Bibliography: leaves 196-251 / ii, 251 leaves : ill ; 31 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, 1987

Neural prostheses (NPs) are electronic stimulators that activate nerves to restore sensory or motor functions. Surface NPs are non-invasive and inexpensive, but are often poorly selective, activating non-targeted muscles and cutaneous sensory nerves that can cause pain or discomfort. Implanted NPs are highly selective, but invasive and costly. The stimulus router system (SRS) is a novel NP consisting of fully implanted leads that capture and route some of the current flowing between a pair of surface electrodes to the vicinity of a target nerve. One end of an SRS lead has a pick-up terminal that is implanted subcutaneously under the location of a surface electrode and the other end has a delivery terminal that is secured on or near the target nerve. The studies presented in this thesis address the development of the SRS from animal testing to its implementation as an upper extremity NP in a tetraplegic subject. Chapters 2 and 3 describe the SRSs basic properties, provide proof-of-principle of the system in animal studies and identify aspects that maximize its performance as a motor NP. The studies showed that selective and graded activation of deep-lying nerves can be achieved with the SRS over the full physiological range. Long term reliability of the system was demonstrated in chronic animal studies. The surface current needed to activate nerves with a SRS was found to depend on the proximity of the delivery terminal(s) to the target nerve, contact areas of the surface electrodes and implanted terminals, electrode configuration and the distances from the surface anode to the surface cathode and delivery terminal. Chapter 4 describes the first human proof-of-principle of the SRS during an intra-operative test. Finally, Chapter 5 describes the implementation of the SRS for restoration of hand function in a tetraplegic subject. Stimulation parameters and force elicited through the SRS, along with usage of the device were monitored up to 10 months after implantation. The system was found to be useful, reliable and robust. It is argued that the results of these studies indicate that the SRS provides the basis for a new family of NPs.

Thesis (M.S.)--Chemical Engineering, Georgia Institute of Technology, 2003. / Sambanis Athanassios, Committee Member ; Sotiropoulos Fotis, Committee Member ; Yoganathan Ajit, Committee Chair. Includes bibliographical references (leaves 239-243).

Thesis (M.S.)--Chemical Engineering, Georgia Institute of Technology, 2004. / Sambanis Athanassios, Committee Member ; Sotiropoulos Fotis, Committee Member ; Yoganathan Ajit, Committee Chair. Includes bibliographical references (leaves 239-243).

Thesis (Ph. D.)--University of Washington, 2003. / Vita. Includes bibliographical references (leaves 104-125).

Thesis (Ph.D)--Biomedical Engineering, Georgia Institute of Technology, 2008. / Committee Chair: Elliot Chaikof; Committee Member: Marc Levenston; Committee Member: Robert Nerem; Committee Member: Vincent Conticello; Committee Member: Yadong Wang. Part of the SMARTech Electronic Thesis and Dissertation Collection.

Testing gait rehabilitation devices on humans can be a difficult task, due to the effects of the neurological controls of the human body. This thesis advances the use of a passive dynamic walker (PDW) tuned to have asymmetric gait patterns similar to those with physical impairments to test rehabilitation devices. A passive dynamic walker is a multipendulum system that has a stable gait pattern when walking down a slope without any energy inputs except the forces due to gravity. A PDW model is better suited for testing rehabilitation devices because it has been shown to resemble human gait and separates the human neurological controls from the purely dynamic aspects of walking. This research uses different asymmetric gait patterns based on an asymmetric PDW to aid in the design of current and future rehabilitation methods. There are four major parts to this research: (1) the derivation of the current nine mass PDW model, (2) the effects of changing the moment of inertia and center of mass on each leg, (3) the effects of having a leg that is longer than the other and adding masses on the opposite leg to generate a symmetric gait, and (4) the design of a theoretical prosthesis that will break the assumption that the knee on the prosthetic leg should be in the same location as the intact leg. The result of changing the moment of inertia and center of mass on each leg in the nine mass model showed that it is an improvement over the previously used five mass model. This is because the five mass model forces the center of mass to change with the moment of inertia, while the nine mass model allows these to be changed independently of each other. A theoretical prosthesis has been developed in this research that is is significantly lighter while maintaining a symmetric gait. This was accomplished by moving the knee of the prosthetic limb below the location of the intact knee.

The human wrist is a vital joint in daily life, and it is subject to injuries and disease. Currently, severe wrist disease is normally treated with wrist arthrodesis, which is normally reliable but results in a fixed wrist incapable of allowing wrist motion. Another method of treating a nonfunctional or severely painful wrist is wrist arthroplasty where the wrist joint is replaced with an implant that allows wrist movement. As of yet, a suitable wrist implant has not been developed, especially for the case of the post-traumatic, young male wrist, and most current wrist implants fail from failure of the bone-implant interface. Through simulation and literature review, it is concluded that implants that restrict axial rotation are bound to fail overtime. With this conclusion, a new wrist implant prototype is designed that incorporates state of the art materials, fluid film lubrication, proper kinematics, a suitable range of motion, and more. This implant contributes several improvements to the field of wrist arthroplasty. / text

Background There are more than 300,000 persons in the U.S. living with transfemoral amputation (TFA). Persons with TFA use a knee prosthesis for gait and mobility. Presently, the C-Leg microprocessor knee prosthesis is the standard of care. C-Leg has significantly improved safety and cost efficacy and has created modest gains in gait efficiency. Recently, a new prosthesis has introduced a new sensor array and processor that reportedly improves knee motion, stair function and standing stability. Early claims of the reported functional benefits of the new Genium knee (formerly X2) have not been validated in a rigorous clinical trial. Therefore, the purpose of this project was to determine if the Genium knee improves safety, function and quality of life compared to the current standard of care (C-Leg). Methods The study is a randomized AB crossover with a control group. Subjects must have used (and still be using) a C-Leg for a minimum of 1yr prior to enrollment. Inclusion criteria beyond this are unilateral transfemoral or knee disarticulation amputation for any etiology, community level ambulation (Medicare level 3 or above), independent ambulation and ability to independently provide written, informed consent. Once enrolled subjects utilize their same socket but receive a study foot (Trias or Axtion). Subjects are randomly assigned to either stay with their C-Leg or be fit with a Genium knee. Subjects accommodate and test (A phase) then crossover to the other knee condition and repeat the testing (B phase). A follow up phase of the study beyond the B phase is ongoing to study longer term preference. For AB assessment, three domains were assessed: Safety, function and quality of life. For safety, the PEQ-A survey of stumbles and falls, posturography (Biodex SD limits of stability and postural stability tests), 4 square step test and 2 minute ramp stand test were completed. For function, a series of timed walking tests, the amputee mobility predictor, kinematic gait assessment and physical functional performance-10 tests were conducted. For quality of life, the socioemotional and situational satisfaction domains of the population specific and validated PEQ (prosthesis evaluation questionnaire) were completed. Results Safety: Posturographic assessment revealed impairment between transfemoral amputees and non-amputees. Stumbles and semi-controlled falls decreased with Genium but were not significantly different. Four square step testing was significantly (p 0.05) improved from 12.2s(3.3) to 11.1s(3.4) for the C-Leg and Genium respectively. Function: Kinematic asymmetry was minimally different between knee conditions. The AMP mean(SD) scores while subjects used C-Leg was 40.8(3.6; 33-45) and 43.3(2.6) [p<0.001]. PFP scores (cumulative), upper body function and endurance scores were improved with Genium compared with C-Leg at 9.1%(p=0.03), 8.7%(0.01) and 10.3%(0.04) respectively. Quality of Life: For quality of life, situational satisfaction favored Genium (p<0.001) which included subject's satisfaction with gait, training and quality of life in general. Conclusion C-Leg and Genium promote static weight bearing beyond asymmetric values reported in the literature. In terms of limits of stability, TFA's are clearly impaired, primarily over the amputated side posteriorly however the Genium seems to enable posterior compensations that coincide with multi-directional stepping improvements. Anteriorly, the C-Leg's toe triggering requirements seem to improve limits of stability but come at the cost of discomfort on ramp ascent. With regard to safety, it seems that both knee systems represent good options for the community ambulating TFA. The largest improvements with Genium were in the activities of daily living assessment; predominantly balance and upper body function. It seems that the combination of multi-direction stepping with starts and stops and stair ascent are key areas of improvement. In conclusion, the sensor array in the Genium knee prosthesis promotes improved function in activities of daily living. Specifically improved in this context were balance, endurance, multi-directional stepping, stair ascent and upper limb function in highly active transfemoral amputees.

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