variability in performance, additional validation testing may be needed for specific applications involving clinical or research-based assessments, including specific patient populations, gait parameters, mobility tasks, and data collection protocols. CLINICAL RELEVANCE: This review article provides guidance on the application of 2D video gait analysis in a clinical or research setting. While not suitable in all instances, 2D gait analysis has promise in specific applications. Recommendations are provided about the patient populations, gait parameters, mobility tasks, and data collection protocols.

Biomechanical responses of young adults with unilateral transfemoral amputation using two types of mechanical stance control prosthetic knee joints.

BACKGROUND: Prosthetic knee joint function is important in the rehabilitation of individuals with transfemoral amputation. OBJECTIVES: The objective of this study was to assess the gait patterns associated with two types of mechanical stance control prosthetic knee joints-weight-activated braking knee and automatic stance-phase lock knee. It was hypothesized that biomechanical differences exist between the two knee types, including a prolonged swing-phase duration and exaggerated pelvic movements for the weight-activated braking knee during gait. STUDY DESIGN: Prospective crossover study. METHODS: Spatiotemporal, kinematic, and kinetic parameters were obtained via instrumented gait analysis for 10 young adults with a unilateral transfemoral amputation. Discrete gait parameters were extracted based on their magnitudes and timing. RESULTS: A 1.01% ± 1.14% longer swing-phase was found for the weight-activated braking knee (p < 0.05). The prosthetic ankle push-off also occurred earlier in the gait cycle for the weight-activated braking knee. Anterior pelvic tilt was 3.3 ± 3.0 degrees greater for the weight-activated braking knee. This range of motion was also higher (p < 0.05) and associated with greater hip flexion angles. CONCLUSIONS: Stance control affects biomechanics primarily in the early and late stance associated with prosthetic limb loading and unloading. The prolonged swing-phase time for the weight-activated braking knee may be associated with the need for knee unloading to initiate knee flexion during gait. The differences in pelvic tilt may be related to knee stability and possibly the different knee joint stance control mechanisms. CLINICAL RELEVANCE: Understanding the influence of knee function on gait biomechanics is important in selecting and improving treatments and outcomes for individuals with lower-limb amputations. Weight-activated knee joints may result in undesired gait deviations associated with stability in early stance-phase, and swing-phase initiation in the late stance-phase of gait.

A custom, functional and lifelike passive prosthetic hand for infants and small toddlers: Clinical note.

BACKGROUND AND AIM: For infants and small toddlers with congenital upper limb deficiencies, terminal devices mainly provide either cosmesis or functionality. We report a clinical note about fitting a child with a low-cost passive hand targeting both functionality and cosmesis. TECHNIQUE: An elastomeric, alloy-wire-reinforced hand was fabricated using additive manufacturing to allow independent positioning of the digits. A clinical pilot in-home evaluation was conducted on a child with upper limb loss. DISCUSSION: The fabricated hand met the functional requirements but required a cover for cosmesis due to a poor surface finish associated with the fabrication technique. The participant child was comfortable using the prosthesis for various tasks. The parents were satisfied with the hand's function and cosmesis when covered with a cosmetic glove. This work demonstrated a new design and process that may in the future improve the utilization of prosthetic hands to promote early prosthesis use and a child's development. CLINICAL RELEVANCE: Early prosthesis use is important for infants and toddlers. Additive manufacturing may enable the fabrication of custom passive prosthetic hands that provide both cosmesis and functionality.