User perspectives of digital manufacturing for lower-limb prosthetic sockets.

BACKGROUND: There is growing interest to use digital technology (DT) for manufacturing lower-limb prosthetic sockets to improve efficiency and clinical outcomes. However, little is known about how lower-limb prosthesis users perceive DTs, such as 3D scanning and 3D printing. OBJECTIVES: This study aimed to provide an understanding of perceptions and experiences with DT for prosthetic socket manufacturing from the perspective of prosthesis users. STUDY DESIGN: A qualitative descriptive research study. METHODS: Nine lower-limb prosthesis users (mean age 56; 5 female; 4 male) participated in one-on-one semistructured telephone interviews. Inductive thematic analysis was performed to identify a codebook and emerging themes from the interview transcripts. RESULTS: Two major themes were identified: (1) expectations and prioritization of 3D printed socket usability and (2) facilitators and barriers to uptake of DT among patients. CONCLUSION: DT methods were found to be acceptable and feasible from a patient perspective, although technological advancements are still required, and real-time communication about the process may be vital for ensuring patient engagement. Consideration of these findings may improve patient satisfaction to emerging prosthesis treatment plans and ultimately support widespread adoption of DT as an additional tool for fabricating prosthetic sockets.

Business practices efficiency: Impact of integrating digital technology on clinical P&O practices.

Additive manufacturing (AM) is on the path to transforming the approach to Prosthetics and Orthotics (P&O) manufacturing. Although digitalization of limbs and other body parts is not new to the field, it has not been widely accepted by the industry for various reasons. However, the reliability and precision that AM can attain, and the availability of various materials is improving rapidly. This professional opinion article discusses the ways that AM has changed P&O services, with a specific focus on prosthetic socket manufacturing. Digitalizing P&O services will eventually change the business model used in clinics, which is further explored here.

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

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

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

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

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

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

A New Modeling Method to Characterize the Stance Control Function of Prosthetic Knee Joints.

OBJECTIVE: Biomechanical models can inform design and optimization of prosthetic devices by connecting empirically derived biomechanical data to device design parameters. A new method is presented to characterize the function of prosthetic stance control under mobility conditions associated with activities of daily living. The method is based on a model of the gait modes corresponding to finite stance control states. METHODS: Empirical data from amputee and simulated gait were acquired using a custom-built wearable instrument and input into the model. RESULTS: The modeling approach was shown to be robust, responsive, and capable of accurate characterization of controller function under diverse locomotor and prosthetic setup conditions. CONCLUSION: Future work is focused on the development of a fully self-contained wearable system, to facilitate collection of large datasets across a variety of user demographics, controller designs, and activities of daily living. SIGNIFICANCE: The method offers predictive capability, which can assist in the virtual testing of new designs or modifications.

Walking and balance in children and adolescents with lower-limb amputation: A review of literature.

BACKGROUND: Children with lower limb loss face gait and balance limitations. Prosthetic rehabilitation is thus aimed at improving functional capacity and mobility throughout the developmental phases of the child amputee. This review of literature was conducted to determine the characteristics of prosthetic gait and balance among children and adolescents with lower-limb amputation or other limb loss. METHODS: Both qualitative and quantitative studies were included in this review and data were organized by amputation etiology, age range and level of amputation. FINDINGS: The findings indicated that the structural differences between children with lower-limb amputations and typically developing children lead to functional differences. Significant differences with respect to typically developing children were found in spatiotemporal, kinematic, and kinematic parameters and ground-reaction forces. Children with transtibial amputation place significantly larger load on their intact leg compared to the prosthetic leg during balance tasks. In more complex dynamic balance tests, they generally score lower than their typically developing peers. INTERPRETATION: There is limited literature pertaining to improving physical therapy protocols, especially for different age groups, targeting gait and balance enhancements. Understanding gait and balance patterns of children with lower-limb amputation will benefit the design of prosthetic components and mobility rehabilitation protocols that improve long-term outcomes through adulthood.

Clinical evaluation of a prosthetic suspension system: Looped silicone liner.

OBJECTIVES: This study aimed to evaluate and compare a newly designed suspension system with a common suspension in the market. STUDY DESIGN: Prospective study. METHODS: Looped liners with hook fastener and Iceross Dermo Liner with pin/lock system were mechanically tested using a tensile testing machine in terms of system safety. A total of 10 transtibial amputees participated in this study and were asked to use these two different suspension systems. The pistoning was measured between the liner and socket through a photographic method. Three static axial loading conditions were implemented, namely, 30, 60, and 90 N. Furthermore, subjective feedback was obtained. RESULTS: Tensile test results showed that both systems could safely tolerate the load applied to the prosthesis during ambulation. Clinical evaluation confirmed extremely low pistoning in both systems (i.e. less than 0.4 cm after adding 90 N traction load to the prosthesis). Subjective feedback also showed satisfaction with both systems. However, less traction at the end of the residual limb was reported while looped liner was used. CONCLUSION: The looped liner with hook fastener is safe and a good alternative for individuals with transtibial amputation as this system could solve some problems with the current systems. Clinical relevance The looped liner and hook fastener were shown to be good alternative suspension for people with lower limb amputation especially those who have difficulty to use and align the pin/lock systems. This system could safely tolerate centrifugal forces applied to the prosthesis during normal and fast walking.

Prosthesis donning and doffing questionnaire: Development and validation.

OBJECTIVES: To develop a questionnaire that specifically evaluates the ability of trans-tibial amputees to don and doff a prosthesis and to investigate the psychometric properties of the newly developed questionnaire. BACKGROUND: Prosthesis should be donned and doffed few times during the day and night; thus, it is important to measure ease of donning and doffing. STUDY DESIGN: A cross-sectional study. METHODS: The questionnaire was designed and evaluated by a group of experts. The final questionnaire was administered to 50 individuals with trans-tibial amputation. A test-retest study was also conducted on 20 amputees to assess the repeatability of questionnaire items. RESULTS: The prosthesis donning and doffing questionnaire was developed and tested through a pilot study. Based on Kappa index, the questionnaire items showed correlation coefficients greater than 0.7, which indicate good reliability and repeatability. The majority of the participants had good hand dexterity (80%) and could perform all types of grasps. The mean satisfaction scores with donning and doffing were 69.9 and 81.4, respectively. Most of the respondents needed to don and doff the prosthesis 3.44 times per day. Based on a 7-point score, the total scores ranged between 3 and 7. CONCLUSION: The prosthesis donning and doffing questionnaire items showed good psychometric properties. A scoring method was suggested based on the pilot sample, which requires further evaluation to be able to differentiate between more suspension types. A larger international multicenter evaluation is required in the future to measure the responsiveness of the scales. This questionnaire will be useful in the evaluation of the ability of amputees to don and doff a trans-tibial limb prosthesis. Clinical relevance Donning and doffing of prostheses are challenging tasks for many lower limb amputees. The prosthesis donning and doffing questionnaire, on its own or combined with other prosthetic evaluation questionnaires, has the potential to help manufacturers, clinicians, and researchers gain knowledge and improve the donning and doffing qualities of prostheses.

The effect of damping in prosthetic ankle and knee joints on the biomechanical outcomes: A literature review.

BACKGROUND: Given the growing number of variable-damping prosthetic knee and ankle components and broad number of potential biomechanical outcomes, a systematic review is needed to assess advantages of damped knee and ankle units over non-damped prostheses. OBJECTIVES: This study provides an overview of the biomechanical outcomes associated with the use of prosthetic knees and ankles with damping mechanisms in individuals with lower limb amputation. STUDY DESIGN: Literature review. METHODS: A systematic search was performed through PubMed, Science Direct, Web of Science, Cochrane, and Scopus databases from June 1994 to March 2016. The level of evidence of each article was assessed using a 13-element checklist for evaluating non-randomized controlled trials for quality assessment. Afterward, the studies were classified as A-level, B-level, or C-level based on total score and positive scores from certain key categories. RESULTS: In total, 22 papers remained for the quality assessment based on the inclusion criteria. In total, 15 studies scored sufficiently high quality scores to be classified. One article scored as A-level, eight as B-level, and six as C-level. In total, 10 studied knees and 5 examined ankles. Sample sizes ranged from 5 to 28 subjects. CONCLUSION: Available studies were evaluated in detail and biomechanical outcomes were extracted from the studies that met criteria. Results of this review indicate that study methodology and outcome measures were heterogeneous across reviewed papers. This could be an explanation for inconsistent findings of the reviewed studies. Only self-selected gait speed showed a consistent difference when dampers were applied to the leg. Thus, further research is required in this area. Clinical relevance This study provides an overview of evidence related to prosthetic knee and foot/ankle components with damping attachments. Research related to biomechanical outcomes is of great importance for researchers and practitioners in this area. The studies drew mixed conclusions, but walking speed was consistently different for damped versus non-damped components.

A comparison of pressure distributions between two types of sockets in a bulbous stump.

BACKGROUND: This article describes a total surface bearing prosthetic socket for a patient (25-year-old female) with a bulbous stump. CASE DESCRIPTION AND METHODS: The subject had unstable excessive soft tissue at the distal end of the residuum. After 2 years of prosthetic use, she experienced several problems, including pain in the residual limb and knee joint. Pressure distribution was evaluated during ambulation. We also designed a total surface bearing socket with Velcro as suspension system to distribute the load evenly on the residual limb, and to facilitate donning procedure. FINDINGS AND OUTCOMES: The main site of weight bearing in the old prosthesis (patellar tendon bearing) was anterior proximal region of the residual limb, especially the patellar tendon. The pressure was almost 10 times higher than the distal region during level walking. Pressures were distributed more evenly with the total surface bearing socket design, and the donning was much easier. CONCLUSION: Pressure distribution within the socket could be affected by socket design and suspension system. Using the total surface bearing socket and Velcro as suspension system might facilitate donning of prosthesis and reduce traction at the end of residual limb during the swing phase of gait. CLINICAL RELEVANCE: Proper socket design and suspension system based on the amputees' need can facilitate rehabilitation process and lead to the amputee's satisfaction. The pressure is distributed more uniformly over the residual limb by the total surface bearing socket compared to the patellar tendon bearing socket for lower limb amputees with unusual stump shape.

Interface stress in socket/residual limb with transtibial prosthetic suspension systems during locomotion on slopes and stairs.

OBJECTIVE: This study aimed to compare the effects of different suspension methods on the interface stress inside the prosthetic sockets of transtibial amputees when negotiating ramps and stairs. DESIGN: Three transtibial prostheses, with a pin/lock system, a Seal-In system, and a magnetic suspension system, were created for the participants in a prospective study. Interface stress was measured as the peak pressure by using the F-socket transducers during stairs and ramp negotiation. RESULTS: Twelve individuals with transtibial amputation managed to complete the experiments. During the stair ascent and descent, the greatest peak pressure was observed in the prosthesis with the Seal-In system. The magnetic prosthetic suspension system caused significantly different peak pressure at the anterior proximal region compared with the pin/lock (P = 0.022) and Seal-In (P = 0.001) during the stair ascent. It was also observed during the stair descent and ramp negotiation. CONCLUSIONS: The prostheses exhibited varying pressure profiles during the stair and ramp ascent. The prostheses with the pin/lock and magnetic suspension systems exhibited lower peak pressures compared with the Seal-In system. The intrasystem pressure distribution at the anterior and posterior regions of the residual limb was fairly homogenous during the stair and ramp ascent and descent. Nevertheless, the intrasystem pressure mapping revealed a significant difference among the suspension types, particularly at the anterior and posterior sensor sites.

Clinical implication of interface pressure for a new prosthetic suspension system.

BACKGROUND: Prosthesis suspension systems can alter the distribution of pressure within the prosthetic socket. This study evaluates a new suspension system for lower limb prostheses, and aims to compare the interface pressure and amputees' satisfaction with the new system compared with a common prosthetic suspension system (pin/lock). METHODS: Ten transtibial amputees walked at a self-selected speed on a level ground with two different suspension systems, namely the pin/lock and HOLO system. The interface pressure was measured using the F-socket transducers at the proximal, middle and distal sites of residual limb. Furthermore, subjective feedback was logged to compare two systems. RESULTS: The pressure was significantly higher at the proximal and distal areas with the pin/lock suspension system during the swing phase of gait (P<0.05). Subjective feedback also showed traction at the stump with the pin/lock system. There were no significant differences in the pressure applied to the mid-anterior and mid posterior stump for both suspension systems. However, the lateral and medial sides exhibited higher pressure with the new system during stance phase. CONCLUSIONS: The intention of this study was to deepen understanding on the effect of suspension system on the load distribution over the residual limb. The new coupling system was proved compatible with the pin/lock system in terms of suspending the leg and amputee's satisfaction. On the other hand, the HOLO system could distribute the pressure more uniformly over the residual limb.

Gait biomechanics of individuals with transtibial amputation: effect of suspension system.

Prosthetic suspension system is an important component of lower limb prostheses. Suspension efficiency can be best evaluated during one of the vital activities of daily living, i.e. walking. A new magnetic prosthetic suspension system has been developed, but its effects on gait biomechanics have not been studied. This study aimed to explore the effect of suspension type on kinetic and kinematic gait parameters during level walking with the new suspension system as well as two other commonly used systems (the Seal-In and pin/lock). Thirteen persons with transtibial amputation participated in this study. A Vicon motion system (six cameras, two force platforms) was utilized to obtain gait kinetic and kinematic variables, as well as pistoning within the prosthetic socket. The gait deviation index was also calculated based on the kinematic data. The findings indicated significant difference in the pistoning values among the three suspension systems. The Seal-In system resulted in the least pistoning compared with the other two systems. Several kinetic and kinematic variables were also affected by the suspension type. The ground reaction force data showed that lower load was applied to the limb joints with the magnetic suspension system compared with the pin/lock suspension. The gait deviation index showed significant deviation from the normal with all the systems, but the systems did not differ significantly. Main significant effects of the suspension type were seen in the GRF (vertical and fore-aft), knee and ankle angles. The new magnetic suspension system showed comparable effects in the remaining kinetic and kinematic gait parameters to the other studied systems. This study may have implications on the selection of suspension systems for transtibial prostheses. Trial registration: Iranian Registry of Clinical Trials IRCT2013061813706N1.

The effects of suction and pin/lock suspension systems on transtibial amputees' gait performance.

BACKGROUND: The suction sockets that are commonly prescribed for transtibial amputees are believed to provide a better suspension than the pin/lock systems. Nevertheless, their effect on amputees' gait performance has not yet been fully investigated. The main intention of this study was to understand the potential effects of the Seal-in (suction) and the Dermo (pin/lock) suspension systems on amputees' gait performance. METHODOLOGY/PRINCIPAL FINDINGS: Ten unilateral transtibial amputees participated in this prospective study, and two prostheses were fabricated for each of them. A three-dimensional motion analysis system was used to evaluate the temporal-spatial, kinematics and kinetics variables during normal walking. We also asked the participants to complete some part of Prosthesis Evaluation Questionnaire (PEQ) regarding their satisfaction and problems with both systems. The results revealed that there was more symmetry in temporal-spatial parameters between the prosthetic and sound limbs using the suction system. However, the difference between two systems was not significant (p<0.05). Evaluation of kinetic data and the subjects' feedback showed that the participants had more confidence using the suction socket and the sockets were more fit for walking. Nevertheless, the participants had more complaints with this system due to the difficulty in donning and doffing. CONCLUSION: It can be concluded that even though the suction socket could create better suspension, fit, and gait performance, overall satisfaction was higher with the pin/lock system due to easy donning and doffing of the prosthesis. TRIAL REGISTRATION: irct.ir IRCT2014012816395N1.

Transfemoral prosthesis suspension systems: a systematic review of the literature.

The purpose of this study was to find the scientific evidence pertaining to various transfemoral suspension systems to provide selection criteria for clinicians. To this end, databases of PubMed, Web of Science, and ScienceDirect were explored. The following key words, as well as their combinations and synonyms, were used for the search: transfemoral prosthesis, prosthetic suspension, lower limb prosthesis, above-knee prosthesis, prosthetic liner, transfemoral, and prosthetic socket. The study design, research instrument, sampling method, outcome measures, and protocols of articles were reviewed. On the basis of the selection criteria, 16 articles (11 prospective studies and 5 surveys) were reviewed. The main causes of reluctance to prosthesis, aside from energy expenditure, were socket-related problems such as discomfort, perspiration, and skin problems. Osseointegration was a suspension option, yet it is rarely applied because of several drawbacks, such as extended rehabilitation process, risk for fracture, and infection along with excessive cost. In conclusion, no clinical evidence was found as a "standard" system of suspension and socket design for all transfemoral amputees. However, among various suspension systems for transfemoral amputees, the soft insert or double socket was favored by most users in terms of function and comfort.

Evaluation of new suspension system for limb prosthetics.

BACKGROUND: Good prosthetic suspension system secures the residual limb inside the prosthetic socket and enables easy donning and doffing. This study aimed to introduce, evaluate and compare a newly designed prosthetic suspension system (HOLO) with the current suspension systems (suction, pin/lock and magnetic systems). METHODS: All the suspension systems were tested (tensile testing machine) in terms of the degree of the shear strength and the patient's comfort. Nine transtibial amputees participated in this study. The patients were asked to use four different suspension systems. Afterwards, each participant completed a questionnaire for each system to evaluate their comfort. Furthermore, the systems were compared in terms of the cost. RESULTS: The maximum tensile load that the new system could bear was 490 N (SD, 5.5) before the system failed. Pin/lock, magnetic and suction suspension systems could tolerate loads of 580 N (SD, 8.5), 350.9 (SD, 7) and 310 N (SD, 8.4), respectively. Our subjects were satisfied with the new hook and loop system, particularly in terms of easy donning and doffing. Furthermore, the new system is considerably cheaper (35 times) than the current locking systems in the market. CONCLUSIONS: The new suspension system could successfully retain the prosthesis on the residual limb as a good alternative for lower limb amputees. In addition, the new system addresses some problems of the existing systems and is more cost effective than its counterparts.

Immediate effect of orthopedic shoe and functional foot orthosis on center of pressure displacement and gait parameters in juvenile flexible flat foot.

BACKGROUND: Flat foot in children is a common deformity in which the medial longitudinal arch is reduced or eliminated. OBJECTIVES: The objective of this article was to compare flat foot and healthy children on the displacement of the center of pressure and walking parameters in children with two common orthoses (functional foot orthosis and medical shoe). STUDY DESIGN: Comparative study. METHODS: This study included 30 children with flat foot and 20 healthy children as a control group. The step length and width, walking velocity, symmetry, and center of pressure (CoP) displacements were recorded and compared for three conditions: functional foot orthosis and regular shoe, a medical shoe and barefoot. RESULTS: The results from the CoP displacements showed that the regular shoe with functional foot orthosis caused a significant decrease in the level of displacement of the CoP in flat foot children. The findings indicated a significant improvement in symmetry of steps and walking speed with the functional foot orthosis in comparison to the medical shoe in flat foot children. CONCLUSION: The CoP displacement was decreased and the percentage of gait symmetry and walking speed were increased by the use of regular shoes with a functional foot orthosis in comparison to the medical shoes. CLINICAL RELEVANCE: An orthopaedic shoe can be expensive, and in particular heavy with most children reluctant to wear it. This study focussed on the CoP displacement and selected gait parameters with an orthopaedic shoe and functional foot orthosis, and showed that a combined prescription of a functional foot orthosis and with regular shoes may be a useful alternative for children with moderate flat foot.

Effect of rocker shoes on pain, disability and activity limitation in patients with rheumatoid arthritis.

BACKGROUND: Rheumatoid arthritis is a chronic inflammatory joint disease which affects the joints and soft tissues of the foot and ankle. Rocker shoes may be prescribed for the symptomatic foot in rheumatoid arthritis; however, there is a limited evidence base to support the use of rocker shoes in these patients. OBJECTIVES: The aim of this study was to evaluate the effectiveness of heel-to-toe rocker shoes on pain, disability, and activity limitation in patients with rheumatoid arthritis. STUDY DESIGN: Clinical trial. METHODS: Seventeen female patients with rheumatoid arthritis of 1 year or more duration, disease activity score of less than 2.6, and foot and ankle pain were recruited. Heel-to-toe rocker shoe was made according to each patient's foot size. All the patients were evaluated immediately, 7 and 30 days after their first visit. Foot Function Index values were recorded at each appointment. RESULTS: With the use of rocker shoes, Foot Function Index values decreased in all subscales. This reduction was noted in the first visit and was maintained throughout the trials. CONCLUSION: Rocker shoe can improve pain, disability, and activity limitation in patients with rheumatoid foot pain. All the subjects reported improved comfort levels. CLINICAL RELEVANCE: The results of this study showed that high-top, heel-to-toe rocker shoe with wide toe box was effective at reducing foot and ankle pain. It was also regarded as comfortable and acceptable footwear by the patients with rheumatoid foot problems.