Articular cartilage stretching

The spine doesn’t react very positively to stretching but what about other cartilagenous regions?  In one post, we discovered that articular cartilage can undergo endochondral ossification and can undergo grow in size.

A big question is whether articular can contribute to height:

The use of knee height to estimate maximum stature in elderly Chinese.

“In a study of 247 (130 men and 117 women) adult ethnic Chinese living in Melbourne, Australia, we tested the hypothesis that knee height is independent of age{thus that articular cartilage degeneration would not affect knee height} and attempted to devise an equation for the estimation of maximum stature (MS) in the this elderly group (aged 65 yrs) of this population. Anthropometric indices, including body weight, stature, arm-span, and knee height were twice measured using standard methods. In both men and women, the younger adults were taller and had a greater arm-span than their elderly counterparts: however, there was no difference in knee height or body weight between the two groups. Knee height was not associated with age, while stature and arm-span{But arm span would be affected by articular cartilage too only} correlated negatively with age.  Knee height provides for a valid estimate of MS during early adulthood than arm-span. Knee height is independent of age and does not appear to decreased over time, in spite of an expected cohort effect in this population. Arm-span, however, appears to change with a cohort as well as with age. Thus, there is a place in a life-time nutritional assessment of the aged to measure both arm-span as an index of cohort status and knee height for an individual’s maximum achieved stature.”

According to Figure 1, the knee height measurement would incorporate the articular cartiage regions of the ankle and the knee.  There was a negative correlation between age and knee height it was just not statistically significant.  Interestingly arm span decreased more than overall stature despite discs not being a factor.

Micromechanical response of articular cartilage to tensile load measured using nonlinear microscopy.

“This work investigates the inhomogeneous distribution of strain in loaded AC by tracking the movement and morphological changes of individual chondrocytes using point pattern matching and Bayesian modeling.”

“Articular cartilage (AC) is a connective tissue found at the ends of articulating bones within the synovial joints of mammals. Healthy AC is composed primarily of a gel of hydrophilic proteoglycan molecules and interstitial fluid, constrained by a dense network of collagen fibres.”

“Tensile loading reveals the interconnectivity of the fibrous protein networks, and facilitates continuity of load transmission through the matrix”

“As well as resisting shear load associated with joint articulation, the superficial zone also provides a strain-limiting surface that restricts bulging close to regions that experience high compressive load.”

“Ridges in the surface of bovine AC that appeared as the tissue was stretched, and attributed these to protruding collagen fibres. Although these were slightly thinner than those found in the present investigation, the size difference could be associated with width contraction under load and the resolution limitations of the camera. The thick palmar cartilage showed regions of blurred and filamented signal near the surface, and filamented patterns throughout the middle and deep zones. Dorsal and cortical ridge samples showed patches of high intensity and varying signal orientation in the middle zone, which are possibly leaves of collagen overlapping at different angles. In the deep zone, images contained streaks of high signal intensity, which are unlikely to be due to tangentially aligned collagen. It is possible that these patterns arise from the interweaving in the horizontal plane of the predominantly perpendicular fibres. Chondrocytes (which appear dark under PLM) are arranged in columns perpendicular to the underlying bone, and regular spacing of these columns may cause the surrounding matrix to appear filamented when viewed en face.”

“Cartilage is thickest in regions that experience the least compressive load”

“The average cellular strain values of 2% in the long axis and −5% in short axis indicate that the cells experienced a mean in-plane compressive force and that ellipticity increased despite an outward force being applied to the sample. This overall compressive strain was not significantly different to that of the surrounding matrix, despite the low mechanical stiffness of chondrocytes”

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