Contact stresses in a patient-specific unicompartmental knee replacement.
BACKGROUND
Unicompartmental knee replacement has gained popularity in recent times, showing improved success rates. The main reasons for the failure of unicompartmental knee replacement are the wear of the polyethylene bearing, aseptic loosening and wear in the opposite compartment. The contact stresses involved are significant contributing factors to these causes of failure.


METHODS
In this study, a patient-specific unicompartmental knee replacement is proposed using a methodology based on neural network modeling of a database of healthy knee geometries. This custom implant was then compared to two conventional implant designs in terms of contact stress in a validated finite element model.


RESULTS
The custom implant experienced lower contact stresses at the tibio-femoral joint compared to a fixed-bearing design and also displayed more uniform stress distribution at the bone-implant interface than any of the other implant designs.


CONCLUSIONS
Custom unicompartmental knee replacements therefore have the potential of providing good contact stress distribution, preserve bone stock and could be more anatomically accurate.
Department of Mechanical and Mechatronic Engineering, Stellenbosch University, South Africa. dawie@sun.ac.za
Dawie J
DJ
van den Heever
Cornie
C
Scheffer
Pieter
P
Erasmus
Edwin
E
Dillon
D003198:Computer Simulation; D017076:Computer-Aided Design; D019544:Equipment Failure Analysis; D005269:Femur / Q000503:physiopathology* / Q000601:surgery; D017276:Friction; D006801:Humans; D007719:Knee Joint / Q000503:physiopathology* / Q000601:surgery*; D007720:Knee Prosthesis; D008954:Models, Biological; D011474:Prosthesis Design; D013314:Stress, Mechanical; D013499:Surface Properties; D013977:Tibia / Q000503:physiopathology* / Q000601:surgery