Browsing by Author "Lubbe, Inge "

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    A statistical shape modelling approach towards the design of a temporomandibular joint implant
    (Stellenbosch : Stellenbosch University, 2023-11) Lubbe, Inge ; Van der Merwe, Johan; Becker, Thorsten Hermann ; Stellenbosch University. Faculty of Engineering. Dept. of Mechanical and Mechatronic Engineering.
    ENGLISH ABSTRACT: The anatomic temporomandibular joint (TMJ) functions as a synovial-joint system whose bilateral bony structures includes the temporal bone and mandible. Articulation is facilitated by the articular disc (within the joint capsule) and ligamentous structures while being supported by the masticatory system. Temporomandibular joint (TMJ) implant design involves the collaborative application of anatomic knowledge and engineering concepts. Medical device design research and development specific to TMJ implant systems is seen to mainly focus on implications of existing systems within implant design history, biomaterial implantology research and clinical success rates. Therefore, in this work a TMJ implant design process was defined from shared attributes in existing TMJ implant systems where the boundaries of development form a sequence of design stages and consistent design features. The developed TMJ implant design process was then implemented in the initial development of a mandibular component design. Anatomic modelling was identified as an important part of the modelling framework to investigate as it can be used to define aspects such as the overall geometric design specifications, geometric design parameters and features within the design formation stage, and validation procedures. A cephalometric analysis of measurements associated with design and surgical navigation was performed followed by the development and implementation of validated statistical shape models to evaluate shape variation. The investigated dataset consisted of 80 subjects (40 males, 52.1 ± 5.9 years; 40 females, 56.7 ± 9.4 years). The data quality and normality were confirmed with a series of inter- and intra-examiner error analyses using an intraclass correlation coefficient (ICC) and Quantile-Quantile (Q-Q) plots, respectively. Size-related anatomic variation (bilateral and sex dimorphism) and anatomic measurement parameter correlations were examined in a cephalometric analysis. Significant sex-related differences (parameter correlation). The mandibular component implant design was formulated using the cephalometric measurements as proposed parameter ranges. In addition, the developed statistical shape models (SSMs) were used to evaluate the level of customisation required in the design implementing a cluster analysis. An implant library size of six implants was determined to sufficiently support the population where the implant-mandible fit was used as the evaluation metric. The female and male implant designs resulted in a mean root means square (RMS) error of 0.71 ± 0.13 mm and 0.67 ± 0.24 mm, respectively. These results were determined to be within the allowable bone modification and screw capability limits (clinically acceptable).