Stress shielding phenomenon is an important issues in considering the primary stability of the cementless hip arthroplasty. Stress shielding occurs when there is a mismatch in the elastic modulus of two materials perfectly bonded to each other, such as the prosthesis stem and the bone. In this study, influences of different prosthesis stem lengths on stress distribution in cementless THA are examined using finite element method. The calculated stress distribution is discussed with respect to stress shielding and primary stability issues in THA femur cases. Results show that similar pattern in stress distribution for intact and THA femur but differs in magnitudes. The stress level increases from the neck to the middle region and peaks at locations coinciding with the tip of the prosthesis. The maximum stress for intact femur is 55.5 MPa, THA with short stem is defined up to 112 MPa, while with medium and long stem are 204 MPa and 278 MPa, respectively.

— Immobilisation in bed for an extended period can cause the patient to experience complications such as muscle atrophy and muscle shortness. Ankle foot orthosis, AFO application can assist the bedridden patient in keeping their calf muscle active. However, the existing AFO used for the bedridden patient is fixed. In contrast, another AFO is only used for assisting the patient to walk. Thus, this project aims to design a customized adjustable AFO for the bedridden patient, analyze the strength of the AFO with different parameters, and fabricate using 3D printing technology to integrate remote control. The project begins with the problem identification, concept generation and selection, preliminary design using CAD software, conducting finite element analysis (FEA) by identifying the effect of using different materials, different thicknesses, and different load applies. Finally, the fabrication of AFO used 3D printing technology with PLA materials, and the integration of remote control was installed. Keywords— Bedridden; Bed-resting; Ankle foot orthosis; 3D printing; IoT controller

Bone loss and bone thickening phenomenon occurred due to different stiffness of the implant and femur. Implant with stiffer materials than the bone carries majority of the load and it transferred down along the implant till the distal tip of the stem. Both phenomenons contribute to stress shielding and loosening of the prosthesis stem. In this study, the stress distributions in intact femur and THR femur are established using finite element method. The THR femur model consists of cemented hip Ti6Al4V and CoCrMo prosthesis stem implanted inside the femur bone. Effects of different material properties of the prosthesis stem on the resulting stress distributions are investigated. Results shows that the largest discrepancy in stress values between intact and THR femur is predicted along the middle region at both lateral and medial planes. The distal region shows that the calculated stress for both THR femur experienced higher stress magnitude than that of intact femur. The higher stress in THR femur leads to bone thickening at the particular region. The corresponding stress magnitude saturates at 25 MPa for THR femur while intact femur is slightly lower at 22 MPa.