Biomedical Engineering Reference
In-Depth Information
Chapter 4
Ligament and Tendon Enthesis: Anatomy
and Mechanics
Matteo M. Tei, Kathryn F. Farraro, and Savio L.-Y. Woo
4.1
Introduction
The insertions of ligaments and tendons to bone are morphologically and
biomechanically complex. Within the length of 1 mm, the insertion is transformed
from soft connective tissue to hard bone. In general, this transformation consists
of four zones; i.e., collagen fibers, non-mineralized fibrocartilage, mineralized
fibrocartilage, and bone, making it suitable to transmit loads with minimal stress
concentration. However, the morphology of ligament and tendon insertions can
vary greatly from one ligament or tendon to another as well as between the two ends
of the same ligament. Adding to this complexity, factors such as age, skeletal
maturation, and physical activity have also been shown to affect the morphological
and biomechanical properties of these entheses, which could, in turn, have a
significant influence on their modes of failure caused by daily or sports activities.
In this chapter, we will begin by discussing the anatomy of the enthesis,
including a review of the gross morphology as well as histology and appearance
of two distinct types of insertions: the direct and indirect insertions to bone. We will
also touch upon the vascular and nerve supply, including associated blood vessels
and neuroreceptors. This will be followed by details on the biomechanical function
of insertion sites, including some challenges with methods involved in determining
their properties.
We will then review the changes that occur across the insertion site during
growth and skeletal maturity. Specific structural changes of insertion sites during
skeletal maturation and the asynchronous change between the properties of the
ligament insertion and substance will be explained using the femur-MCL-tibia
complex (FMTC) as an example. This will be followed by a description of
M.M. Tei • K.F. Farraro • S.L.-Y.Woo ( * )
Musculoskeletal Research Center, Department of Bioengineering, Swanson School
of Engineering, University of Pittsburgh, Pittsburgh, PA, USA
e-mail: mmt44@pitt.edu ; kff7@pitt.edu ; ddecenzo@pitt.edu
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