A non-invasive method of tendon force measurement

A non-invasive method of tendon load measurement was developed and patended in 2005 at the Laboratoire de Biomécanique et Pathologie Locomotrice du Cheval, Maisons-Alfort (France).
The method is based on a probe composed by an ultrasonic pulse emitter and two or more receivers. The probe is placed in contact with the skin, in front of a superficial tendon, and its emitter sends an ultrasonic pulse through the skin and inside the tendon. The ultrasonic wave propagating in the tendon radiates a so-called "lateral wave" back through the skin and to the probe. Two receivers detect the lateral wave, enabling the calculus of its apparent velocity. Since the time of flight necessary for the wave to cross the skin, propagate through the tendon and back across the skin is common to the two receivers, the wave apparent velocity does not depend on the skin thickness.
See the scheme below for a representation of the path followed by the wave, and see the original paper for more information (Pourcelot et al., 2005).

Probe propagation