Basic Principles of Musculosketal Ultrasound
Tendons are critical biomechanical units in the musculoskeletal system, the function of which is to transmit muscular strength to mobile skeletal segments. Tendons are extremely resistant to traction, almost like bone, being able to bear up to 1000 kg per 10 mm2 transverse section. Conversely, tendons are not very elastic, being only able to tolerate a maximum elongation of 6% before being damaged. Tendons have very slow metabolism, even during action, and it can only be significantly increased by inflammatory conditions and traumas. Tendons macroscopically appear as ribbon-like structures, with extremely variable shape and dimensions, characterized by the presence of dense fibrous tissue arranged in parallel bundles. Primary bundles are assembled to form secondary bundles (representing the tendon’s functional unit), which are in turn clustered in tertiary bundles.