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The Concept of Prestress

By August 18, 2014Blog

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

 

The Concept of Prestress:

Prestressing means the intentional creation of permanent stresses in a structure for the purpose of improving its performance under various service conditions. There are the following basic types of prestressing:

  • Precompression (mostly, with the weight of the structure itself)
  • Pretensioning with high-strength embedded tendons
  • Post-tensioning with high-strength bonded or unbonded tendons

Chen and Ingber discuss prestress in articular joints:

“The stable position of the bones that articulate at any joint depends on the tensile forces of the muscles, tendons, and ligaments that bridge them. In the knee, for example, the cartilaginous regions at the end of apposing bones come into direct contact due to compression. Most of this compression is not due to gravity, rather it is created by the surrounding ligaments and tendons that cross the joint, and these are always under tension. The internal tension and/or pre-stress in this system stabilizes the joint….”

“To understand the critical importance of these internal tensions and/or pre-stress in this complex structure, one only needs to examine the case where tendons and ligaments loosen: this results in joint instability, increased wear on the articular cartilage, pain and loss of function.”

Our next blog will be on Wolff’s Law.

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