In vitro mechanical testing of knee cartilage implant(s)
Avaznejad, Parya (2024)
2024
Master's Programme in Biomedical Sciences and Engineering
Lääketieteen ja terveysteknologian tiedekunta - Faculty of Medicine and Health Technology
Hyväksymispäivämäärä
2024-12-13
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:tuni-2024120810844
https://urn.fi/URN:NBN:fi:tuni-2024120810844
Tiivistelmä
Articular cartilage is a complex connective tissue that covers and protects the ends of bones in synovial joints. There are several functions that it plays throughout the body, including load bearing, lubrication, shock absorption, and providing a low coefficient of friction. Untreated damaged surfaces of articulating joints can lead to pain and loss of joint function. The cartilage cannot self-repair on its own, so a clinical procedure such as microfracture is necessary to prevent further joint degeneration. After creating microfractures in tissue, biomaterial-based scaffolds like COPLA (which is composed of PLA/collagen) can be inserted into the lesion to provide a supporting structure for cartilage regeneration. It is crucial to know the mechanical properties of scaffolds used in load bearing joints, since scaffolds with inappropriate properties can impair the tissue integration and cellular growth. There are various mechanical testing methods (time-dependent and independent tests) that can be used to perform material analysis.
The aim of this study was to determine the optimal mechanical test setup and parameters for COPLA product and assess its mechanical properties under simulated physiological condition (in PBS at 37 °C) and in ambient laboratory environment. COPLA samples were subjected to compression mechanical tests such as static compression, stress relaxation, creep-recovery, and dynamic testing, as well as shear tests such as amplitude and frequency sweep, under both conditions. As part of these various tests, parameters such as elastic modulus, equilibrium stress, equilibrium creep deformation, recovery ratio, loss and storage modulus were determined.
Results of different tests such creep and stress relaxation showed that COPLA samples exhibit viscoelasticity behavior in both conditions. In addition, the Young's modulus of both dry and wet samples was not significantly different, but the Young's modulus of wet samples was slightly higher. As a last point, the storage modulus of both dry and wet samples exceeded the loss modulus, demonstrating that the material was able to recover most of the deformation energy rather than dissipate it.
To conclude, this study not only provided optimal parameters and test setups for investigating COPLA samples' mechanical properties in vitro, but also demonstrated the mechanical behavior of COPLA products under various time-dependent and independent mechanical tests.
The aim of this study was to determine the optimal mechanical test setup and parameters for COPLA product and assess its mechanical properties under simulated physiological condition (in PBS at 37 °C) and in ambient laboratory environment. COPLA samples were subjected to compression mechanical tests such as static compression, stress relaxation, creep-recovery, and dynamic testing, as well as shear tests such as amplitude and frequency sweep, under both conditions. As part of these various tests, parameters such as elastic modulus, equilibrium stress, equilibrium creep deformation, recovery ratio, loss and storage modulus were determined.
Results of different tests such creep and stress relaxation showed that COPLA samples exhibit viscoelasticity behavior in both conditions. In addition, the Young's modulus of both dry and wet samples was not significantly different, but the Young's modulus of wet samples was slightly higher. As a last point, the storage modulus of both dry and wet samples exceeded the loss modulus, demonstrating that the material was able to recover most of the deformation energy rather than dissipate it.
To conclude, this study not only provided optimal parameters and test setups for investigating COPLA samples' mechanical properties in vitro, but also demonstrated the mechanical behavior of COPLA products under various time-dependent and independent mechanical tests.