Reverse shoulder arthroplasty (RSA) is a joint replacement procedure used mainly to treat patients with severe shoulder osteoarthritis combined with massive rotator cuff tears. It involves reversing the `ball and socket' orientation of the glenohumeral joint in the shoulder. While RSA has been largely successful in treating pain and improving function in these patients, complication rates remain high. Many of these complications, including joint instability and scapular notching (excessive bone wear), are caused or exacerbated by impingement of the humerus or the humeral component against the scapula. Adduction deficit refers to a patient's inability to fully adduct the arm due to impingement. Minimizing adduction deficit may improve RSA patients' functional outcomes. An existing mechanical shoulder simulator was further developed to model glenohumeral range of motion in RSA. The three heads of the deltoid were modelled using polyethylene cable and electric linear actuators with inline load cells. RSA components were implanted in Sawbones scapula and humerus bone models. The scapula was fixed in the frame of the simulator. Triads of optical tracking markers were attached to the humerus and simulator frame and used to track segment motion. A data analysis technique was developed to determine when joint impingement occurred. The convex and concave surfaces of the glenoid and humeral components were digitized, and a least-squares sphere fit was used to find their centres. The distance between these centres was then calculated during passive abduction and adduction of the humerus, and labeled d_GH. Impingement onset was defined as the point where d_GH was five standard deviations above its baseline value, indicating that the components were no longer concentric. This technique was used to determine the effects of humeral neck-shaft angle, socket depth, glenosphere diameter and eccentricity on range of motion and adduction deficit. A retentive humeral cup depth increased adduction deficit by 14 degrees and reduced range of motion by 26 degrees. A decreased neck-shaft angle reduced adduction deficit by 10 degrees but had little effect on overall range of motion. Diameter and eccentricity had no effect on either measure. / Thesis (Master, Mechanical and Materials Engineering) -- Queen's University, 2014-04-03 13:34:07.404

There is little evidence that Health Technology Assessment (HTA) is much used in dentistry. Dental implant technology is an example of innovative oral health technology. The objectives of this research were to gather the evidence needed for the assessment of overdenture implant treatment so that both patients and dental practitioners can make informed decisions about this technology. These objectives included 1) investigating what types of dental clinicians adopt and provide dental implants 2) determining the effect of the clinicians' experience in the provision of implant supported prostheses and 3) measuring the patients' preference in provision of mandibular 2-implants overdenture technology. / For the first part, a cross-sectional survey was sent to all licensed Canadian Dentists to measure the adoption and provision of implant technology. For the second part, we used the data on the first 140 edentulous elders who were enrolled in a randomized controlled clinical trial to compare the effects of mandibular conventional (CD) and 2-implant overdentures (IOD) on nutrition. The change in patient ratings of satisfaction after treatment, laboratory costs and the number of unscheduled visits were compared. For the last part, edentulous elders (N=36) who were wearing maxillary dentures and either a mandibular conventional denture (CD, n=13) or a two-implant overdenture (IOD, n=23) participated in this study. Participants' preference was measured during a 20-minute interview. / Multivariate regression analysis on the data from the first part of the study shows that the Dentist's gender, province of practice, specialty, and whether they practice alone or in association with other practitioners, are significantly associated with the adoption of implant technology (p<0.05). It is also shown that there was no difference in satisfaction scores for either prosthesis between the groups treated by experienced specialists or new dentists. Furthermore, it is shown that IOD wearers were willing to pay three times more than the current cost of conventional dentures for implant prostheses (p<0.05). / Overall, the results of this study 1) inform decision makers on what types of clinicians provide implant technology and 2) suggest that, with minimal training, all dental clinicians irrespective of their specialty, can provide successful implant overdenture prostheses that edentulous patients are willing to pay for.

To a person with an upper limb amputation or congenital defect, a well-functioning prosthesis can open the door to many work and life opportunities. A fundamental component of many modern prostheses is the myoelectric control system, which uses the myoelectric signals from an individual's muscles to control prosthetic movements. Though much research has been done involving the myoelectric control of arm and gross hand movements, more dexterous finger control has not received the same attention. Consequently, the goal of this study was to determine an optimal approach to the myoelectric signal classification of a set of typing motions. Two different movement sets involving the fingers of the right hand were tested: one involving digits two through five (4F - "four finger"), and the other involving digits one and two (FT - "finger/thumb"). Myoelectric data were collected from the forearm muscles of twelve normally-limbed subjects as they performed a set of typing tasks. These data were then used to test a series of classification systems, each comprising a different combination of system element choices. The best classification system over all subjects and the best classification system for each subject were determined for both movement sets. The optimal subject-specific classification systems yielded classification accuracies of 92.8 ± 2.7% for the 4F movement set and 93.6 ± 6.1% for the FT movement set, whereas the optimal overall classification systems yielded significantly lower performance (p<0.05): 89.6 ± 3.4% for the 4F movement set and 89.8 ± 8.5% for the FT movement set. No significant difference in classification accuracy was found between movement sets (p=0.802). A two-way repeated measures ANOVA (α=0.05) was used to determine both significance results. / Thesis (Master, Electrical & Computer Engineering) -- Queen's University, 2008-10-31 14:59:43.151

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Animals effectively move and negotiate a variety of environments exemplifying the neuromuscular system's ability to produce complex coordinated movements. Our central thesis is that the nonlinear dynamical properties of muscle play a critical role in power production and stability during such movements. We have developed a closed-loop system that couples an isolated muscle to a physical or computational load, facilitating the study of the interactions between intrinsic muscle properties and external forces. We used this system to determine how elastic elements in the frog semimembranosus can improve power production during a jumping task and how the contractile element automatically manages energy to maintain a stable bouncing gait. Our results reveal that, during ballistic movements (e.g. jumping), series elastic elements stretch and shorten to temporally concentrate energy transfer from the contractile element to the body, amplifying power production. We measured peak instantaneous power greater than twice the maximum power the contractile element could produce alone. Our results show how, during a bouncing gait, the contractile and elastic elements autonomously interact to produce, dissipate, and recycle energy and to maintain dynamic stability without sensory feedback. Our data suggest that muscles can recover over 75% of the kinematic energy from one step and apply it to the next. These results demonstrate the effects and importance of intrinsic muscle properties during movements. Ultimately, this research can guide the development of biomimetic robotic and prosthetic technologies capable of life-like mobility.

Background. A visual prosthesis is a conceptual device designed to activate residual functional neurons in the visual pathway of blind individuals to produce artificial vision. Such device, when applied to stimulate the vitreous surface of the retina, has proven feasible in producing patterned light perception in blind individuals suffering from dystrophic diseases of the retina, such as aged-related macular degeneration (AMD). However the practicality of such approach has been challenged by the difficulty of surgical access and the risks of damaging the neuroretina. Positioning a visual implant over the scleral surface of the eye could present a safer alternative but this stimulation modality has not been tested in diseased retinas. Additionally, recent research has shown that the adult neocortex retains substantial plasticity following a disruption to its visual input and the potential deterioration in visual capabilities as a result of such experience modification may undermine the overall bionic rescue strategy. Methods. Two animal models mimicking the principal pathologies found in AMD, namely photoreceptor degeneration and reduced retinal ganglion cell mass, were used to evaluate the efficacy of trans-scleral stimulation of the retina by recording electrical evoked potentials in the visual cortex. The visual performance following the loss of pattern vision induced by bilateral eyelid suturing in adult mice was examined by analysing visual evoked potentials. Findings. Spatially differentiated cortical activations were obtained notwithstanding the underlying retinopathy in the experiment animals. The charge density thresholds were found to be similar to controls and below the bioelectric safety limit. After prolonged visual deprivation (weeks) in the mouse, the visual cortical responses evoked by either electrical or photic stimuli were both significantly reduced. An assessment of different visual capabilities using patterned stimuli demonstrated that whilst visual acuity and motion sensitivity were preserved, significant depression in luminance and contrast sensitivities was detected. Conclusion. Trans-scleral stimulation of the retina is a feasible approach for the development of a visual prosthesis. Following visual loss the adult brain exhibits significant experience-dependent modifications. These new insights may force a revision on the current bionic rescue strategy.