Finite element analysis of a novel design approach to resisting total hip dislocation.
OBJECTIVE
A new design concept has been developed to reduce the propensity for dislocation in total hip patients. The ability of this design to increase the stability of the hip joint is studied.


METHODS
The new design involves a convex-curved acetabular lip, extending from the hemispherical articulating surface to the outer edge of the cup. The femoral component has a matching, reverse curve.


BACKGROUND
Dislocation is a continuing problem in total hip arthroplasty, a complication experienced by 2-11% of patients with primary surgeries, and much higher percentage of patients in revision series. Confounding factors and sources of variability in the clinical domain make it difficult to identify specific parameter influences.


METHODS
A three-dimensional nonlinear finite element model has been developed for the purpose of studying the dislocation event. We report the first use of this finite element model to analyze the potential for improving hip stability by a new total hip component design concept.


RESULTS
The results show that this new design achieves 28% more resisting moment build-up during dislocation, and has a higher range of motion from impingement to onset of subluxation. The new curved lip design also develops 50% less polyethylene von Mises stress in the impingement zone.


CONCLUSIONS
This design has excellent potential for increasing the inherent stability of the total hip joint.


CONCLUSIONS
Recurrent dislocation is the second leading cause of total hip failure next to late loosening. This study shows the potential of a new total hip design to increase the stability of the artificial hip joint.
Scifert
C F
CF
Department of Orthopaedic Surgery, University of Iowa, Iowa City, 52242, USA.
Brown
T D
TD
Lipman
J D
JD
D019644:Arthroplasty, Replacement, Hip; D001696:Biomechanical Phenomena; D003198:Computer Simulation; D017076:Computer-Aided Design; D020342:Finite Element Analysis; D006617:Hip Dislocation / Q000503:physiopathology* / Q000517:prevention & control; D006621:Hip Joint / Q000503:physiopathology; D006622:Hip Prosthesis; D006801:Humans; D011474:Prosthesis Design; D011475:Prosthesis Failure