Crystals are energized to vibrate at an ultrasonic frequency. The crystals are coupled to an insert having a body portion coaxial with the crystals so as to vibrate the insert at the ultrasonic frequency. At least one sharp cutting edge extends from one end of the body portion of the insert. The thickness...http://www.google.de/patents/US4838853?utm_source=gb-gplus-sharePatent US4838853 - Apparatus for trimming meniscus
