Arthroscopic devices and methods

Abstract

An electrosurgical probe can be detachably secured to a handpiece having a motor drive unit and an RF current contact. The electrosurgical probe includes an elongate shaft having a longitudinal axis, a distal dielectric tip, and a proximal hub which is detachably securable to the handpiece. A hook electrode is reciprocatably mounted in the distal dielectric tip, and an RF connector on the hub is couplable to the RF current contact in the handpiece when the hub is secured to the handpiece. A drive mechanism in the hub mechanically couples to the hook electrode, and drive mechanism engages a rotational component in the motor drive unit when the hub is secured to the handpiece. The drive mechanism converts rotational motion from the rotational component into axial reciprocation and transmits the axial reciprocation to the hook electrode to axially displace the hook electrode between a non-extended position and an extended position relative to the dielectric tip.

What is claimed is: 
     
         1 . An electrosurgical probe for use with a handpiece having a motor drive unit and an RF current contact, said probe comprising:
 an elongate shaft having a longitudinal axis, a distal dielectric tip, and a proximal hub configured to be detachably secured to the handpiece;   a hook electrode reciprocatably mounted in the distal dielectric tip;   an RF connector on the hub configured to couple to the RF current contact in the handpiece when the hub is secured to the handpiece; and   a drive mechanism in the hub mechanically coupled to the hook electrode, wherein the drive mechanism is configured to engage a rotational component of the motor drive unit when the hub is secured to the handpiece and wherein the drive mechanism converts rotational motion from the rotational component into axial reciprocation and transmits the axial reciprocation to the hook electrode to axially shift the hook electrode between a non-extended position and an extended position relative to the dielectric tip.   
     
     
         2 . The electrosurgical probe of  claim 1  wherein the drive mechanism comprises an elongate member disposed in the elongate shaft and having a distal end attached to the hook electrode. 
     
     
         3 . The electrosurgical probe of  claim 2  wherein the drive mechanism further comprises a rotatable a cam assembly located in the hub to receive rotational motion from the rotational component of the motor drive unit and covert the rotational motion into axial reciprocation which is delivered to the elongate member. 
     
     
         4 . The electrosurgical probe of  claim 2  wherein the elongate member is electrically conductive and connected to deliver RF current from the RF connector on the hub to hook electrode. 
     
     
         5 . The electrosurgical probe of  claim 4  wherein a proximal portion of the elongate member extends through a central opening in the hub and an intermediate portion of the elongate member extends through a central lumen in the shaft, wherein the hook electrode is reciprocatably disposed in an opening in the dielectric tip. 
     
     
         6 . The electrosurgical probe of  claim 5  wherein the central lumen in the shaft is configured to be connected to a negative pressure source. 
     
     
         7 . The electrosurgical probe of  claim 6  wherein the hub is configured to connect the central lumen to the negative pressure source. 
     
     
         8 . The electrosurgical probe of  claim 1 , wherein the shaft comprises an outer tube having a longitudinal lumen and an inner member reciprocatably received in the longitudinal lumen of the outer tube. 
     
     
         9 . The electrosurgical probe of  claim 8  wherein the dielectric tip is attached to a distal end of the outer tube and has an opening which communicates with the longitudinal lumen of the outer tube which is configured to be connected to a negative pressure source. 
     
     
         10 . The electrosurgical probe of  claim 9  wherein the hook electrode extends from a distal end of the inner member. 
     
     
         11 . The electrosurgical probe of  claim 9  wherein the inner member comprises a rod and the hook electrode comprises a bent wire attached to a distal end of the rod. 
     
     
         12 . The electrosurgical probe of  claim 11  wherein a distal face of the distal tip has a notch and wherein a lateral end of the bent wire of the hook electrode is configured to be retracted into the notch when the hook electrode is in its non-extended position. 
     
     
         13 . The electrosurgical probe of  claim 1  wherein the dielectric tip has at least one flow channel communicating with at least one interior channel in the shaft, said interior channel being configured to be connected to a negative pressure source. 
     
     
         14 . The electrosurgical probe of  claim 13  wherein the at least one flow channel has a cross-sectional area of at least 0.001 square inch. 
     
     
         15 . The electrosurgical probe of  claim 14  wherein the cross-sectional area of said at least one flow channel is configured to accommodate fluid outflows of at least 50 ml/min when said at least one interior channel and said at least one flow channel are connected to the negative pressure source. 
     
     
         16 . The electrosurgical probe of  claim 13  wherein said at least one flow channel comprises a portion of an opening in the dielectric tip which receives the hook electrode. 
     
     
         17 . The electrosurgical probe of  claim 13  wherein the  1  dielectric tip has at least one opening to receive the hook electrode in addition to the at least one flow channel. 
     
     
         18 . The electrosurgical probe of  claim 13  wherein the dielectric tip includes at least one opening to receive the hook electrode. 
     
     
         19 . The electrosurgical probe of  claim 18  wherein the at least one opening which receives the hook electrode is shaped with (i) a plurality of support elements adapted to support an elongate member which supports the hook electrode and (ii) a plurality of flow channels adapted to provide fluid flow in response to suction from the negative pressure source. 
     
     
         20 . The electrosurgical probe of  claim 19  comprising at least three support elements. 
     
     
         21 . The electrosurgical probe of  claim 1  wherein the dielectric tip comprises a ceramic material. 
     
     
         22 . An electrosurgical system comprising:
 the electrosurgical probe of  claim 1 ; and   a handpiece configured to be detachably connected to the hub on the electrosurgical probe, wherein the handpiece includes a motor drive unit configured to mechanically couple to the drive mechanism in the electrosurgical probe for longitudinally reciprocating the elongate member and hook electrode between the non-extended position and the extended position when the hub is secured to the handpiece.   
     
     
         23 . The electrosurgical system of  claim 22  further comprising a controller configured to activate and de-activate the motor drive unit to shift the elongate member and hook electrode between the non-extended position and the extended position relative to the dielectric tip. 
     
     
         24 . The electrosurgical system of  claim 23  wherein the controller is configured to deliver RF current to the electrode only in the extended position. 
     
     
         25 . The electrosurgical system of  claim 24  wherein the RF current has a waveform is selected from a group of waveforms consisting of a cutting waveform and a coagulation waveform. 
     
     
         26 . The electrosurgical system of  claim 24  wherein the controller is configured to longitudinally reciprocate the elongate member and hook electrode. 
     
     
         27 . The electrosurgical system of  claim 23  wherein the controller is configured to simultaneously reciprocate the hook electrode and deliver RF current to the hook electrode. 
     
     
         28 . The electrosurgical system of  claim 22  wherein the drive mechanism, motor drive unit, and the controller are configured to reciprocate the hook electrode over a distance between 0.01 mm and 5 mm, or between 0.1 mm and 4 mm. 
     
     
         29 . The electrosurgical system of  claim 22  wherein the controller and the motor drive unit are configured to reciprocate the hook electrode at a rate in a range from 5 Hz to 500 Hz, or in a range from 10 Hz to 100 Hz. 
     
     
         30 . A method for assembling an electrosurgical probe system, said method comprising:
 providing a first electrosurgical probe as in  claim 1 ;   providing a handpiece including a motor drive unit and an RF current contact; and   removably attaching the hub on the first electrosurgical probe to the handpiece, wherein such attachment mechanically couples the motor drive unit in the handpiece to the drive mechanism in the electrosurgical probe for longitudinally reciprocating an elongate member in the probe to reciprocate an RF electrode between the non-extended position and the extended position.   
     
     
         31 . A method as in  claim 30 , wherein removably attaching the hub on the electrosurgical probe to the handpiece also couples an RF connector on the hub to the RF current contact on the handpiece. 
     
     
         32 . A methods as in  claim 31 , further comprising detaching the first electrosurgical probe from the handpiece after the electrosurgical probe system has been used to treat a patient. 
     
     
         33 . A method as in  claim 32 , further comprising removably attaching the hub on a second different probe to the handpiece and treating the patient with the probe. 
     
     
         34 . A method for electrosurgically resecting tissue, said method comprising:
 positioning a distal end of a shaft having a longitudinal axis at a tissue target site so that a distal tip of the shaft is adjacent a target tissue;   rotating a motor in a handpiece attached to a proximal end of the shaft to axially reciprocate a hook electrode at the distal tip of the shaft between an axially non-extended position and an extended position relative to the dielectric tip;   engaging the hook electrode against target tissue; and   delivering electrical current through the hook electrode to the target tissue engaged by the electrode.   
     
     
         35 . The method of  claim 34 , wherein the motor is rotating so that the hook electrode is reciprocating when the hook electrode is engaged against the target tissue. 
     
     
         36 . The method of  claim 34 , wherein the motor is stopped so that the hook electrode is stationary when the hook electrode is engaged against the target tissue. 
     
     
         37 . The method of  claim 34 , further comprising drawing a negative pressure through a central lumen of the shaft to aspirate a region surrounding the target tissue when the hook electrode is engaged against the target tissue. 
     
     
         38 . The method of  claim 37  wherein the distal end of the shaft is submerged in a conductive fluid when the distal tip of the shaft is engaged against the target tissue. 
     
     
         39 . The method of  claim 38  wherein the current is radiofrequency current delivered to cauterize or ablate the target tissue.