Tag: Michael Hahn

Analysis of Dynamic Balance Control in Below-Knee Amputees with Use of Powered Prosthetic Foot

Presenter: Shaun Resseguie

Mentors: Michael Hahn and Jake Hinkel-Lipsker, Human Physiology

Poster: 55

Major: Human Physiology 

The powered prosthetic foot (PPF) is designed to provide below-knee amputees (BKA) with active propulsion and plantar flexion similar to that of the biological limb. Previous studies have demonstrated the PPF’s ability to increase BKA walking speeds, while reducing the energetic costs, however, little is known about its effects on dynamic balance control. The purpose of this study was to assess dynamic balance control in a sample of BKA subjects during level-ground walking and obstacle crossing tasks. Control subjects (n=5) and BKA subjects (n=4) were instructed to complete a series of functional walking tasks during each lab visit. The BKA subjects completed the walking protocol twice, first in their traditional passive prosthetic foot and again in the prescribed PPF after two weeks of acclimation. Motion data were collected via a 10-camera system with a 53-marker and 15-segment body model. Center of mass (CoM) motion and peak velocity within the frontal plane were analyzed and used as functional indicators of dynamic balance control. Preliminary findings from the study indicate that BKA subjects wearing the PPF generally experienced a greater mediolateral CoM motion and peak velocity, thus signifying a reduced ability to maintain dynamic balance control. Our findings may be of particular interest to clinicians and PPF designers working to improve the amputee population’s quality of life. Further data analysis is needed to support these initial findings.

The Effect of Rigid Ankle-Foot Orthotics on Joint Range of Motion and Temporospatial Parameters

Presenter: Therese Wichmann

Faculty Mentor: Shannon Pomeroy, Michael Hahn

Presentation Type: Oral

Primary Research Area: Science

Major: Human Physiology

Ankle arthritis is the debilitating deterioration of the joint cartilage, resulting in pain and diminished quality of life. A surgical fusion of the affected bones can be performed on the ankle to alleviate pain and remove damaged cartilage, but ankle range of motion (ROM) becomes severely limited. Rigid ankle-foot orthotics (AFOs) have had positive outcomes regarding ankle mobility, stability, and pain relief in clinical populations, however, much is unknown about how externally limiting motion affects gait function. This preliminary work will help determine how wearing AFOs affect ROM and temporospatial parameters. We performed standard gait analysis on 16 healthy adult subjects during a baseline walking test without wearing an AFO and throughout thirty minutes of wearing an AFO on a treadmill. Reflective markers were placed on anatomical landmarks to capture segment motion and calculate lower extremity joint angles. Changes in ROM and stride length were analyzed and compared from baseline to minute one, minute fifteen, and minute thirty within the AFO test. Initial results reveal noticeable changes compared to baseline. Continued collections and analysis will be utilized to observe how these acute changes form overtime with AFO use. These data will assist in determining how rigid AFOs maintain normal mobility despite restricting the ankle, potentially giving support to the usage of rigid AFOs in some ankle arthritis cases rather than invasive surgery.

Center of Mass Displacement with a Rigid Ankle-Foot Orthotic in Healthy Individuals

Presenter: Spencer Smith

Co-Presenters: Therese Wichmann, Shannon Pomeroy, Michael Hahn,

Faculty Mentor: Shannon Pomeroy, Michael Hahn

Presentation Type: Poster 83

Primary Research Area: Science

Major: Human Physiology

Ankle arthritis is inflammation of the articular cartilage, resulting in pain, stiffness and diminished quality of life. Ankle arthritis is often treated with a complete artificial fusion of the affected bones and removal of the damaged cartilage, which can lead to significantly altered gait and further long-term complications. Rigid ankle-foot orthotics (AFOs) have been used in similar clinical populations to stabilize the joint; however, they have been shown to retain many gait characteristics and improve stability despite limiting ankle range of motion (ROM). In order to better understand how the body adapts to such a sudden and severe limitation of ankle ROM, we performed a gait analysis on 16 healthy individuals within the lab. Each subject went through a normal baseline walking trial on the treadmill followed by a 30 minute walking trial in which they were equipped with a rigid AFO. We used motion capture cameras to collect the 3D motion of strategically placed reflective markers. Subsequently, whole-body marker position data was used to calculate and observe the subjects’ center of mass between walking without an AFO and with an AFO over time. Preliminary data analysis indicates that a rigid AFO may result in increased COM displacement with a range less than baseline following 30 minutes of AFO acclimation, suggesting that an AFO leads to return to more normal gait given an acclimation period.

Correlation of Ground Reaction Force Transient Impact Peak and Peak Lower Limb Acceleration in Elite Endurance Athletes

Presenter(s): Alex Denton − Human Physiology

Faculty Mentor(s): Michael Hahn

Poster 26

Research Area: Biomechanics

Stress fractures are the result of repetitive high impact loading on the skeletal system followed by insufficient recovery. Elite endurance athletes, such as competitive cross-country runners, are inherently at risk of developing stress fractures in the lower extremities. The purpose of this study was to identify the relationships between peak lower limb acceleration and ground reaction force (GRF) transient impact peak, as well as peak lower limb acceleration and GRF loading rate. It was hypothesized that both GRF transient impact peak and GRF loading rate would correlate with peak lower limb acceleration. Data was collected from 8 competitive endurance athletes using an instrumented split belt treadmill and three inertial measurements units (IMUs) placed on both shanks and superficial to the sacrum. Data were analyzed using a Matlab script to conclude peak lower limb acceleration is moderately associated with GRF transient impact peak, but peak lower limb acceleration is not associated with GRF loading rate. Further analysis of additional subjects is necessary to identify a quantitative abnormality in order to prevent stress fractures before they occur.