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Introduction: In the United States, access to microprocessor-controlled prosthetic ankles is limited to patients with lower-limb loss classified as unlimited community ambulators or greater. However, the potential benefits of these devices have not been evaluated among patients classified as household or limited community ambulators. This study examined the benefit of hydraulic- and microprocessor-controlled prosthetic ankles for patients classified as limited community ambulators. Materials and Methods: Four different treatment configurations were evaluated using a randomized crossover study design. These four configurations included the participant's current flexible keel (FK) prosthetic foot, an energy-storage-and-return foot (ESAR), a hydraulic ankle (HA), and amicroprocessor ankle (MPA). After a 2-week accommodation period, both patient-reported and performance-based outcome measures were recorded for each ankle foot system. A StepWatch activity monitor and two-dimensional video motion analysis were also used to evaluate each system. Results: A single participant meeting the inclusion criteria was recruited. The patient-reportedmobility and socket fit instruments were greatest with the HA system. When assessed on slopes and stairs, the MPA demonstrated benefits on hill ascent and stair descent. In considering the walking speed and perceived exertion jointly, the HA system allowed similar walking speed but lower exertion compared with fixed-ankle systems. The patient-reported low back pain and balance confidence instruments did not provide useful data for interpretation. Two-dimensional videomotion analysis showed that the HA and MPA contributed to improved ankle and knee postures when ascending and descending a slope. The step activity data showed the greatest activity with the HA. Discussion: The results from the outcome measures showed a varying level of benefit across all four of the treatment configurations. Both the HA and MPA had favorable scores in varying performance-based outcome measures, but the HA scored the most favorable in a majority of the patient-reported outcome measures. Conclusion: The results show varying benefits of the microprocessor- and hydraulic-controlled prosthetic components over fixed-ankle ESAR and FK feet, based on both performance-based and patient-reported outcome measures. Further studies are needed to fully evaluate these benefits in larger sample sizes. [ABSTRACT FROM AUTHOR]

BACKGROUND: Lower limb amputees have a high incidence of comorbidities, such as osteoarthritis, which are believed to be caused by kinetic asymmetries. A lack of prosthetic adaptation to different terrains requires kinematic compensations, which may influence these asymmetries. METHOD: Six SIGAM grade E-F trans-tibial amputees (one bilateral) wore motion capture markers while standing on force plates, facing down a 5° slope. The participants were tested under three prosthetic conditions; a fixed attachment foot (FIX), a hydraulic ankle (HYD) and a microprocessor foot with a ‘standing support’ mode (MPF). The resultant ground reaction force (GRF) and support moment for prosthetic and sound limbs were chosen as outcome measures. These were compared between prosthetic conditions and to previously captured able-bodied control data. RESULTS: The distribution of GRF between sound and prosthetic limbs was not significantly affected by foot type. However, the MPF condition required fewer kinematic compensations, leading to a reduction in sound side support moment of 59% (p=0.001) and prosthetic side support moment of 43% (p=0.02) compared to FIX. For the bilateral participant, only the MPF positioned the GRF vector anterior to the knees, reducing the demand on the residual joints to maintain posture. CONCLUSION: For trans-tibial amputees, loading on lower limb joints is affected by prosthetic foot technology, due to the kinematic compensations required for slope adaptation. MPFs with ‘standing support’ might be considered reasonable and necessary for bilateral amputees, or amputees with stability problems due to the reduced biomechanical compensations evident. Layman’s Abstract: Lower limb prostheses work well on flat ground but often don’t adapt well to uneven ground or slopes. As a result, amputees tend to put more of their weight through their healthy leg. This can lead to problems like back pain and arthritis. In this study, the posture and weight distribution of below knee amputees were analysed while they stood facing down a slope. They did this with three different prosthetic feet; one with no ‘ankle’ joint, one with an ‘ankle’ (which could always move) and one with a computer-controlled ‘ankle’ (which could adapt to the slope but then resist movement when the wearer was stood still). Changing the prosthetic feet did not affect the amount of weight put through each limb, but when they had ‘ankle’ joints, the amputees were able to stand up straight, with a better posture. This meant that the demand on their joints was reduced, particularly on the healthy limb. One participant had below knee amputations on both legs. For this participant, only the computer-controlled device allowed her to stand up straight and well balanced. Article PDF Link: https://jps.library.utoronto.ca/index.php/cpoj/article/view/33517/25933 How To Cite: McGrath M, Davies KC, Laszczak P, Rek B, McCarthy J, Zahedi S, Moser D. The influence of hydraulic ankles and microprocessor-control on the biomechanics of trans-tibial amputees during quiet standing on a 5° slope. Canadian Prosthetics & Orthotics Journal. 2019;Volume2, Issue2, No.2. https://doi.org/10.33137/cpoj.v2i2.33517 Corresponding Author: Dr. Michael McGrath, Research Scientist–Clinical Evidence Blatchford Group, Unit D Antura, Bond Close, Basingstoke, RG24 8PZ, United Kingdom Email: mike.mcgrath@blatchford.co.uk ORCID: https://orcid.org/0000-0003-0195-970X

Introduction: Since their release, prosthetic feet with integrated hydraulic ankle units have proved a popular prescription choice among individuals with amputation, as quantified in previous studies. Since the release of the Avalon foot, a new design specifically aimed at less active individuals with amputation, all the patients prescribed this foot within our clinic have been asked to trial and then evaluate it using the Seattle Prosthesis Evaluation Questionnaire. Materials and Methods: Fourteen established K2 activity level patients with amputation were asked to evaluate their existing prosthetic foot using the Seattle Prosthesis Evaluation Questionnaire before beginning a trial of the new Avalon foot for a period of 4 weeks. The Avalon foot was then evaluated using the same tool after this trial. Results: The results showed the patients recorded an improvement in all the domains evaluated. There were significant improvements noted in both the overall prosthetic satisfaction and in the patients' overall gait satisfaction. Conclusions: The results showed a marked improvement in the patients' perception of their prosthesis when using the Avalon foot, and further studies including gait analysis are warranted to help in our understanding of this. [ABSTRACT FROM AUTHOR]

Most clinically available prosthetic feet have a rigid attachment or incorporate an “ankle” device allowing elastic articulation during stance, with the foot returning to a “neutral” position at toe-off. We investigated whether using a foot with a hydraulically controlled articulating ankle that allows the foot to be relatively dorsiflexed at toe-off and throughout swing would increase minimum toe clearance (MTC). Twenty-one people with unilateral transtibial amputation completed overground walking trials using their habitual prosthetic foot with rigid or elastic articulating attachment and a foot with a hydraulic ankle attachment (hyA-F). MTC and other kinematic variables were assessed across multiple trials. When using the hyA-F, mean MTC increased on both limbs (p = 0.03). On the prosthetic limb this was partly due to the device being in its fully dorsiflexed position at toe-off, which reduced the “toes down” foot angle throughout swing (p = 0.01). Walking speed also increased when using the hyA-F (p = 0.001) and was associated with greater swing-limb hip flexion on the prosthetic side (p = 0.04), which may have contributed to the increase in mean MTC. Variability in MTC increased on the prosthetic side when using the hyA-F (p = 0.03), but this did not increase risk of tripping. [ABSTRACT FROM AUTHOR]

Background: Lower limb amputees have a high incidence of comorbidities, such as osteoarthritis, which are believed to be caused by kinetic asymmetries. A lack of prosthetic adaptation to different terrains requires kinematic compensations, which may influence these asymmetries., Method: Six SIGAM grade E-F trans-tibial amputees (one bilateral) wore motion capture markers while standing on force plates, facing down a 5° slope. The participants were tested under three prosthetic conditions; a fixed attachment foot (FIX), a hydraulic ankle (HYD) and a microprocessor foot with a 'standing support' mode (MPF). The resultant ground reaction force (GRF) and support moment for prosthetic and sound limbs were chosen as outcome measures. These were compared between prosthetic conditions and to previously captured able-bodied control data., Results: The distribution of GRF between sound and prosthetic limbs was not significantly affected by foot type. However, the MPF condition required fewer kinematic compensations, leading to a reduction in sound side support moment of 59% (p=0.001) and prosthetic side support moment of 43% (p=0.02) compared to FIX. For the bilateral participant, only the MPF positioned the GRF vector anterior to the knees, reducing the demand on the residual joints to maintain posture., Conclusions: For trans-tibial amputees, loading on lower limb joints is affected by prosthetic foot technology, due to the kinematic compensations required for slope adaptation. MPFs with 'standing support' might be considered reasonable and necessary for bilateral amputees, or amputees with stability problems due to the reduced biomechanical compensations evident., Competing Interests: The authors are full time employees of the manufacturer of the prosthetic devices examined in this study., (Copyright (c) 2020 Michael McGrath, Katherine C. Davies, Piotr Laszczak, Beata Rek, Joe McCarthy, Saeed Zahedi, and David Moser.)

Introduction: Asymmetrical limb loading is believed to cause health problems for lower limb amputees and is exacerbated when walking on slopes. Hydraulically damped ankle-feet improve ground compliance on slopes compared to conventional prosthetic feet. Microprocessor-controlled hydraulic ankle-feet provide further adaptation by dynamically adjusting viscoelastic damping properties., Method: Using a case series design, gait analysis was performed with four trans-tibial amputees. There were two walking conditions (ramp ascent and descent) and two prosthetic foot conditions (microprocessor-control on and off - MPF-on and MPF-off). Total support moment integral ( M I sup ) and degree-of-asymmetry were compared across foot conditions., Results: During ramp descent, the transition of prosthetic ankle moment from dorsiflexion to plantarflexion occurred earlier in stance phase with MPF-on, slowing the angular velocity of the shank. During ramp ascent, the MPF-on dorsiflexion/plantarflexion moment transition occurred later, meaning less resistance to shank rotation in early stance and increasing walking speed by up to 6%. For both slope conditions, sound limb M I sup was universally decreased with MPF-on (4-13% descent, 3-11% ascent)., Discussion: Microprocessor-control of hydraulic ankle-feet reduced the total loading of the sound limb joints, for both walking conditions, for all participants. This may have beneficial consequences for long-term joint health and walking efficiency., Competing Interests: The author(s) declared following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: The authors are full time employees of the manufacturer of the prosthetic device examined in this study.

Introduction: Trans-femoral amputees are at risk of musculoskeletal problems that are in part caused by loading asymmetry during activities, such as prolonged standing, particularly on uneven or sloped ground., Methods: Four prosthetic conditions were tested; microprocessor knee 'standing support' mode activated (ON) and deactivated (OFF), combined with a rigidly attached foot (RA) and with an articulating, hydraulic ankle-foot (HA). Five trans-femoral amputees and five able-bodied controls were measured using a motion capture system and a force plate while standing, facing down a 5° slope. Ground reaction force distributions and centre-of-pressure root-mean-square (COP RMS) were calculated as outcome measures., Results: Compensatory kinematic adjustments were observed for RA conditions but not for HA conditions. HA-OFF reduced ground reaction force degree-of-asymmetry for all five amputees, compared to RA-OFF. RA-ON reduced ground reaction force degree-of-asymmetry for four amputees, compared to RA-OFF. In terms of balance, the HA conditions reduced the mean inter-limb COP RMS by 24-25% compared to equivalent RA conditions, while ON conditions reduced it by 9-11%, compared to equivalent OFF conditions., Conclusions: It is important to consider both prosthetic knee and ankle technologies when prescribing devices to trans-femoral amputees. The combination of hydraulic ankle and knee standing support technologies produced outcomes closest to normal biomechanics., Competing Interests: The author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: The authors are full time employees of the manufacturer of all the prosthetic devices tested in this study.