PhD Projects for Prospective Students

• Lifespan Gait
• Muscle stiffness reduction in healthy and pathological populations
• Amputee Gait
• Sensorimotor integration in the hand

Note: Parts of these projects may be suitable for AMS, Honours, or Masters  students

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Lifespan Gait

Contact person: Dr Noel Lythgo

Gait maturation is a major developmental milestone in early childhood. In contrast, gait changes in the elderly usually signal the need for a change of lifestyle and possibly supported living. There is an indisputable need to acquire reference data in order to examine the variability in healthy people and mechanisms of gait maturation, malfunction and decline. Current decisions about the quality or abnormality of gait are based on limited reference data that is unrepresentative of specific age groups.
Technology now available at the Rehabilitation Sciences Research Centre allows the easy collection and examination of numerous gait parameters over many trials for large groups of people within a laboratory or field setting. The current generation of instrumented gait mats, such as the GAITRite walkway system for example, allows gait to be comprehensively examined since large amounts of data can be collected in relatively short periods of time. High speed 3-dimensional motion analysis systems combined with force plates allow the collection of complex information such as lower limb joint powers and moments, foot clearance, joint angular data and segment accelerations. Importantly, these systems allow the mechanisms of gait to be examined. The specific aims of this work are to: (1) develop a reference data set of walking in healthy people (2) identify markers of gait maturation and decline; (3) better understand mechanisms of gait maturation and decline; and (4) better understand gait in even (level ground) and uneven terrain (e.g. stairs or steps) and terrain requiring a sudden stop or turn.

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Muscle stiffness reduction in healthy and pathological populations

Contact person: Dr Noel Lythgo, Prof Mary Galea

Short resting lengths of the lower limb muscles restrict mobility and can lead to acute injuries such as Achilles tendon rupture or chronic injuries such as plantar fasciitis.   In populations recovering from pathologies such as a stroke, high levels of muscle stiffness in the gastrocnemius and soleus muscles restrict movement by reducing the amount of dorsi and plantar flexion in the stance phase of gait. Basically, reductions in the range of lower limb motion predispose a person to injury and lessen the capacity of people recovering from pathology to live independently or move freely within the community.  
The aim of this research is threefold. Firstly, to develop innovative measurement techniques (eg. muscle length) in order to better understand the mechanisms behind muscle stiffness. Secondly, to ascertain the value of intervention programs designed to prevent, alleviate or reduce muscular stiffness. By so doing, the degree or extent of departure from normal movement can be determined and the progressive changes resulting from intervention strategies can be assessed. The specific interventions to be undertaken involve eccentric exercise programs, muscle and neural stimulation by vibration systems, PNF and traditional stretching. Thirdly, to examine the effects of different whole body vibration systems upon muscle stiffness and length-tension especially in people recovering from stroke.

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Amputee Gait

Contact person: Dr Noel Lythgo

Project 1
Recent advances in lower limb prosthetic design (knee and foot devices) claim to improve walking smoothness, movement efficiency and physical function by reducing factors such as hip hiking (reduces energy cost), increasing foot-ground/obstacle clearance and push-off power (increases walking speed and ability to avoid obstacles such as a step or low barrier). Although work has provided valuable information about the characteristics of amputee gait in level terrain, it has not provided any insight into the characteristics of amputees when traversing uneven or winding terrain commonly encountered in “everyday” life. These terrains are challenging since they may require a sudden increase or reduction in speed (e.g. pedestrian crossings), a sudden change in direction to avoid an object such as a pothole or accommodation of an object such as a step or stair.

This project has four aims. Firstly, to examine the gait patterns of a group of unilateral above knee amputees in even (flat ground) and uneven (containing a step or small obstacle) terrain, and in terrain that requires a change of direction. Secondly, to examine the effect of knee and foot prosthetic devices (traditional versus novel) upon amputee gait in these terrains. The selected knee devices have different braking and damping qualities, whereas the selected foot devices differ in stiffness or rigidity. Specifically, gait patterns will be examined in terrain that requires level walking at preferred and fast speeds, step ascent and descent, obstacle avoidance and steering control. A second aim is to ascertain the effect of knee/foot device (traditional versus novel) upon daily physical activity, duration and function. The final aim is to develop superior gait models through software development to record amputee gait. The gait patterns of the amputees will be recorded by a high-tech “state of the art” motion analysis system housed in the Movement Laboratory at the RSRC. The system simultaneously records distance and speed measures of gait and measures of muscular force and timing. This information is then used to derive precise measures of limb movement such as 3D joint angles, limb rotary forces and muscle activation.

Project 2
The purpose of any artificial limb / prosthesis is to restore some function and mobility. The lower limb prosthesis for a trans-tibial amputee (amputation below the knee) consists of a socket enclosing the stump, a shank and a foot. The most important aspect of a lower leg artificial limb is the socket, which constitutes the critical interface between the amputee’s stump and prosthesis. The design and fitting of the socket is the most difficult task due to the uniqueness of each amputee’s stump. Every fitting requires much attention from the prosthetist. Although there exists some systematic guidelines to design and fit sockets, a successful fitting is still highly dependent on the skill and experience of the prosthetist. This project is to develop a robust and highly portable scientific technique for socket production and fitting. The technique is based on a novel pressure casting technique (PCSAT).  Essentially, subjects place their stump in a tank so that it is separated by a diaphragm (i.e. stump is kept dry) and low pressure is introduced to the stump by water. Prior to the amputee placing his/her stump in the tank, a plaster wrap cast is applied over the stump. The patient then stands without any aid in a normal standing position (weight bearing position) where half their body weight is supported by the water on the amputated side. Weight bearing is a unique feature of the PCAST technique compared to all other techniques used to take a cast. Upon the plaster wrap hardening, the system depressurises and the plaster is removed from the stump. A positive model is generated from the wrap cast and then a socket made using traditional lamination methods. A very important aspect of this project is  that no rectification of the cast is required. Rectification is a labour-intensive process that is highly dependent on the skill of the prosthetist.
The main advantage of this technique is that it allows socket fitting to be done scientifically and yet speedily. It lets gravity and the subject’s weight determine the shape of the socket. The pressurised casting technique has the potential to produce high quality socket fittings that can be objectively assessed by scientific methods. If successful, this technique will reduce skill dependency in fitting an artificial limb which will ultimately lead to a reduction in fitting errors (i.e. reduced patients visits, improved services, improved comfort).
The specific aims of the project are,
• To further refine and perfect the PCAST technique.
• To evaluate PCAST in a clinical setting.
• To measure, through gait analysis and pressure mapping, the biomechanical outcomes of the PCAST socket.

 

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Sensorimotor integration in the hand


Contact Person: Prof Mary Galea

The purpose of this project is to investigate some of the mechanisms underlying sensorimotor integration in the hand, through observation of performance of a simple manipulative task.  The hand is the primary way by which we interact with the environment.  Through exploration and manipulation of everyday objects, we are able to learn about our environment and perform essential tasks. This project will explore the mechanisms of sensorimotor integration in people with central or peripheral nervous system injury using a simple grasp and lift task. Information about force generation at the fingertips is collected from two highly sensitive strain gauge transducers located within the grasping surfaces of the test object (Figure 1)

Participants for this project will have either suffered a first time stroke, have a diagnosed peripheral neuropathy affecting the hands, or have another neurological disease (e.g. MS). Clinical assessments of neurological function (sensory, motor and functional tasks) will be performed. Participants will then be asked to grasp the test object using a precision grip, lift it approximately 5cms vertically and hold it in this position for approximately 5 seconds before gently replacing the object back on the table and releasing their grip.  Characteristics of the test object, such as the weight, curvature and texture will be systematically varied between lifting trials. Grip force, loading force and minimum force required to prevent the object dropping will be recorded.



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