초록
Total joint replacement (TJR) has been used for treating joint diseases since 1960s to restore function and mobility without pain that result of osteoarthritis, rheumatoid arthritis and femoral neck fractures. Co-Cr alloy and ultra-high molecular polyethylene (UHMWPE) are widely used for articulating bearing component with its biocompatibility and excellent mechanical properties. In this study, we evaluated frictional characteristics of three kinds of the most representative UHMWPEs against Co-Cr alloy under a contact pressure of 5MPa in two different kinematic motions with a Pin-on-Disk type tribo-tester. Conventional gamma-irradiated UHMWPE (GIPE) specimens were machined from ramextruded Chirulen$^{(R)}$1020 rod and then gamma-irradiated with a dose of 4.0Mrad. Remelted highly cross-linked UHMWPE (RXLPE) were machined from hip liner of Zimmer$^{TM}$ product. Sequentially irradiated and annealed highly cross-linked UHMWPE (AXLPE) were machined from knee liner of Striker$^{TM}$ product. To evaluate the effect of kinematic motion on the coefficients of friction (COF) between UHMWPE cylindrical pin specimens and orthopaedic grade Co-Cr alloy disk specimens, a repeat passed rotational motion and a linear reciprocal sliding motion tests were conducted and their COF were compared. As a result, the mean COF of all kinds of UHMWPEs in a reciprocal motion were significantly higher than in a rotational motion. Mean COF of GIPE were higher than two kinds of highly crosslinked UHMWPEs in both kinematic motions. Consequently, based on this comparative analyses in this study, kinematic motion gave a significant influence on the frictional property of tested all kinds of UHMWPEs.