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Wolff’s Law

By August 25, 2014Blog

“Tensegrity and mechanoregulation: from skeleton to cytoskeleton”, Christopher S. Chen and Donald E. Ingber, Children’s Hospital and Harvard Medical School. Osteoarthritis and Cartilage (1999) 7, 81-94. doi:10.1053/joca.1998.1064

Wolff’s law: A law according to which biologic systems such as hard and soft tissues become distorted in direct correlation to the amount of stress imposed upon them.

Mosby’s Dictionary of Complementary and Alternative Medicine. (c) 2005, Elsevier.

Chen and Ingber discuss Wolff’s law and use the femur as an example and point out that the bony trabeculae that make up the cancellous bone in the medial and lateral sides of the femur have different structure due to the different localized forces upon them.

“This observation suggests that the living cells that continually remodel bone are able to sense changes in mechanical stresses in their local environment and that they respond by depositing new Extracellular Matrix (ECM) where it is needed and remove it from where it is not.”

“Architectural organization on yet a smaller size scale (the molecular level) also contributes to the mechanical strength of biological tissue. In the bone, the matrix of each trabeculum consists of a composite material containing hydroxyapatite crystals embedded within a network of collagen fibrils. The collagen augments the tensile strength of the bone, while the minerals contribute largely to its compressive stiffness and strength. In the living organism, the stress in the bone ECM is influenced by the shape of the entire bone, the pull of the surrounding muscles and tendons, and its loading conditions.”

And besides bone, what about the soft tissues:

“Pre-stress also plays an important role in determining the mechanics of cartilage, tendons, and ligaments. In cartilage, the loose collagen network is stretched open and pre-stressed by the osmotic force of hydration of embedded proteoglycan molecules, however, the cellular components (chondrocytes) and their internal support elements (cytoskeleton, nucleus) may also bear some mechanical loads. In soft tissues that are composed mostly of parallel collagen fibers and elastin, such as ligaments and tendons, the pre-stress results from the active contraction of living cells (myofibroblasts) that are embedded within its ECM.”

So far, the discussion of tensegrity and mechanotransduction has focused on the gross anatomy level:

In the next few blog posts: Tensegrity and Mechanotransduction at the cellular level

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