Evaluation Of Load-Transfer Pattern In Implanted Femur By Patient-Specific Fe Analysis

• Main Author: Mohamad, Faiz
• Format: Monograph
• Language: English
• Published: Universiti Sains Malaysia 2017
• Subjects: T Technology; TJ Mechanical engineering and machinery
• Online Access: http://eprints.usm.my/53701/1/Evaluation%20Of%20Load-Transfer%20Pattern%20In%20Implanted%20Femur%20By%20Patient-Specific%20Fe%20Analysis_Faiz%20Mohamad_M4_2017.pdf; http://eprints.usm.my/53701/
• Institution: Universiti Sains Malaysia

Total hip replacement (THR) is considered the most successful orthopedics surgery but eventually there is flaw rise from the effect of post-surgery itself which is stress shielding. Nature behavior of bone is considered a complex biological material due to its heterogeneous and anisotropic properties. The differences in stiffness between bone and the implant which is one of the main factor of occurring shielding stress. Stress shielding occurred in structures combining stiff with more flexible, in which results in bone loss and cortical thinning which lead to joint prosthesis failure. This research aims to explores the shielding stress would become severe when different types of orthopedic implant materials is used in THR. Therefore, 3-D bone model was developed based on CT-data scan by patient-specific and isotropic with heterogeneous material properties was assigned to the femur, whereby Ti-6Al-4V and Co-Cr-Mo were chosen as standard orthopedic implant materials. The maximum load generated during one complete gait cycles in normal walking and climbing upstairs were chosen for FE analysis. The principle elastic strain along the femur, both in intact and implanted femur conditions, were investigated based on Gruen mapping zone. Results show that maximum tension favors on the lateral side at region 4 and maximum compression mostly tends to occur on medial side at region 3 and 4. For both type of activities, there are percentage difference in strain value between femur and implanted femur, where differences is higher in CoCr-alloy implants rather than Ti-alloy implant. The large percentage difference between intact and implanted femur indicates that that gap strain value is high, and this is merely due to effect of stiffness used in implants that eventually shielded the stress from distribute along the femur, which can lead to implant loosening and prosthetic failure.