In non-impaired human locomotion, sagittal-plane slope adaptation of the foot-ankle complex is a volitional function driven by neuromotor control to support upright posture and forward ambulation. Loss of this adaptation due to transtibial amputation can lead to instability and compensatory motions as most commercially-available prosthetic feet do not permit automatic slope adjustments. A selection of slope-adaptive feet (SAF) have been developed to promote biomimetic ankle motion while ambulating over slopes. This review evaluated the current literature to assess the effects of SAF prostheses on sloped gait performance in unilateral transtibial prosthesis users. Four databases (PubMed, Embase, CINAHL, IEEE Xplore) were searched on April 28, 2022, for relevant articles. Search keywords covered the general terms "transtibial," "amputation," "slope," "adaptive," and "gait", and included articles comparing a SAF prosthesis to a non-SAF prosthesis condition. Data were extracted for analysis and results were grouped according to outcomes to identify trends and aid interpretation of slope adaptation effects on gait. Of the 672 articles screened, 24 met the selection criteria and were included in this review, published between 2009 and 2022. The non-SAF condition included dynamic response feet and SAF prostheses with the adaptability function inactive. Outcomes included biomechanical variables (joint dynamics, gait symmetry, toe clearance), clinical outcome measures, and energy expenditure. All SAF demonstrated some form of foot-ankle slope gradient adaptability, but effects on other joint dynamics were inconsistent. Minimum toe clearance during incline and decline walking was greater when using SAF compared to non-SAF in all reporting studies. Results generally suggest improvements in gait quality, comfort, and safety with use of SAF compared to non-SAF during slope walking. However, variations in tested SAF and walking gradients across studies highlight the need for research to elucidate walking condition effects and advantages of specific designs. Slope-adaptive prosthetic feet may improve user gait quality and comfort and enhance gait safety by increasing minimum toe clearance. Patients who encounter slopes regularly should be considered as potential users of SAF if indicated appropriately.
During aquatic therapy, without a prosthesis, individuals with lower-limb difference are limited in navigating stairs or ladders, performing gait training, balance, and strengthening exercises. A noncustom prosthesis for individuals with transtibial limb difference in aquatic therapy, consisting of interchangeable sockets and pylons, does not exist. Dilatancy has not been applied within a socket to provide an accommodative shape for multiple users. This study explores the development and usability of an adjustable prosthesis, utilizing dilatancy, for aquatic therapy. The design of this study is developmental. Participants underwent an informed written consent process (IRB STU00219525). Three individuals (1 male, 55 years; and 2 female, 47 and 22 years) with unilateral transtibial amputations were recruited. A set of interchangeable adjustable sockets and pylons were developed. Utilizing dilatant properties, small particles under vacuum were assessed for their ability to provide a rigid, lightweight, and remoldable pouch within the socket. Participants trialed the prosthesis during two fittings and three aquatic therapy sessions. Upon completion, participants and treating therapists completed the System Usability Scale. Survey results were converted to a 100-point scale. Time to don the prosthesis was recorded, and socket comfort scores at the final session were averaged. The System Usability Scale indicated that the prosthesis was usable for aquatic therapy. Participant scores were 97.5, 95, and 87.5, and therapist's scores were 92.5 and 85 of a total possible 100. Average socket comfort scores were 10, 9, and 7.6/10. Times to don the prosthesis were 5:45, 5:32, and 4:10 (minutes:seconds). This system functioned successfully as a noncustom prosthesis for multiple users in aquatic therapy from the participant and therapists' perspective. The novelty of this system is utilizing a prosthesis for multiple users, improving the rehabilitation capabilities during aquatic therapy.
Postural control and balance are necessary for activities of daily living. Passive prostheses that reduce ankle dorsiflexion/plantarflexion control can require different balance strategies compared with able-bodied individuals. Powered prostheses may restore ankle joint control and improve balance compared with passive prostheses. Muscle activity as the prosthetic control input leverages the human neural control system to directly modulate prosthetic dynamics. This study evaluates continuous myoelectric control during quiet standing tasks with an untethered electromechanically actuated bionic ankle prosthesis. Six individuals with transtibial amputation conducted four 30-second trials of quiet standing for four standing conditions (Eyes Open, Eyes Closed, Eyes Open Foam, and Eyes Closed Foam) using their passive, prescribed prosthesis and a bionic prosthesis under two types of myoelectric control. One strategy solely used residual gastrocnemius muscle as input (GAS), whereas the second used the gastrocnemius and tibialis anterior (GAS+TA). Postural stability was evaluated via Total Excursion, Body Sway Area, and Prediction Ellipse Area center of pressure measures from force plates. We hypothesized that the bionic prosthesis would improve balance control compared with the passive prosthesis. We also quantified weight bearing of prosthetic and sound limbs. Participants completed a preference/sense of stability survey between the prostheses. We found no significant differences in individual prostheses and controllers across our four standing conditions, or between prostheses and controllers for a single standing condition for all center of pressure measures. Participants tended to increase weight on their sound limb from Eyes Open to Eyes Closed Foam conditions. Participants trended toward preferring myoelectric control, but there were no significant differences among prostheses. Compared with a passive transtibial prosthesis, a myoelectrically controlled bionic prosthesis did not alter standing balance performance. Our study did not demonstrate differences between the myoelectrically controlled bionic transtibial prosthesis and the prescribed passive prosthesis in balance control. It is possible that other metrics would be necessary to increase sensitivity in comparisons.
The design and selection of lower-limb prosthetic devices is currently hampered by a shortage of evidence to drive the choice of prosthetic foot parameters. We propose a new approach wherein prostheses could be designed, specified, and provided based on individualized measurements of the benefits provided by candidate feet. In this manuscript, we present a pilot test of this evidence-based and personalized process. We previously developed a "prosthetic foot emulator," a wearable robotic system that provides users with the physical sensation of trying on different prosthetic feet before definitive fitting. Here we detail preliminary demonstrations of two possible approaches to personalizing foot design: 1) an emulation and test-drive strategy of representative commercial foot models, and 2) a prosthetist-driven tuning procedure to optimize foot parameters. The first experiment demonstrated large and sometimes surprising differences in optimal prosthetic foot parameters across a variety of subjects, walking conditions, and outcome measures. The second experiment demonstrated a quick and effective simple manual tuning procedure for identifying preferred prosthetic foot parameters. Emulator-based approaches could improve individualization of prosthetic foot prescription. The present results motivate future clinical studies of the validity, efficacy, and economics of the approach across larger and more diverse subject populations. Today, emulator technology is being used to accelerate research and development of novel prosthetic and orthotic devices. In the future, after further refinement and validation, this technology could benefit clinical practice by providing a means for rapid test-driving and optimal selection of clinically available prosthetic feet.
Ankle osteoarthritis (AOA) is a progressive condition that impairs mobility and reduces quality of life. Conservative treatments like rocker bottom (RB) shoes and ankle-foot orthoses (AFOs) are commonly prescribed, but their effectiveness in managing AOA is not well understood, and patient preferences are underexplored. This is a pilot study aimed to evaluate the effect of RB shoes and AFOs in managing AOA and to identify factors influencing patient preferences for these conservative treatments. This was a cross-over telehealth study involving 10 participants with doctor-diagnosed AOA. Each participant wore three footwear conditions: control shoes, RB shoes, and AFOs, each for 3 weeks. Participants completed baseline pain ratings and functional assessments using PROMIS and FAAM questionnaires. After each 3-week footwear session, participants reported pain levels and provided feedback on their preferred footwear. Younger participants (aged 56-63) preferred AFOs for pain relief and improved mobility, while older (aged 66-75) and taller participants preferred RB shoes for their comfort. No significant differences were found in pain or function across footwear conditions, but AFO-preferred participants experienced significant reductions in maximum pain compared to the RB group. Footwear preferences were influenced by age and activity level. Younger participants preferred AFOs for functional benefits, while older participants prioritized comfort and selected RB shoes. These findings emphasize the need for personalized conservative treatment strategies in managing AOA. This pilot study highlights the importance of tailoring conservative treatments for AOA based on age and activity level. Understanding patient preferences can help guide clinical decisions and improve patient outcomes.
Women with lower limb loss represent a relevant and growing patient cohort with unique rehabilitation needs. These needs are emphasized in a growing body of literature and the most recent Veteran Affairs/Department of Defense clinical practice guidelines. Women with limb loss experience greater dissatisfaction with prosthetic fit, appearance, and types of footwear they can use. There is a lack of prosthetics solutions to accommodate the desire of women to wear different footwear varieties, including high heels. The choice to wear a variety of footwear is important to attire and hence community participation. Despite these recognized challenges, women are still underserved in prosthetics research, which limits available information to guide the rehabilitation process. This narrative review describes considerations of lower limb prosthesis prescription and use by women, and examples of current research to address these topics. Research efforts are beginning to explore factors that contribute to prosthetics prescription for women, and design creative prosthetics solutions to expand the range of available footwear options. Research is still needed to characterize the types of footwear women with limb loss prefer to use, and the effects of prosthesis designs, footwear, and lower limb loss on women mobility outcomes and community participation. Through targeted research initiatives, scientists and clinicians can be responsive to the specific needs of women to provide evidence-based guidelines for prosthetics prescription and improve the patient-centered care after limb loss.
The aim of this study was to establish the mobility, satisfaction, and quality of life (QoL) among prosthesis users with dysvascular/diabetic amputation at both acute and long-term phases of prosthetic rehabilitation. This is a multisite, cross-sectional outcomes analysis. A total of 341 individuals met the inclusion/exclusion criteria. Individuals were grouped into acute phases (0-3 months [n = 24], 4-6 months [n = 72]) and chronic phases (24-36 months [n = 91], 37-48 months [n = 53], 49-60 months [n = 47], and 60-84 months [n = 54]) after amputation. Mobility was measured with the Prosthetic Limb Users Survey of Mobility (PLUS-M), whereas QoL and satisfaction (Sat) were reported using 10-point scales adapted from the Prosthesis Evaluation Questionnaire-Well-Being (PEQ-WB). Composite PEQ-WB scores were also compared. The average mobility, QoL, and Sat among prosthesis users was, respectively, 44.8 ± 10.6, 7.6 ± 2.2, and 7.6 ± 2.2. There were no observed differences in mobility (F 5,330 = 1.52, P = 0.18), QoL (F 5,333 = 0.78, P = 0.57), or PEQ-WB (F 5,335 = 1.618, P = 0.155) between any groups. For Sat, there was a group difference (F 5,334 = 2.44, P = 0.03) as individuals appear to experience an initial increase in Sat with receipt of a prosthesis (0-3 months) compared with 25 to 36 months (P = 0.005), 49 to 60 months (P = 0.008), and 61 to 84 months (P = 0.009). Those individuals with amputation secondary to dysvascular disease and diabetes who continue to participate in prosthetic rehabilitation appear to experience levels of mobility, Sat, and QoL 7 years after amputation comparable to that reported in the first 6 months postamputation. There may be a modest increase in Sat with receipt of an initial prosthesis, potentially due to an increased optimism for one's situation. Notably, the mobility levels observed in the dysvascular population through a range of long-term postamputation periods remain within a single standard deviation of the population mean for individuals with a lower-limb amputation using a prosthesis for mobility.
Intentional interruption of upper and lower limb coordination of able-bodied subjects alters their gait biomechanics. However, the effect of upper-limb loss (ULL) on lower-limb gait biomechanics is not fully understood. The aim of this secondary study was to perform a follow-up analysis of a previous dataset to characterize the spatiotemporal parameters and lower-limb kinematics and kinetics of gait for persons with ULL when wearing and not wearing an upper limb prosthesis (ULP). We were particularly interested in quantifying the effects of matching the mass and inertia of the prosthetic limb to the sound limb. Ten persons with unilateral ULL walked at a self-selected speed under three randomly presented conditions: 1) not wearing a prosthesis, 2) wearing their customary prosthesis, and 3) wearing a mock prosthesis that can be adjusted to match the length, mass, and inertial properties of each subject's sound limb. Walkway-embedded force plates and a 12-camera digital motion capture system recorded ground reaction forces (GRFs) and retroreflective marker position data, respectively. Average spatiotemporal (walking speed, cadence, stance time, swing time, step length, double support time), lower-limb kinematic (joint angles), and lower-limb kinetic (ground forces, joint moments and powers) data were processed and their statistical significance were analyzed. Walking speed for each condition was nearly equivalent (1.20±0.01 m/s) and differences between condition were non-significant (p=0.769). The interaction effect (side× prosthesis) was significant for peak hip extension (p=0.01) and second peak (propulsive) vertical GRF (p=0.028), but separate follow-up analyses of both main effects were not significant (p≥0.099). All other main effect comparisons were not significant (p≥0.102). Although the sample cohort was small and heterogeneous, the results of this study suggest that persons with unilateral ULL did not display significant limb side asymmetry in lower-limb gait spatiotemporal, kinetic, and kinematic parameters, regardless of ULP use.
The development of multiarticulating hands holds the potential to restore lost function for upper-limb amputees. However, access to the full potential of commercialized devices is limited due to conventional control strategies for switching prosthesis modes, such as hand grips. For example, to switch grips in one conventional strategy, the prosthesis user must generate electromyogram (EMG) triggers (such as a cocontraction), which are cumbersome and nonintuitive. For this reason, alternative control strategies have emerged, which seek to facilitate grip switching. One specific application uses radio frequency identification (RFID) tags programmed with grip information. These tags can be placed on objects in the environment or carried on person. Upon approaching an RFID tag, the user's prosthesis reads the grip programmed on the tag and commands the hand into that grip. The purpose of this study was to compare the conventional strategy (using EMG triggers) with the alternative strategy (using RFID tags). The study evaluated three subjects: two users who actively use multiarticulating hands ("experienced" users) and one user who had never worn a multiarticulating hand ("new" user). Subjects were evaluated on two performance metrics: trigger completion time and the percentage of triggers that were successful on first attempt (first attempt success rate). Subjects also rated the difficulty, effort, and frustration with each strategy. Results suggested faster trigger completion times with the EMG strategy for the experienced users and mixed results for the new user. Overall, the three subjects rated the RFID strategy as less difficult, tiring, and frustrating than the EMG strategy. Continued studies with a larger subject pool are necessary to determine factors influencing performance and patient preference. This would allow identification of best strategies to access the full potential of new commercial devices. Still, the authors suggest that the synergistic use of both strategies can yield great benefits for both experienced and new multiarticulating hand users.
Mobility tests are increasingly used in prosthetic rehabilitation to evaluate patient outcomes. Knowledge of the space, equipment, and time resources available to clinicians who work in different settings can guide recommendations for which tests are most clinically-feasible and promote coordination of mobility testing among members of the rehabilitation team. The primary aim of this study was to characterize the different resources available to clinicians for measuring mobility of people with lower limb amputation. A secondary aim was to identify performance tasks that clinicians use to evaluate prosthetic mobility. Semi-structured interviews were conducted with prosthetists, physical therapists, and physiatrists who treat people with lower limb amputation. Researchers used convenience and snowball sampling to identify participants. Interviews included questions about the resources available for conducting mobility tests, as well as questions about which tasks clinicians deemed valuable to assessing mobility of patients with lower limb amputation. Interviews were audio-recorded and transcribed. Summary and frequency statistics were calculated for quantitative data; explanatory comments were summarized. Interviews were conducted with 25 clinicians (8 prosthetists, 9 physical therapists, and 8 physiatrists). Participants had access to multiple spaces and basic measurement equipment. The maximum time participants were willing to spend on performance tests varied. Physiatrists reported less time available (median=10 minutes, range 5-30 minutes) than prosthetists and physical therapists (median=30 minutes, range 5-60 minutes for both professions). Mobility tasks commonly used to evaluate patients with lower limb amputation included sit-to-stand, standing balance, walking, and varying speed. Participant comments suggested that mobility tests need to be quick, simple, and add value; existing mobility tests are beneficial but challenging to incorporate into practice; mobility tests should reflect real-world activities; and technological advancements could improve mobility testing. Clinicians generally had small-to-medium spaces, basic measurement equipment, and sufficient training to administer mobility tests in their clinics. A limiting factor was time, which can be addressed through selection of efficient measures and collaboration within the rehabilitation team.
Lower-limb prosthesis users (LLPUs) experience increased fall risk due to gait and balance impairments. Clinical outcome measures are useful for measuring balance impairment and fall risk screening but suffer from limited resolution and ceiling effects. Recent advances in wearable sensors that can measure different components of gait stability may address these limitations. This study assessed feasibility and construct validity of a wearable sensor system (APDM Mobility Lab) to measure postural control and gait stability. Lower-limb prosthesis users (n=22) and able-bodied controls (n=24) completed an Instrumented Stand-and-Walk Test (ISAW) while wearing the wearable sensors. Known-groups analysis (prosthesis versus controls) and convergence analysis (Prosthetic Limb Users Survey of Mobility [PLUS-M] and Activity-specific Balance Confidence [ABC] Scale) were performed on 20 stability-related measures. The system was applied without complications; however missing anticipatory postural adjustment data points for nine subjects affected the analysis. Of the 20 analyzed measures output by the sensors, only three significantly differed (p≤.05) between cohorts, and two demonstrated statistically significant correlations with the self-report measures. The results of this study suggest the clinical feasibility but only partial construct validity of the wearable sensor system in conjunction with the ISAW test to measure LLPU stability and balance. The sample consisted of high-functioning LLPUs, so further research should evaluate a more representative sample with additional outcome measures and tasks.
The current method for fabricating prosthetic sockets is to modify a positive mold to account for the non-homogeneity of the residual limb to tolerate load (i.e., rectified socket). We tested unrectified sockets by retaining the shape of the residual limb, except for a distal end pad, using an alginate gel process instead of casting. This investigation compared rectified and unrectified sockets. Forty-three adults with unilateral transtibial amputations were tested after randomly wearing both rectified and unrectified sockets for at least 4 weeks. Testing included a gait analysis, energy expenditure and Prosthesis Evaluation Questionnaire (PEQ). Results indicated no differences between sockets for gait speed and timing, gait kinematics and kinetics, and gait energy expenditure. There were also no differences in the Prosthetic Evaluation Questionnaire and 16 subjects selected the rectified socket, 25 selected the unrectified socket, and 2 subjects selected to use both sockets as their exit socket. Results seemed to indicate that more than one paradigm exists for shaping prosthetic sockets, and this paradigm may be helpful in understanding the mechanisms of socket fit. The alginate gel fabrication method was simpler than the traditional method. The method could be helpful in other countries where prosthetic care is lacking, may be helpful with new amputees, and may be helpful in typical clinics to reduce costs and free the prosthetist to focus more time on patient needs.
Custom accommodative insoles have become the gold standard for managing plantar pressures and reducing ulceration risk in persons with diabetes. With advances in 3D printing technologies, methods of fabricating 3D printed accommodative insoles have emerged. Clinician feedback is imperative to developing a 3D printed accommodative insole that meets clinical needs and is more effective than the current standard of care. To inform the development of 3D printed accommodative insoles by gaining clinician perspective on insole requirements and application of the digital workflow for seamless translation into the clinical setting. Qualitative study. Four focus groups with a total of 16 Orthotists were held, prompting discussions on the current standard of care accommodative insole and other 3D printed insoles we have developed. Sessions were recorded, transcribed, and main themes were derived from transcriptions. Review and analysis of the transcripts resulted in four main themes: 1) Reimbursement, 2) Durability, 3) Effectiveness, and 4) Workflow application in clinic. The responses showed areas to focus improvements on the 3D printed insole design and ways to ease the transition into a clinical setting. Clinician support is crucial in the adoption of a new device to clinical practice. Their feedback is essential to ensuring the item meets the clinical needs and the workflow is not disruptive to the clinical setting. Understanding clinician perspective on current SoC disadvantages and shortcomings, areas for improvement in the 3D printed insole fabrication, and what is feasible in clinic appointments will help inform insole design and aid in translating new 3D-printing technology to clinical care for improved patient outcomes.
The January 12, 2010 earthquake devastated Port-Au-Prince, the capital of the Republic of Haiti, and its surroundings. Among the 300,000 injured, 1,200 to 1,500 people underwent traumatic /surgical amputations. The purpose of this study was to describe the functional and psychosocial impact of prostheses users who suffered a traumatic lower-limb amputation after the earthquake of 2010 in Haiti. We recruited 140 participants in collaboration with a large health care organization in Port-au-Prince from October 2011 to May 2012. Participants underwent an evaluation of physical impairments and completed questionnaires translated into Haitian Creole. The Trinity Amputation and Prosthesis Experience Scale (TAPES), and the Locomotor Capabilities Index (LCI) were used in this study. The questionnaires were administered verbally in Haitian Creole by a trained staff. We conducted descriptive statistics and t-tests using SPSS for data analysis. Participants had a mean age of 34.9 ± 12.0; 51.4% were women; 48.6% were transfemoral amputees. The mean of TAPES general adjustment (3.65 ± 0.59) and adjust to limitation (3.67 ± 0.86) were higher than the score for the social adjustment (2.58 ± 0.49). The LCI showed over 90% of subjects were physically independent in self-care; fewer were independent walking on uneven ground or inclement weather (69%). The relatively poor social adjustment is consistent with the literature that describes limited acceptance of people with physical disabilities in Haitian society. Prostheses users in Haiti would benefit from a health delivery infrastructure that also addresses the psychosocial reintegration of individuals with physical disabilities.
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. 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. 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/°. 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.
Prosthetists have limited knowledge of their patients' use of a prosthesis outside of the clinical environment. Prosthesis-mounted monitors can be used to directly measure patients' prosthesis use and activity. Prosthetists' opinions regarding potential clinical applications for sensor-based information may inform further development of this technology. A pilot study was conducted to assess prosthetists' perceptions of prosthesis use and activity information obtained by a monitoring system. Three local prosthetists were recruited to participate in the study. One patient with transtibial amputation from each prosthetist volunteered to wear limb presence and activity monitors for two weeks. Collected data were used to determine prosthesis use and activity. Each prosthetist completed a survey, examined clinical reports of their patient's prosthesis use and activity, and participated in a semi-structured interview. Survey results and interview transcripts were analyzed to identify and compare prosthetists' perceptions. Prosthesis use and activity varied among patients. Prosthetists over- and under-estimated patient activity, relative to measurements recorded by the monitors. All three prosthetists selected multiple clinical applications for the prosthesis use and activity information in the survey, and several additional applications were suggested during the interviews. When presented with multiple report formats, prosthetists found features of each to be clinically useful. Prosthesis-mounted monitors may provide prosthetists with a better understanding of their patients' prosthesis use and activity. Information provided by the monitoring system may inform clinical decisions and promote evidence-based practices.
Individuals with a loss of sensation in the lower limbs frequently experience postural instability, altered gait patterns, and an increased risk of falling culminating in a decreased quality of life. Previous studies have documented that using ankle-foot orthoses (AFOs) help such individuals to maintain their balance. This study was conducted to investigate whether somatosensory cues delivered to the intact tissues of the lower limbs above the ankle joints enhance the control of posture in individuals with peripheral neuropathy. The study involved 12 individuals with sensory neuropathy because of diabetes who participated in static and dynamic balance tests with and without specially designed AFOs that provided auxiliary sensory cues to the lower limbs without stabilizing the ankle joints. During the tests, the subjects were required to alternately stand on a fixed and moving platform with their eyes alternately open or closed. Equilibrium scores and response latencies were obtained. The results showed that equilibrium scores were significantly higher in experiments with the specially modified AFOs compared with conditions without AFOs. Smaller latency scores were recorded in conditions with AFOs as well. The outcome indicates that AFOs that substitute for the lack of proprioceptive feedback may improve automatic postural responses in individuals with diabetic peripheral neuropathy. It also highlights the need for further research focused on the design of assistive means that could improve the balance and the performance of activities of daily living in individuals with proprioceptive deficits.
Mechanically induced skin breakdown is a significant problem for many lower-limb prosthesis users. It is known that skin can adapt to the mechanical stresses of prosthesis use thereby reducing the risk of breakdown, yet little is understood about the biology behind skin adaptation. This is a proof-of-concept study for the use of novel, noninvasive optical coherence tomography (OCT) imaging techniques to investigate skin adaptation. Two OCT imaging-based tests were used to evaluate features of the skin that may be involved in adaptation to limb-socket interface stresses. The tests were used to assess the function and structure of the cutaneous microvasculature, respectively. Epidermal thickness was also quantified. Tests were run on three lower-limb prosthesis users in a region of the residual limb believed to be highly stressed within the prosthetic socket. The measurements were compared with measurements taken at a location-matched site on the contralateral limb. Two of three participants demonstrated a faster time-to-peak and larger peakmagnitude reactive hyperemia response in their residual limb compared with their contralateral limb. Two of three participants also demonstrated a larger magnitude vessel density at maximum dilation in their residual limb versus contralateral limb. The epidermal thickness was greater in the residual limb versus contralateral limb for all participants. This study demonstrated the utility of two novel OCT imaging techniques for investigating skin adaptation in users of lower-limb prostheses. If we are able to confirm these findings on a larger subject population, we will better understand the biology behind mechanically induced skin adaptation. These findings, along with the noninvasive OCT imaging methods introduced here, would have the potential to improve clinical practice by enabling the development of rehabilitation techniques and therapeutics to better strengthen skin, thereby reducing the incidence of harmful skin breakdown.
The performance of pattern recognition based myoelectric control has seen significant interest in the research community for many years. Due to a recent surge in the development of dexterous prosthetic devices, determining the clinical viability of multifunction myoelectric control has become paramount. Several factors contribute to differences between offline classification accuracy and clinical usability, but the overriding theme is that the variability of the elicited patterns increases greatly during functional use. Proportional control has been shown to greatly improve the usability of conventional myoelectric control systems. Typically, a measure of the amplitude of the electromyogram (a rectified and smoothed version) is used to dictate the velocity of control of a device. The discriminatory power of myoelectric pattern classifiers, however, is also largely based on amplitude features of the electromyogram. This work presents an introductory look at the effect of contraction strength and proportional control on pattern recognition based control. These effects are investigated using typical pattern recognition data collection methods as well as a real-time position tracking test. Training with dynamically force varying contractions and appropriate gain selection is shown to significantly improve (p<0.001) the classifier's performance and tolerance to proportional control.
A lower-limb prosthesis is the mechanical device with which an amputee's residual limb interacts with the walking surface. The pressure and shear forces that affect the residuum due to prosthesis use are the sources of pain, residual-limb skin problems and gait deviations. Direct approaches to reducing these problems include improving fit, alignment technique and socket design as well as increasing cushioning with socket liners. A summary of typical malalignments and their consequences is presented. The malalignments are considered sources of excessive moments applied to the residuum, which simplifies the analysis of a patient's gait. A better design of prosthetic joints could improve prosthetic gait. This article addresses the key mechanical parameter of prosthetic joints, namely the dependence "moment of resistance/angle of deflection." A mathematical model has been developed that links stresses on the residuum in transtibial amputees with the moment of resistance in the prosthetic ankle at the critical gait phases. Analysis of the model yields a substantial decrease in stresses on the residuum during the most demanding, load-bearing phase of stance if the moment of resistance in the ankle is similar to that seen in the biological ankle joint. Gait study shows use of the experimental rolling-joint prosthetic foot more closely simulates normal gait synergy than the SACH foot.