Award Date


Degree Type


Degree Name

Doctor of Philosophy (PhD)


Interdisciplinary Programs

First Committee Member

Szu-Ping Lee

Second Committee Member

Gaby Wulf

Third Committee Member

Robert Gregor

Fourth Committee Member

Mark Grabiner

Fifth Committee Member

Lung-Chang Chien

Number of Pages



Previous studies have shown that individuals with various physical, sensory and neuromuscular impairments are at higher risks of falls. Individuals with unilateral transtibial amputation (UTTA) suffered from all these impairments, and tripping not surprisingly caused a considerable number of falls in this population. To study falls, researchers have to put participants in a well-protected environment and reproduce tripping fall scenarios. Furthermore, the perturbation delivery needs to be precise in terms of temporo-spatial timing. These features would ensure the quality of responses elicited and reproducibility of the results. Thus, in Chapter 2, we developed a treadmill-based perturbation delivery protocol and confirmed that by referencing ground reaction force, the system was able to consistently and precisely deliver perturbations in early stance phase to elicit tripping falls.Because tripping usually arrests only one side of the limb, individuals with UTTA may respond differently when encountering trips with their prosthetic versus non- prosthetic limb. Understanding the biomechanical differences in fall recovery response between these two tripping conditions will facilitate ideas for patient-specific intervention targeting tripping fall prevention. Therefore, in Chapter 3, we utilized the protocol developed in Chapter 2 to deliver destabilizing perturbations to the participants in order to examine the limb-to-limb differences during fall recovery. We found that while the gross fall recovery strategies (i.e. the stepping response) were similar, there existed key biomechanical differences. Perturbation during a static standing condition was typically arrested with the perturbed limb making the recovery step. Dynamic perturbation condition was recovered with the contralateral (non-perturbed) limb making the first recovery step followed by the ipsilateral limb making the reciprocal second recovery step. We observed that certain defined response times were longer when the recover step was executed by the prosthetic limb in both static and dynamic perturbation conditions, suggesting the impaired sensory detection or motor execution of the prosthetic limb. Currently, clinical practitioners are encouraged to include balance training in post amputation rehabilitation. A balance training that focuses on weight-shifting may prepare individuals with lower limb loss the essential ability to make successful recovery step when encountering destabilizing scenarios. However, it is currently unknown if a training program focusing solely on balance control can improve fall recovery response. Hence, in Chapter 4, we examined the effects of a 2-day weight-shifting balance training using protocols developed in Chapters 2 and 3. We found that certain biomechanical variables relevant to weight-shifting and weight-bearing during fall recovery were altered by the training. For instance, the duration for unloading the prosthetic limb before taking the recovery step during static perturbation condition were improved after training. Another example was that when the prosthetic limb was perturbed, the duration of the first recovery step increased; meanwhile, when the non-prosthetic limb was perturbed, the duration of the second recovery step increased. These two durations were the non- prosthetic limb executing the recovery step in which the prosthetic limb providing the stance support, and the stance time increased. Overall, our findings suggest that sensorimotor deficits related to UTTA may lead to longer duration of step time when the prosthetic limb executed the recovery step. This is a promising direction to intervene in the future. Our balance training protocol appears to improve components that were related to participants’ weight-shifting ability. Whilst for altering the global fall recovery responses, we concluded that a more perturbation-based approach may be required and should be investigated in the future.


Amputation; Balance Training; People with disabilities--Rehabilitation



File Format


File Size

1634 KB

Degree Grantor

University of Nevada, Las Vegas




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Biomechanics Commons