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 of the insert may taper progressively from the body portion to the sharp cutting edge. The sharp cutting edge may actually constitute a pair of edges disposed in a scissor relationship. The cutting edge(s) may progressively converge to a sharp point. Alternately, the sharp cutting edge may be disposed at the inner periphery of an aperture. Instead of being vibrated at a single ultrasonic frequency, the insert may be vibrated at a pair of ultrasonic frequencies to impart a vibration of the insert simultaneously in the coaxial direction and in a direction perpendicular to the coaxial direction. The insert engages a meniscus to trim fragments from the meniscus. The fragments may be removed from the area of the meniscus by an aspirator which may be disposed in coaxial and enveloping relationship with the insert. The aspirator also acts to pull the partially removed fragments from the meniscus, thereby facilitating the continued operation of the sharp cutting edge(s) in removing the fragment from the meniscus.