Finite element analysis of the cervico-trochanteric stemless femoral prosthesis.
OBJECTIVE
To investigate the biomechanical performance of a newly designed cervico-trochanteric stemless prosthesis by comparing the stress distribution with that of the traditional stem-type porous-coated anatomic prosthesis.


METHODS
Three-dimensional finite element models were created for the intact femur, cervico-trochanteric implanted femur and porous-coated anatomic implanted femur. The stress distributions on the femur and the implant were compared. The effects of using two or three screws fixation for the cervico-trochanteric implanted femur were also investigated.


BACKGROUND
Local bone loss after implantation of traditional stem-type prostheses remains an unsolved problem during the long-term application of total hip replacement. The stress shielding effect and osteolysis were thought to be the two main factors that result in local bone loss after prosthesis implantation. In order to eliminate the mechanical and the biological causes of bone loss after total hip arthroplasty, a newly designed stemless femoral prosthesis was investigated.


METHODS
Three-dimensional finite element models were created for the intact, cervico-trochanteric (with two or three fixation screws), and porous-coated anatomic implanted femora with the geometry of a standardized composite femur. Analysis was performed for a loading condition simulating the single-legged stance. The von Mises stress distributions of each model were analyzed and compared.


RESULTS
The results can be summarized as follows: (1) Von Mises stress in the proximal, medial femur for the cervico-trochanteric implanted model was higher than that of the intact model and the porous-coated anatomic implanted model; (2) stress-shielding effect of the cervico-trochanteric models (with two or three fixation screws) were eliminated as compared with the porous-coated anatomic model; (3) no obvious difference in von Mises stress distribution for the cervico-trochanteric implanted model with two or three fixation screws.


CONCLUSIONS
The cervico-trochanteric femoral prosthesis may reduce the stress-shielding effect of the proximal femur and achieve a more physiological stress distribution on the proximal femur than that of the porous-coated anatomic prosthesis.


CONCLUSIONS
The new concept of cervico-trochanteric stemless prosthesis has proven to possess several advantages based on the current results, and may be an alternative for traditional stem-type prostheses in future clinical applications.
Tai
Ching-Lung
CL
Department of Biomedical Engineering, Chung Yuan Christian University, Chungli 320, Taiwan, ROC.
Shih
Chun-Hsiung
CH
Chen
Weng-Pin
WP
Lee
Shiuann-Sheng
SS
Liu
Yu-Liang
YL
Hsieh
Pang-Hsin
PH
Chen
Wen-Jer
WJ
D001696:Biomechanical Phenomena; D001863:Bone Screws; D005269:Femur; D020342:Finite Element Analysis; D006622:Hip Prosthesis; D006801:Humans; D011474:Prosthesis Design