Ultrasonic spectroscopy describes the microstructure of tendon

The strong dependence of tendon echogenicity on insonation angle is explored by analyzing echo spectra. The hypothesis is that the angle-dependent properties are determined by tendon microstructure and thus can be used to detect sub-clinical focal damage. The highly anisotrophic microstructure includes fluid spaces surrounding fibers and fascicles that are the most likely sources of ultrasonic backscatter. Echo spectra from spontaneously damaged equine tendon samples were compared to normal equine tendon and found to exhibit a dramatic decrease in anisotropic properties that appears to be related to the spatial organization and type of collagen generated during repair. Variation in echo spectra with insonation angle was found to be a robust indicator of mechanical damage.