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.

Development and alpha testing of a patient shared decision aid for prosthesis design for new lower limb prosthesis users.

BACKGROUND: After lower limb amputation, several prosthesis design options exist. However, prosthesis design decisions do not always reflect a prosthesis user's needs, values, and preferences. OBJECTIVE: To develop a patient decision aid (PDA) prototype for prosthetists and new prosthesis users facing prosthesis design decisions after lower limb amputation, and to assess its usability, accuracy, and comprehensibility. STUDY DESIGN: Exploratory mixed methods. METHODS: PDA development was informed by a qualitative needs assessment and guided by the International Patient Decision Aid Standards. The PDA was evaluated by steering groups of experienced prosthesis users and prosthetic professionals (prosthetists and researchers) to test usability, accuracy, and comprehensibility through focus groups, individual interviews, and rating on a Likert scale ranging from 1 to 10. RESULTS: The resulting PDA included 6 sections: (1) Amputation and Early Recovery, (2) Communication, (3) Values, (4) Prosthesis Design, (5) Preferences, and (6) Prosthetic Journey. Usability, accuracy, and comprehensibility were rated as 9.2, 9.6, and 9.6, respectively, by prosthetic professionals, and 9.4, 9.6, and 9.6, respectively, by prosthesis users. DISCUSSION: The PDA incorporated guidance by relevant stakeholders and was rated favorably, emphasizing a need for shared decision-making support in prosthesis design. One challenge was determining the amount of information in the PDA, highlighting the diversity in end users' informational needs. Future iterations of the PDA should undergo beta testing in clinical settings. CONCLUSIONS: A standardized, iterative method was used to develop a PDA for new lower limb prosthesis users and prosthetists when considering prosthesis design decisions. The PDA was considered useable, accurate, and comprehensible.

Individualized orthotic alignment and footwear for balance and mobility in children with bilateral spastic cerebral palsy: A randomized trial.

AIM: To examine whether designed-to-be-rigid ankle-foot orthoses and footwear combinations with individualized alignment and footwear designs (AFO-FC/IAFD) would be more effective than designed-to-be-rigid AFO with non-individualized alignment and footwear designs (AFO-FC/NAFD) in children with cerebral palsy (CP). METHOD: Nineteen children with bilateral spastic CP were randomized to AFO-FC/NAFD (n = 10) or AFO-FC/IAFD (n = 9) groups. Fifteen were male, average age 6 years 11 months (range 4 years 2 months-9 years 11 months), classified in Gross Motor Function Classification System levels II (n = 15) and III (n = 4). The Pediatric Balance Scale (PBS), Gait Outcomes Assessment List (GOAL), Patient-Reported Outcomes Measurement Information System (PROMIS), and Orthotic and Prosthetic Users' Survey (OPUS) measures of satisfaction were collected at baseline and after 3 months' wear. RESULTS: Compared with the AFO-FC/NAFD group, those with AFO-FC/IAFD demonstrated greater change in PBS total scores (mean 12.8 [standard deviation 10.5] vs 3.5 [5.8]; p = 0.03) and GOAL total scores (3.5 [5.8] vs -0.44 [5.5]; p = 0.03). There were no significant changes in OPUS or PROMIS scores. INTERPRETATION: After 3 months, individualized orthosis alignment and footwear designs had a greater positive effect on balance and parent-reported mobility than a non-individualized approach. No effect was documented for the PROMIS and OPUS. Results may inform orthotic management for ambulatory children with bilateral spastic CP. WHAT THIS PAPER ADDS: Balance and parent-reported mobility increased more over time for the ankle-foot orthoses and footwear combinations with individualized alignment and footwear designs (AFO-FC/IAFD) group. Changes in balance over time suggest a therapeutic effect of the AFO-FC/IAFD approach.

After scaling to body size hip strength of the residual limb exceeds that of the intact limb among unilateral lower limb prosthesis users.

BACKGROUND: Hip muscles play a prominent role in compensating for the loss of ankle and/or knee muscle function after lower limb amputation. Despite contributions to walking and balance, there is no consensus regarding hip strength deficits in lower limb prosthesis (LLP) users. Identifying patterns of hip muscle weakness in LLP users may increase the specificity of physical therapy interventions (i.e., which muscle group(s) to target), and expedite the search for modifiable factors associated with deficits in hip muscle function among LLP users. The purpose of this study was to test whether hip strength, estimated by maximum voluntary isometric peak torque, differed between the residual and intact limbs of LLP users, and age- and gender-matched controls. METHODS: Twenty-eight LLP users (14 transtibial, 14 transfemoral, 7 dysvascular, 13.5 years since amputation), and 28 age- and gender-matched controls participated in a cross-sectional study. Maximum voluntary isometric hip extension, flexion, abduction, and adduction torque were measured with a motorized dynamometer. Participants completed 15 five-second trials with 10-s rest between trials. Peak isometric hip torque was normalized to body mass × thigh length. A 2-way mixed-ANOVA with a between-subject factor of leg (intact, residual, control) and a within-subject factor of muscle group (extensors, flexors, abductors, adductors) tested for differences in strength among combinations of leg and muscle group (α = 0.05). Multiple comparisons were adjusted using Tukey's Honest-Difference. RESULTS: A significant 2-way interaction between leg and muscle group indicated normalized peak torque differed among combinations of muscle group and leg (p < 0.001). A significant simple main effect of leg (p = 0.001) indicated peak torque differed between two or more legs per muscle group. Post-hoc comparisons revealed hip extensor, flexor, and abductor peak torque was not significantly different between the residual and control legs (p ≥ 0.067) but torques in both legs were significantly greater than in the intact leg (p < 0.001). Peak hip abductor torque was significantly greater in the control and residual legs than the intact leg (p < 0.001), and significantly greater in the residual than control leg (p < 0.001). CONCLUSIONS: Our results suggest that it is the intact, rather than the residual limb, that is weaker. These findings may be due to methodological choices (e.g., normalization), or biomechanical demands placed on residual limb hip muscles. Further research is warranted to both confirm, expand upon, and elucidate possible mechanisms for the present findings; and clarify contributions of intact and residual limb hip muscles to walking and balance in LLP users. CLINICAL TRIAL REGISTRATION: N/A.

Development of an item bank for measuring prosthetic mobility in people with lower limb amputation: The Prosthetic Limb Users Survey of Mobility (PLUS-M).

BACKGROUND: Achieving mobility with a prosthesis is a common post-amputation rehabilitation goal and primary outcome in prosthetic research studies. Patient-reported outcome measures (PROMs) available to measure prosthetic mobility have practical and psychometric limitations that inhibit their use in clinical care and research. OBJECTIVE: To develop a brief, clinically meaningful, and psychometrically robust PROM to measure prosthetic mobility. DESIGN: A cross-sectional study was conducted to administer previously developed candidate items to a national sample of lower limb prosthesis users. Items were calibrated to an item response theory model and two fixed-length short forms were created. Instruments were assessed for readability, effective range of measurement, agreement with the full item bank, ceiling and floor effects, convergent validity, and known groups validity. SETTING: Participants were recruited using flyers posted in hospitals and prosthetics clinics across the United States, magazine advertisements, notices posted to consumer websites, and direct mailings. PARTICIPANTS: Adult prosthesis users (N = 1091) with unilateral lower limb amputation due to traumatic or dysvascular causes. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Candidate items (N = 105) were administered along with the Patient Reported Outcome Measurement Information System Brief Profile, Prosthesis Evaluation Questionnaire - Mobility Subscale, and Activities-Specific Balance Confidence Scale, and questions created to characterize respondents. RESULTS: A bank of 44 calibrated self-report items, termed the Prosthetic Limb Users Survey of Mobility (PLUS-M), was produced. Clinical and statistical criteria were used to select items for 7- and 12-item short forms. PLUS-M instruments had an 8th grade reading level, measured with precision across a wide range of respondents, exhibited little-to-no ceiling or floor effects, correlated expectedly with scores from existing PROMs, and differentiated between groups of respondents expected to have different levels of mobility. CONCLUSION: The PLUS-M appears to be well suited to measuring prosthetic mobility in people with lower limb amputation. PLUS-M instruments are recommended for use in clinical and research settings.

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.

Improving shared decision-making for prosthetic care: A qualitative needs assessment of prosthetists and new lower-limb prosthesis users.

BACKGROUND: Prosthesis design is complex and multiple appropriate options exist for any individual with lower-limb amputation. However, there is insufficient evidence for guiding decision-making. Shared decision-making (SDM) offers an opportunity to incorporate patient-specific values and preferences where evidence is lacking for prosthesis design decisions. To develop resources to facilitate SDM, and consistent with the International Patient Decision Aid Standards, it is necessary to identify the decisional needs of prosthetists and prosthesis users for prosthesis design decisions. OBJECTIVES: To assess the needs of prosthetists and new prosthesis users for SDM about the first prosthesis design. STUDY DESIGN: Qualitative descriptive design. METHODS: Six focus groups were conducted with 38 prosthetists. Individual semistructured interviews were conducted with 17 new prosthesis users. Transcripts were analyzed using directed content analysis, with codes defined a priori using existing frameworks for SDM: the Three Talk Model for SDM and the Ottawa Decision Support Framework. RESULTS: Four main themes were identified among prosthetists and prosthesis users: acknowledging complexity in communication, clarifying values, recognizing the role of experience to inform preferences , and understanding the prosthetic journey . CONCLUSIONS: Resources that support SDM for the first prosthesis design should consider methods for identifying individual communication needs, support with clarifying values, and resources such as experience for achieving informed preferences, within the context of the overall course of rehabilitation and recovery following lower-limb amputation. The themes identified in this work can inform SDM to promote collaborative discussion between prosthetists and new prosthesis users when making prosthesis design decisions.

Normalization alters the interpretation of hip strength in established unilateral lower limb prosthesis users.

BACKGROUND: Valid comparisons of muscle strength between individuals or legs that differ in size requires normalization, often by simple anthropometric variables. Few studies of muscle strength in lower-limb prosthesis users have normalized strength data by any anthropometric variable, potentially confounding our understanding of strength deficits in lower-limb prosthesis users. The objective of this pilot study was to determine the need for as well as effectiveness and impact of normalizing hip strength in lower-limb prosthesis users. METHODS: Peak isometric hip extension and abduction torques were collected from 28 lower-limb prosthesis users. Allometric scaling was used to determine if hip torque values were significantly associated with, and therefore needed to be adjusted for, body mass, thigh length, or body mass x thigh length, and whether normalization was effective in reducing any associations. Between limb differences in peak hip torque, and correlations with balance ability, were inspected pre- and post-normalization. FINDINGS: Hip torques were consistently and significantly associated with body-mass x thigh length. Associations between peak hip torque and body-mass x thigh length were reduced by normalization. After normalization by body-mass x thigh length, between limb differences in hip extension torque, as well as the correlation between hip abduction torque and balance ability, changed from non-significant to significant. INTERPRETATION: In the absence of normalization, hip strength (i.e., peak torque) in lower-limb prosthesis users remains dependent on basic anthropometric variables, masking relationships between hip strength and balance ability, as well as between limb differences.

Correction: Using mechanical testing to assess texturing of prosthetic sockets to improve suspension in the transverse plane and reduce rotation.

[This corrects the article DOI: 10.1371/journal.pone.0233148.].

Comparison of Ischial Containment and Subischial Sockets Effect on Gait Biomechanics in People With Transfemoral Amputation: A Randomized Crossover Trial.

OBJECTIVE: To compare gait biomechanics of the Northwestern University Flexible Sub-Ischial Vacuum (NU-FlexSIV) Socket to the ischial containment (IC) socket. DESIGN: Randomized crossover trial with 2, 7-week periods. SETTING: Private prosthetic clinics and university research laboratory. PARTICIPANTS: A total of 30 enrolled (n=30); 25 participants completed the study with full (n=18) or partial data (n=7). INTERVENTIONS: Two custom-fabricated sockets (IC and NU-FlexSIV), worn full-time for 7 weeks, with testing at 1, 4, and 7 weeks after socket delivery. MAIN OUTCOME MEASURES: Gait analyses were conducted at 1, 4, and 7 weeks post socket delivery. Differences between sockets in selected gait variables related to hip motion and coronal plane socket stability were assessed. RESULTS: For participants with data for both sockets at week 7 (n=19), there were no significant differences in any gait variables between sockets at self-selected normal walking speed. However, when all participants and all study time points were assessed (n=25), there was a significant main effect of socket (P=.013), with prosthetic side sagittal plane hip range of motion being significantly greater for the NU-FlexSIV Socket at self-selected normal walking speed. There were no other significant effects. CONCLUSIONS: The results suggest that, compared to the IC socket, the NU-FlexSIV Socket did not alter gait biomechanics related to hip motion and coronal plane socket stability in people with unilateral transfemoral amputation.

Comparison of Sagittal Plane Stiffness of Nonarticulated Pediatric Ankle-Foot Orthoses Designed to be Rigid.

INTRODUCTION: When studying the effect of ankle-foot orthoses (AFOs) on gait, it is important to know their sagittal plane stiffness. However, there are no established thresholds for stiffness of non-articulated AFOs designed to be rigid. If wanting to implement published algorithms for ankle-foot orthosis-footwear combinations (AFO-FCs), the AFOs must be equally as stiff as those of the developer of the published AFO-FC algorithms. Hence, the aim of this work was to compare the sagittal plane stiffness of AFOs designed to be rigid, made for a clinical trial in the USA, and following algorithms for AFO-FC designs, to those made and used clinically in the UK by the developer of the AFO-FC algorithms. MATERIALS AND METHODS: Stiffness of 9 pediatric polypropylene AFOs was tested (UK: 6; USA: 3). A computer-controlled motorized device was used in which all AFOs were clamped with the calf shell in a fixed vertical component and the foot section in a rotating plate. Each AFO was tested for 3 trials, loading the foot plate 30 Nm towards dorsiflexion and 20 Nm towards plantarflexion. Torque-angle graphs were plotted and deflection and stiffness compared descriptively across AFOs. RESULTS: Average deflection of AFOs was UK: 3.42±0.83° and USA: 4.81±1.05°. Average stiffness of AFOs was UK: 14.34±3.34 Nm/° and USA: 10.30±1.92 Nm/°. CONCLUSIONS: All tested AFOs deflected only a few degrees in either direction (range: 2.59° to 6.02°), providing the first information reported for the stiffness of rigid pediatric non-articulated AFOs. Overall, the UK AFOs were stiffer and deflected less than the USA study AFOs. AFO design features should be carefully considered as they likely influence sagittal plane stiffness and deflection under load.

Myoelectric Arm Orthosis in Motor Learning-Based Therapy for Chronic Deficits After Stroke and Traumatic Brain Injury.

BACKGROUND: Technologies that enhance motor learning-based therapy and are clinically deployable may improve outcome for those with neurological deficits. The MyoPro™ is a customized myoelectric upper extremity orthosis that utilizes volitionally generated weak electromyographic signals from paretic muscles to assist movement of an impaired arm. Our purpose was to evaluate MyoPro as a tool for motor learning-based therapy for individuals with chronic upper limb weakness. METHODS: This was a pilot study of thirteen individuals with chronic moderate/severe arm weakness due to either stroke (n = 7) or TBI (n = 6) who participated in a single group interventional study consisting of 2 phases. The in-clinic phase included 18 sessions (2x per week, 27hrs of face-to-face therapy) plus a home exercise program. The home phase included practice of the home exercise program. The study did not include a control group. Outcomes were collected at baseline and at weeks 3, 5, 7, 9, 12, 15, and 18. Statistics included mixed model regression analysis. RESULTS: Statistically significant and clinically meaningful improvements were observed on Fugl-Meyer (+7.5 points). Gains were seen at week 3, increased further through the in-clinic phase and were maintained during the home phase. Statistically significant changes in Modified Ashworth Scale, Range of Motion, and Chedoke Arm and Hand Activity Inventory were seen early during the in-clinic phase. Orthotic and Prosthetic User's Survey demonstrated satisfaction with the device throughout study participation. Both stroke and TBI participants responded to the intervention. CONCLUSIONS: Use of MyoPro in motor learning-based therapy resulted in clinically significant gains with a relatively short duration of in-person treatment. Further studies are warranted. CLINICAL TRIAL REGISTRATION: www.ClinicalTrials.gov, identifier: NCT03215771.

Comparison of Ischial Containment and Subischial Sockets on Comfort, Function, Quality of Life, and Satisfaction With Device in Persons With Unilateral Transfemoral Amputation: A Randomized Crossover Trial.

OBJECTIVE: To compare comfort and functional performance of the Northwestern University Flexible Subischial Vacuum (NU-FlexSIV) Socket with the ischial containment (IC) socket in persons with unilateral transfemoral amputation. DESIGN: Randomized crossover trial with two 7-week periods. SETTING: Private prosthetic clinics and university research laboratory. PARTICIPANTS: A total of 30 enrolled (N=30); 25 participants completed the study with full (n=18) or partial data (n=7). INTERVENTIONS: Two custom-fabricated sockets (IC and NU-FlexSIV), worn full-time for 7 weeks, with testing at 1, 4, and 7 weeks after socket delivery. MAIN OUTCOME MEASURES: The primary outcome was change in Socket Comfort Score (SCS) at 7 weeks. Secondary outcomes at 7 weeks included the Orthotic and Prosthetic Users' Survey (OPUS) to assess lower extremity functional status, health-related quality of life, and satisfaction with device, as well as the 5-Times Rapid Sit-to-Stand Test, Four Square Step Test, and T-Test of Agility to assess functional performance. RESULTS: At 7 weeks, the mean SCS for IC (7.0±1.7) and NU-FlexSIV (8.4±1.1) Sockets were significantly different (P<.001; 95% confidence interval, 0.8-2.3). Results from a linear mixed-effects model, accounting for data from all time points, indicated that the SCS was 1.7 (SE=0.45) points higher for the NU-FlexSIV Socket (P<.001). For the secondary outcomes, only OPUS satisfaction with device was significantly better in the NU-FlexSIV Socket after accounting for all data points. CONCLUSIONS: The results suggest that after 7 weeks' accommodation, the NU-FlexSIV Socket was more comfortable and led to greater satisfaction with device than the IC socket in persons with unilateral transfemoral amputation and K3/K4 mobility. Other patient-reported outcomes and function were no different between sockets.

Orthotists' and physical therapists' perspectives on quality of care indicators for persons with custom ankle-foot orthoses.

Purpose: To describe the priorities of orthotists and physical therapists about quality measurement themes, and the feasibility and utility of collecting data from persons using custom AFOs that could inform quality measure development.Materials and Methods: Online survey assessed respondents' perspectives and experiences. An Advisory Committee representing professional, organizational, and accreditor groups distributed survey invitations.Results: 461 orthotists and 153 physical therapists completed part or all of the survey; 60% rated 9 quality themes and 20 quality of care topics as extremely important, and 12 standard instruments as feasible and good to use for quality measurement. Patients were the preferred source of information for ease of scheduling, device weight, ease of donning and doffing, adherence to device use, beneficial effects, activity level and independence, and quality of life. Clinicians were the preferred source for material quality, device modifiability, and joint range of motion. Facility records were the preferred source for timeliness of device delivery and clinician follow-up. Respondents reported that gait speed and walking endurance were best obtained by patient performance.Conclusions: Results provide insight on the topics orthotists and physical therapists regard as priorities for defining healthcare quality for persons using custom ankle-foot orthoses and instruments for data collection.

Identifying Instruments to Assess Care Quality for Individuals With Custom Ankle Foot Orthoses: A Scoping Review.

OBJECTIVES: We conducted 2 complementary scoping reviews to identify instruments that assess the experience and outcomes of custom ankle-foot orthosis (AFO) care in individuals with neurologic and traumatic conditions and to determine to what extent they might be psychometrically sound for AFO users. A stakeholder advisory committee considered to what extent the identified and psychometrically sound instruments might be feasible for use in developing quality measures for custom AFO users. DATA SOURCES: Both scoping reviews were conducted using PubMed, the Cumulative Index to Nursing and Allied Health Literature, Embase, and Cochrane Systematic Reviews. The following were used for the first scoping review only: Cochrane Central Register of Controlled Trials and the Physiotherapy Evidence Database. STUDY SELECTION: The initial scoping review yielded 79 articles with 82 instruments, 16 of which were used in 4 or more studies. The second scoping review yielded 57 articles reporting psychometric properties. DATA EXTRACTION: Psychometric properties for populations who use AFOs were summarized for 15 of the 16 instruments. The advisory committee eliminated 2 insrtruments, noted overlap between 4 instruments in terms of the constructs measured, and suggested 6 potential contemporary substitutes. DATA SYNTHESIS: Most instruments assessed activity (specifically mobility) and pertained to the National Quality Forum domain of "Health-Related Quality of Life." The 10-meter walk test, 6-minute walk test, Berg Balance Scale, Timed Up and Go, and Rivermead Mobility Index were reported to have adequate reliability and validity, and were considered feasible for administration in a clinical setting. CONCLUSIONS: Complementary scoping reviews demonstrated that some instruments with reasonable psychometric properties are available that are feasible to use in developing quality measures for custom AFO care. However, experience of care instruments suitable for this population were not identified but are needed for a comprehensive evaluation of care quality for AFO users.

Wireless sensors for continuous, multimodal measurements at the skin interface with lower limb prostheses.

Precise form-fitting of prosthetic sockets is important for the comfort and well-being of persons with limb amputations. Capabilities for continuous monitoring of pressure and temperature at the skin-prosthesis interface can be valuable in the fitting process and in monitoring for the development of dangerous regions of increased pressure and temperature as limb volume changes during daily activities. Conventional pressure transducers and temperature sensors cannot provide comfortable, irritation-free measurements because of their relatively rigid construction and requirements for wired interfaces to external data acquisition hardware. Here, we introduce a millimeter-scale pressure sensor that adopts a soft, three-dimensional design that integrates into a thin, flexible battery-free, wireless platform with a built-in temperature sensor to allow operation in a noninvasive, imperceptible fashion directly at the skin-prosthesis interface. The sensor system mounts on the surface of the skin of the residual limb, in single or multiple locations of interest. A wireless reader module attached to the outside of the prosthetic socket wirelessly provides power to the sensor and wirelessly receives data from it, for continuous long-range transmission to a standard consumer electronic device such as a smartphone or tablet computer. Characterization of both the sensor and the system, together with theoretical analysis of the key responses, illustrates linear, accurate responses and the ability to address the entire range of relevant pressures and to capture skin temperature accurately, both in a continuous mode. Clinical application in two prosthesis users demonstrates the functionality and feasibility of this soft, wireless system.

Using mechanical testing to assess the effect of lower-limb prosthetic socket texturing on longitudinal suspension.

To function effectively, a lower limb prosthetic socket must remain securely coupled to the residual limb during walking, running and other activities of daily living; this coupling is referred to as suspension. When this coupling is insufficient longitudinal pistoning of the socket relative to the residual limb occurs. Increasing friction of the socket/liner interface may improve socket suspension and textured sockets may be fabricated relatively easily with 3D printing. The aim of this study was to investigate longitudinal displacement of sockets with different types of textures under two suspension conditions: passive suction and active vacuum. In order to do this, we developed a mock residual limb and mechanical testing protocol. Prosthetic sockets, 14 textured sockets and an Original Squirt-Shape (OSS) Socket, were fabricated from polypropylene copolymer using the Squirt-Shape™ 3D Printer and compared to a smooth socket thermoformed from polypropylene copolymer. Sockets were mounted onto a dual durometer mock residual limb and subjected to four levels of distraction forces (100 N, 250 N, 500 N and 650 N) using a hydraulic material testing system. There was a statistically significant three-way interaction between suspension, force level and texture (p < 0.0005). Longitudinal displacements between textured and reference sockets, for all force levels and both suspension conditions, were significantly different (p < 0.0005). Using these newly developed mechanical testing protocols, it was demonstrated that texturing of polypropylene copolymer sockets fabricated using Squirt-Shape significantly decreased longitudinal displacements compared to a smooth socket. However, none of the novel textured sockets significantly reduced longitudinal displacement compared to the OSS socket under passive suction suspension.