How Prosthetic Ankle Stiffness Affects Balance and Gait
Individuals with lower limb loss improve the quality of their lives by using modular prosthetic ankle components. However, it’s important to set up these ankles properly for good stability when standing. But how do we know what is the correct setup for better balance and gait?
Researchers studied ten people with single below-knee limb loss to find the best way to adjust prosthetic ankles for better balance and walking.
The study
In addition to having a single below-knee limb loss, the ten study participants were also categorized as at least K3-level ambulators. People in this category are known as community ambulators, having the ability to traverse most environmental barriers. They may also have activities that demand prosthetic limb use beyond simple walking, like hiking.
To test standing and walking stability with a prosthetic foot, the researchers tested three ankle dorsiflexion stiffness levels—soft, medium, and firm. Dorsiflexion happens when the ankle of the prosthetic foot bends, raising the toes upward.
For the study, they used the College Park Venture foot at three speeds.
Results
The study revealed that a firm prosthetic ankle setup, with its reduced body sway and step length asymmetry, offered the best balance and gait improvements.
Moreover, when the stiffness of the prosthetic ankle was firm, the participants’ roll-over shape (ROS), or the prosthetic leg’s ability to roll forward during a step, was found to be closer to that of able-bodied individuals.
This is a crucial finding for prosthetists and researchers because a prosthetic foot’s ROS is essential to foot alignment. An inappropriate ROS can reduce the user’s quality of gait and comfort.
The bottom line
The study shows the importance of a properly adjusted prosthetic ankle for individuals with lower limb loss, particularly for those classified as K3-level ambulators. A firm prosthetic ankle setup positively impacts the user’s balance, gait, and roll-over shape, indicating potential improvements in walking speed and foot alignment.
The results of this study also emphasize the importance of further research to optimize prosthetic foot design and consider factors such as ankle stiffness to enhance the overall quality of life for prosthetic users.
