Fabrication and assessment of partial finger prostheses made using 3D-printed molds: A case study.

3D printing for custom prosthetic finger fabrication can have better fit and comfort than non-custom off-the-shelf ones while reducing fabrication labor time. The purpose of this case study was (1) to design and fabricate custom prosthetic fingers using 3D-printed molds for the treatment of partial finger amputation; (2) to evaluate patient satisfaction of the custom prosthetic fingers fabricated using 3D-printed molds and compare them to the custom prosthetic fingers fabricated through a conventional method of molding using plaster casts. The method to develop the custom prosthetic finger are as follows: (1) The shapes of the residual digits and contralateral fingers were acquired using a high-resolution 3D optical scanner. (2) Prosthetic fingers were designed by modifying the model of the residual digits and the contralateral fingers. (3) Molds of the prosthetic fingers were designed using computer-aided design software and fabricated by 3D printing. The study compared hand function tests and rehabilitation outcome surveys to evaluate the performance of the prosthetic fingers fabricated using 3D-printed molds and plaster casts. This case suggests that the prosthetic fingers fabricated using 3D-printed molds had comparable performance to the prosthetic fingers fabricated using plaster casts. The aesthetics and transparency of the prosthetic fingers contributed highly to the low satisfaction of the prosthetic fingers fabricated using 3D-printed molds.

Design of a segmented custom ankle foot orthosis with custom-made metal strut and 3D-printed footplate and calf shell.

BACKGROUND: 3D-printing is a potential manufacturing process for optimizing the design and manufacture of ankle foot orthosis (AFOs). The feasibility of an AFO with interchangeable strut that is suitable for 3D-printing is created and evaluated. OBJECTIVE: A segmented AFO with 3D-printed custom footplate and calf shell connected by a custom-made strut is studied. STUDY DESIGN: The duration of a healthy subject wearing the 3D-printed segmented AFO in daily activities is used to evaluate the feasibility and durability to integrate 3D-printed AFOs into orthotics practice. TECHNIQUE: The 3D-scanning of a patient's leg is first conducted. The scanned 3D surface is modified by creating the clearance around bony prominences and trimlines for the footplate and calf shell. The footplate has a custom-shaped inside to match with the foot and a standard shape outside at the top to match and connect with the strut. For the calf shell, the inside shape is custom fit with the shank and the outside shape is standard to connect with the strut. Material extrusion is the 3D-printing process selected. Tree-like support structures are used to avoid the use of soluble support material and to eliminate the risk of residual chemical solvent in the orthosis. RESULTS: The segmented AFO with material extrusion footplate and calf shell was tested in a healthy subject with an active lifestyle, offering comfort, and stability for over 4 months without breakage. CONCLUSIONS: This segmented AFO is durable, requires short 3D-printing time, and enables the quick adjustment of bending stiffness via an interchangeable strut design.

The influence of powered prostheses on user perspectives, metabolics, and activity: a randomized crossover trial.

BACKGROUND: Powered prosthetic ankles provide battery-powered mechanical push-off, with the aim of reducing the metabolic demands of walking for people with transtibial amputations. The efficacy of powered ankles has been shown in active, high functioning individuals with transtibial amputation, but is less clear in other populations. Additionally, it is unclear how use of a powered prosthesis influences everyday physical activity and mobility. METHODS: Individuals with unilateral transtibial amputations participated in a randomized clinical trial comparing their prescribed, unpowered prosthesis and the BiOM powered prosthesis. Participants' metabolic costs and self-selected walking speeds were measured in the laboratory and daily step count, daily steps away from home, and walking speed were measured over two weeks of at-home prosthesis use. Participants also rated their perception of mobility and quality of life and provided free-form feedback. Dependent measures were compared between prostheses and the relationships between metabolic cost, perception of mobility, and characteristics of walking in daily life were explored using Pearson's correlations. RESULTS: Twelve people were randomly allocated to the powered prosthesis first (n = 7) or unpowered prosthesis first (n = 5) and ten completed the full study. There were no differences in metabolic costs (p = 0.585), daily step count (p = 0.995), walking speed in-lab (p = 0.145) and in daily life (p = 0.226), or perception of mobility between prostheses (p ≥ 0.058). Changes varied across participants, however. There were several medium-sized effects for device comparisons. With the powered prosthesis, participants had increased self-reported ambulation (g = 0.682) and decreased frustration (g = 0.506). CONCLUSIONS: There were no universal benefits of the powered prosthesis on function in the lab or home environment. However, the effects were subject-specific, with some reporting preference for power and improved mobility, and some increasing their activity and decreasing their metabolic effort. Additionally, self-reported preferences did not often correlate with objective measures of function. This highlights the need for future clinical research to include both perception and objective measures to better inform prosthetic prescription. TRIAL REGISTRATION: https://clinicaltrials.gov , #NCT02828982. Registered 12 July 2016, https://clinicaltrials.gov/ct2/show/NCT02828982.

Wearable Sensors Quantify Mobility in People With Lower Limb Amputation During Daily Life.

It is necessary to effectively assess functional mobility for appropriate prosthetic prescription and post-amputation rehabilitation. As part of this process, patients' ability for variable cadence and community ambulation are assessed in-clinic, often through visual assessments and without objective standards. The purpose of this study was to explore the clinical viability of using wearable sensors to characterize the functional mobility of people with lower limb amputation. We collected inertial measurement unit (IMU) and global positioning system (GPS) data over two weeks, from 17 individuals with lower limb amputation and 14 healthy non-amputee controls. We calculated stride-by-stride cadence, walking speed and stride lengths, along with whether they occurred in or out of the home. Self-selected walking speed was also assessed in the lab. Compared to the lab, both groups walked slower and with a lower cadence during their daily lives. There were no differences in cadence variability between groups or between strides taken in and out of the home. Both groups walked faster and with greater stride lengths away from the homes. The results suggest that functional capacity measured in the lab was not necessarily reflected in routine walking during daily life. The walking measures derived in this approach can be used to aid in the prosthetic prescription process or in the assessment of different interventions.

A controlled clinical trial of a clinically-tuned powered ankle prosthesis in people with transtibial amputation.

OBJECTIVE: To determine whether there are changes in level walking performance for people using a powered ankle prosthesis that was tuned by an independent, manufacturer-certified prosthetist in accordance with device recommendations. DESIGN: Intervention study with cross-over design. SETTING: Laboratory. PARTICIPANTS: Convenience sample of 10 individuals with unilateral, transtibial amputation, and 10 age- and gender-matched control participants. INTERVENTIONS: Powered ankle prosthesis (BiOM T2 Ankle System). Main outcome metrics: Metabolic costs of walking, preferred walking speed. RESULTS: There were no significant differences in oxygen consumption (2.9% difference; P = 0.606, d = 0.26), cost of transport (~1% difference; P = 0.652, d = 0.23), or preferred walking speed (~1% difference; P = 0.147, d = 0.76) when using the powered ankle compared to unpowered prostheses. Secondary analyses of user characteristics revealed that participants who were classified as having the highest function (K4 on Medicare's 5-point scale from K0 to K4) were significantly more likely to exhibit energy cost savings than those classified as having lower function (K3; P = 0.014, d = 2.36). CONCLUSIONS: Participants did not demonstrate significant improvements in energetics or preferred speed when wearing a clinically tuned powered ankle prosthesis compared to their non-powered prostheses. Prescribers of powered devices should understand that not all users will show an immediate reduction in energy expenditure.

Locomotor Adaptation by Transtibial Amputees Walking With an Experimental Powered Prosthesis Under Continuous Myoelectric Control.

Lower limb amputees can use electrical activity from their residual muscles for myoelectric control of a powered prosthesis. The most common approach for myoelectric control is a finite state controller that identifies behavioral states and discrete changes in motor tasks. An alternative approach to state-based myoelectric control is continuous proportional myoelectric control where ongoing electrical activity has a proportional relationship to the prosthetic joint torque or power. To test the potential of continuous proportional myoelectric control for powered lower limb prostheses, we recruited five unilateral transtibial amputees to walk on a treadmill with an experimental powered prosthesis. Subjects walked using the powered prosthesis with and without visual feedback of their control signal in real time. Amputee subjects were able to adapt their residual muscle activation patterns to alter prosthetic ankle mechanics when we provided visual feedback of their myoelectric control signal in real time. During walking with visual feedback, subjects significantly increased their peak prosthetic ankle power ( p = 0.02, ANOVA) and positive work ( p = 0.02, ANOVA) during gait above their prescribed prosthesis values. However, without visual feedback, the subjects did not increase their peak ankle power during push off. These results show that amputee users were able to volitionally alter their prosthesis mechanics during walking, but only when given an explicit goal for their residual muscle motor commands. Future studies that examine the motor and learning capabilities of lower limb amputees using their residual muscles for continuous proportional myoelectric control are needed to determine the viability of integrating continuous high-level control with existing finite state prosthetic controllers.

A novel shear reduction insole effect on the thermal response to walking stress, balance, and gait.

Shear stresses have been implicated in the formation of diabetes-related foot ulcers. The aim of this study was to evaluate the effect of a novel shear-reducing insole on the thermal response to walking, balance, and gait. Twenty-seven diabetes peripheral neuropathy patients were enrolled and asked to take 200 steps in both intervention and standard insoles. Thermal foot images of the feet were taken at baseline (1) following a 5-minute temperature acclimatization and (2) after walking. Testing order was randomized, and a 5-minute washout period was used between testing each insole condition. Sudomotor function was also assessed. Gait and balance were measured under single and dual task conditions using a validated body worn sensor system. The mean age was 65.1 years, height was 67.3 inches, weight was 218 pounds, and body mass index was 33.9, 48% were female, and 82% had type 2 diabetes. After walking in both insole conditions, foot temperatures increased significantly in standard insoles. The intervention insole significantly reduced forefoot and midfoot temperature increases (64.1%, P = .008; 48%, P = .046) compared to standard insoles. There were significant negative correlations with sudomotor function and baseline temperatures (r = .53-.57). The intervention demonstrated 10.4% less gait initiation double support time compared to standard insoles (P = .05). There were no differences in static balance measures. We found significantly lower forefoot and midfoot temperature increases following walking with shear-reducing insoles compared to standard insoles. We also found improvements in gait. These findings merit future study for the prevention of foot ulcer.