Nonlinear three-dimensional finite element analysis of newly designed cementless total hip stems.
We designed 2 new types of proximally coated stems (the FMS and FMS-anatomic) based on the endosteal geometry of femora with congenital dislocation or dysplastic hip. The FMS was symmetric while the FMS-anatomic was asymmetric. We compared the proximal fit and fill to the femoral canal, contact stress, relative motion, and load transfer to the femur of 5 stems (FMS, FMS-anatomic, Omnifit, Omniflex, and individual stem) using three-dimensional computer simulation and finite element analysis. The FMS and FMS-anatomic showed a significantly greater fit and fill than conventional stems. The dispersion of the contact stresses and reduction of relative motions in the proximal area were the best in the FMS-anatomic compared to other stems with the exception of the individual stem. In addition, the FMS-anatomic stem transferred most of the load to the proximal femur. Our results suggest that the FMS-anatomic should provide better biomechanical stability at least in the early postoperative period.
Ando
M
M
Department of Orthopaedic Surgery, School of Medicine, Fukui Medical University, Japan.
Imura
S
S
Omori
H
H
Okumura
Y
Y
Bo
A
A
Baba
H
H
D019644:Arthroplasty, Replacement, Hip; D002484:Cementation; D003198:Computer Simulation; D005260:Female; D005269:Femur / Q000502:physiology; D020342:Finite Element Analysis; D006622:Hip Prosthesis; D006801:Humans; D008875:Middle Aged; D015207:Osteoarthritis, Hip / Q000503:physiopathology / Q000601:surgery; D011474:Prosthesis Design; D013314:Stress, Mechanical