Whole-body angular momentum during sloped walking using passive and powered lower-limb prostheses

Area of Science:

• Biomechanics
• Human Movement Science
• Prosthetics and Orthotics

Background:

• Sloped walking necessitates different dynamic balance strategies than level walking, impacting sagittal-plane whole-body angular momentum (H).
• Ankle plantarflexor muscles are crucial for regulating H, and their loss due to transtibial amputation impairs this control.
• The effect of powered versus passive prostheses on H during sloped walking remains unclear.

Purpose of the Study:

• To investigate whole-body angular momentum (H) in individuals with unilateral transtibial amputation during sloped walking.
• To compare the effects of powered and passive prosthetic limbs on dynamic balance control.
• To understand how prosthetic technology influences gait adjustments on inclines and declines.

Main Methods:

• Comparison of sagittal-plane whole-body angular momentum (H) between able-bodied individuals and those with transtibial amputation.
• Analysis of gait parameters on a -10° decline and a +10° incline using both powered and passive prosthetic limbs.
• Measurement of ground reaction forces and joint power absorption/generation during prosthetic stance.

Main Results:

• Individuals with amputation showed a greater range of H compared to able-bodied individuals on slopes.
• On declines, amputees had reduced H regulation, less prosthetic braking force, and lower knee power absorption.
• On inclines, amputees exhibited a larger relative H increase, more anterior foot placement, and higher hip power generation.
• The powered prosthesis resulted in a smaller H range during stance than the passive prosthesis, but still exceeded able-bodied levels.

Conclusions:

• Prosthetic ankle power may aid dynamic balance during sloped walking, but is insufficient to normalize H compared to able-bodied individuals.
• Further research is needed on the roles of knee extensors and the gastrocnemius muscle in regulating H on slopes.
• Altered gait strategies in transtibial amputees on slopes highlight the need for advanced prosthetic designs to restore dynamic balance.