Accuracy, Repeatability, and Reproducibility of a Hand-Held Structured-Light 3D Scanner across Multi-Site Settings in Lower Limb Prosthetics.

The aim of this work was to assess the accuracy, repeatability, and reproducibility of a hand-held, structured-light 3D scanner (EINScan Pro 2X Plus with High Definition Prime Pack, SHINING 3D Tech. Co., Ltd., Hangzhou, China), to support its potential use in multi-site settings on lower limb prosthetics. Four limb models with different shapes were fabricated and scanned with a metrological 3D scanner (EINScan Laser FreeScan 5X, SHINING 3D Tech. Co., Ltd., Hangzhou, China) by a professional operator (OP0). Limb models were then mailed to three sites where two operators (OP1, OP2) scanned them using their own structured-light 3D scanner (same model). OP1 scanned limb models twice (OP1-A, OP1-B). OP0, OP1-A, and OP2 scans were compared for accuracy, OP1-A and OP1-B for repeatability, and OP1-A and OP2 for reproducibility. Among all comparisons, the mean radial error was <0.25 mm, mean angular error was <4°, and root mean square error of the radial distance was <1 mm. Moreover, limits of agreement were <3.5% for perimeters and volumes. By comparing these results with respect to clinically-relevant thresholds and to the literature available on other 3D scanners, we conclude that the EINScan Pro 2X Plus 3D Scanner with High Definition Prime Pack has good accuracy, repeatability, and reproducibility, supporting its use in multi-site settings.

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.

Development of Instrumented Running Prosthetic Feet for the Collection of Track Loads on Elite Athletes.

Knowledge of loads acting on running specific prostheses (RSP), and in particular on running prosthetic feet (RPF), is crucial for evaluating athletes' technique, designing safe feet, and biomechanical modelling. The aim of this work was to develop a J-shaped and a C-shaped wearable instrumented running prosthetic foot (iRPF) starting from commercial RPF, suitable for load data collection on the track. The sensing elements are strain gauge bridges mounted on the foot in a configuration that allows decoupling loads parallel and normal to the socket-foot clamp during the stance phase. The system records data on lightweight athlete-worn loggers and transmits them via Wi-Fi to a base station for real-time monitoring. iRPF calibration procedure and static and dynamic validation of predicted ground-reaction forces against those measured by a force platform embedded in the track are reported. The potential application of this wearable system in estimating determinants of sprint performance is presented.

Assessment of anatomical and reverse total shoulder arthroplasty with the scapula-weighted Constant-Murley score.

AIM OF THE STUDY: To evaluate total (TSA) and reverse total shoulder arthroplasty (RTSA) using the Constant-Murley score (CMS) and the scapula-weighted (SW) CMS, an integrated outcome measure that takes into account the compensatory movements of the scapula. METHODS: Twenty-five consecutive patients, 12 with TSA and 13 with RTSA, underwent kinematic analysis before and after shoulder replacement. Measurements included flexion (FLEX) and abduction (ABD) for the humerus and Protraction-Retraction (PR-RE), Medio-Lateral rotation (ME-LA), and Posterior-Anterior tilting (P-A) for the scapula. They were recorded at baseline (T0) and at six (T1) and 12 months (T2). Reference data were obtained from 31 control shoulders. RESULTS: At T1, differences in CMS and SW-CMS were not significant in either group, whereas values at T2 were significantly lower in RTSA patients (p = 0.310 and p = 0.327, respectively). In TSA shoulders, the compensatory scapular movements in FLEX were all reduced from T0 to T2, whereas P-A was increased in ABD. In RTSA patients, the compensatory scapular movements in FLEX showed a general reduction at T1, with an increase in P-A at T2, whereas in ABD, all increased at T1 and decreased at T2 except for P-A, which did not decrease. DISCUSSION: The SW-CMS showed that the physiological scapulothoracic motion was not restored in TSA and RTSA patients; it may be used as a reference for the gradual progression of deltoid and scapular muscle rehabilitation. CONCLUSIONS: The worse CMS and SW-CMS scores found in RTSA patients at six months may be due to the biomechanics of the reverse prosthesis and to the weakness of deltoid and periscapular muscles.

Energy storing and return prosthetic feet improve step length symmetry while preserving margins of stability in persons with transtibial amputation.

BACKGROUND: Energy storing and return (ESAR) feet are generally preferred over solid ankle cushioned heel (SACH) feet by people with a lower limb amputation. While ESAR feet have been shown to have only limited effect on gait economy, other functional benefits should account for this preference. A simple biomechanical model suggests that enhanced gait stability and gait symmetry could prove to explain part of the difference in the subjective preference between both feet. AIM: To investigate whether increased push-off power with ESAR feet increases center of mass velocity at push off and enhance intact step length and step length symmetry while preserving the margin of stability during walking in people with a transtibial prosthesis. METHODS: Fifteen people with a unilateral transtibial amputation walked with their prescribed ESAR foot and a SACH foot at a fixed walking speed (1.2 m/s) over a level walkway while kinematic and kinetic data were collected. Push-off work generated by the foot, center of mass velocity, step length, step length symmetry and backward margin of stability were assessed and compared between feet. RESULTS: Push-off work was significantly higher when using the ESAR foot compared to the SACH foot. Simultaneously, center of mass velocity at toe-off was higher with ESAR compared to SACH, and intact step length and step length symmetry increased without reducing the backward margin of stability. CONCLUSION: Compared to the SACH foot, the ESAR foot allowed an improvement of step length symmetry while preserving the backward margin of stability at community ambulation speed. These benefits may possibly contribute to the subjective preference for ESAR feet in people with a lower limb amputation.

Reference values for gait temporal and loading symmetry of lower-limb amputees can help in refocusing rehabilitation targets.

BACKGROUND: The literature suggests that optimal levels of gait symmetry might exist for lower-limb amputees. Not only these optimal values are unknown, but we also don't know typical symmetry ratios or which measures of symmetry are essential. Focusing on the symmetries of stance, step, first peak and impulse of the ground reaction force, the aim of this work was to answer to three methodological and three clinical questions. The methodological questions wanted to establish a minimum set of symmetry indexes to study and if there are limitations in their calculations. The clinical questions wanted to establish if typical levels of temporal and loading symmetry exist, and change with the level of amputation and prosthetic components. METHODS: Sixty traumatic, K3-K4 amputees were involved in the study: 12 transfemoral mechanical knee users (TFM), 25 C-leg knee users (TFC), and 23 transtibial amputees (TT). Ninety-two percent used the Ossur Variflex foot. Ten healthy subjects were also included. Ground reaction force from both feet were collected with the Novel Pedar-X. Symmetry indexes were calculated and statistically compared with regression analyses and non-parametric analysis of variance among subjects. RESULTS: Stance symmetry can be reported instead of step, but it cannot substitute impulse and first peak symmetry. The first peak cannot always be detected on all amputees. Statistically significant differences exist for stance symmetry among all groups, for impulse symmetry between TFM and TFC/TT, for first peak symmetry between transfemoral amputees altogether and TT. Regarding impulse symmetry, 25% of TFC and 43% of TT had a higher impulse on the prosthetic side. Regarding first peak symmetry, 59% of TF and 30% of TT loaded more the prosthetic side. CONCLUSIONS: Typical levels of symmetry for stance, impulse and first peak change with the level of amputation and componentry. Indications exist that C-leg and energy-storage-and-return feet can improve symmetry. Results are suggestive of two mechanisms related to sound side knee osteoarthritis: increased impulse for TF and increased first peak for TT. These results can be useful in clinics to set rehabilitation targets, understand the advancements of a patient during gait retraining, compare and chose components and possibly rehabilitation programs.

Methodological factors affecting joint moments estimation in clinical gait analysis: a systematic review.

Quantitative gait analysis can provide a description of joint kinematics and dynamics, and it is recognized as a clinically useful tool for functional assessment, diagnosis and intervention planning. Clinically interpretable parameters are estimated from quantitative measures (i.e. ground reaction forces, skin marker trajectories, etc.) through biomechanical modelling. In particular, the estimation of joint moments during motion is grounded on several modelling assumptions: (1) body segmental and joint kinematics is derived from the trajectories of markers and by modelling the human body as a kinematic chain; (2) joint resultant (net) loads are, usually, derived from force plate measurements through a model of segmental dynamics. Therefore, both measurement errors and modelling assumptions can affect the results, to an extent that also depends on the characteristics of the motor task analysed (i.e. gait speed). Errors affecting the trajectories of joint centres, the orientation of joint functional axes, the joint angular velocities, the accuracy of inertial parameters and force measurements (concurring to the definition of the dynamic model), can weigh differently in the estimation of clinically interpretable joint moments. Numerous studies addressed all these methodological aspects separately, but a critical analysis of how these aspects may affect the clinical interpretation of joint dynamics is still missing. This article aims at filling this gap through a systematic review of the literature, conducted on Web of Science, Scopus and PubMed. The final objective is hence to provide clear take-home messages to guide laboratories in the estimation of joint moments for the clinical practice.

A Motion Analysis Protocol for Kinematic Assessment of Poly-Articulated Prosthetic Hands With Cosmetic Gloves.

To provide upper-limb amputees with devices that best fit their needs and to test innovative solutions, it is necessary to quantitatively appraise a device performance with rigorous measurement methods. The aim of this work was to define an optimal motion analysis protocol, suitable for optoelectronic systems, to measure the kinematics of poly-articulated hands even when covered by a cosmetic glove. This is a fundamental aspect, because gloves can decrease device speed and range of motion and, ultimately, patients' acceptance of the artificial limb. In this work, different mathematical models of the joints and marker-sets for motion analysis were conceived. A regression model to choose a reduced marker-set for studying the hand performance with different cosmetic glove models was developed. The proposed approaches for finger motion analysis were experimentally tested on the index finger of the i-Limb, a commercial myoelectric poly-articulated prosthetic hand, but the results can be easily extended to the whole hand and to other poly-articulated prosthetic hands. The methods proposed for the performance analysis of prosthetic hands points out that the cosmetic gloves imply a reduction of the finger flexion/extension (F/E) angles and of the motion velocity. This draws attention to the need for performing independent cyclic tests on commercial products with various cosmetic solutions to better guide component selection.

Clinical gait analysis for amputees: innovation wishlist and the perspectives offered by the outwalk protocol.

Clinical gait analysis (CGA) has shown potentials for the prosthetics field and has been found effective for scientific purposes and to design general rehabilitation models. However, intrinsic limitations of the "artificial" laboratory environment usually result in recording performances not representative patients' real-life gait. In order to promote the diffusion of CGA in the clinical decision-making process, a framework for developing novel, more ecological CGA applications is presented. Moreover, the Outwalk protocol, based on wearable sensors and developed within this framework guidelines, is described and validated for its inter-rater agreement on a population of transtibial amputees walking in a real-life scenario. Results show the possibility of drawing precise conclusions over different aspects of amputees' gait and prostheses' performance in every-day life conditions.

Assessment of lower limb prosthesis through wearable sensors and thermography.

This study aimed to explore the application of infrared thermography in combination with ambulatory wearable monitoring of temperature and relative humidity, to assess the residual limb-to-liner interface in lower-limb prosthesis users. Five male traumatic transtibial amputees were involved, who reported no problems or discomfort while wearing the prosthesis. A thermal imaging camera was used to measure superficial thermal distribution maps of the stump. A wearable system for recording the temperature and relative humidity in up to four anatomical points was developed, tested in vitro and integrated with the measurement set. The parallel application of an infrared camera and wearable sensors provided complementary information. Four main Regions of Interest were identified on the stump (inferior patella, lateral/medial epicondyles, tibial tuberosity), with good inter-subject repeatability. An average increase of 20% in hot areas (P < 0.05) is shown after walking compared to resting conditions. The sensors inside the cuff did not provoke any discomfort during recordings and provide an inside of the thermal exchanges while walking and recording the temperature increase (a regime value is ~+1.1 ± 0.7 °C) and a more significant one (~+4.1 ± 2.3%) in humidity because of the sweat produced. This study has also begun the development of a reference data set for optimal socket/liner-stump construction.

Digital design and fabrication of multi-material hand orthoses to allow an athlete with scleroderma to play sitting volleyball.

Scleroderma is a chronic and progressive autoimmune disorder of connective tissues often causing lesions and deformities of the hands. Individuals affected by this condition experience daily life limitations and are typically unable to take part in sport activities that involve impacts on the hands. In this article we describe the design and manufacturing of custom-made hand orthoses to play sitting volleyball, for an elite paralympic athlete affected by scleroderma. The devices consist of a carbon fibre shell with an internal silicone padding and an external polymeric multilayer cover. The manufacturing of the orthoses involves digital modelling, 3D printing, composite lamination and an innovative method to create a strong and durable chemical bonding between silicone and carbon fibre. The internal silicone padding proved to be effective in hosting and protecting the hands, whereas the external shell with polymeric multilayer cover allowed to dampen the ball shocks while effectively hitting the ball. Indeed, these devices allowed the athlete to take part in the 2020 Tokyo Paralympic games and were used for two years without showing any damage.

A digital process to replicate the socket-foot alignment in below-knee running specific prostheses.

A well-fitting socket and a fine-tuned foot alignment are crucial elements in a running-specific prosthesis to allow Paralympic athletes with below-knee amputation to express their full competitive potential. For this reason, once a satisfactory socket-foot configuration is established after dynamic alignment, it is fundamental to reproduce the same conditions when constructing the definitive carbon fiber socket, and when renewing or constructing a back-up prosthesis, without dismantling the original. In addition, to cope with emerging needs of the athlete, it would be beneficial to implement fine-tuning adjustments of the alignment in a very controlled manner. At present, this requires elaborate bench procedures, which tend to be expensive, time consuming, prone to manual errors, cumbersome in use and most often require damaging or disposing of the current socket. In this study, we propose an original CAD/CAM workflow that allows replicating the desired socket-foot configuration for below-knee sprinting prostheses, as well as performing socket adaptations and introducing fine-tuning adjustments to the alignments. The workflow is exemplified with reference to two case studies involving elite Paralympic runners with transtibial and partial foot amputations, respectively.

Biomechanical determinants of top running speeds in para-athletes with unilateral transfemoral amputation.

BACKGROUND: An increased understanding of biomechanical determinants that influence the sprint performance of para-athletes with a unilateral transfemoral amputation will provide us with a basis for better evaluating athletes' sprint performance and would be expected to aid in the development of more effective training methods and running-specific prosthesis selection guidelines. OBJECTIVES: The aim of this study was to investigate the relative contributions of mechanical determinants to the top running speeds of para-athletes with unilateral transfemoral amputation wearing a running-specific prosthesis. STUDY DESIGN: Observational study within the subject. METHODS: Nine para-athletes with unilateral transfemoral amputation wearing a running-specific prosthesis were recruited in this study. They were asked to run at their respective constant top speeds on an instrumented treadmill. From the ground reaction force and spatiotemporal parameters, three mechanical variables-step frequency, mass-specific averaged vertical ground-reaction force, and contact length-were determined for both the affected and unaffected limbs. RESULTS: Stepwise regression analysis showed that the contact length of the affected limb was significant and an independent factor of top running speed ( ß = 0.760, P < 0.05), with a coefficient of determination ( R2 ) of 0.577 ( P < 0.05), whereas the other variables were not associated. CONCLUSION: These results suggest that prosthetic components and alignment are crucial to determining the maximal sprinting performance in uTFA.

Static strength of lower-limb prosthetic sockets: An exploratory study on the influence of stratigraphy, distal adapter and lamination resin.

Knowledge about the mechanical properties of lower-limb prosthetic sockets fabricated with resin infusion lamination and composite materials is limited. Therefore, sockets can be subject to mechanical failure and over-dimensioning, both of which can have severe consequences for patients. For this reason, an exploratory study was conducted to analyze the effect of stratigraphy (layup and fibers), matrix (resin) and mechanical connection (socket distal adapter) on socket static strength, with the objectives of: 1) implementing a mechanical testing system for lower-limb prosthetic sockets based on ISO 10328:2016 and provide the mechanical design of the loading plates, 2) apply the testing system to a series of laminated sockets, and 3) for each type of distal adapter, identify the combinations of stratigraphy and matrix with acceptable strength and minimum weight. Twenty-three laminated sockets were produced and tested. Sixteen met the required strength, with ten exhibiting an excessive weight. Among the remaining six, four combinations of stratigraphy and resin were identified as best option, as they all overcame ISO 10328 P6 loading level and weighted less than 600 g. The selected stratigraphies had limited or absent amount of Perlon stockinettes, which seems to increase weight without enhancing the mechanical strength. Sockets based on Ossur MSS braids and connector show the best compromise between strength and weight when the amount of carbon braids is halved.

Mechanical testing of transtibial prosthetic sockets: A discussion paper from the American Orthotic and Prosthetic Association Socket Guidance Workgroup.

BACKGROUND: The advent of novel manufacturing technologies, materials, and socket design concepts could introduce risks to prosthetic limb users, as the existing knowledge base for safe fabrication may not apply. Moreover, although structural test standards exist for mass-produced prosthetic components, they are not applicable to prosthetic sockets. METHODS: The "AOPA Socket Guidance Workgroup" was formed in 2020 to provide the prosthetic community with evidence-based clinical best practices and methods in the field of prosthetic socket structural analysis. This multidisciplinary expert workgroup undertook a critical analysis of the knowledge gaps regarding the requirements for mechanical testing of lower limb prosthetic sockets. RESULTS: The Workgroup identified knowledge gaps in 4 domains. Domain 1 describes the shape and composition of a mock residual limb, required to support and generate in vivo representative loading within the socket. Domain 2 concerns prosthetic socket coordinate systems and alignment. Domain 3 regards the components and requirements of test specimens. Finally, Domain 4 considers test conditions, loading parameters, and acceptance criteria. CONCLUSIONS: This paper describes these knowledge gaps in detail and recommends potential solution approaches based on literature review, group consensus around existing knowledge, or the formation of new study groups to fill each knowledge gap. Our intent is for the recommendations arising from this paper to support the community (e.g., researchers in the clinic, academia, industry, and funders) in addressing these knowledge gaps.

Shoulder Rehabilitation Exercises With Kinematic Biofeedback After Arthroscopic Rotator Cuff Repair: Protocol for a New Integrated Rehabilitation Program.

BACKGROUND: The recovery of scapular and humeral physiological kinematic parameters, as well as the sensorimotor control of movement, plays a primary role in the rehabilitation process after arthroscopic rotator cuff repair. A highly customized rehabilitation approach is required to achieve this aim. Biofeedback can be a useful tool, but there is poor evidence of its application in the rehabilitation after arthroscopic rotator cuff tear repair. OBJECTIVE: The aim of this paper is to outline an innovative exercise-based rehabilitation program exploiting visual biofeedback for the recovery of patients arthroscopically treated for rotator cuff repair. METHODS: For establishment of the innovative program, a multidisciplinary team involving experts in shoulder surgery, rehabilitation medicine, physical therapy, and biomedical and clinical engineering was formed. Starting from a conventional rehabilitation program, the team selected a set of exercises to be integrated with a biofeedback tool, named the INAIL (National Institute for Insurance against Accidents at Work) Shoulder and Elbow Outpatient program (ISEO program). ISEO is a motion analysis system based on inertial wearable sensors positioned over the thorax, scapula, humerus, and forearm. ISEO can return a visual biofeedback of humerus and scapula angles over time or of the scapula-humeral coordination, with possible overlap of patient-specific or asymptomatic reference values. A set of 12 progressive exercises was defined, divided into four groups based on humerus and scapula movements. Each group comprises 2-4 of the 12 exercises with an increasing level of complexity. Exercises can require the use of a ball, stick, rubber band, and/or towel. For each exercise, we present the starting position of the patient, the modality of execution, and the target position, together with notes about the critical factors to observe. The type of visual biofeedback to adopt is specified, such as the coordination between angles or the variation of a single angle over time. To guide the therapist in customizing the patient's rehabilitation program, a list of operative guidelines is provided. RESULTS: We describe various applications of the ISEO exercise program in terms of frequency and intensity. CONCLUSIONS: An innovative rehabilitation program to restore scapular and humeral kinematics after rotator cuff repair based on kinematic biofeedback is presented. Biofeedback is expected to increase patient awareness and self-correction under therapist supervision. Randomized controlled trials are needed to investigate the potential effect of the exercise-based biofeedback in comparison with conventional rehabilitation programs. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): DERR1-10.2196/35757.

Structural testing of lower-limb prosthetic sockets: A systematic review.

A lower-limb prosthetic socket is the custom-made structural element interfacing the residual limb of a person with an amputation to their prosthetic leg comprising off-the-shelf componentry. The socket can be subject to mechanical failure, especially when new fabrication methods and materials are introduced (e.g. 3D printing). Failures can have severe consequences for patients. A systematic review was conducted to collect information about available socket mechanical testing methods, to support the definition of widely accepted guidelines. To this aim the structural testing methods were reviewed, but not the results of the individual studies. 729 records were retrieved, of which 16 articles were included. No articles addressed transfemoral socket testing, as all focused on transtibial sockets. Thirteen articles used some sort of adaptation of ISO 10328, and all of them simulated the toe-off instant of gait, with load level acceptable for patients from 100 to 125 kg of weight. Ten considered a rigid limb dummy. Overall, ISO 10328 appears as a viable starting point for defining a testing guideline, but a considerable number of details has to be agreed upon, starting from clear definitions of anatomical landmarks and socket axes, which are required to implement a representative and repeatable test method.

Ambulatory measurement of shoulder and elbow kinematics through inertial and magnetic sensors.

Inertial and magnetic measurement systems (IMMSs) are a new generation of motion analysis systems which may diffuse the measurement of upper-limb kinematics to ambulatory settings. Based on the MT9B IMMS (Xsens Technologies, NL), we therefore developed a protocol that measures the scapulothoracic, humerothoracic and elbow 3D kinematics. To preliminarily evaluate the protocol, a 23-year-old subject performed six tasks involving shoulder and elbow single-joint-angle movements. Criteria for protocol validity were limited cross-talk with the other joint-angles during each task; scapulohumeral-rhythm close to literature results; and constant carrying-angle. To assess the accuracy of the MT9B when measuring the upper-limb kinematics through the protocol, we compared the MT9B estimations during the six tasks, plus other four, with the estimations of an optoelectronic system (the gold standard), in terms of RMS error, correlation coefficient (r), and the amplitude ratio (m). Results indicate that the criteria for protocol validity were met for all tasks. For the joint angles mainly involved in each movement, the MT9B estimations presented RMS errors <3.6 degrees , r > 0.99 and 0.9 < m < 1.09. It appears therefore that (1) the protocol in combination with the MT9B is valid for, and (2) the MT9B in combination with the protocol is accurate when, measuring shoulder and elbow kinematics, during the tasks tested, in ambulatory settings.

Corrections to "Treatment of the Partial Hand Amputation: An Engineering Perspective".

In the above paper, by Imbinto et al. (IEEE Rev. Biomed. Eng., vol. 9, pp. 32-48, 2016), typographical errors appear in (1) (2) (3), whereas (4) is missing of a factor; all the equations are reported within Section III-C of the paper. The modifications are provided in this paper.