Analysis of wear produced by a 100-station wear test device for UHMWPE with different contact pressures

Saikko, Vesa

doi:10.1016/j.triboint.2022.107560

Cited by 12 publications

(13 citation statements)

References 21 publications

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“…This involved a lip being formed by plastic deformation at the surface of the polymer. The formation of protrusions by plastic deformation has also been proposed by Saikko [48]. In plastic deformation it can be envisaged that the continuous change in direction leads to repeated folding of this "lip" to form the protrusions seen on the pins (Fig.…”

Section: Discussionmentioning

confidence: 76%

Anomalous Wear Behavior of UHMWPE During Sliding Against CoCrMo Under Varying Cross-Shear and Contact Pressure

et al. 2022

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Wear of ultra-high-molecular weight polyethylene (UHMWPE) in joint implant applications has been shown to increase with cross-shear (CS, i.e., multidirectional sliding) but decrease with higher contact pressure (CP). Moreover, structural changes, resulting in protrusions, are known to occur to the surface of the pin following multidirectional sliding. However, these phenomena are not yet fully understood. In this study, we simultaneously varied CP and CS to derive an empirical formula for the wear factor as a function of these parameters. The wear factor increased when going from unidirectional sliding to multidirectional sliding but decreased with increasing CP, as has been previously observed. Following these tests, the protrusions on the pin surface were chemically and mechanically characterized to gain insights into both their origin and influence on wear behavior. Micro-FT-IR confirmed that the structures consist of polyethylene, rather than adsorbed, denatured proteins. It also allowed the crystallinity of both the protrusions and unaffected UHMWPE to be estimated, showing a strong positive correlation with the hardness of these different areas on the surface. Time-of-flight secondary-ion mass spectrometry was used to probe the chemistry of the surface and near-surface region and indicated the presence of contamination from the test fluid within the structure. This suggests that the protrusions are formed by the folding of UHMWPE following plastic deformation. It is also suggested that the higher hardness of the protrusions affords some protection of the surface, leading to the observed anomalous behavior, whereby wear increases with decreasing CP. Graphical Abstract

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Section: Discussionmentioning

confidence: 76%

Anomalous Wear Behavior of UHMWPE During Sliding Against CoCrMo Under Varying Cross-Shear and Contact Pressure

et al. 2022

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“…25 Protuberances were observed also on conventional, gamma-sterilized UHMWPE pins with nominal contact pressures above 2.0 MPa in multidirectional SuperCTPOD tests. 12 The present wear factor for VEXLPE, 1.64 6 0.22 3 10 27 mm 3 /Nm, was remarkably close to the value obtained for the same VEXLPE material against 54 mm diameter femoral heads and with a similar lubricant in a multidirectional hip joint simulator using ISO 14242-1 26 test conditions, 1.41 3 10 27 6 0.19 3 10 27 mm 3 /Nm. 27 This indicates that the wear factor is a useful way to compare wear produced by different test devices, such as pin-on-disk versus hip joint simulator.…”

Section: Discussionmentioning

confidence: 99%

“…This serum has commonly been used as the lubricant in orthopaedic tribology since the 1990s. 3,4,11,12,22 The protein concentration of the lubricant was 20 mg/ml. Antibiotic/antimycotic solution SV30079 (Cytiva, HyClone Laboratories, Logan, UT, USA) was added to the lubricant (10 ml/l) to prevent microbial growth.…”

Section: Methodsmentioning

confidence: 99%

“…Therefore, for an adequate power of test, larger sample sizes are needed. 12 In order to test several samples simultaneously, the wear test device needs to have a high capacity, preferably above 100 test stations. 12 With the use of XLPE in acetabular liners of total hip prostheses, clinical wear and revision rates have decreased significantly.…”

Section: Introductionmentioning

confidence: 99%

“…12 In order to test several samples simultaneously, the wear test device needs to have a high capacity, preferably above 100 test stations. 12 With the use of XLPE in acetabular liners of total hip prostheses, clinical wear and revision rates have decreased significantly. 13,14 Due to its wear resistance and stability against oxidation, vitamin E stabilized, highly cross-linked polyethylene, VEXLPE, is strongly gaining popularity as the bearing material in orthopaedic practice.…”

Section: Introductionmentioning

confidence: 99%

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Statistical analysis of VEXLPE wear against alumina produced by a new 200-station, multidirectional pin-on-disk device

Saikko

2024

Proc Inst Mech Eng H

Self Cite

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With low wear rates shown by contemporary bearing materials of total hip prostheses, the standard deviation of wear rate is relatively high. Therefore, large sample sizes are needed for an adequate power of test. Because wear tests take a long time, it is practical to test several samples simultaneously. A new high-capacity, multidirectional wear test device, called the SuperCTPOD-200, was introduced. A 3 million-cycle wear test with an unprecedented sample size of 200 was performed for VEXLPE. The duration of the test was 6 weeks. The wear factor was normally distributed with a mean ± SD of 1.64 × 10−7 mm3/Nm ± 0.22 × 10−7 mm3/Nm ( n = 200). The observation that SD was 13.1% of the mean can be useful in power analyses of future tests with other highly cross-linked polyethylenes. Burnishing was the most typical feature on the worn pins, which was in agreement with clinical findings on retrieved acetabular liners. The present study emphasizes statistics that often plays a minor role only in wear studies.

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Wear Mechanism and Wear Debris Characterization of ULWPE in Multidirectional Motion

Liu,

Zhang,

et al. 2024

Tribol Lett

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Analysis of wear produced by a 100-station wear test device for UHMWPE with different contact pressures

Cited by 12 publications

References 21 publications

Anomalous Wear Behavior of UHMWPE During Sliding Against CoCrMo Under Varying Cross-Shear and Contact Pressure

Anomalous Wear Behavior of UHMWPE During Sliding Against CoCrMo Under Varying Cross-Shear and Contact Pressure

Statistical analysis of VEXLPE wear against alumina produced by a new 200-station, multidirectional pin-on-disk device

Wear Mechanism and Wear Debris Characterization of ULWPE in Multidirectional Motion

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