Abstract:
A surgical instrument that includes a probe that is extended into a body cavity and a handle held by a surgeon outside the body cavity, where the surgical instrument includes both an optical system and surgical tool operable by the surgeon that passes through the handle and probe includes a connection configuration on its proximal end of the probe and elements within a bore of the handle which allows for securely locking the probe in at least two different orientations. In particular, the proximal end of the probe includes a pair of axial slots and a twist region which cooperate with inwardly projecting land regions in a bore of the handle. A locking mechanism is used to selectively move a locking member into and out of one or the other of said pair of axial slots so as to secure the probe on the handle in the desired orientation.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention generally relates to surgical instruments used for carpal tunnel release, and is particularly directed to an improved hub and handle design. 
   2. Background Description 
   MicroAire Surgical Instruments has been marketing for a number of years a surgical tool based on U.S. Pat. No. 4,962,770 to Agee et al., U.S. Pat. No. 4,963,147 to Agee et al., U.S. Pat. No. 5,089,000 to Agee et al., and U.S. Pat. No. 5,306,284 to Agee et al, each of which is incorporated fully herein by reference. This surgical tool is used to inspect and manipulate selected tissue in a body cavity, and has particular application to performing safe and effective carpal tunnel release. These tools include a handle assembly, a probe member, an optical system, and a cutting system. The optical system and cutting system extend through the handle and into the probe and permit a surgical blade to be selectively deployed and retracted from a lateral opening in the top surface of the probe at its distal end. 
   The preferred use of the surgical instrument in performing carpal tunnel release is accomplished by forming a short transverse incision located proximal to the carpal tunnel and the wrist flexion crease. After longitudinal spreading dissection, to avoid injury to the sensory nerves, the incision is continued through the deep fascia of the forearm, the distal extension of which leads to the flexor retinaculum. After an incision through the finger flexor synovium, extension of the wrist will then expose the proximal opening of the carpal tunnel, thereby forming a passage to the carpal tunnel. The rotational orientation of the probe relative to the handle or holder is adjustable to suit the needs of the surgeon. After adjusting the rotational orientation of the probe, the probe is inserted through the incision and desirably through the length of the carpal tunnel to the distal edge of the flexor retinaculum. 
   By employing the optical system, and through manipulation of the patient&#39;s extremities, the anatomy within the carpal tunnel can be clearly visualized on a display of a video monitor connected to a video camera and lighting source associated with the optical system. The distal end of probe will desirably have gently displaced the tendons, bursa and median nerve found within the carpal tunnel to facilitate insertion of the probe. Then the lateral aperture of the probe will be positioned adjacent the medial surface of the flexor retinaculum and, desirably, the configuration of the probe upper surface (which is preferably a flat surface) will exclude the displaced tissues from the region surrounding the lateral aperture. Markers can be used to indicate the point on the probe where the blade elevates, and help facilitate proper placement of the probe relative to the distal edge of the flexor retinaculum. 
   At the appropriate location, a cutting blade will be extended to contact the distal edge of the flexor retinaculum, while the surgeon views the tissue to be divided via the display. The blade point will desirably be extended to a position sufficient to completely release the ligament. While viewing (through the lateral aperture in the probe) the intended path of the extended cutting blade, the probe is then withdrawn, thereby dividing the flexor retinaculum and releasing the carpal tunnel. 
   The surgical tool described by Agee et al. is safe and effective and well regarded in the surgical community. Improvements to the mechanism for securely fastening the probe to the handle and for orienting the lateral opening of the probe to either side of the handle will be well regarded within the community. Currently, the tool includes a spring loaded knob and locking member which cooperates with an annular groove in the probe end. To align the probe to one side or another, the surgeon must align indicia or a rib member on the probe with indicia on the handle and screw the knob a sufficient amount to tighten the locking member against the probe 
   SUMMARY OF THE INVENTION 
   It is therefore an object of this invention to provide an improved hub and handle design for a surgical instrument, such as a carpal tunnel release tool described above in conjunction with the Agee et al. patents (U.S. Pat. Nos. 4,926,770, 4,963,147, 5,089,000, and 5,306,284, each of which are herein incorporated by reference). 
   According to the invention, the proximal end of a probe is provided with a pair of axial grooves that lead to a slotted twist region, and the handle includes a bore with inwardly projecting land regions sized to fit within the axial grooves and the slotted twist region. This allows the probe to slide within the bore, and then be twisted to its proper orientation. The pair of axial grooves on the probe end also serve the function of interacting with a locking member actuated by a button, slider, or similar device on the handle surface. Once the probe is twisted to the left or the right side of the handle, the locking member will be moved into position in at least one of the axial slots preferably under the influence of a spring bias. This prevents the probe from rotating accidentally during use. In addition, the slotted twist region and inwardly projecting lands of the bore prevent the probe from being removed from the handle accidentally during use. In a variation on the design, the locking member can cooperate with a series of depressions formed in the proximal end of the probe so that the probe can be oriented at a number of discrete angles. The slotted twist region can take a number of different forms including an annular groove in the circumference of the proximal end of the probe, or a pair of slotted pathways that accommodate a partial twist, such as a quarter twist, of the probe (it being understood that the slotted pathways could be sized for different amounts of twisting depending on the tool design). A variety of locking mechanisms can be used including, for example, pushbuttons at the top and front of the handle, or sliders at the top of the handle (it being recognized that the actuators can be positioned at a number of different locations on the handle, and can take a number of different forms). Preferably, the probe is disposable and made of a durable plastic material; however different materials such as composites, glass and metal can be used. Furthermore, to lighten the instrument, it is preferable that the handle be made of a rugged plastic material. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The foregoing and other objects, aspects and advantages will be better understood from the following detailed description of a preferred embodiment of the invention with reference to the drawings, in which: 
       FIGS. 1A-1D  are isometric, top, side, and end views of a two position screw lock hub design for a probe; 
       FIGS. 2A-2D  are isometric, top, side and end views of a two position twist lock hub design for a probe; 
       FIGS. 3A-3D  are isometric, top, side and end views of an adjustable position twist lock hub design for a probe; 
       FIGS. 4A-4D  are isometric views of probe and handle combinations where  FIG. 4A  shows the probe of  FIG. 1A  being inserted into a handle with a button release,  FIG. 4B  shows the probe of  FIG. 1A  being inserted into a handle with a slide release,  FIG. 4C  shows the probe of  FIG. 2A  being inserted into a handle with a top button release, and  FIG. 4D  shows the probe of  FIG. 3A  being inserted into a handle with a top button release; 
       FIGS. 5A-5D  are cut away illustrations of the probe and handle combinations of  FIGS. 4A-4D  where the probe has been inserted into the handle, twisted so that the upper face of the probe is oriented to one side of the handle, and locked in place using a locking mechanism that includes an actuator on the handle; 
       FIG. 6  is a schematic drawing of a bore hole with two inwardly projecting land regions; and 
       FIG. 7  shows an example of a retractable cutting blade and optical system positioned within a probe. 
   

   DETAILED DESCRIPTION 
     FIGS. 1A-1D  and  2 A- 2 D show probe designs where the probe can be selectively locked in a position that is oriented towards the left or right side of a surgical tool handle.  FIGS. 3A-3D  show a variation on the design shown in  FIGS. 2A-2D  where the probe can be locked in additional positions to the right and left side orientation. In each of these Figures, like elements use the same numbers. The probe designs primarily differ at the proximal end, as will be discussed in more detail below. 
   The probe  10  is preferably a disposable item that is attachable to a handle device and its proximal end  12 . Its distal end  14  can be inserted into a body cavity, and particularly into incision sites used when performing carpal tunnel release. The probe  10  preferably has a flat top surface that has a lateral opening  16  near the distal end. The lateral opening  16  allows for a cutting blade (not shown) located inside the probe  10  to be selectively deployed to performing cutting at locations selected by the surgeon. After cutting, the cutting blade is fully retractable within the lateral opening. Cutting is performed using an optical system (not shown) that passes through the probe  10  from an opening  18  in its proximal end  12  to the lateral opening  16 . The optical system may include optical fibers, optical waveguides, or a series or lenses or other suitable components. Preferably the optical system includes a camera, a display, and other components which allow the surgeon to view the tissue located at the lateral opening  16  using a remotely positioned display device. This enables a surgeon to make cuts at precise locations where tissue manipulation would provide benefit to the patient. 
   From the top view ( FIGS. 1B ,  2 B, and  3 B) it can be seen that a rib  20  can be provided which preferably precisely aligns with the path taken by the cutting blade when it is deployed from the lateral opening  16 . While not shown in the figures, markings or other indicia can be advantageously positioned on the top surface of the probe  10  to assist the surgeon in placing the probe in the proper location. While the embodiments shown herein have a single lateral opening  16  in the top surface near the distal end of the probe  10 , it should be understood that more than one opening could be provided (e.g., there could be separate openings for the optical system and the blade). 
   From the side view ( FIGS. 1C ,  2 C, and  3 C) it can be seen that the distal end of the probe  10  is closed  22  and preferably has a curved shape. This allows the end of the probe  22  to gently displace the tendons, bursa and median nerve found within the carpal tunnel, thus facilitating insertion of the probe. Pivot pin  24  is shown on the side of the probe  10 . The blade is preferably deployed and retracted using a tool extension shaft (not shown) that passes through the probe  10  and cooperates with a pivot pin  24  for pivoting the blade open and closed. 
   From the end view ( FIGS. 1D ,  2 D, and  3 D) it can be seen that the proximal end  12  has two axial slots  24  on opposite sides. These slots  24  serve the dual function of guiding the proximal end  12  of the probe  10  into a bore of surgical tool handle and interacting with a locking mechanism, as is discussed in detail below.  FIG. 6  schematically shows that the bore  25  of the handle includes inwardly projecting land regions  26 . To install the probe on the handle or to remove the probe from the handle, the two axial slots  24  must be aligned with the inwardly projecting land regions  26 . 
     FIGS. 1A-1C  show an embodiment of the probe where there are two slotted pathways  28  in the form of a threaded screw partial twist in a slotted twist region  30  of the proximal end  12  of the probe. The two slotted pathways  28  begin just after the two axial slots  24  and are connected therewith. The inwardly projecting lands  26  of the bore  25  ( FIG. 6 ) fit within the two slotted pathways  28  and permit a partial twist similar to a threaded screw. While  FIGS. 1A-1C  show a ¼ turn twist, it should be understood that pathways of different length and turn radius can be used. The ¼ twist has the advantage of being able to turn the lateral opening  16  of the probe  10  such that it is either facing in the direction of the left side or the right side of the handle. 
   In contrast, the embodiments shown in  FIGS. 2A-2C  and  3 A- 3 C show that the slots  24  lead to an annular groove  32  which spans the circumference of the proximal end  12  of the probe  10  at the slotted twist region  30 . Similar to the description above for  FIGS. 1A-1C , once the inwardly projecting lands  26  of the bore  25  pass through the slots  24  of the probes  10  depicted in  FIGS. 2A-2C  and  3 A- 3 C, they enter the annular groove  32 , thus enabling the probe  10  to be twisted to the left or right. 
     FIGS. 3A-3D  also show the inclusion of a series of depressions  34  in the proximal end  12  of the probe  10 . In the embodiment shown in  FIGS. 3A-3D , a locking member (discussed below) will be able to extend into each of the depressions  34 , as well as each of the slots  24  to lock the probe  10  to a handle of a surgical tool. 
   Also, by contrasting  FIGS. 2A-2D  with  FIGS. 3A-3D , it can be seen that the location of the slots  24  can vary depending on the design choice of the manufacturer. That is, the slots  24  can be oriented to the sides of the top surface of the probe  10  ( FIGS. 2A-2D ) or in alignment with the top and bottom surface of the probe ( FIGS. 3A-3D ) or at any other orientation desired. 
     FIGS. 4A-4D  respectively show probes being inserted into a different handles, and  FIGS. 5A-5D  show cut away illustrations with probe inserted into and locked to the handle using different locking mechanisms. 
   With reference to  FIG. 4A , a probe  10  is inserted into the bore  25  of a handle  34  which has an actuator  36 , in the form of a button, on its front surface. With reference to  FIG. 5A , the actuator  36  is spring  38  biased and includes a locking pawl or member  40  which fits within either one of the two slots  24  (best shown in  FIGS. 1A ,  1 C, and  1 D) at the proximal end  12  of the probe. In operation, the actuator  36  is depressed and the probe  10  has its proximal end slid into the bore  25 . Once the lands  26  have cleared the two axial slots  24 , the probe is twisted to have the lateral opening on its top surface face in the direction of either the left side or right side of the handle  34  (note that the lateral opening faces into the paper in  FIG. 5A ). Then, the actuator is released to cause the locking pawl or member  40  to slide into one of the two axial slots  24 . This firmly secures the probe  10  to the handle  34  as the locking pawl or member  40  prevents rotation of the probe  10  within bore  25  of the handle, and the lands  26  within the slotted twist region  30  prevent axial movement of the probe  10  out of the bore  25  in the handle  34 . The optical system can be inserted through the housing and into the probe  10  after its installation on the handle  34 , and the tool extension shaft can be connected (it being understood that connection of these elements can occur also occur before or during the insertion and twisting of the probe  10 ). Removal of the probe  10  from the handle  10  occurs in the reverse order by beginning with depressing of the button actuator  36 . 
   An advantage of the design shown in  FIGS. 4A and 5A  is that the opening can be securely locked in an orientation facing in the same direction as the left or right side of the handle  34  without requiring the surgeon to line up the rib with indicia on the handle. Further, the design allows locking of the probe in place simply by releasing a button actuator and without having to twist a knob for tightening a screw to a point where unintentional rotation of the probe is avoided. 
   The configuration shown in  FIGS. 4B and 5B  is similar to that shown in  FIGS. 4A and 4B . However, the configuration shown in  FIGS. 4B and 5B  shows a spring biased slider  42  on the top of the handle  34 . The slider  42  could be positioned almost anywhere on the handle. The key feature is that the slider has a locking pawl or member  44  which slides into one of the two axial slots  24  at the proximal end  12  of the probe  10 . With the slider  42  arrangement, the spring biasing might not be used. If not, the surgeon would be required to slide the slider into a position where the locking pawl or member  44  fits in an axial slot  24  at the proximal end  12  of the probe  10  when it is desired to secure the probe  10 . Attachment and removal of the probe is achieved in the same manner discussed above with respect to  FIGS. 4A and 5A . 
   The configuration shown in  FIGS. 4C and 5C  is similar to that shown in  FIGS. 4A and 5A ; however, a locking button  46  at the top of the handle  34  is employed.  FIGS. 4C and 5C  also show a probe similar to that depicted in  FIGS. 2A-2D  being attached to the handle  34 . The locking button  46  is preferably spring biased and includes a locking pawl or member  48  that fits within the axial slots  24  at the proximal end  12  of the probe  10 . Attachment and removal of the probe  10  is achieved in the same manner as discussed above with respect to  FIGS. 4A and 5A . 
   The configuration shown in  FIGS. 4D and 5D  is similar to that shown in  FIGS. 4C and 5C , except that a probe similar to that depicted in  FIGS. 3A-3D  is being attached to the handle  34 , thus, the locking pawl or member  48  fits into one of the depressions in the series of depressions  34  at the proximal end  12  of the probe  10 . The inwardly projecting lands  26  are depicted at the top and bottom of the bore in  FIG. 5D  since the slots  24  in the proximal end of the probe are on the top and bottom as shown in  FIGS. 3A-D . The configuration shown in  FIGS. 4D and 5D  allows for a surgical tool to have the lateral opening  16  of the probe positioned at a number of different orientations (as opposed to being positioned only facing the left or the right side). 
   There are a number of cutting tool operating mechanism and optical system  10  can be inserted into the probe  10  (see for example U.S. Pat. Nos. 4,962,770, 4,963,147, 5,089,000, and 5,306,284, each of which is incorporated by reference).  FIG. 7  shows one example where an optical system  50  extends within the probe  10  to the lateral opening  16 . A cutting blade  52  is selectively deployed or retracted using the tool extension shaft  54 . This and other configurations can be used within the practice of this invention. 
   While the invention has been described in terms of its preferred embodiments, those skilled in the art will recognize that the invention can be practiced with modification within the spirit and scope of the appended claims.