The influence of a microprocessor-controlled hydraulic ankle on the kinetic symmetry of trans-tibial amputees during ramp walking: A case series

Abstract

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 ( ) 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 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.

Impact of a Powered Prosthetic Ankle-Foot Component on Musculoskeletal Pain in Individuals with Transtibial Amputation: A Real-World Cross-Sectional Study with Concurrent and Recalled Pain and Functional Ratings

“…The PwrAF surveyed in this study has a plantarflexion range of motion of 22° that is not only used for powered push-off but also passively for foot-flat during level walking and terrain adaptation. Descending a slope or negotiating uneven terrain with a passive microprocessor-controlled prosthetic ankle resulted in reduced (more normal) early stance knee flexion, slowed (better passively controlled) forward shank rotation, reduced negative (dampening) work in the residual knee, and thus, improved control over downhill walking speed as compared with a foot with fixed ankle attachment 59 . Therefore, even passive adaptation of microprocessor-controlled ankles significantly reduced biomechanical compensations and residual knee loading during slope descent and uneven terrain ambulation, both on the sound and amputated side 59,60 .…”

“…Descending a slope or negotiating uneven terrain with a passive microprocessor-controlled prosthetic ankle resulted in reduced (more normal) early stance knee flexion, slowed (better passively controlled) forward shank rotation, reduced negative (dampening) work in the residual knee, and thus, improved control over downhill walking speed as compared with a foot with fixed ankle attachment. 59 Therefore, even passive adaptation of microprocessor-controlled ankles significantly reduced biomechanical compensations and residual knee loading during slope descent and uneven terrain ambulation, both on the sound and amputated side. 59,60 These results may also be assumed for the PwrAF, which may explain the reduction in amputated side knee pain found by the PwrAF.…”

“…59 Therefore, even passive adaptation of microprocessor-controlled ankles significantly reduced biomechanical compensations and residual knee loading during slope descent and uneven terrain ambulation, both on the sound and amputated side. 59,60 These results may also be assumed for the PwrAF, which may explain the reduction in amputated side knee pain found by the PwrAF.…”

Free-Living User Perspectives on Musculoskeletal Pain and Patient-Reported Mobility With Passive and Powered Prosthetic Ankle-Foot Components: A Pragmatic, Exploratory Cross-Sectional Study

“…All these effects of a prosthetic ankle joint result in decreased loading of the residual knee (46). In addition, the adaptability of the prosthetic ankle on slopes and uneven terrain reduces biomechanical compensations on the prosthetic and sound limbs, facilitates faster foot-flat, improves the control of downhill walking speed, and significantly reduces the biomechanical loading of the residual knee (47)(48)(49)(50). These effects that have been shown for passive feet with non-microprocessor and microprocessor-controlled ankles may also be assumed for the powered ankle-foot components surveyed and may explain the reduction in amputated side knee pain.…”

Benefits of a microprocessor-controlled prosthetic foot for ascending and descending slopes

“…With focusing on commercially available MPF without powered ankle support, previous studies on slope ambulation have shown mixed results with improvements in some biomechanical parameters but deterioration in others [ 21 ], further complicated by high inter-subject variability [ 13 ]. Many of these studies were limited by the only gradual and partial adaptation of the studied MPF to slopes [ 13 , 21 ] or testing on only shallow slopes of 5° of a MPF with very limited ROM at the ankle joint [ 11 , 18 , 22 ]. Moreover, the vast majority of studies investigated slope ambulation with MPF only for persons with TTA.…”