The Functional Roles of Muscles, Passive Prostheses, and Powered Prostheses During Sloped Walking in People With a Transtibial Amputation

Abstract

Sloped walking is challenging for individuals with transtibial amputation (TTA) due to the functional loss of the ankle plantarflexors. Prostheses that actively generate ankle power may help to restore this lost function. The purpose of this study was to use musculoskeletal modeling and simulation to quantify the mechanical power delivered to body segments by passive and powered prostheses and the remaining muscles in the amputated and intact legs during sloped walking. We generated walking simulations from experimental kinematic and kinetic data on slopes of 0, ±3 deg and ±6 deg in eight people with a TTA using powered and passive prostheses and eight nonamputees. Consistent with our hypothesis, the amputated leg hamstrings generated more power to both legs on uphill slopes in comparison with nonamputees, which may have implications for fatigue or overuse injuries. The amputated leg knee extensors delivered less power to the trunk on downhill slopes (effect size (ES) ≥ 1.35, p ≤ 0.02), which may be due to muscle weakness or socket instability. The power delivered to the trunk from the powered and passive prostheses was not significantly different (p > 0.05), However, using the powered prosthesis on uphill slopes reduced the contributions from the amputated leg hamstrings in all segments (ES ≥ 0.46, p ≤ 0.003), suggesting that added ankle power reduces the need for the hamstrings to compensate for lost ankle muscle function. Neither prosthesis replaced gastrocnemius function to absorb power from the trunk and deliver it to the leg on all slopes.

Individual Leg and Joint Work during Sloped Walking for People with a Transtibial Amputation Using Passive and Powered Prostheses

“…Therefore, it is possible that a powered ankle-foot prosthesis that can only replace the function of the uni-articular soleus is incapable of fully replicating biological ankle function during walking. Furthermore, musculoskeletal modeling studies have found that the use of powered or passive-elastic prostheses increases whole-body sagittal plane angular momentum compared to non-amputees and that neither device is capable of providing power to the trunk similar to the biological gastrocnemius (Pickle et al, 2016(Pickle et al, , 2017. Future studies should investigate the mechanical energy loss and transfer from the prosthetic ankle to the residual limb, and investigate the role of the socket-limb interface in this energy transfer.…”

“…Use of the powered prosthesis normalized metabolic cost while walking on level ground and normalized trailing leg step-to-step transition work on both level ground and a 5° uphill ramp (Russell Esposito et al, 2016). Use of the powered compared to passive-elastic prosthesis reduced hamstring muscle activation on uphill slopes of +3°, +6°, and +9° (Pickle et al, 2017) and reduced the range of sagittal plane whole-body angular momentum on slopes of −10°, −5°, 0°, and +5° (Pickle et al, 2016). It remains unclear how use of a powered ankle-foot prosthesis affects leg joint work contributions during uphill and downhill walking over a range of slopes compared to use of a passive-elastic prosthesis.…”

Statistical analysis of timeseries data reveals changes in 3D segmental coordination of balance in response to prosthetic ankle power on ramps

“…Yet despite these biomechanical limitations of active prostheses, the issue is further complicated by studies finding that users prefer an active prosthesis over a passive one 3 . The discrepancy between quantitative biomechanical measures and qualitative user feedback suggests that it is important to consider not only local joint mechanics (e.g., prosthetic ankle power generation) or lumped whole-body measures (e.g., net metabolic energy expenditure, step-to-step transition work 5 , range of H ) but also the effects of the device on segmental coordination during gait 15–17 . Here, we define “coordination” as the contributions of individual segments to whole-body movement at specific times during a movement.…”

Maintenance of muscle strength retains a normal metabolic cost in simulated walking after transtibial limb loss

“…[ 15 ]. Several previous studies have used optimal control methods [ 8 , 9 , 15 – 18 ] and other related methods [ 19 ] to simulate limb loss gait, but have not modeled changes in muscle strength with limb loss, and it is unknown how various levels of bilateral or unilateral (residual limb) muscle strength loss affect the metabolic cost of walking post-limb loss.…”