Patent ID: 8088136

Claim:
A medical instrument for cutting tissue, comprising a tubular outer shaft having a distal end and having at least one first window arranged at the distal end, a tubular inner shaft arranged in the outer shaft and having a longitudinal axis and a distal end and being rotatable about the longitudinal axis, the tubular inner shaft having a second window arranged in a region of the at least one first window of the outer shaft, the second window being provided with at least one cutting element, and a fixing element for holding the inner shaft relative to the outer shaft in a preset rotational position, the fixing element being breakable through a rotational movement of the inner shaft about the longitudinal axis relative to the outer shaft so that once the fixing element is broken, the inner shaft is freely rotatable with respect to the outer shaft; wherein said medical instrument further comprises a coupling element connected non-rotatably to the outer shaft for connecting the outer shaft to a handgrip, a rotation transfer element connected to the inner shaft for connecting the inner shaft to drive means, wherein the fixing element connects the coupling element with the rotation transfer element.