Technische Dokumentation zur Medizinprodukteverordnung (MDR) 2021 »

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Product(s): Elan and Echelon

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.

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.

View the full study here. 

Product(s): Silcare Breathe

For lower limb amputees, excessive sweating is a common issue affecting their quality of life. It is particularly problematic for the skin of the amputated limb, which may be scarred and is loaded unnaturally by the prosthetic socket. Silicone liners are often worn to provide a close fit and for cushioning but they create a warm environment that traps sweat against the skin, leading to bacterial growth. Additionally, sweat on the skin can increase the amount of movement between the amputated limb and the socket, affecting prosthetic control. In order to address this problem, silicone liners have been designed with perforations in them to allow warm air and sweat to move away from the skin. This report describes three cases of patients who suffered from long-standing wounds, blisters or skin infections on their amputated limbs. Each was prescribed with a perforated silicone liner and changes in their skin conditions were observed. In all cases, the wounds healed and each patient reported a noticeable reduction in problematic sweating on their residual limb, without limiting their prosthetic use.

McGrath M, McCarthy J, Gallego A, Kercher A, Zahedi S, Moser D. The influence of perforated prosthetic liners on residual limb wound healing: a case report. Canadian Prosthetics & Orthotics Journal. 2019; volume2, Issue1, No.3. https://doi.org/10.33137/cpoj.v2i1.32723.

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The energy consumption of trans-tibial amputees, walking at various speeds and over different gradients, were measured when using a hydraulic ankle unit (Echelon) and a rigidly-attached prosthesis. Using Echelon significantly reduced the metabolic energy cost of walking and hence increased energy efficiency. During level walking, the mean reduction in metabolic cost was 11.8% with Echelon, so for the same amount of effort, walking speed increased by 8.3%. When walking on slopes, the mean reduction in metabolic cost was 20.2% with Echelon.
 
Askew GN, McFarlane LA, Minetti AE, Buckley JG. Energy cost of ambulation in trans-tibial amputees using a dynamic-response foot with hydraulic versus rigid ‘ankle’: insights from body centre of mass dynamics. Journal of neuroengineering and rehabilitation. 2019;16(1):39.
 
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The biomechanical effects of a rigidly-attached foot, a passive hydraulic ankle and a microprocessor-controlled hydraulic ankle were measured during slope ascent and descent for trans-femoral amputees. The hydraulic ankles showed improved bio-mimicry in both walking conditions and better prosthetic knee stability during slope descent.

Bai X, Ewins D, Crocombe AD, Xu W. A biomechanical assessment of hydraulic ankle-foot devices with and without micro-processor control during slope ambulation in trans-femoral amputees. PLOS ONE. 2018; 13(10):e0205093.

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Using a case series design, gait analysis was performed with four trans-tibial amputees to identify differences in the underlying walking biomechanics between the on and off conditions. With microprocessor-control active, there was less reliance on the sound limb for support in both ascent and descent walking conditions. 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.

McGrath M, Laszczak P, Zahedi S, Moser D. The influence of a microprocessor-controlled hydraulic ankle on the kinetic symmetry of trans-tibial amputees during ramp walking: a case series. J Rehabil Assist Technol Eng. 2018; 5:2055668318790650.

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The study sought to investigate the effects of a microprocessor-controlled hydraulic ankle compared to a fixed ankle design when walking at a range of graded inclines, ranging from -12 to + 12 degrees. The gait of one individual with unilateral TF amputation, using the same prosthetic foot with rigid and hydraulic ankle components, was analysed and compared with a control group of 18 able-bodied participants.  It was concluded that during sloped walking, the use of a hydraulically articulating versus rigid ankle joint component reduced the joint moments observed at the hip joint of the residual limb in an individual with unilateral TF amputation. This indicates a benefit for persons with TF amputation as the increased ankle function reduces the moment producing requirements of the hip joint, which may result in decreased energy consumption and subsequently a more efficient gait.

Alexander N, Strutzenberger G, Kroell J, Barnett CT, Schwameder H. Joint Moments During Downhill and Uphill Walking of a Person with Transfemoral Amputation with a Hydraulic Articulating and a Rigid Prosthetic Ankle—A Case Study. JPO J Prosthet Orthot. 2018; 30(1):46–54.

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The study looked at the biomechanical differences when trans-femoral amputees were standing on a slope. 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). Both technologies in isolation improved inter-limb load distribution and balance, with the combination of the two technologies providing the best performance.

McGrath M, Laszczak P, Zahedi S, Moser D. Microprocessor knees with ‘standing support’ and articulating, hydraulic ankles improve balance control and inter-limb loading during quiet standing. J Rehabil Assist Technol Eng. 2018; 5:2055668318795396.

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Eight trans-femoral amputees, using an integrated limb system (Linx), performed gait terminations while walking downhill. Two prosthetic conditions were tested; microprocessor-control active and inactive. Greater involvement of the prosthetic limb with the microprocessor active indicated greater confidence in their prosthesis.

Abdulhasan ZM, Scally AJ, Buckley JG. Gait termination on a declined surface in trans-femoral amputees: Impact of using microprocessor-controlled limb system. Clin Biomech. 2018; 57:35–41.

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Effect of a Prosthetic Foot with a Hydraulic Ankle Unit on the Contralateral Foot Peak Plantar Pressures in Individuals with Unilateral Amputation Peak plantar pressures of 13 participants with established K3 activity levels were measured before and after the addition of a prosthetic foot with hydraulic ankle unit using an Amcube pressure plate. The results showed a statistically significant reduction in contralateral peak plantar pressures with the use of a prosthetic foot containing a hydraulic ankle unit. The benefits of changing to a prescription including a foot with integrated hydraulic ankle unit can have significant effects on the forces acting on the remaining foot of an individual with amputation.

Moore R. Effect of a Prosthetic Foot with a Hydraulic Ankle Unit on the Contralateral Foot Peak Plantar Pressures in Individuals with Unilateral Amputation. JPO J Prosthet Orthot. 2018; 30(3):165–70.

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Two minute walk tests and 3D gait analysis were performed on lower mobility amputees, using both a rigidly-attached ankle-foot and an articulating, hydraulic ankle-foot (Avalon). The effects on gait performance were investigated using a non-energy-storage-and-return foot with a hydraulic attachment during overground walking. Kinematic and kinetic data was recorded while five individuals with UTA, deemed K2 activity level by their prescribing physician, performed two-minute walk tests (2MWTs) and 10 overground gait trials. The hydraulic device was shown to increase walking speed and inter-limb loading symmetry in comparison with a rigid attachment when the results were compared.

Barnett CT, Brown OH, Bisele M, Brown MJ, De Asha AR, Strutzenberger G. Individuals with Unilateral Transtibial Amputation and Lower Activity Levels Walk More Quickly when Using a Hydraulically Articulating Versus Rigidly Attached Prosthetic Ankle-Foot Device. JPO J Prosthet Orthot. 2018; 30(3):158–64.

View the full study here.