The influence of kinematic conditions and design on the wear of patella-femoral replacements.
The success rate of patella-femoral arthroplasty varies between 44% and 90% in 17 years of follow-up. Several studies have been performed previously for assessing the surface wear in the patella-femoral joint. However, they have not included all six degrees of freedom. The aim of this study was to develop a six-axis patella-femoral joint simulator to assess the wear rate for two patellae designs (round and oval dome) at different kinematic conditions. An increase in patellar rotation from 1° to 4° led to a significantly (p<0.049) increased wear rate of round dome from 8.6 mm(3)/million cycles to 12.3 mm(3)/million cycles. The wear rate for oval dome increased from 6.3 mm(3)/million cycles to 14.5 mm(3)/million cycles. However, the increase was nonsignificant (p>0.08). The increase in wear rate was likely due to the higher cross shear. A decrease in patellar medial lateral displacement from passive to constrained resulted in a nonsignificant reduction in wear (p>0.06). There was no significant difference in wear rate between the two patellae designs (p>0.28). The volumetric wear under all conditions was positively correlated with the level of passive patellar tilt (rho>0.8). This is the first report of preclinical wear simulation of patella-femoral joint in a six-axis simulator under different kinematic conditions.
Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, Leeds, UK.
Raman
R
Maiti
John
J
Fisher
Liam
L
Rowley
Louise M
LM
Jennings
D000704:Analysis of Variance; D019645:Arthroplasty, Replacement, Knee; D001696:Biomechanical Phenomena / Q000502:physiology*; D006801:Humans; D007720:Knee Prosthesis; D008422:Materials Testing; D010329:Patella / Q000502:physiology*; D011474:Prosthesis Design; D012399:Rotation
Knee replacement; arthroplasty; in vitro; patella-femoral joint; wear