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Objective To evaluate test-retest reliability and related measurement properties of items developed to assess best, worst, and average prosthetic socket comfort. Design Methodological research to assess test-retest reliability of four individual socket comfort survey items. Socket comfort items were included in a self-report paper survey, which was administered to participants 2-3 days apart. Setting General community. Participants A minimum convenience sample of 63 participants was targeted for this study; 72 lower limb prosthesis users (>1-year post-amputation) completed the survey and were included in the final dataset. Interventions Not applicable. Main Outcome Measure The Expanded Socket Comfort Score (ESCS) was adapted from the original Socket Comfort Score (SCS). The original SCS is a single-item self-report instrument developed to assess a lower limb prosthesis user's current socket comfort. Three additional items were designed to assess the user's best, worst, and average socket comfort over the previous seven days. Results Best, worst, and average socket comfort items demonstrated better reliability, as indicated by higher intra-class correlation coefficients. As such, these items also exhibited lower measurement error and smaller minimal detectable change values than the item that measured current socket comfort. However, test-retest coefficients for all four items were below the level desired for evaluation of within-individual changes of socket comfort. Conclusions Items that assess best, worst, and average comfort provide a more stable measurement of socket fit than the existing SCS instrument. While administration of all four items may provide more comprehensive assessment of a lower limb prosthesis user's socket fit, administrators should expect variations in scores over time due to the variable nature of the underlying construct over time. Future research should examine whether a multi-item socket comfort scale provides an improved overall assessment of socket fit.

Management of socket fit is challenging for people using lower-limb prostheses because of residual limb volume fluctuation throughout the day. Releasing socket pressures during sitting (partial doffing) may help users increase their limb volume after they have undergone volume loss earlier in the day. The purpose of this research was to develop and evaluate a system to allow for quick and easy locking pin and socket panel release during sitting and relock upon standing. The system was to allow the partial doff tether length to be custom set for each user, accomplish release and relock in less than 2.0 s each, require only one hand, and require a finger push force comparable to a push button on a phone. A motor-driven release/relock system (240 g build weight) housed within the socket adjusts locking pin tether length, and an instrumented ratcheting dial adjusts socket panel position. Three participants with a trans-tibial amputation operated the system properly using one hand. For a partial doff, users preferred a tether length between 5 and 6 cm. All users executed release within 1.5 s and relock within 1.5 s.

Step activity monitors provide insight into the amount of physical activity prosthesis users conduct but not how they use their prosthesis. The purpose of this research was to help fill this void by developing and testing a technology to monitor bodily position and type of activity.Thin inductive distance sensors were adhered to the insides of sockets of a small group of transtibial prosthesis users, two at proximal locations and two at distal locations. An in-lab structured protocol and a semi-structured out-of-lab protocol were video recorded, and then participants wore the sensing system for up to 7 days. A data processing algorithm was developed to identify sit, seated shift, stand, standing weight-shift, walk, partial doff, and non-use. Sensed distance data from the structured and semi-structured protocols were compared against the video data to characterize accuracy. Bodily positions and activities during take-home testing were tabulated to characterize participants' use of the prosthesis.Sit and walk detection accuracies were above 95% for all four participants tested. Stand detection accuracy was above 90% for three participants and 62.5% for one participant. The reduced accuracy may have been due to limited stand data from that participant. Step count was not proportional to active use time (sum of stand, walk, and standing weight-shift times).Step count may provide an incomplete picture of prosthesis use. Larger studies should be pursued to investigate how bodily position and type of activity may facilitate clinical decision-making and improve the lives of people with lower limb amputation.

Background Small intermittent adjustments of socket size using adjustable sockets may be a means for people with transtibial amputation to better maintain residual limb fluid volume and limb position while using a prosthesis. Methods Socket size, limb fluid volume, and distance from the limb to the socket, termed “sensed distance,” were recorded while participants with transtibial amputation walked on a treadmill wearing a motor-driven, cabled-panel, adjustable socket. Researchers made frequent socket size adjustments using a mobile phone app to identify participants' acceptable socket size range. Limb fluid volume and sensed distance were then monitored as incremental adjustments were made to the socket. Findings Prosthesis users in this study (n = 10) accepted socket sizes between −5% and +5% of their neutral socket volume. There was a rapid increase in limb fluid volume and sensed distance upon socket enlargement, and a rapid decrease upon reduction. Subsequently, there were gradual changes in fluid volume and sensed distance. While visually monitoring limb fluid volume data in real time, researchers were able to adjust socket size to maintain consistent limb fluid volume within a −0.7% to +0.9% volume change for 24 min. Interpretation Participant residual limbs compensated to socket size adjustment. Using socket-mounted sensors to monitor limb-socket mechanics, an automatic adjustable socket that maintains limb fluid volume may be possible and may improve socket fit in instances where fit deteriorates during use.

People with lower limb amputation are unable to reliably sense ground characteristics due to compromised sensory inputs from the missing limb. As a result, they may rely on compensatory strategies, such as use of cognitive resources, when walking over complex surfaces. This study examined interactions between cognition and walking over a compliant surface in 14 people with transfemoral amputation (TFA) and 14 controls using a dual-task paradigm. Walking was assessed with quantitative motion analysis in both single-task (walking alone) and dual-task (walking while performing a cognitive task) conditions over a compliant foam surface. Outcomes were walking speed, step width, step time asymmetry, step time variability, and the speed and accuracy of cognitive task performance. For each outcome, effects of task (single-task, dual-task) and group (TFA, control) were examined with repeated-measures analysis of variance. No significant group-by-task interactions were observed for cognitive task performance. A significant group-by-task interaction for step time asymmetry indicated that participants with TFA increased temporal asymmetry in dual-task relative to single-task conditions, while control participants maintained symmetrical gait. The addition of a concurrent cognitive task did not differentially affect other aspects of gait between groups. Significant main effects of group for all walking outcomes indicated that participants with TFA walked slower, with wider, more asymmetric, and more variable steps than controls. Results suggest that gait quality degrades in challenging dual-task conditions for people with TFA, but not controls, consistent with the idea that people with TFA may use increased cognitive resources to control walking in complex environments.

To assess construct validity of the Prosthetic Limb Users Survey of Mobility (PLUS-M), a self-report mobility measure for people with lower limb amputation (LLA).Cross-sectional study.Private prosthetic clinics (n=37).Current lower limb prosthesis users (N=199; mean age ± SD, 55.4±14.3y; 71.4% men) were assessed before receiving a replacement prosthesis, prosthetic socket, and/or prosthetic knee.Not applicable.Convergent construct validity was examined using correlations between participants' PLUS-M T-scores and measures of physical function, mobility, and balance, including the Amputee Mobility Predictor (AMP), timed Up and Go (TUG), Patient-Reported Outcomes Measurement Information System-Physical Function (PROMIS-PF), Prosthesis Evaluation Questionnaire-Mobility Subscale (PEQ-MS), and Activities-specific Balance Confidence (ABC) Scale. Known-groups construct validity was evaluated by comparing differences in PLUS-M T-scores among participants grouped by Medicare Functional Classification Level (MFCL).PLUS-M T-scores demonstrated a moderate positive relationship with AMP scores (ρ=.54, P.001) and a moderate negative relationship with TUG times (ρ=-.56, P.001). The PLUS-M also showed a strong positive relationship with PEQ-MS scores (ρ=.78, P.001), ABC Scale scores (ρ=.81, P.001), and PROMIS-PF T-scores (ρ=.81, P.001). Significant differences (P.05) in PLUS-M T-scores were found among groups of people classified by different MFCLs.Study results support the validity of the PLUS-M as a self-report measure of prosthetic mobility. Correlations between PLUS-M and measures of physical function, mobility, and balance indicate convergent construct validity. Similarly, significant differences in PLUS-M T-scores across MFCL groups provide evidence of known-groups construct validity. In summary, evidence indicates that PLUS-M has good construct validity among people with LLA.

To investigate differences between self-reported cognitive concerns in people with lower limb loss (LLL) and normative data derived from the U.S. general population, and secondarily to determine whether there were cognitive differences based on amputation etiology or age.Survey.General community.A volunteer sample of persons with LLL (N=1086) resulting from trauma or dysvascular complications who regularly use a prosthetic limb.Not applicable.The Quality of Life in Neurological Disorders Applied Cognition-General Concerns Short Form version 1.0 (Neuro-QoL ACGC), an 8-item self-report measure of general cognitive concerns.People with LLL reported significantly more cognitive concerns than the Quality of Life in Neurological Disorders normative sample. Mean Neuro-QoL ACGC scores were significantly lower than normative values (P.001) across subgroups defined by age (ie,40, 40-49, 50-59, 60-69, and 70+ years) and subgroups defined by etiology (ie, traumatic and dysvascular LLL). However, there were no significant differences in cognitive concerns among age subgroups (P=.84) or between the etiology subgroups (P=.58).When compared with the Quality of Life in Neurological Disorders normative sample, individuals with LLL report greater concerns with cognitive health. Cognitive concerns were not differentially affected by age or cause of amputation. The presence of cognitive concerns in people with LLL suggests a need to assess perceived cognitive function in order to tailor education and training in prosthetic use and care.

Background Residual limb volume loss is a source of prosthetic socket fit problems in people with lower-limb amputation. The aim of this study was to investigate a novel volume recovery strategy for people with trans-tibial amputation. Methods Test sockets for people with trans-tibial amputation were created that allowed panels of an adjustable socket and the underlying elastomeric liner to be pulled radially outward, using small motors mounted to the socket. One Control and one Intervention session were conducted with each participant. During Intervention sessions, panel-pull was executed during the sits of a multi-cycle sit/walk protocol. No panel-pull was executed during the Control sessions. Residual limb fluid volume was monitored in anterior and posterior regions using bioimpedance analysis. Findings Results from 12 participants demonstrated that short-term (12 min after the intervention was applied) median posterior residual limb fluid volume change for Intervention (0.44%) was higher than that for Control (−0.02%) (P = .015). Long-term (40 min after the intervention was applied) median posterior residual limb fluid volume change for Intervention (0.95%) was higher than that for Control (−0.26%) (P = .002). Interpretation If a panel-pull mechanism that was easy to assemble and operate could be created, then panel-pull may be an effective accommodation strategy to reduce daily limb volume loss in trans-tibial prosthesis users.

OBJECTIVE: To evaluate the content, construct, and discriminant validity of the Narrowing Beam Walking Test (NBWT), a performance-based balance test for lower limb prosthesis users. DESIGN: Cross-sectional study. SETTING: Research laboratory and prosthetics clinic. PARTICIPANTS: Forty unilateral transtibial and transfemoral prosthesis users. INTERVENTION: Not applicable. MAIN OUTCOME MEASURE(S): Content validity was examined by quantifying the percentage of participants receiving maximum or minimum scores (i.e. ceiling and floor effects). Convergent construct validity was examined using correlations between participants’ NBWT scores and scores or times on existing clinical balance tests regularly administered to lower limb prosthesis users. Known-groups construct validity was examined by comparing NBWT scores between groups of participants with different fall histories, amputation levels, amputation etiologies, and functional levels. Discriminant validity was evaluated by analyzing the area under each test’s Receiver Operating Characteristic (ROC) curve. RESULTS: No minimum or maximum scores were recorded on the NBWT. NBWT scores demonstrated strong correlations (|r(s)|=.70‒.85) with scores/times on performance-based balance tests (Timed up and Go, Four Square Step Test, and Berg Balance Scale), and a moderate correlation (|r(s)|=.49) with the self-report Activities-specific Balance Confidence scale. NBWT performance was significantly lower among participants with a history of falls (p=.003), transfemoral amputation (p=.011), and a lower mobility level (p

Hafner BJ, Willingham LL, Buell NC, Allyn KJ, Smith DG. Evaluation of function, performance, and preference as transfemoral amputees transition from mechanical to microprocessor control of the prosthetic knee. Objective To evaluate differences in function, performance, and preference between mechanical and microprocessor prosthetic knee control technologies. Design A-B-A-B reversal design. Setting Home, community, and laboratory environments. Participants Twenty-one unilateral, transfemoral amputees. Intervention Mechanical control prosthetic knee versus microprocessor control prosthetic knee (Otto Bock C-Leg). Main Outcome Measures Stair rating, hill rating and time, obstacle course time, divided attention task accuracy and time, Amputee Mobility Predictor score, step activity, Prosthesis Evaluation Questionnaire score, Medical Outcomes Study 36-Item Short-Form Health Survey score, self-reported frequency of stumbles and falls, and self-reported concentration required for ambulation. Results Stair descent score, hill descent time, and hill sound-side step length showed significant ( P P P Conclusions The study population showed improved performance when negotiating stairs and hills, reduced frequency of stumbling and falling, and a preference for the microprocessor control C-Leg as compared with the mechanical control prosthetic knee.

The development and prescription of energy storage and return prosthetic feet in favor of conventional feet is largely based upon prosthetist and amputee experience. Regretfully, the comparative biomechanical analysis of energy storage and return and conventional prosthetic feet is rarely a motivation to either the technical development or clinical prescription of such devices. The development and prescription of prosthetic feet without supportive scientific evidence is likely due to the conflicting or non-significant results often presented in the scientific literature. Despite the sizeable history of comparative prosthetic literature and continued analysis of prosthetic components, the link between clinical experience and scientific evidence remains largely unexplored.A review of the comparative analysis literature evaluating energy storage and return and conventional prosthetic feet is presented to illustrate consistencies between the perceptive assessments and the objective biomechanical data. Results suggest that while experimental methodologies may limit the statistical significance of objective gait analysis results, consistent trends in temporal, kinetic, and kinematic parameters correlate well with perceptive impressions of these feet. These correlations provide insight to subtle changes in gait parameters that are deemed neither clinically nor statistically significant, yet are perceived by amputees to affect their preference for and performance of prosthetic feet during locomotion. Acknowledging and targeting areas of perceptive significance will help researchers develop more structured protocols for energy storage and return prosthesis evaluation as well as provide clinicians with information needed to enhance the appropriateness of their clinical recommendations. Expanding test environments to measure activities of perceived improvement such as high-velocity motions, stair ascent/descent, and uneven ground locomotion will provide a more appropriate assessment of the conditions for which energy storage and return prosthetic feet were designed. Concentrating research to specific test populations by age or amputation etiologies can overcome statistical limitations imposed by small study samples. Finally, directing research toward the areas of gait adaptation, heel performance, and the temporal release of energy in energy storage and return feet may reinforce the selection and utilization of advanced prosthetic components. These enhancements to current biomechanical analyses may serve to reduce the boundaries of perceptive significance and provide clinicians, designers, and researchers with the supportive data needed to prescribe, design, and evaluate energy storage and return prosthetic feet.