In vitro evaluation of stiffness graded artificial hip joint femur head in terms of joint stresses distributions and dimensions: finite element study

• Published in: Journal of materials science. Materials in medicine Vol. 22; no. 6; pp. 1589 - 1598
• Main Author: Fouad, H.
• Format: Journal Article
• Language: English
• Published: Boston Springer US 01.06.2011; Springer; Springer Nature B.V
• Subjects: Biological and medical sciences; Biomaterials; Biomedical engineering; Biomedical Engineering and Bioengineering; Biomedical materials; Ceramics; Chemistry and Materials Science; Chromium Alloys - chemistry; Cobalt base alloys; Composites; Computer Simulation; Elasticity - physiology; Equipment Failure Analysis; Femur; Femur Head - cytology; Finite Element Analysis; Finite element method; Glass; Hip joint; Hip Joint - cytology; Hip Prosthesis; Humans; In Vitro Techniques; Joint strength; Materials Science; Mathematical analysis; Medical sciences; Models, Theoretical; Natural Materials; Orthopedic surgery; Polymer Sciences; Prosthesis Design - methods; Regenerative Medicine/Tissue Engineering; Stainless Steel - chemistry; Stiffness; Stress, Mechanical; Stresses; Surfaces and Interfaces; Surgery (general aspects). Transplantations, organ and tissue grafts. Graft diseases; Surgical implants; Technology. Biomaterials. Equipments; Thin Films; Titanium - chemistry; Titanium base alloys; Contact Stress; UHMWPE; Ultra High Molecular Weight Polyethylene; Radial Clearance; Femur Head; Hip joint; Titanium alloy; Femur; Femoral head; Prosthesis; Mechanical properties; Dimension; Modeling; In vitro; Finite element method; Stress distribution; Stainless steel; Chromium alloy; Cobalt alloy; Biomaterial; Stiffness; Biomedical engineering
• ISSN: 0957-4530; 1573-4838
• DOI: 10.1007/s10856-011-4319-2

The aim of the present work is to evaluate the artificial hip joint femur head that is made of Stiffness Graded (SG) material in terms of joint stresses distributions and dimensions. In this study, 3D finite element models of femur head that is made of SG material and traditional femur heads made of Stainless Steel (SS), Cobalt Chromium alloy (Co Cr Mo) and Titanium alloy (Ti) have been developed using the ANSYS Code. The effects on the total artificial hip joint system stresses due to using the proposed SG material femur head (with low stiffness at the outer surface and high stiffness at its core) have been investigated. Also, the effects on the polymeric cup contact stresses due to the use of different sizes of femur heads, presence of metal backing shell and presence of radial clearance (gap) between cup and femur head have been investigated. The finite element results showed that using SG femur head resulted in a significant reduction in the cup contact stresses even for small femur heads compared with Ti alloy, SS and Co Cr Mo femur heads. The presence of radial clearance resulted in significant increase in the cup stresses especially for small femur heads. Finally, the presence of SS metal backing shell resulted in slight increase in the hip joint stresses especially for small femur head joints. This work analyzes successfully the usage of proposed SG material as femur head in order to reduce the predicted stresses at the total hip joint replacement due to the redistribution of strain energy in the hip prostheses. Therefore, the present results suggest that minor changes in design and geometrical parameters of the hip joint have significant consequences on the long term use of the joint and should be taken into consideration during the design of the hip joint.