Novel Assessment Of Gait And Mobility Function In Transtibial Amputees

Author: Brenton Graham Hordacre

Hordacre, Brenton Graham, 2014 Novel Assessment Of Gait And Mobility Function In Transtibial Amputees, Flinders University, School of Health Sciences

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Lower-limb amputees require extensive rehabilitation to restore gait and mobility function and achieve successful re-integration into the community. Decreasing length of hospital stays and resources shortages have increased the need for more efficient treatment to hasten recovery. However, complex issues such as older age, various levels of amputation and associated comorbidities pose additional challenges to the restoration of gait and mobility function. Much research into lower-limb amputees has focussed on vascular interventions and prosthetic technology, with limited literature investigating alternative approaches to characterise gait and mobility function. A good understanding of issues influencing amputee rehabilitation is necessary to help identify aspects of amputee rehabilitation requiring attention and to drive more effective and efficient rehabilitation approaches. New assessments of gait and mobility function have the potential to progress our understanding of lower-limb amputee rehabilitation. The purpose of this thesis was to investigate novel assessments of gait and mobility function in transtibial amputees. These assessments were investigated from a clinical rehabilitation perspective to determine their potential contribution to future amputee rehabilitation. There are four sections to this thesis. The first section established the state of amputee rehabilitation in Australia by reviewing contemporary data from amputee rehabilitation services at a national level (n = 6,588), and from a single regional rehabilitation service (n = 531). Trends for increasing length of stay and decreasing age were identified. Many amputees (43.4%) presented with multiple comorbidities. Time to achieve key rehabilitation milestones increased over the period of observation. These findings identified shifts in patient characteristics which affected the timely and optimal restoration of function by amputee rehabilitation services. New and novel assessments of gait and mobility function may assist future amputee rehabilitation and should be investigated. Greater understanding of amputee gait and mobility may allow for more efficient functional assessments and identify individuals likely to need additional therapy input, assisting rehabilitation units in planning and prioritising treatment. The second section of the thesis investigated the potential that spatial-temporal gait variability has as a measure of gait function in transtibial amputees. Forty-seven community dwelling amputees were recruited from the single prosthetic rehabilitation facility reviewed in the first section of this thesis. The influence of intra-subject gait speed variability was examined and the variability of speed normalised spatial-temporal gait parameters was calculated for individual participants. Greater normalised gait variability was observed in amputees with a history of falls. This study identified that gait variability may be an important measure of gait function and additionally demonstrated the importance of normalising for walking speed in the analysis of gait variability. The third section of the thesis investigated wearable technology as a novel method to assess community activity and participation. Amputees recruited for the previous gait variability study also participated in this experiment. Data from an accelerometer based device to assess step counts, and a global positioning system (GPS) to assess community visits, were linked to identify community activity and participation. Measures of activity and participation in the community were negatively associated with normalised gait variability, further suggesting gait variability is an important clinical marker of gait function. The final section of the thesis investigated the use of transcranial magnetic stimulation to determine if neurophysiological measures of brain function may assist clinical practice as neural biomarkers of gait function. A subset of community living transtibial amputees who had participated in the previous studies were recruited. A ratio of corticomotor excitability of ipsilateral and contralateral projections to the amputated limb (index of corticospinal excitability, ICE) was calculated. Relatively greater excitability of ipsilateral compared to contralateral projections to motoneurons innervating residual muscles of the amputated limb was associated with increased normalised gait variability. Further investigation of the contribution of ipsilateral and contralateral motor cortex to gait function was conducted in amputees completing prosthetic rehabilitation. Bilateral reorganisation of the motor cortex occurred following lower-limb amputation and continued through prosthetic rehabilitation. Intracortical inhibition within a hemisphere at key phases of rehabilitation was predictive of gait function at discharge. For the contralateral motor cortex, reduced intracortical inhibition at admission to rehabilitation and when undertaking first walk with a prosthetic limb was associated better gait function. However, for the ipsilateral motor cortex, reduced intracortical inhibition at discharge from rehabilitation was associated with poor gait function. Combining outcomes from these two studies, it appears that ongoing cortical reorganisation of the ipsilateral motor cortex following rehabilitation is associated with poor gait function. Both ICE and intracortical inhibition may be appropriate neurophysiological biomarkers of gait function in transtibial amputees. In summary, three aspects of gait and mobility function in transtibial amputees were investigated. These findings expand current understanding of amputee gait and mobility and demonstrate the importance of investigating alternative assessments that may improve outcomes of clinical rehabilitation. The results of the work in this thesis have potential to improve understanding and knowledge of transtibial amputee rehabilitation and may inform future studies to improve outcomes of amputee rehabilitation.

Keywords: amputee,rehabilitation,transcranial magnetic stimulation,wearable technology

Subject: Health Sciences thesis

Thesis type: Doctor of Philosophy
Completed: 2014
School: School of Health Sciences
Supervisor: Professor Maria Crotty