The direction of osteons in cortical bone has been shown to be well correlated with the strongest loading direction of the bone as a whole. Therefore, determining the orientation of osteons in the rib cage is an important step in understanding the behavior of the rib cage under mechanical load. A total of 37 specimens were removed from several rib locations from a male and female cadaver. Eight histological slides were created from each 5 mm long section. Image analysis included the use of a computer algorithm created in Matlab to track the center of each osteon throughout the rib section. Analysis of the results showed variations in the osteon direction between samples taken from the anterior, lateral and posterior surfaces of the rib cage. The average offset angle between the osteon direction and the rib axis was determined to be 4.1, 3.2 and 1.9 degrees for the anterior, lateral and posterior surfaces respectively. The average offset angle for the anterior specimens was significantly higher than that of the posterior rib specimens (P=0.01) The lateral specimens also showed a significantly higher average offset angle than the posterior rib specimens (P=0.01). The results indicate a trend in osteon offset angle between the three locations studied. The offset angle is highest in the anterior region, then decreases in the lateral and is lowest in the posterior regions of the rib cage. Determining the risk of injury from an automobile collision to the thorax requires knowledge of the properties of the skeletal components that comprise the thorax. The purpose of this study was to investigate the strength of human ribs subjected to dynamic three-point bending. A total of four human cadavers were utilized by removing 16 rib sections from the right side of each thorax. One or two sections were removed from a single rib at the lateral, anterior and posterior locations of the thorax. The strain rates resulting from the dynamic loading ranged from 0.5 to 5.44 strains per second. Three-axis strain gage rosettes were used for one series of tests showing small variation of the principal strain axis from the direction of bending. For all subjects, the anterior specimens failed at a significantly lower peak stress than the lateral (p=0.01) and posterior (p=0.01) specimens. The average elastic modulus from all tests was 22 GPa. The average peak stress for all specimens was 115 MPa, with an average peak strain of 11,460 microstrain. / Master of Science

Cylindric (10 mm diameter X 15 mm deep) osteochondral defects were created in the medial femoral condyles of 5 horses to mimic clinical cases of subchondral bone cysts after debridement. The defects were created with either a standard square ended drill bit or a compaction drill bit. The compaction drill bit compresses bone laterally and distally creating a dense wall and floor. Twelve-mm sternal cancellous cylinders were compressed to 9.25 mm and inserted into the femoral defects where they were presumed to expand and tighten the fit. The end result was sternal cancellous bone that exactly fit the femoral defects. Fluorochrome bone labels were used to confirm the origin of bone present in the defects at necropsy, which was performed after 6 months. Successful graft incorporation occurred in 3 of the compacted and 2 of the noncompacted defects. The surfaces of the successful cancellous bone grafts contained predominately fibrocartilage. The unsuccessful noncompacted defects expanded laterally and deeply into the parent bone epiphysis while the unsuccessful compacted defects remained confined to the originally created size. / Master of Science

>Magister Scientiae - MSc / Aneurysmal Bone Cysts (ABC) and Solitary Bone Cysts (SBC), both non-epithelial cysts of the jaws are defined as benign lesions of an unclear aetiology. There is limited literature available on these two primary non-epithelial cysts of the jaws, especially in African populations. This retrospective study focused on the clinical and radiographic features, as well as management of the non-epithelial cysts of the jaws presenting at the University of the Western Cape Oral Health Centre from 1970-2018. The aim of this study was to describe the clinical and radiological features of non-epithelial cysts of the jaws that presented at the Departments of Maxillo-Facial and Oral Surgery and Diagnostics and Radiology at the University of the Western Cape Oral Health Centre as well as their management and recurrence patterns.

The purpose of this action-oriented needs assessment was to ascertain the knowledge, motivation, and culture (KMC) needs of Blacks regarding joining the Be The Match bone marrow registry and participating in the bone marrow donation process. This needs assessment will be utilized to lay the foundation for an educational and research based nonprofit organization, Angels In Disguise, that I developed. This study will also be used to inform the bone marrow registry of the KMC needs of the Blacks who participated in this study. The data collection came from nine observations, four post-observation surveys, five donor interviews, two prototype development groups, and a prototype field test. The formative results from the data collection partially aligned with the literature, which showed that a lack of knowledge resulted in Blacks not joining the Registry. An outlier materialized from the formative data, indicating that all five donor interviewees had joined the bone marrow registry without having knowledge of it, its processes, or the critical need for Blacks to join. On the other hand, the formative data supported the literature when the donor interviewees became a bone marrow match and were faced with the decision to move forward with the bone marrow donation process. All five donor interviewees sought and obtained knowledge about the bone marrow registry prior to being able to move forward with the donation process. In contrast, the formative data around motivation fully aligned with the literature. Blacks who lacked motivation do not join the bone marrow registry or participate in the bone marrow donation process, whereas the literature stated that many Blacks do not join the bone marrow registry due to cultural attitudes and beliefs. Research indicates that the Black community distrusts the medical community due to their being used as medical guinea pigs in the past. Also, Blacks fear pain and their health being compromised due to bone marrow donation. Interestingly, the formative data results did not support or show a lack of support of the literature. Cultural attributes and beliefs did not manifest themselves in the formative data results. The two prototype development groups participated in design thinking utilizing iterative brainstorming exercises, rapid prototyping, and assumption testing. The prototype development groups analyzed the data by categorizing and coding the data into themes through participatory research and collaborative analysis. The results of the two prototype development groups culminated into a final prototype. The final prototype was aimed at addressing the KMC needs of the Black participants, which were two-fold. First, the Registry needs to build a relationship with the Black community. Second, participants required knowledge about the Registry, the matching and donation processes, and the critical need for Blacks to join the Registry and participate in the donation process be provided to them in an educational setting, a symposium. The final prototype culminated into a bone marrow symposium that was tested in the field. The final prototype consisted of three videos about the bone marrow registry, a panel discussion with three Black bone marrow donors who had donated to non-relatives, and a pre- and post-prototype field test survey. The summative findings of this study were the results of the pre- and post-prototype field test surveys and post prototype field test. The findings of the pre-prototype field test survey, regarding knowledge, indicate the participants knew nothing or very little about the bone marrow registry. After being exposed to the prototype, the participants indicated in the post-prototype field test survey they had learned by joining the bone marrow registry they could possibly save a life. They also indicated they did not need any additional information about the bone marrow registry in order to make a decision to join and participate in the bone marrow donation process. Regarding motivation, there was not much change between the pre- and post-prototype field test survey results. The participants had indicated in both the pre- and post-prototype field test surveys that they would be motivated to join the bone marrow registry and participate in the bone marrow donation process if it could save a life. With regard to culture, the participants indicated in both the pre- and post-prototype field test surveys that no beliefs would affect their decision to join the registry and participate in the bone marrow donation process.

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published_or_final_version / abstract / Medicine / Doctoral / Doctor of Philosophy

published_or_final_version / abstract / Orthopaedics and Traumatology / Doctoral / Doctor of Philosophy

Bone drilling is a major part of orthopaedic surgery performed during the internal fixation of fractured bones. At present, information related to drilling force, drilling torque, rate of drill bit penetration and drill bit rotational speed is not available to orthopaedic surgeons, clinicians and researchers as bone drilling is performed manually. This research demonstrates that bone drilling force data if recorded in-vivo, during the repair of bone fractures, can provide information about the strength/quality of the bone. Drilling force does not give a direct measure of bone strength; therefore it has been correlated with the shear strength and screw pullout strength to determine the efficacy in estimating the bone strength. Various synthetic bone material densities and animal bones have been tested to demonstrate the use of drilling force data. A novel automated experimental test rig, which enables drilling tests, screw insertion and screw pullout tests to be carried out in a controlled environment, has been developed. Both drilling and screw pullout tests have been carried out in a single setting of the specimen to reduce the experimental errors and increase repeatability of the results. A significantly high value of correlation (r² > 0.99) between drilling force & shear strength and also between drilling force & normalised screw pullout strength in synthetic bone material was found. Furthermore, a high value of correlation (r² = 0.958 for pig bones and r² = 0.901 for lamb bones) between maximum drilling force & normalised screw pullout strength was also found. The result shows that drilling data can be used to predict material strength. Bone screws are extensively used during the internal fixation of fractured bones. The amount of screw been tightened is one of the main factor which affects the bone-screw fixation quality. Over tightening of screw can result into the loss of bone-screw fixation strength, whereas under tightening can result in the screw loosening. Therefore, optimum tightening of the screw is important to achieve the maximum bone-screw fixation strength. At present, optimum tightening of the screw is entirely dependent upon the skill and judgment of the surgeon, which is predominantly based on the feel of the screw tightening torque. Various studies have been reported in the literature to develop an algorithm to set an optimum tightening torque value to be used in surgery. A method which is based on the use of rotation angle of the screw while tightening, rather than using screw insertion/tightening torque, to optimise the bone-screw fixation strength is proposed in this research. The effectiveness of the proposed method has been successfully demonstrated on the synthetic bone material using the designed test rig. The optimum angle for the tested screw was found to be 120° which is equivalent to 33% of the screw pitch.

Both science and empirical knowledge seem to indicate that anatomical considerations relating to potential muscular interference be established at the incipiency of the serious study of voice. Experience shows that if this aspect of vocal development is not pursued with utmost diligence, an early deterioration of the vocal instrument is possible many years before a normal expectancy. It has been discovered, also, that the study of articulation, pronunciation, modulation, emphasis, gestures and interpretation seem to avoid, primarily, the necessity of muscular training, per. This thesis will not include, in detail, the aspects of the use of the breath, except in a perfunctory manner. The same can be said of resonance and diction. It will endeavor, however, to indicate the muscular differences of the singing and swallowing actions. Furthermore, it will advance some suggestions for the avoidance of constrictive muscular influences which might impede the singing musculature. Finally, a phonatory process will be presented for consideration as a muscular mechanism to be made operative in connection with a direct control procedure.

Clinicians have described the success rates of dental implants. The use of implants is projected to increase in the future. With a 5-10% failure rate, it is unclear the exact factors that are associated with implant failures. To improve upon these success rates, it is critical to understand parameters associated with implant failure including: periodontitis, peri-implantitis, systemic diseases, site preparation, dental history of the implant site, bone quality, materials, occlusion, and treatment timelines. While bone quality is associated with failure, objective measures to assess bone quality and characteristics are scarce. Therefore, the aim of this study is to determine whether possible comorbidities, associated dental parameters, and measurable bone quality are possible predictors of implant failure. In this study, we utilized the electronic health record system axiUm® to retrospectively investigate non-failed (NF) and failed (F) dental implants from a patient cohort with 149 implants placed between 2012-2015 at Virginia Commonwealth University School of Dentistry. A chart review was conducted extracting information on age, gender, systemic diseases, smoking, occlusal trauma, parafunction, bone grafting history, treatment timelines, implant site/type/placement protocol, infection, torque at placement, bone quality and microarchitecture assessed by the novel, innovative technology: trabecular bone score (TBS). A total of 149 implants, 46 failures and 105 non-failed controls, were selected based on similar implant sites. Preliminary data obtained from analysis suggests that average time from implant placement to failure was 6.6 months (0.55 years). Parafunction habit (p=0.0202) and increased number of implants (p=0.0478) were found to be associated with increased implant failure.