Explore the vast range of titles available.

Articular cartilage exhibits site-specific biomechanical properties. However, no study has comprehensively characterized site-specific cartilage properties from the same knee joints at different stages of osteoarthritis (OA). Cylindrical osteochondral explants (n = 381) were harvested from donor-matched lateral and medial tibia, lateral and medial femur, patella, and trochlea of cadaveric knees (N = 17). Indentation test was used to measure the elastic and viscoelastic mechanical properties of the samples, and Osteoarthritis Research Society International (OARSI) grading system was used to categorize the samples into normal (OARSI 0–1), early OA (OARSI 2–3), and advanced OA (OARSI 4–5) groups. OA-related changes in cartilage mechanical properties were site-specific. In the lateral and medial tibia and trochlea sites, equilibrium, instantaneous and dynamic moduli were higher (p < 0.001) in normal tissue than in early and advanced OA tissue. In lateral and medial femur, equilibrium, instantaneous and dynamic moduli were smaller in advanced OA, but not in early OA, than in normal tissue. The phase difference (0.1–0.25 Hz) between stress and strain was significantly smaller (p < 0.05) in advanced OA than in normal tissue across all sites except medial tibia. Our results indicated that in contrast to femoral and patellar cartilage, equilibrium, instantaneous and dynamic moduli of the tibia and trochlear cartilage decreased in early OA. These may suggest that the tibia and trochlear cartilage degrades faster than the femoral and patellar cartilage. The information is relevant for developing site-specific computational models and engineered cartilage constructs.

Osteoarthritis is well established to be a whole joint disease, and previous studies have found degenerative changes in periarticular tendons around osteoarthritic joints. Thus, we aimed to assess whether potential periarticular adaptations (patellar tendon) are related to intraarticular changes (tibial cartilage) at material-level. As they are both connected to the tibia, we explored the relationships between patellar tendon and tibial cartilage viscoelastic properties obtained from eight osteoarthritic cadaver knees. Six patellar tendon regions and six to eight tibial cartilage samples per knee underwent tensile and indentation sinusoidal measurements, respectively, at 0.1, 0.5, and 1 Hz. Osteoarthritis Research Society International (OARSI) grades were obtained from tibial cartilage histological sections and tested for associations with patellar tendon properties. All knees were deemed osteoarthritic according to tibial cartilage OARSI grades. Comparing the two tissues, we found strong inverse correlations in the phase difference between stress and strain (r: −0.887 to −0.934). Patellar tendon phase difference was also strongly, inversely correlated with average tibial cartilage OARSI grade (r: −0.889 to −0.890). Patellar tendon dynamic modulus was moderately correlated with tibial cartilage dynamic modulus (r: −0.561 to −0.575) and OARSI grade (r: 0.631–0.646). For the first time, we show that the viscoelastic properties of the human patellar tendon are strongly, inversely related to tibial cartilage viscoelastic properties and OARSI grades in osteoarthritic knees, suggesting these two tissues may undergo diverging adaptations with osteoarthritis. These results provide a foundation for more detailed future investigations on patellar tendon-cartilage interactions in knee osteoarthritis.

Osteoarthritis degenerates cartilage and impairs joint function. Early intervention opportunities are missed as current diagnostic methods are insensitive to early tissue degeneration. We investigated the capability of visible light-near-infrared spectroscopy (Vis-NIRS) to differentiate normal human cartilage from early osteoarthritic one. Vis-NIRS spectra, biomechanical properties and the state of osteoarthritis (OARSI grade) were quantified from osteochondral samples harvested from different anatomical sites of human cadaver knees. Two support vector machines (SVM) classifiers were developed based on the Vis-NIRS spectra and OARSI scores. The first classifier was designed to distinguish normal (OARSI: 0–1) from general osteoarthritic cartilage (OARSI: 2–5) to check the general suitability of the approach yielding an average accuracy of 75% (AUC = 0.77). Then, the second classifier was designed to distinguish normal from early osteoarthritic cartilage (OARSI: 2–3) yielding an average accuracy of 71% (AUC = 0.73). Important wavelength regions for differentiating normal from early osteoarthritic cartilage were related to collagen organization (wavelength region: 400–600 nm), collagen content (1000–1300 nm) and proteoglycan content (1600–1850 nm). The findings suggest that Vis-NIRS allows objective differentiation of normal and early osteoarthritic tissue, e.g., during arthroscopic repair surgeries.