Abstract:
A motorized drill is mounted in the handle of a Kerrison Rongeur System utilized by a surgeon to perform surgical procedures on a patient, includes mechanism for moving the rotating drill toward the fixed upstanding foot mounted at the remote end of the pistol-shaped handle for removing bone which is located between the upstanding foot and the drill bit. In another embodiment, the drill is removably fixed in the handle and the foot moves relative to the drill bit. In either embodiment a trigger operated by the surgeon actuates the foot/drill and the trigger is biased to maximize the space between the foot and the drill bit. The foot shape and dimension can be modified for perfecting given surgical procedures. In one embodiment the drill motor releasing mechanism includes a pinion gear and rack performing the additional function of releasing the motor locked in position in the handle.

Description:
TECHNICAL FIELD  
         [0001]    This invention relates to Kerrison-like Rongeur systems and particularly to a Kerrison-like Rongeur system that has been modified to include a powered cutting end (hereinafter referred to as a PKS system).  
         BACKGROUND OF THE INVENTION  
         [0002]    As is well known in medical technology, the Kerrison Rongeur system is utilized in certain types of spinal operations where it is necessary to cut bone near the spinal column. For example, in a laminectomy procedure it may be necessary to trim away some of the bone that may be in close proximity to the nerve passing through the spinal canal and the Kerrison Rongeur system includes an elongated scissor type of instrument that includes a pair of small end plates that are spaced from each other and movable relative to the other, and a trigger-like device that moves one of the end plates relative to the other. The manual force exerted by the operator operating the trigger moving the plates together bites the boney structure for removing the same. Obviously, the end plates are relatively large in order to have sufficient strength to manifest the biting operation. Also, the shape of the end plate, that is that portion located at the very end of the instrument needs to be blunt. The shape and size of the end (often referred to as the foot plate) is predicated on the brute force that must be generated to do the bone biting and the foot plate must generate a counter force that matches the force of the other end plate that is moved relative thereto. An analogy to this operation is a pair of scissors that have cutting blades that are moved relative to each other. Obviously, the size of the scissors is predicated on the resistance exerted on the cutting blades. The more resistance offered to the cutting blade, the larger the required scissor. A scissor designed to cut sewing thread would be much smaller than a scissor designed to cut through cardboard and similarly, a scissor for cutting floor tile would presumably be larger than a scissor for cutting cardboard. Also, the force required by the operator would be different in each circumstance and the harder the material being cut would presumably require more force supplied by the operator.  
           [0003]    We have found that we can obviate the force requirement that is necessary in use for surgical operations for cutting or chipping bone that has been heretofore done by a Kerrison Rongeur or other bone and tissue biting instrument by designing the instrument with a powered operated rotating cutter that is either moveable relative to an end mounted foot plate or vice versa, that is, moving the end mounted foot plate relative to the rotating cutter. This inventive instrument affords a number of advantages over the heretofore known Kerrison Rongeur System which are listed immediately hereinbelow. These advantages merely give examples and are not to be considered limitations to the scope of this invention.  
           [0004]    1) The foot plate and cutter are smaller and the outside diameter at the working end is smaller allowing the surgeon to reach areas of the anatomy of the patient that were not heretofore reachable or as easily reachable;  
           [0005]    2) The leading edge of the foot plate can be contoured so that it can be used to free tissue from the bone, enhancing the use of the PKS system;  
           [0006]    3) Since the motor driving the cutter absorbs most of the load, the work required by the surgeon is much reduced; and  
           [0007]    4) By having the cutter movable relative to the foot plate, the surgeon increases his feel as to the positioning of the cutter relative to the bone and hence, the hands-on feel of the surgeon is improved.  
           [0008]    This invention contemplates the use of a pinion and rack gear system for longitudinal movement of the motor driving the cutter in one of the embodiments and the pinion gear is judiciously mounted so that it also functions as a pivot for the ingress and egress of the motor from the main body of the PKS system.  
         SUMMARY OF THE INVENTION  
         [0009]    An object of this invention is to provide an improved Kerrison Rongeur system for biting bone and tissue of a patient.  
           [0010]    A feature of this invention is to provide a motor driven cutter in the PKS system that is movable relative to the foot plate. An alternative embodiment of this invention is a fixed motor/cutter and a movable foot plate.  
           [0011]    Another feature of this invention for a PKS system that positions the cutter relative to the foot plate, is that the pinion gear that functions to move complementary rack gears also functions as a pivot for removing and inserting the motor into the PKS system.  
           [0012]    Another feature of this invention is to provide a PKS system having a rotating cutter that is designed with a smaller overall outside diameter than heretofore known Kerrison Rongeur systems.  
           [0013]    Another feature of this invention is to provide a powered PKS system with a contoured foot plate having the leading edge designed to participate in the surgical procedure.  
           [0014]    A still further feature of this invention is to provide a powered PKS system that alleviates the force requirements of the surgeon and/or affords an enhanced feel to the surgeon.  
           [0015]    The foregoing and other features of the present invention will become more apparent from the following description and accompanying drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]    [0016]FIG. 1 is an exploded view in elevation illustrating the major components of the PKS system with a movable motor of this invention;  
         [0017]    [0017]FIG. 2 is an exploded view in perspective illustrating the details of the mechanism for positioning the motor shown in the embodiment of depicted in FIG. 1;  
         [0018]    [0018]FIG. 3 is a perspective view of the handle of the embodiment depicted in FIG. 1;  
         [0019]    [0019]FIG. 4 is a view partly in section and partly full illustrating the PKS system of this invention depicted in FIG. 1;  
         [0020]    [0020]FIG. 5 is a side view in elevation showing the assembled PKS system depicted in FIG. 1;  
         [0021]    [0021]FIG. 6 is the handle and the mechanism for positioning the motor of the PKS system depicted in FIG. 1 illustrating a first position;  
         [0022]    [0022]FIG. 6A is the same Fig. as depicted in FIG. 6 where the trigger is positioned to a second position;  
         [0023]    [0023]FIG. 7 is a sectional view of another embodiment of this invention where the trigger moves the foot plate relative to the motor and drill bit; and  
         [0024]    [0024]FIG. 8 is a top plan view of the embodiment depicted in FIG. 7. 
     
    
       [0025]    These figures merely serve to further clarify and illustrate the present invention and are not intended to limit the scope thereof.  
       DETAILED DESCRIPTION OF THE INVENTION  
       [0026]    This invention in its preferred embodiment utilizes an air driven motor for powering the cutter and it should be obvious to anyone skilled in this technology that any surgical motor using various mediums can be utilized to power the cutter. Moreover, the invention is being described utilizing Micro Max®, Black Max® and eMax™ motors which are products available from the assignee of this patent application, and it should be understood that other types of pneumatic motors could be substituted therefor. In addition to the pneumatic powered motors, motors powered by different mediums could also be utilized in this invention. Suffice it to say that any motor that is capable of being inserted into and operable with the PKS system of this invention could be employed and that the scope of this invention is not limited to the motor disclosed in the preferred embodiment.  
         [0027]    This portion of the description is directed to the embodiment of the PKS system where the motor/cutter is positioned relative to the foot plate and the following portion of the description will be directed to the embodiment of the PKS system where the foot plate is moved relative to the motor/cutter. As best seen in FIG. 1 the PKS system for the rectilinear movement of the motor/cutter is best illustrated in FIG. 1 which is an exploded view showing the PKS system generally illustrated by reference numeral  10  comprised of the motor  12 , nose sleeve  14 , cutter  16 , pistol-shaped member or gun  18  and foot plate support  20 . The foot plate support is an elongated tubular member that fits over the nose sleeve  14  when assembled. The motor  12 , which in this embodiment, is a pneumatic motor, the nose sleeve  14  and the cutter  16  are well known and commercially available from the assignee. The gun  18  is shaped as a pistol handle for ease of operation but any other shape is considered to be within the scope of this invention and should afford a good feel to the surgeon when performing the medical procedure. As will be described in more detail hereinbelow, a trigger  22  is slidably mounted in the gun  18  and rectilinearly positions the motor  12 . The foot plate support  20  is suitably removably attached to the end of gun  18  by any well known chuck or attachment mechanism. A foot plate  24  is carried at the end of foot plate support  20  and is angularly disposed relative to the axial axis of the foot plate support  20  and extends so as to be oriented in-line with the end of cutter  16 . Hence, when assembled, the drill bit  24  of cutter  16  is in-line with the foot plate  24  and by virtue of being attached to motor  12  moves relative thereto when the trigger positions the motor rectilinearly. Because of this invention the foot plate  24  can be designed to accommodate surgical procedure requiring different sizes and shapes of the foot-plate. For example, the angle relative to the axial axis of the foot plate support  20  can be 30 degrees (°), 45°, etc.  
         [0028]    The assembly of the PKS system is as follows, noting all the subassemblies can be readily removed and replaced. The nose sleeve  14  is suitably attached to the end of the motor  12  by any commercially available attaching mechanism  26 . The shaft  28  of cutter  16  slides into the nose sleeve  14  and is supported for rotary motion by bearings (not shown) and includes an attachment end  30  that fits into a commercially available chuck  32  (not shown) carried by motor  12 . As mentioned in the above paragraphs these components are commercially available from the assignee of this patent application.  
         [0029]    The motor  12 , nose sleeve  14  and cutter  16  fit into an axial bore extending through the main body  32  of handle  18  and the nose sleeve  14  extends through the handle  18  so that the central passage extending through foot support  20  slides over the nose sleeve  14  and locates the bit  24  adjacent to the foot plate  22 . The handle  18  (FIG. 3) includes a through axial bore  38  in the main body  40  extending on the underneath side of the main body  32  and into the hand held portion  42  of the handle  18  for receiving the trigger  22 . From the foregoing it is apparent that the motor fits into the wider portion  44  of the bore  38  and the chuck portion  26  of the nose sleeve  14  fits into the smaller diameter portion  46  of the bore  38  and the movable trigger  22  fits into the slot  40 . FIGS. 4 and 5 illustrate the PKS system in the assembled condition.  
         [0030]    The next portion of the disclosure describes the mechanism for the trigger for rectilinearly positioning the motor and locking the motor into place. As best seen in FIGS. 2, 4,  6  &amp;  6 A, the motor support mechanism  50  includes a guide sleeve  52  mounted in the wider diameter portion  44  of the axial bore  38  and is biased on one end by coil spring  54  bearing against the shoulder  56  at the end of the wider diameter portion  44  and the front bushing  60  mounted adjacent to the end of guide sleeve  52 . A back bushing  61  is mounted at the rear end of the guide sleeve  52  and together with the front bushing  60  support the motor when inserted into the bore  44 . A boss  56  carried on the bottom of the guide sleeve  52  supports the motor lock  58  which will be described in further detail hereinbelow.  
         [0031]    As mentioned above the trigger  22  is slidably mounted in slot  40  and includes a generally U-shaped portion or channel  60 , a circular finger opening  62 , an upper extending portion  64  and the limit slot  66 . A rack gear  68  with the gear teeth facing upwardly is mounted in the channel  60  and rigidly supported therein by a pin  70 . The pinion gear  72  is rotatory supported by axle or pin  74  that fits through diametrically opposing apertures  76  formed in main portion  32  of pistol  18 . A bushing  78  fits into the central bore  80  of pinion gear  72  for ease of rotation. A spherical ball  82  fits into a slot formed on the bottom of the channel  60  for ease of movement of the trigger  22 . The complementary rack gear  84  is carried on the bottom surface of the motor lock  58  with the gear teeth diametrically opposing the gear teeth of the rack gear  68 . Coil spring  88  is sandwiched between the shoulder  90  and the rear edge  92  of the channel portion  60 . The coil spring  88 , which serves to return trigger  22  to the starting position (when the cutter bit is furthest from the foot plate) in conjunction with the coil spring  54  acting on the end of guide sleeve  52  which biases the motor to the starting position, affords a balanced force on the PKS system to assure that the operator or surgeon has a good feel as to the handling of the gun and positioning of the cutter.  
         [0032]    As mentioned above the motor lock  58  serves to lock the motor into place and is designed so that it automatically locks the motor when it is inserted into bore  44  and is released by depressing the end of the motor lock  58  when the trigger is in a given position. This assures that the motor will not disengage when the surgeon is performing the surgical procedure. In accordance with this invention, the motor lock  58  is mounted to the boss  56  via the upstanding parallel arms  96  and by the dowel pin  98 . Coil spring  100  is fitted into a drilled hole formed on the bottom of boss  56  and bears against the top surface  102  of motor lock  58  at one end of the pivot remote from the front end. Ramp  104  is mounted on the aft end of motor lock  58  and fares from the thin portion at the aft end to a thicker portion forming a ramp so that when the motor is inserted and moved inwardly toward the front end of the gun a flange on the gun runs up the slope of the ramp and forces the motor lock  58  to pivot about pinion gear  72  and compresses spring  100  until the shoulder on the motor passes shoulder  106  at the end of ramp  104  on the motor lock  58  and drops into the recess  110  between the arms  96  and the end of the fore end of the ramp  104 . The spring will force the motor lock to return to the original position locking the motor into place. It will be noted and in accordance with this invention, the motor lock  58  rotates about the pinion gear  72 , i. e. the pinion gear  72  serves the dual function of the gear and pivot. Hence, when the trigger is withdrawn, namely when it places the cutter toward the foot plate and the stop pin  111  is at the end of the slot  66 , the motor lock  58  cannot pivot and. (See FIG. A). The only time that the motor can be removed is when the pinion gear  72  is closer to the fore end of rack gear  84  so that it can pivot about the pinion gear  72  as shown in FIG. 6.  
         [0033]    To operate the PKS system, the surgeon merely has to insert the foot plate in the position necessary to remove the bone from the patient, power the drill motor to rotate the cutter and squeeze the handle to position the cutter toward the foot plate. Obviously, the surgeon can move the PKS System when the cutter is exposed to the bone for not only localized cutting, but can also slide the cutter to follow a given path, if so desired, and cut the bone along a longitudinal path.  
         [0034]    The next portion of the description relates to the other embodiment of this invention where the motor remains stationary and the foot plate is moved relative to the cutter. In this embodiment, as exemplified in FIGS. 7 and 8, the foot plate  120  attached to the foot plate support  122 , similar in shape to the foot plate support depicted in FIG. 1, is attached to the trigger  124  so that when the trigger is retracted toward the handle  126  the foot plate  120  will move toward the drill bit  128  of cutter  130 . Handle  126  is similar in its outer dimensions to the handle depicted in FIG. 1 and includes a through bore extending through the main portion  132  of handle  126  including a larger diameter portion  128  at the aft end  130  and stepped to smaller diameter portions toward the forward end  131  and increase again in the more forward portion  134 . The motor  133 , similar to the motor described in connection with FIG. 1 is installed in the rear portion of handle  126  and a suitable finger lock  136  movable in two positions locks and unlocks the motor  133 . The cutter is removably attached to the motor in the customary fashion which is well known in the art. The handle  126 , similarly shaped as a pistol handle, includes a hand held portion  140  extending downwardly from the main portion  132 . Surrounding the foot plate support  122  is a conically shaped nose  141  that includes a well known attachment end that fits on the outer diameter of the reduced portion  142  adjacent the fore end of the trigger  124  that locks the foot plate support  142  to the trigger  124 . The fore end of trigger  124  includes the torroidally shaped end portion  148  that extends rearwardly and defines a conically shaped bore  150 . This shape assures that when the trigger is withdrawn, the foot plate will have sufficient room to allow the drill bit to move its intended distance and not lock up against the chuck end of the motor  133 .  
         [0035]    The trigger  124  is biased in the first position, which is the most forward position by the coil spring  156  mounted in bore  158  formed in the fore end of the hand-held portion  140  of handle  126 . Coil spring  156  acts against the end face  160  of bore  158  and the piston  162  that includes tab  164  that fits into slot  166  of trigger  124 .  
         [0036]    In operation the surgeon holds the handle  128  as if it were a pistol and inserts a finger in the through opening  170 . By squeezing the trigger  124  and handle  126  the trigger mechanism, just described, will move rearwardly bring the foot plate  120  closer to the drill bit  129  and with the motor turned on, allowing the surgeon to perform the procedure necessary to remove the intended bone of the patient. As is the case of the embodiment depicted in FIG. 1, the surgeon can move the instrument laterally from the local target so as to remove bone along the lateral direction. Also, since the PKS system utilizes a motor and drill bit and doesn&#39;t rely on brute force to remove bone, the foot plate can be designed into different shapes and angles so as to fit into areas of the body that were otherwise unavailable for this type of procedure.  
         [0037]    Although this invention has been shown and described with respect to detailed embodiments thereof, it will be appreciated and understood by those skilled in the art that various changes in form and detail thereof may be made without departing from the spirit and scope of the claimed invention.