Forces in Joints, Skeletal Biology, Analysis of Bone Remodeling, Mechanical Properties of Bone, Fatigue and Fracture Resistance of Bone, Mechanical Adaptation of the Skeleton, Synovial Joint Mechanics, Mechanical Properties of Ligament and Tendon

Skeletal Tissue Mechanics

https://onlinelibrary.wiley.com/doi/pdf/10.1016/j.orthres.2004.08.008

Rapid phenotypic changes in passaged articular chondrocyte subpopulations.

Design of porous scaffolds for cartilage tissue engineering using a three-dimensional fiber-deposition technique.

Rational design of hydrogels for tissue engineering: impact of physical factors on cell behavior.

3D fiber-deposited scaffolds for tissue engineering: Influence of pores geometry and architecture on dynamic mechanical properties

Comparison of the equilibrium response of articular cartilage in unconfined compression, confined compression and indentation

Biomechanical properties of knee articular cartilage.

Fibrillation of articular surface and depletion of proteoglycans are the structural changes related to early osteoarthrosis. These changes make cartilage softer and prone to further degeneration. The aim of the present study was to combine mechanical and acoustic measurements towards quantitative arthroscopic evaluation of cartilage quality. The performance of the novel ultrasound indentation instrument was tested with elastomers and bovine articular cartilage in vitro. The instrument was capable of measuring elastomer thickness (r = 1.000, p < 0.01, n = 8) and dynamic modulus (r = 0.994, p < 0.01, n = 13) reliably. Osteochondral plugs were tested before and after enzymatic degradation of cartilage proteoglycans by trypsin or chondroitinase ABC, and of cartilage collagens by collagenase. Trypsin and collagenase induced a mean decrease of −31.2 ± 12.3% (±SD, p < 0.05) and −22.9 ± 20.8% (p = 0.08) in dynamic modulus, respectively. Rate of cartilage deformation, i.e. creep rate, increased by +117.8 ± 71.4% (p < 0.05) and +24.7 ± 35.1% (p = 0.17) in trypsin and chondroitinase ABC treatments, respectively. Collagenase induced a greater decrease in the ultrasound reflection from the cartilage surface (−54.2 ± 29.6%, p < 0.05) than trypsin (−17.1 ± 13.5%, p = 0.08). In conclusion, combined quantitation of tissue modulus, viscoelasticity and ultrasound reflection from the cartilage surface provides a sensitive method to distinguish between normal and degenerated cartilage, and even to discern proteoglycan loss and collagen degradation from each other.

https://iopscience.iop.org/article/10.1088/0967-3334/23/3/302/pdf

Novel mechano-acoustic technique and instrument for diagnosis of cartilage degeneration.

Ultrasound (US) has been suggested as a means for the quantitative detection of early osteoarthrotic changes in articular cartilage. In this study, the ability of quantitative US 2-D imaging (20 MHz) to reveal superficial changes in bovine articular cartilage after mechanical or enzymatic degradation was investigated in vitro. Mechanical degradation was induced by grinding samples against an emery paper with the grain size of 250 μm, 106 μm, 45 μm or 23 μm. For enzymatic degradation, samples were digested with collagenase, trypsin or chondroitinase ABC. Variations of the US reflection coefficient induced by the degradation were investigated. Furthermore, two novel parameters, the US roughness index (URI) and the spatial variation of the US reflection coefficient (SVR), were established to quantitate the integrity of the cartilage surface. Statistically significant decreases (p < 0.05) in US reflection coefficient were observed after mechanical degradations or enzymatic digestion with collagenase. Increases (p < 0.05) in URI were also revealed after these treatments. We conclude that quantitative US imaging may be used to detect collagen disruption and increased roughness in the articular surface. These structural damages are typical of early osteoarthrosis.

Ultrasonic quantitation of superficial degradation of articular cartilage

The sensitivity of the reflection coefficient, attenuation and velocity to the enzymatic degradation of bovine patellar cartilage was evaluated in real-time with high-frequency ultrasound (US) (29.4 MHz). These parameters were estimated from the radiofrequency (RF) signal, which was recorded at 5-min intervals during the digestion of the tissue by collagenase or by trypsin. The coefficient of reflection at cartilage surface decreased by 78.5% and 10.5% (p < 0.05) after 6 h of exposure to collagenase and 4 h of exposure to trypsin, respectively. During the trypsin digestion, the attenuation in cartilage increased by 0.274 dB/mm (p < 0.05) and the velocity decreased by 7 m/s (p < 0.05). The coefficient of reflection at the cartilage surface was the most sensitive acoustic parameter to the enzymatic degradation of cartilage and may be the easiest to implement for clinical diagnosis of cartilage quality. US velocity was found to be insensitive to degradation. The small difference in mean velocity between the control and degraded cartilage suggests that a constant predefined US velocity value can be used to obtain diagnostically acceptable measurement of the cartilage thickness.

Jani Hirvonen

Papers

Comparison of the equilibrium response of articular cartilage in unconfined compression, confined compression and indentation

Biomechanical properties of knee articular cartilage.

Novel mechano-acoustic technique and instrument for diagnosis of cartilage degeneration.

Ultrasonic quantitation of superficial degradation of articular cartilage

Real-time ultrasound analysis of articular cartilage degradation in vitro.