US Patent 9421027 Method of creating a shear stress field with medical device

An ultrasonic horn for use with an ultrasonic surgical hand piece including a resonator comprises a contacting annulus having a plurality of angled lands. The lands are alternated around the annulus such that adjacent lands have opposite angles. As a result of the adjacent angled lands, a shear stress field is developed in contacted tissue due to the promotion of refracted longitudinal ultrasonic waves propagating in different directions at the interface to the coupled tissue. The shear stress field enhances the fragmentation and removal rate of fibrous, elastic, and tenacious tissue. The horn is hollow permitting suction to be applied to the tissue for controlling tissue contact with the lands.