Thesis (M.S.M.E.)--University of Delaware, 2006 / Principal faculty advisors: Sun, Jian-Qiao, Dept. of Mechanical Engineering; Katherine Rudolph, Dept. of Physical Therapy. Includes bibliographical references.

Background: Unilateral transtibial amputees (TTAs) show subtle gait variations while using different prosthetic feet. These variations have not been detected consistently with previous experimental measures. In this research project a novel measure for quantifying kinetic gait differences among prosthetic feet, called Symmetry in External Work (SEW), was introduced. The reliability of the SEW measure was calculated and its correlation with selected clinical measures was determined. The SEW measure was then applied to determine gait differences among four categories of prosthetic feet during various functional activities. Methodology: The study was conducted in three phases. Phase I was a single subject Pilot study to determine the sensitivity of the SEW measure to different prosthetic feet and functional activities. In Phase II, test-retest reliability of the SEW measure was determined for 5 TTAs during the functional activities of level walking, incline walking, decline walking, ascending stairs, descending stairs, sit-to-stand and stand-to-sit. The agreement between SEW values obtained from F-scan and force plates was also calculated. In Phase III, 11 subjects underwent 6 testing sessions over a period of 10-12 weeks. In session 1 subjects were tested wearing their existing prostheses (Baseline session), were given specialized prosthetic training and were tested again after 2 weeks (Training session). For sessions 3 through session 6, subjects were tested with a study socket and one of four randomized test feet. The test feet were SACH, SAFE, Talux and Proprio foot, classified as K1_foot, K2_foot, K3_foot and MP_foot, based on Medicare Functional Classification Level. The Step Watch Activity Monitor (SAM) recorded their daily activities in the 10-14 day accommodation period between two sessions. At each testing session, subjects completed the Prosthesis Evaluation Questionnaire (PEQ-13) and Usability questionnaire, and were evaluated using the Amputee Mobility Predictor (AMP) and the 6-minute walk test (6MWT). Ground reaction forces were collected using F-scan in-sole sensors as subjects performed the above mentioned functional activities. SEW values between the intact limb and the prosthetic limb were computed by integrating vertical ground reaction forces. Intra-class Correlation Coefficients (ICCs) were calculated to determine test-retest reliability and a repeated measure ANOVA was used to establish differences between the prosthetic feet. Results: The ICC values for Test-Retest reliability ranged from 0.84-0.94 for the various functional activities. There was moderate agreement between the SEW values calculated with F-scan and force plates. The SEW values were significantly different between the K3_foot and other feet during level walking and decline walking. During stair ascent, the MP_foot had a significantly higher SEW value than the other feet. There were no differences between feet during incline walking and stair descent. Training resulted in a significant improvement in symmetry from the Baseline session during sit-to-stand, while for stand-to-sit there were no differences between sessions. The PEQ-13 score was not different between sessions, while the Usability scores were significantly different between the K3_foot/MP_foot and K1_foot/K2_foot. The AMP score had a significant increase following Training while the 6MWT score showed a significant increase in the distance walked with the K1_foot, K3_foot and MP_foot over Baseline. The output of SAM did not show any difference in the number of steps or activity level of subjects. There was good to excellent correlation between the SEW values for level walking and other clinical outcome measures. Discussion and Conclusion: The SEW measure had excellent test-retest reliability and the agreement between the F-scan and force plates values could not be established because of a small sample size. The variations in SEW values were the result of distinctive designs of prosthetic feet. The high SEW value of the K3_foot can be attributed to its heel-toe foot plate and "J" shaped ankle spring design, which allowed for greater late stance stability. The active dorsiflexion feature of the MP_foot caused a change in strategy, typically used during stair ascent, resulting in a greater inter-limb symmetry. The SEW measure is a viable method to detect kinetic gait differences among prosthetic feet and represents a resource-effective alternative to traditional gait laboratories. It has several advantages and with further development of in-sole sensor technology, the potential for clinical use due to its relatively low cost instrumentation and minimal subject intervention.

The goal of this research work was to introduce the whole process of developing and validating a 3D lower extremity musculoskeletal model and to test the ability of the model to predict the muscles recruitment of the different muscles involved in human locomotion as well as determining the corresponding forces and moments generated around the different joints in the lower extremity. Therefore the model can be applied in one of the important fields of orthopaedics which is joint replacement; the case study used in such application is the total knee replacement. The knee reaction forces were compared to the pattern obtained by Harrington (1992), where the hip moment components (Flexion/extension, internal/external, and abduction/adduction) were all compared to the patterns obtained from the Hip98 data base. It was shown in the different graphs of joints forces and moments that the model was able to produce very close results when comparing pattern and magnitude to the literature data. Thus, this 3D biomechanical model is sophisticated enough to be used for surgery evaluation such as in total knee replacement, where the damaged cartilage and bone are removed from the surface of the knee joint and replaced with a man-made. The case study of the second part of the research work presented involved the comparison of the gait pattern between two main knee joint types, Metallic and Allograft knee joints against normal subjects (Control group). A total of fifteen subjects participated in this study, five subjects in each group. It was concluded that based on the study conducted and the statistical evidence obtained that the introduced model can be used for applications that involves joint surgeries such as knee replacement that ultimately can be utilized in surgery evaluation.

The aim of this study was to determine the combined effects of high-heeled shoes and load carriage on gait and posture adaptation. Furthermore, the adaptation of gait and posture to the combined two conditions was examined by a comparison of the measured parameters between experienced and novice groups. 30 participants underwent a quantitative measurement of temporospatial, kinematic, and kinetic parameters of hip, knee, and ankle on both loaded and unloaded limbs using 3D motion analysis. Double support time and stride length increased during high-heeled gait and the magnitude of alteration was greater with a load. Increased plantarflexion was main cause of raised heel. Ankle plantarflexor moment increased with high-heeled but decreased with load carriage. As a result, plantarflexor moment diminished, in addition knee extensor moment exaggerated further. Hip extensor moment increased with heel height but not with load weight, however, hip angle was affected only by the load.

With the popularity of outdoor activities like hiking, the demands of certain types of employment, or being a student, an individual’s ability to carry a load is an important mobility consideration. By understanding the changes to an individual’s gait when supporting a backpack load, an individual’s ability to carry heavy loads for prolonged periods could be improved. Most biomechanical studies have examined the changes in able-bodied gait when carrying a load. However, research is lacking on the effect of backpack loads on amputee gait patterns. This project examined the effects of a backpack load on the gait patterns of unilateral transtibial amputees. Ten participants performed walking trials on four surfaces (level ground, uneven ground, walking up an incline, and walking down an incline), without a pack and with a pack. A total of 40 trials were collected per subject, with 10 trials collected on each surface. Three-dimensional motion data were collected with an eight-camera Vicon Motion Analysis system to describe limb motion as well as compare kinematic outcomes between tasks and conditions. Force platform data were collected during the level ground trials and used to calculate kinetic measures for both limbs. With the addition of the pack changes were seen on each surface, with different changes occurring to each limb. The ramp up surface created the most changes when comparing the two conditions. The only change seen across all four surfaces was a decrease in ankle dorsiflexion before push-off on the prosthetic limb. The two next most common changes were increases in knee and hip flexion during weight-acceptance.

The effects of multiple sclerosis (MS) on the central nervous system often manifest as abnormalities in gait kinematics. Clinically practical, valid, and reliable measures of gait kinematics are necessary to address research and clinical questions about MS. Wireless flexible electrogoniometry (EG) is a clinically practical measure of joint angles. The GAITRite walkway system is a clinically practical, valid and reliable measure of temporal and spatial gait characteristics. The overall objective of this two-study research project was to explore whether these clinically practical measures of gait kinematics can be used to accurately detect gait abnormalities in people with multiple sclerosis. Study 1 examined the reliability and validity of EG and Study 2 examined the gait kinematics of people with MS (PWMS) using EG and GAITRite. For Study 1, angle at initial contact and total joint excursion were measured by EG at both the knee and ankle while ten healthy adults walked at a self-selected comfortable speed. Measurements were repeated for two testers and two visits to assess reliability. The same variables were measured concurrently with three-dimensional motion analysis (3D) to assess validity. For all variables, reliability was good as indicated by low measurement error and validity was good as indicated by association and agreement of EG with 3D. For Study 2, the same joint angles, along with speed, cadence, step length, stride length, stance duration and double support duration were assessed for six PWMS and six controls without MS. PWMS showed significantly reduced speed, cadence, and ankle excursion and increased stance and double support duration as previously shown with 3D. Spasticity and/or instability may lead to these kinematic gait abnormalities in PWMS; however, reduced velocity may confound this interpretation by affecting the other observed gait abnormalities. Further research about the determinants of gait dysfunction in PWMS is required. EG and GAITRite are clinically practical, valid and reliable measures of gait kinematics and should be included in further clinic-based research to determine which kinematic gait abnormalities are causes and which are effects of the observed decrease in gait speed in PWMS.

Individuals with Multiple Sclerosis commonly use assistive mobility devices, such as rollators, to compensate for their mobility impairments. However, the effect of these devices on their foot placement during gait has not been explored in the community. The objective of experiment one was to develop and validate a tool that quantifies medio-lateral foot placement characteristics during rollator use. In this study, a technique was developed for an instrumented rollator (i.e. iWalker) and validated against a Vicon motion capture system in able-bodied young adults. The two systems were in strong agreement. The objective of experiment two was to apply this iWalker-based technique to individuals with Multiple Sclerosis to identify environment-related foot placement changes. This study revealed that step width variability, but not step width, can be influenced by certain outdoor environments. Therefore, environmental context is important to consider when investigating user-device interactions and factors responsible for safe mobility in this population.

Individuals with Multiple Sclerosis commonly use assistive mobility devices, such as rollators, to compensate for their mobility impairments. However, the effect of these devices on their foot placement during gait has not been explored in the community. The objective of experiment one was to develop and validate a tool that quantifies medio-lateral foot placement characteristics during rollator use. In this study, a technique was developed for an instrumented rollator (i.e. iWalker) and validated against a Vicon motion capture system in able-bodied young adults. The two systems were in strong agreement. The objective of experiment two was to apply this iWalker-based technique to individuals with Multiple Sclerosis to identify environment-related foot placement changes. This study revealed that step width variability, but not step width, can be influenced by certain outdoor environments. Therefore, environmental context is important to consider when investigating user-device interactions and factors responsible for safe mobility in this population.

The aim of this study was to determine the combined effects of high-heeled shoes and load carriage on gait and posture adaptation. Furthermore, the adaptation of gait and posture to the combined two conditions was examined by a comparison of the measured parameters between experienced and novice groups. 30 participants underwent a quantitative measurement of temporospatial, kinematic, and kinetic parameters of hip, knee, and ankle on both loaded and unloaded limbs using 3D motion analysis. Double support time and stride length increased during high-heeled gait and the magnitude of alteration was greater with a load. Increased plantarflexion was main cause of raised heel. Ankle plantarflexor moment increased with high-heeled but decreased with load carriage. As a result, plantarflexor moment diminished, in addition knee extensor moment exaggerated further. Hip extensor moment increased with heel height but not with load weight, however, hip angle was affected only by the load.

Hexplorer is a six-legged walking robot developed at the University of Waterloo. The robot is controlled by a network of seven digital signal processors, six of which control three motors each, for a total of 18 motors. Brand new custom electronics were designed to house the digital signal processors and associated circuitry. A variable duty factor wave gait, developed by Yoneda et al. was simulated and implemented on the robot. Simulation required an in-depth kinematic analysis that was complicated by the mechanical design of parallel mechanism comprising the legs. These complications were handled in both simulation and implementation. However, due to mechanical issues Hexplorer walked for only one or two steps at a time.