1. Discussion and Conclusions: Materials and Methods:
Comparing Ankle Angles of Transtibial K2 and K3 Prosthetic Feet
Ameralys Correa, Alyssa J Schnorenberg, Christopher Burckardt, Brooke A Slavens, PhD
College of Health Sciences: Department of Occupational Science and Technology
Introduction:
Results:
Purpose: Improve quality of life and ease of movement for amputees by objectively analyzing ankle movement
Why: Insurance companies want quantitative data
Past diagnosis limited by subjective observation and human reaction time [1]
Transtibial means “through the tibia bone” amputation (below the knee)
Types of Ankle Prostheses [4]:
K1 : Home Walker
K2 : Community Walker
K3 : Active Walker
K4 : High Impact Walker
Hypothesis:
Range of Motion will be greater with K3 foot in the sagittal plane
K2 foot will have faster climb time (small angles mean less chance of stumble)
Related Research:
Multi-axis ankles improve gait because they allow better propulsive impulses [2]
“Propio-Foot” is a “smart” ankle with microprocessor [3]
Figure 2. Markers and 15 Motion Capture Cameras report subject’s movement to VICON Nexus Program
Seattle Light Foot [5]:
Use: Low Activity
Classification: K2
Weight Limit: 366 pounds
Dimensions: cm long
Features: Multi-axial ankle
Ideal for: Walking in retail stores, sidewalks, and other even surfaces
Difference from K3 Level: Stiffer ankle for less flexion
Catalyst Foot [5]:
Use: Moderate to High Activity
Classification: K3
Weight Limit: 366 pounds
Dimensions: cm long
Features: Multi-axial ankle
Vertical Shock Absorption
Ideal for: Walking on grassy parks, gravel roads, and other uneven surfaces
Difference from K2 Level: K3 feet return more energy to propel the person forward
Discussion and Conclusions:
Materials and Methods:
Subject:
Left Leg Transtibial Amputee
Location:
UWM Mobility Laboratory in Wauwatosa, Wisconsin
Equipment:
Four AMTI Optima force plates installed flush with floor
21” high and 32” long stair case (3 steps)
39 reflective markers on subject – Vicon Plug-in-Gait model
15 Vicon T-Series Motion Capture Cameras mounted around
ceiling
Procedure:
Ascends stairs with K2 foot several times
Subject uses two people’s forearms as handrails
Change K2 foot for K3 foot
Allow subject to acclimate to K3 foot for a week
Repeat stair ascension
Data Collection:
Data collected by VICON motion capture system
Data Processing:
Markers labeled to create animated stick person
VICON Nexus model calculated 3D joint angles
Analyzed sagittal plane ankle angles
Output to .csv file for further analysis using Microsoft Excel
Data time normalized to percent gait cycle
Catalyst Foot had greater maximum of dorsiflexion of degrees compared to Seattle Light Foot’s degrees
Neither prosthetic foot experienced plantar flexion
There was sharp decrease for both K2 and K3 feet in dorsiflexion when left foot toed off
Although the K3 foot allows greater range of motion, the natural angle is not significantly different. The range of motion of the two feet and their natural angles differ from one another by about a degree.
K3 foot peaks sooner in the gait cycle than the K2 foot. The earlier peaking may be due to the better propulsion provided by the K3 foot.
K3 foot has more gradual changes in angles than K2 foot. The sharper changes in angle change may be due to the K2’s limited mobility. K3 feet may offer a more comfortable stair climb due to this gradual sweep
When climbing the stairs, the K2 and K3 feet angles are similar. The repetitive dimensions of the stairs may have caused both types of feet to conform to one another. Future research can analyze if there is a greater difference between K2 and K3 in other daily activities and if differing angles contribute to better comfort and or ease of the patient mobility.
References:
Acknowledgments:
Figure 1. Transtibial subject ascends stairs
[1] Biswas, Ajoy. (2006). Dynamic Gait Stability Index Using a Fuzzy Logic Model, (master’s thesis). Retrieved from uOttawa Research database.
[2] Robert J. Zmitrewicz, et al. (2006). Archives of Physical Medicine and Rehabilitation. Vol. 87 Issue 10: Page
[3] Merkur Alimusaj, et. al. (2009) Gait and Posture. Vol. 30 Issue 3:
[4] Leimkuehler, Paul E. (2015) American Academy of Orthoptists & Prosthetics.
[5] Trulife. (2015) Seattle Catalyst. Kinetic Light.
We would like to acknowledge UWM College of Health Sciences (CHS) Stimulus Program to Accelerate Research Clusters (SPARC) grant for support of this work. Assistance for this project has also been provided by Dr. Joel Kempfer and Marissa Thill.