Creating a statistical shape model to aid in the estimation of incomplete soft tissue segments of the surface of South African faces

Thesis (PhD (Anatomy))--University of Pretoria, 2024.Introduction: A critical gap exists in population-specific data for facial morphology of black South Africans which are essential for the accurate reconstruction of facial features in fields such as aesthetic and reconstructive surgery, prosthodontics and extra-oral facial prosthetics, as well as forensic facial approximations. The objectives of this research were to generate normative reference values of black South African faces for various inter-landmark distances, and to derive a statistical shape model (SSM) of 3D facial shape variation which can be applied to estimate missing soft tissue segments on simulated defective faces. Methods: The study included of 235 computed tomography (CT) and cone-beam computed tomography (CBCT) scans from black South African individuals between the ages of 18 and 87 years. The scans were collected from retrospective records of three medical institutions and excluded individuals that showed conditions potentially affecting facial morphology, including orthodontic treatments, pathological conditions, facial asymmetry, or any history of facial reconstructive surgery. The scans were processed to obtain 3D facial meshes and landmarks were placed at anatomically important loci. For the first objective, inter-landmark distances were calculated, statistically analysed, and compared to published literature on other populations. For the second objective, correspondence of the 3D meshes utilising the landmarks were achieved, and generalised Procrustes analysis and principal component analysis conducted. These steps are crucial in obtaining an SSM comprising the modes of variation and the normal range variance along each mode, which together defines multinormal parameterisation of shape variation. Defect estimations were done by using the SSM to estimate the linear combination of the modes of variation that most closely approximates the intact regions of each face, and estimate the missing regions using a weighted projection onto the modes of variation. Results: Chapter 3 reports on normative facial capulometric measurements specific to the black South African population. It highlights significant differences in facial parameters between sexes and between different populations. The data reveal notable similarities with other African populations, especially in oral features, but significant disparities with non-African groups. Chapter 4 introduces the innovative SSM for extra-oral prosthetic design. This model accurately estimates missing soft tissues, demonstrating a high degree of precision with root mean square errors consistently below 2.58 mm for various facial defects. Conclusion: The normative measurements highlight the unique facial characteristics of the black South African population, demonstrating the necessity of population-specific data in clinical and forensic applications. The development of the SSM represents a novel advancement in digital reconstruction methodologies. It offers a more objective and patient-specific approach in prosthetic design, especially in addressing complex facial defects such as bi-orbital defects or those crossing the facial midline in a demographic that has been largely overlooked in previous research. This model, by reducing the subjectivity and artistic skill previously required in prosthetic design, aligns with the evolving digital trends in medical technology and aims to address specific local needs and challenges in South Africa, and also have potential for global application.UP Doctoral Bursary Bakeng se Afrika Grant/Award Number: 597924-EPP-1-2018-1-ZA-EPPKA2- CBHE-JAnatomyPhD (Anatomy)UnrestrictedFaculty of Health Science

Predicting and optimising the postoperative outcomes of sagittal craniosynostosis correction

The neonate skull consists of several flat bones, connected by fibrous joints called sutures. Sutures regulate the bone formation along their adjoining edges, while providing mailability to assist with the early phases of rapid brain growth and passing through the birth canal with minimal restriction. By adolescents, these sutures fuse into solid bone, protecting the brain from impacts. The premature fusion of one or more of these sutures is a medical condition known as craniosynostosis, with its most common form being sagittal craniosynostosis (fusion of the midline suture). The condition results in compensatory overgrowth perpendicular to the fused suture, leading to calvarial deformation and possible neurofunctional defects. Surgeons have developed several surgical techniques to restore the normative shape. This has led to debates as to which surgical option provides the most beneficial long term outcome. The overall aim of this thesis was to develop a computational approach using the finite element (FE) method capable of predicting and optimising the long term outcomes for treating sagittal craniosynostosis. A generic 3D pre-operative FE model was developed using patient specific CT data. The FE model was parameterised to predict the long term calvarial growth, the pattern of suture and bone formation, the pattern of bone healing across the replicated surgical techniques, and the changes in contact pressure levels across the modelled brain. All techniques underwent simulated growth up to the maximum age of 76 months. Morphological results were compared against the patient specific CT data at the same age. Where absent, technique specific follow up CT data were used instead. Results highlighted a good morphological agreement between the predicted models and their comparative CT data. The FE model was highly sensitive to the choice of input parameters. Based on the findings of this thesis, the *** approach proved the most optimal across the predicted outcomes. The novel methodology and platform developed here has huge potential to better inform surgeons of the impact various techniques could have on long term outcomes and continue to improve the quality of care for patients undergoing corrective surgery

Modelling, Simulation and Data Analysis in Acoustical Problems

Modelling and simulation in acoustics is currently gaining importance. In fact, with the development and improvement of innovative computational techniques and with the growing need for predictive models, an impressive boost has been observed in several research and application areas, such as noise control, indoor acoustics, and industrial applications. This led us to the proposal of a special issue about “Modelling, Simulation and Data Analysis in Acoustical Problems”, as we believe in the importance of these topics in modern acoustics’ studies. In total, 81 papers were submitted and 33 of them were published, with an acceptance rate of 37.5%. According to the number of papers submitted, it can be affirmed that this is a trending topic in the scientific and academic community and this special issue will try to provide a future reference for the research that will be developed in coming years

Life Sciences Program Tasks and Bibliography

This document includes information on all peer reviewed projects funded by the Office of Life and Microgravity Sciences and Applications, Life Sciences Division during fiscal year 1995. Additionally, this inaugural edition of the Task Book includes information for FY 1994 programs. This document will be published annually and made available to scientists in the space life sciences field both as a hard copy and as an interactive Internet web pag

2015 Oklahoma Research Day Full Program

This document contains all abstracts from the 2015 Oklahoma Research Day held at Northeastern State University