Tribometer for measuring coefficients of friction of uneven surfaces like articular cartilage

Schütte, A.; Behler, Helmut; Ruland, Michael; Weiß, Christel; Schwarz, Markus

doi:10.1063/1.5124006

Cited by 5 publications

(25 citation statements)

References 35 publications

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“…For the calculation of the COF, the friction force is a major component that acts parallel to the surfaces of the pair-specimens. Another component is the normal force acting perpendicular to the surfaces [88][89][90]. Thus, we wanted to explore if the different HLs could be caused, and thus explained, by different friction forces acting at the interface of the tribological surfaces of the articular pair-specimens.…”

Section: Friction Forcesmentioning

confidence: 99%

“…In the present study, a drawback of the calculation of the friction force can be seen in the fact that the pin moved over an uneven plate and the friction force was not adjusted to the inclination of the surface at each contact point as described by Schütte et al [90]. However, we think that the presented procedure is sound, because we calculated the friction force during each cycle, establishing the mean values of the friction force measured during the forward and the backward movements.…”

Section: Friction Forcesmentioning

confidence: 99%

“…We thus imitated the anatomical situation. But the combination of a pin and a plate simulating the sliding situation in vitro cannot entirely reproduce the physiological reality even if pin-on-plate devices were used in several former studies [5,6,10,40,45,90,91]. However, all cartilage pair-specimens were analyzed according to the same protocol where cartilage was slid against cartilage and in the same tribometer.…”

Section: The Testing Device and Protocolmentioning

confidence: 99%

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Resilience to height loss of articular cartilage of osteoarthritic stifle joints of old pigs, compared with healthy cartilage from young pigs in a tribological pin—on—plate exposure, revealing similar friction forces

Engelhardt¹,

Schütte²,

Hetjens

et al. 2021

PLoS ONE

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Introduction We saw a lack of data on the biomechanical behavior of degenerated articular cartilage (OA) compared with that of healthy cartilage, even though the susceptibility to wear and tear of articular cartilage plays a key role in the progression of osteoarthritis (OA). Therefore, we performed a comparison between naturally occurring OA and healthy cartilage from pigs, before and after tribological stress. Aim The aim of the study was to compare OA-cartilage with healthy cartilage and to analyze the resilience to tribological shear stress, which will be measured as height loss (HL), and to friction forces of the cartilage layers. The findings will be substantiated in macro- and microscopical evaluations before and after tribological exposure. Methods We assessed stifle joints of fifteen old and sixteen young pigs from the local abattoir radiologically, macroscopically and histologically to determine possible OA alterations. We put pins from the femoral part of the joints and plates from the corresponding tibial plateaus in a pin-on-plate tribometer under stress for about two hours with about 1108 reciprocating cycles under a pressure of approximately 1 MPa. As a surrogate criterion of wear and tear, the HL was recorded in the tribometer. The heights of the cartilage layers measured before and after the tribological exposure were compared histologically. The condition of the cartilage before and after the tribological exposure was analyzed both macroscopically with an adapted ICRS score and microscopically according to Little et al. (2010). We assessed the friction forces acting between the surfaces of the cartilage pair–specimens. Results Articular cartilage taken from old pigs showed significant degenerative changes compared to that taken from the young animals. The macroscopic and microscopic scores showed strong alterations of the cartilage after the tribological exposure. There was a noticeable HL of the cartilage specimens after the first 100 to 300 cycles. The HL after tribological exposure was lower in the group of the old animals with 0.52 mm ± 0.23 mm than in the group of the young animals with 0.86 mm ± 0.26 mm (p < 0.0001). The data for the HL was validated by the histological height measurements with 0.50 mm ± 0.82 mm for the old and 0.79 mm ±0.53 mm for the young animals (p = 0.133). The friction forces measured at the cartilage of the old animals were 2.25 N ± 1.15 N and 1.89 N ± 1.45 N of the young animals (p = 0.3225). Conclusion Unlike articular cartilage from young pigs, articular cartilage from old pigs showed OA alterations. Tribological shear stress exposure revealed that OA cartilage showed less HL than healthy articular cartilage. Tribological stress exposure in a pin–on–plate tribometer seemed to be an appropriate way to analyze the mechanical stability of articular cartilage, and the applied protocol could reveal weaknesses of the assessed cartilage tissue. Friction and HL seemed to be independent parameters when degenerated and healthy articular cartilage were assessed under tribological exposure in a pin–on- plate tribometer.

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Section: Friction Forcesmentioning

confidence: 99%

Section: Friction Forcesmentioning

confidence: 99%

Section: The Testing Device and Protocolmentioning

confidence: 99%

See 1 more Smart Citation

Resilience to height loss of articular cartilage of osteoarthritic stifle joints of old pigs, compared with healthy cartilage from young pigs in a tribological pin—on—plate exposure, revealing similar friction forces

Engelhardt¹,

Schütte²,

Hetjens

et al. 2021

PLoS ONE

Self Cite

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“…For the tribological examinations in a pin-on-plate tribometer [ 2 ], osteochondral specimens had to be isolated from the operated stifle joints. They served as pins and plates.…”

Section: Methodsmentioning

confidence: 99%

“…Regenerated AC tissue should provide a CoF comparable to that of natural and healthy AC to ensure the functionality of chondral lesions in diarthrodial joints after treatment. Thus, the determination of the CoF of regenerated cartilage could serve as a useful ex vivo tool for the assessment of strategies for treatment [ 1 , 2 , 3 ].…”

Section: Introductionmentioning

confidence: 99%

Coefficient of Friction and Height Loss: Two Criteria Used to Determine the Mechanical Property and Stability of Regenerated Versus Natural Articular Cartilage

et al. 2022

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Background: The coefficient of friction (CoF) serves as an indicator for the mechanical properties of natural and regenerated articular cartilage (AC). After tribological exposure, a height loss (HL) of the cartilage pair specimens can be measured. Our aim was to determine the CoF and HL of regenerated AC tissue and compare them with those of natural AC from non-operated joints and AC from joints where the regenerated tissues had been created after different treatments. Methods: In partial-thickness defects of the trochleae of the stifle joints of 60 Göttingen Minipigs, regenerated AC was created. In total, 40 animals received a Col I matrix, 20 laden with autologous chondrocytes, and 20 without. The defects of 20 animals were left empty. The healing periods were 24 and 48 weeks. A total of 10 not-operated animals, delivered the “external” control specimens. Osteochondral pins were harvested from defect and non-defect areas, the latter serving as “internal” controls. Using a pin-on-plate tribometer, we measured the CoF and the HL. Results: The CoF of the regenerated AC ranged from 0.0393 to 0.0688, and the HL, from 0.22 mm to 0.3 mm. The differences between the regenerated AC of the six groups and the “external” controls were significant. The comparison with the “internal” controls revealed four significant differences for the CoF and one for the HL in the operated groups. No differences were seen within the operated groups. Conclusions: The mechanical quality of the regenerated AC tissue showed inferior behavior with regard to the CoF and HL in comparison with natural AC. The comparison of regenerated AC tissue with AC from untreated joints was more promising than with AC from the treated joints.

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New experimental methodology to evaluate lubrication properties of synovial fluid containing worn tissue particles in osteoarthritis patients

Dvir

Abd-Rbo

Segal³

et al. 2023

Friction

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Studying the lubrication properties of osteoarthritis (OA) synovial fluid (SF) enables an understanding of the boundary lubrication joint, mobility, and friction. However, tribology has never been combined with the clinical reality of the presence of worn particles within the synovial fluid and how they affect the osteoarthritic joints. Part of the problem relates to the tribology methods studying friction by applying inadequate pin-on-disc techniques. In this study, synovial fluid with and without worn particles was studied using a customized tribometer. This method enables opening the contact at the end of each cycle and simulates better contact conditions of a natural knee joint and can thus be applied for evaluating the severity of joint OA and the treatment given to the patient.

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Tribometer for measuring coefficients of friction of uneven surfaces like articular cartilage

Cited by 5 publications

References 35 publications

Resilience to height loss of articular cartilage of osteoarthritic stifle joints of old pigs, compared with healthy cartilage from young pigs in a tribological pin—on—plate exposure, revealing similar friction forces

Resilience to height loss of articular cartilage of osteoarthritic stifle joints of old pigs, compared with healthy cartilage from young pigs in a tribological pin—on—plate exposure, revealing similar friction forces

Coefficient of Friction and Height Loss: Two Criteria Used to Determine the Mechanical Property and Stability of Regenerated Versus Natural Articular Cartilage

New experimental methodology to evaluate lubrication properties of synovial fluid containing worn tissue particles in osteoarthritis patients

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