Biomechanical Analysis of Fixation and Bone

Long-term survivorship of a total knee replacement (TKR) relies on the strength of bone around the implant and its initial stability. Aseptic component loosening caused by mechanical factors is a recognised failure mode for knee prostheses. Bone resorption due to “stress-shielding” of the stiff stemmed implants will potentially lead to weakened bone strength, and presents a challenge for revision TKR surgery. The aim of this study was to develop analytical methodologies for the investigation of fixation performance of TKR, and to gain a better understanding of the prosthetic design requirements, addressing two major mechanical problems of bone remodelling and aseptic loosening. Patient-specific finite element (FE) modelling incorporated with a strain-adaptive bone remodelling theory was used to simulate bone remodelling responses of the postoperative tibial fixation. The choice of cementing technique was found to influence the remodelling behaviour; cemented fixationmodelled as a firm anchorage of the prosthesis onto the bone, was predicted to induce greater stress-shielding effect consequently leading to severe proximal bone resorption; for a fixation relying on biological attachment of bony ingrowthmodelled as a less firmly anchored boneprosthesis interface, lesser proximal bone resorption was predicted. The consideration of bone remodelling in FE simulations for fixation analyses is paramount as it influenced the risk prediction of aseptic loosening between prosthesis designs. The cement tensile stresses and bone-prosthesis interface micromotions predicted were different prior to and after bone adaptation. FE predictions of the MIS mini-keel and standard stemmed prosthesis fixations after simulating six months of bone adaptation correlated well with the RSA measurements at a similar period. A modified in-vitro technique of measuring bone-prosthesis relative micromotion was developed for relating initial stability of the cemented and cementless (press-fit) tibial prostheses fixations to late aseptic loosening. The developed computational and invitro methods should be applicable to other joint replacements

Integrating Simulation in the Singapore Institute of Technology-University of Glasgow Mechanical Engineering Curriculum

Modelling and simulation (M and S) have been widely used for the design and improvement of mechanical and structural systems. Together with the use of simulation tools and technologies, M and S have become common in modern engineering workplace (Magana et al., 2019). Many learning strategies have been developed and implemented to integrate M and S in engineering courses, providing the opportunity to the students to gradually develop their competence in M and S and prepare them for the workplace(Navaee and Kang, 2017; Young et al., 2012). Technologies in M and S can also be used to enhance the learning and teaching of various engineering courses. West and Graham (2005) identified five factors that positively influence the learning process using technology: (a) visualization, (b) interactions, (c) reflection, (d) authenticity and engagement, and (e) practice. These factors can be directly related to M and S in the education of engineers. For example, in Mechanics of Materials, the students can visualize patterns of deformation and stress within a loaded structure and have an increased understanding on the effects of some variables on the behaviour of a structure. Additionally, McGrath and Brown (2005) showed that visual learning methods can open up new ways to solve engineering problems. In this study, M and S, such as, finite element analysis (FEA) and computational fluid dynamics (CFD), have been integrated in various modules in the SIT-UofG Mechanical Engineering programme, to be able to: 1. enhance the learning of mechanical engineering modules (mechanics of solids, dynamics, heat transfer, fluid mechanics and additive manufacturing); 2. expose the students on M and S practices early on their engineering education to gradually develop their modelling and simulation skills and prepare them for the workplace; 3. identify opportunities so students can conduct “experiments” in a safe environment, especially during the Covid pandemic; and 4. identify the learning process to be able to develop effective active learning strategies for students to successfully acquire M and S skills. M and S has been integrated in the courses, non-placement learning activities and work integrated learning (internship). M and S have been integrated in the modules, ranging from mechanics of solids, dynamics, heat transfer, fluid mechanics and additive manufacturing. Workshops on the use of simulation softwares, such as ANSYS, have been conducted to train the students to develop FE and CFD models and analyze them. Project assessments have been assigned to students for them to learn and apply simulation to solve engineering problems. These will be illustrated through examples of assessments across various modules. Students were able apply their knowledge and skills in M and S through project-based modules, such as, the Overseas Immersion Programme that due to the limited opportunities to develop physical prototypes for their designs during the pandemic, the students need to develop simulation models. It is observed that the M and S competencies of the students have been demonstrated in non-placement learning activities. Examples of the students’ projects will be shown to illustrate this. About 10% of the mechanical engineering IWSP students are currently assigned to projects that requires simulations. This provides an opportunity to further evaluate the knowledge, skills and graduate attributes that the students learnt in the university. Focus group interviews will be conducted to both the students and the work supervisors to assess the effectiveness of the simulation integrated curriculum. The outcomes of integrating simulation throughout the curriculum and its effects on the graduate attributes are studied. Examples of assessments are presented to demonstrate the students’ competencies across the modules in the degree programme. The students were observed to successfully apply their knowledge and skills in simulation on non-placement learning activities. Following which, the current IWSP provides an opportunity to evaluate the knowledge and skills gained by the students on simulation and identify areas of improvements