TY - JOUR
T1 - Effect of temperature on UHMWPE and VEXLPE friction and wear against CoCr in noncyclic tests
AU - Saikko, Vesa
AU - Morad, Omar
AU - Viitala, Raine
N1 - Funding Information:
The study was funded by Aalto University . This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.
Publisher Copyright:
© 2021 The Authors
PY - 2022/2/15
Y1 - 2022/2/15
N2 - In prosthetic joints, frictional heating may cause protein denaturation in synovial fluid which may affect its lubrication properties. In arthroplasty, conventional ultra-high molecular weight polyethylene (UHMWPE) is being gradually replaced by vitamin E stabilized, extensively cross-linked UHMWPE (VEXLPE) with a superior combination of wear and oxidation resistance. There is scarcity of literature on UHMWPE vs.VEXLPE friction. A noncyclic, single-station friction measurement device, the Friction RandomPOD, was recently introduced. The direction of sliding, velocity, acceleration, and load varied randomly within certain, biomechanically justified limits. The measurement of the coefficient of friction was based on a three-axial load cell. In order to increase the testing capacity, the number of test stations was now increased to 4 using similar load cells. One-week tests were performed with pins made of UHMWPE and VEXLPE against CoCr in calf serum lubrication at 4 °C, 20 °C and 37 °C. The lower temperatures were included to prevent or retard protein denaturation. The lowest friction and wear were observed at 37 °C. At this temperature, the mean of the coefficient of friction of VEXLPE was 55% lower than that of UHMWPE. The wear of VEXLPE was always lower than that of UHMWPE.
AB - In prosthetic joints, frictional heating may cause protein denaturation in synovial fluid which may affect its lubrication properties. In arthroplasty, conventional ultra-high molecular weight polyethylene (UHMWPE) is being gradually replaced by vitamin E stabilized, extensively cross-linked UHMWPE (VEXLPE) with a superior combination of wear and oxidation resistance. There is scarcity of literature on UHMWPE vs.VEXLPE friction. A noncyclic, single-station friction measurement device, the Friction RandomPOD, was recently introduced. The direction of sliding, velocity, acceleration, and load varied randomly within certain, biomechanically justified limits. The measurement of the coefficient of friction was based on a three-axial load cell. In order to increase the testing capacity, the number of test stations was now increased to 4 using similar load cells. One-week tests were performed with pins made of UHMWPE and VEXLPE against CoCr in calf serum lubrication at 4 °C, 20 °C and 37 °C. The lower temperatures were included to prevent or retard protein denaturation. The lowest friction and wear were observed at 37 °C. At this temperature, the mean of the coefficient of friction of VEXLPE was 55% lower than that of UHMWPE. The wear of VEXLPE was always lower than that of UHMWPE.
KW - Dynamic friction measurement
KW - Noncyclic pin-on-disk
KW - Orthopaedic tribology
KW - Servo-drive
KW - Vitamin E stabilized, extensively cross-linked UHMWPE
UR - http://www.scopus.com/inward/record.url?scp=85120832588&partnerID=8YFLogxK
U2 - 10.1016/j.wear.2021.204190
DO - 10.1016/j.wear.2021.204190
M3 - Article
AN - SCOPUS:85120832588
VL - 490-491
JO - Wear
JF - Wear
SN - 0043-1648
M1 - 204190
ER -