Abstract
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 mm3/million cycles to 12.3 mm3/million cycles. The wear rate for oval dome increased from 6.3 mm3/million cycles to 14.5 mm3/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.
Highlights
More than 2.7 million joint replacement surgeries have been performed globally.[1]
With a decrease in rotation from 4° to 1° and similar medial lateral (ML) displacement, the wear rate of round dome significantly decreased to 8.6 6 3.4 mm3/million cycles (MC) (p \ 0.049)
The wear rate of the oval dome patella decreased to 6.3 6 3.9 mm3/MC, but this was not significant (p . 0.08) compared to the wear rate of oval dome at higher kinematics
Summary
The success rate of patella-femoral arthroplasty lies between 44% and 90% in 17 years of follow-up studies.[8,12] The major reasons for the failures in patella-femoral joint replacements are loosening, infection, fracture, instability, maltracking, wear and overstuffing.[13,14,15] It has been widely reported that failures in artificial tibia femoral joint were due to wear debris– induced osteolysis leading to implant loosening.[16,17] Ellison et al.[18] reported a 19% increase in the generation of wear debris when patella-femoral joint (PFJ) particles were included alongside the tibia femoral joint in an in vitro wear simulator comprising five degrees of motion. The generation of wear debris is dependent on many factors, including the surface roughness of the metallic femoral component, artificial knee joint design, oxidative degradation of polyethylene, patient activities, surgical alignment and kinematic input profiles.[19,20]
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Schedule a callMore From: Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine
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