Abstract: A unit (10) for causing angular momentum (11) about an axis (13a), which unit includes, inflow sequence, an incoming fluid pathway (12), a first fluid pathway (14a) in fluid communication with the incoming fluid pathway (12), a second fluid pathway (16a) in fluid communication with the incoming fluid pathway (12), an outgoing fluid pathway (18) in fluid communication with the first and second fluid pathway (14a, 16a), a flow regulating means (20a) for regulating the proportional flow in the first and second fluid pathways (14a, 16a), and wherein the first and second fluid pathways (14a, 16a) are respectively arranged about the axis (13a) generally in a plane transverse to the axis (13a).

Abstract: The invention provides a variety of surgical instruments for forming a liquid jet, which are useful for performing a wide variety of surgical procedures. In some embodiments, the invention provides surgical liquid jet instruments having a pressure tube and an evacuation tube, where the pressure tube includes at least one nozzle for forming a liquid jet and where the evacuation tube includes a jet-receiving opening for receiving the liquid jet when the instrument is in operation. In some embodiments, the surgical liquid jet instrument is constructed to minimize damage to the tissue surrounding the tissue that is desired to be removed. In some embodiments, the outer surface of the distal tip of the evacuation tube wall and/or the pressure tube wall is blunted to minimize tissue damage. The invention also provides surgical methods utilizing the inventive surgical liquid jet instruments for cutting or ablating a selected tissue within portions of a patient's spine, such as within the intervertebral disc.