Wave velocities in articular cartilage measured by micro-Brillouin scattering technique.

Micro-Brillouin scattering was used to measure gigahertz ultrasonic wave velocities in the articular cartilage of a bovine femur. Velocities propagating parallel to the surface of the subchondral bone were 3.36-3.83 × 103 m/s in a dry cartilage sample. Anisotropy measurements were also performed in a 10-µm-diameter local area of the cartilage matrix. A weak velocity anisotropy reflected characteristics of the layers. The velocity also depended on the water content. In the middle layer, the velocity in the dry sample was 3.58 × 103 m/s, whereas that for a fully wet sample was 2.04 × 103 m/s.