Viscoelasticity and histology of the human cartilage in healthy and degenerated conditions of the knee

Abstract

Background There are many studies on osteoarthritis, but only a few studies deal with human arthrosis, comparing the mechanical properties of healthy and diseased samples. In most of these studies, only isolated areas of the tibia are examined. There is currently only one study investigating the complete mapping of cartilage tissue but not the difference between instantaneous modulus (IM) in healthy and diseased samples. The aim of this study is to investigate the relationship between the biomechanical and histological changes of articular cartilage in the pathogenesis of osteoarthritis. Methods The study compared 25 tibiae with medial gonarthrosis and 13 healthy controls. The IM was determined by automated indentation mapping using a Mach-1 V500css testing machine. A grid was projected over the sample and stored so that all measurements could be taken at the same positions (100 ± 29 positions across the tibiae). This grid was then used to perform the thickness measurement using the needle method. Samples were then taken for histological examinations using a hollow milling machine. Then Giemsa and Safranin O staining were performed. In order to determine the degree of arthrosis according to histological criteria, the assessment was made with regard to Osteoarthritis Research Society International (OARSI) and AHO scores. Results A significant difference ( p < 0.05) could be observed in the measured IM between the controls with 3.43 ± 0.36 MPa and the samples with 2.09 ± 0.18 MPa. In addition, there was a significant difference in IM in terms of meniscus-covered and meniscus-uncovered areas. The difference in cartilage thickness between 2.25 ± 0.11 mm controls and 2.0 ± 0.07 mm samples was highly significant with p < 0.001. With regard to the OARSI and AHO scores, the samples differed significantly from the controls. The OARSI and AHO scores showed a significant difference between meniscus-covered and meniscus-uncovered areas. Conclusions The controls showed significantly better viscoelastic behavior than the arthrotic samples in the measured IM. The measured biomechanical values showed a direct correlation between histological changes and altered biomechanics in gonarthrosis.

Osteoarthritis-Related Degeneration Alters the Biomechanical Properties of Human Menisci Before the Articular Cartilage

“…While Sim et al post hoc graded the asymptomatic articular surfaces of their eight specimens on an adapted macroscopic Committee of the International Cartilage Repair Society (ICRS) score (Mainil-Varlet et al, 2003) and histological Mankin scoring (Mankin et al, 1981), we grouped our 24 knees a priori into two different degeneration groups, which was based on KL and macroscopic Pauli scorings. Despite the use of different measurement methods, the IM values for the tibial AC were similar to those reported in the literature (Deneweth et al, 2013;Sim et al, 2014Sim et al, , 2017Seidenstuecker et al, 2019): while Sim et al (2014Sim et al ( , 2017 and Seidenstuecker et al (2019) used the same automated indentation mapping method, Deneweth et al (2013) performed a manual mapping method, where fullthickness 4-mm diameter cylindrical AC explants were extracted from the tibial plateau and exposed to unconfined compression. The IM values were lower in the study of Seidenstuecker et al (2019), which might be due to the fact that no section-specific subdivision of the tibial plateau was performed during their examinations.…”

“…Despite the use of different measurement methods, the IM values for the tibial AC were similar to those reported in the literature (Deneweth et al, 2013;Sim et al, 2014Sim et al, , 2017Seidenstuecker et al, 2019): while Sim et al (2014Sim et al ( , 2017 and Seidenstuecker et al (2019) used the same automated indentation mapping method, Deneweth et al (2013) performed a manual mapping method, where fullthickness 4-mm diameter cylindrical AC explants were extracted from the tibial plateau and exposed to unconfined compression. The IM values were lower in the study of Seidenstuecker et al (2019), which might be due to the fact that no section-specific subdivision of the tibial plateau was performed during their examinations. While they divided their tibial AC into meniscuscovered and uncovered regions, we additionally grouped the covered parts in the three anatomical regions of the menisci, resulting in more diverging IM results.…”

“…In accordance with Seidenstuecker et al (2019) , we identified the P max , which equals the force registered by the load cell after reaching the AC and the meniscus-specific indentation amplitude. The initial viscous response of the tissues was examined by the determination of the E t20 :…”

“…On the basis of the results of a similar study investigating IM differences between healthy and degenerated tibial cartilage ( Seidenstuecker et al, 2019 ), an a priori sample size calculation [G ∗ Power 3.1 ( Faul et al, 2007 ): α = 0.05, Power (1 − β) = 0.95, effect size (dz) = 4.71, n = 6] was performed to ensure sufficient statistical power of the study. Because no data exist on IM measurements on meniscus samples, the medical epidemiology and statistics department recommended increasing the sample size to n = 12 for both groups, resulting in a total sample size of n = 24.…”

“…Despite several authors having investigated the biomechanical properties of isolated meniscal and tibial and femoral cartilage specimens utilizing indentation mapping ( Sim et al, 2014 , 2017 ; Hadjab et al, 2018 ; Pflieger et al, 2019 ; Seidenstuecker et al, 2019 ), a combined complementary characterization of the articulating partners within the knee joint remains lacking. Consequently, an exact understanding of the interplay between these tissues in relation to the degenerative process is of considerable interest.…”