Patent Publication Number: US-6702820-B2

Title: Surgical cutting instrument having concative jaw tips

Description:
RELATED APPLICATION DATA 
     This patent is a continuation-in-part of U.S. patent application Ser. No. 09/695,356, which was filed on Oct. 24, 2000, now issued as U.S. Pat. No. 6,517,545. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to surgical instruments, and more particularly to a surgical instrument for cutting that has a pair of opposed cutting jaws with concavely curved jaw tips. 
     BACKGROUND OF THE INVENTION 
     There are many different types surgical instruments that include a pair of jaws and that are used to cut bone or other material during surgical procedures. One such instrument is known as a rongeur which has a pair of closeable jaws at one end that are utilized for cutting away bone, and particularly to smooth off a bone surface. A known rongeur instrument has a jaw tip end on each jaw that is outwardly curved or convex in a direction away from the tool or instrument. When a rongeur having a convex jaw tip end is utilized to smooth a bone surface, the device will typically leave small trenches or grooves in the bone surface because of the curvature of the jaw tip ends. This is caused by the convex curve of the jaw tip which leaves a small mirror-image concave groove or trench in the bone during each cut. 
     For many surgical procedures, this imprecise cutting technique leaves a satisfactory bone surface. However, for certain surgical procedures it is often desirable to leave a smooth bone surface or an outwardly or convex curved bone surface once material has been cut away. For example, when operating on the spine of an individual and approaching the anterior cervical spine, it is beneficial to be able to easily remove bone spurs or anterior osteophytes and also to leave the bone surface relatively smooth and slightly outwardly curved. Following such a procedure, a metal plate is sometimes screwed to the anterior surface of the vertebrae. The smooth and slightly outwardly curved anterior surface allows for better seating of the metal plate and screws. Utilizing a conventional convex curved jaw rongeur essentially prevents one from cutting away these osteophytes and simultaneously leaving the bone or vertebrae with a satisfactorily smooth and curved surface. 
     SUMMARY OF THE INVENTION 
     In order to overcome the above-described deficiencies in the prior art and other problems, a surgical instrument is provided in accordance with the teachings of the present invention. In one example, a surgical instrument has a pair of opposed jaws that are constructed and arranged to open and close relative to one another. Each jaw has a proximal end connected to part of the surgical instrument, an opposite end or free jaw tip end, and a confronting surface arranged facing the opposite jaw. A perimeter defines a boundary of the confronting surface and jaw tip end of each respective jaw. At least a first cutting edge portion is provided on a part of each jaw perimeter that defines the jaw tip end. Each first cutting edge is oriented such that it extends toward or faces the corresponding first cutting edge portion of the opposite jaw. Each first cutting edge portion is curved concavely inward toward the proximal end of the respective jaw. 
     In one example, the surgical instrument can be a rongeur surgical instrument for cutting bone. 
     In one example, a longitudinal axis of the instrument extends in a direction from the proximal end to the free end of the jaws. The curvature or arc of the first cutting edge portion of each jaw tip end is symmetrically arranged relative to the longitudinal axis such that the axis bisects the arc of the first cutting edge portion of each jaw. 
     In another example, the first cutting edge portion of each jaw tip end is arranged asymmetrically relative to the longitudinal axis. A line that bisects the arc of curvature of each cutting edge portion is disposed at an angle or offset relative to the axis such that the arc is slanted or canted more to one side of the axis. 
     In one example, each jaw of the surgical instrument can have a pair of spaced apart second cutting edge portions provided on a substantial remaining part of each jaw perimeter. Each pair of second cutting edge portions can continue from opposite ends of the respective first cutting edge portion toward the proximal end of the jaw and can be oriented extending toward the corresponding pair of second cutting edge portions of the opposite jaw. In a further example, a concave hollow can be formed in the confronting surface surrounded by the respective perimeter of each jaw. The hollow can be arranged facing the hollow of the opposite jaw. 
     In one example, each jaw of the surgical instrument also can have a concave curved end face that is disposed at the jaw tip end and can have a surface curvature that corresponds to a curvature of the concavely curved first cutting edge portion of the respective jaw. In one example, the concavely curved first cutting edge portion of each jaw can have a curvature defined by a two-inch radius arc. 
     In another example constructed according to the teachings of the present invention, a rongeur surgical instrument has a pair of handles extending from a pivot that are moveable toward and away from one another. The rongeur instrument also includes a pair of opposed jaws that are positioned opposite the handles relative to the pivot and that are constructed and arranged to open and close relative to one another by movement of the handles. In one example, the rongeur surgical instrument is constructed wherein each jaw has a proximal end pivotally coupled to a portion of the instrument, an opposite free jaw tip end, and a confronting surface arranged facing the opposite jaw. Each jaw also has a perimeter that defines a boundary of the confronting surface and jaw tip end of each respective jaw. At least a first cutting edge portion is provided on a part of each jaw perimeter wherein that part of the perimeter defines the jaw tip end. Each first cutting edge portion is oriented extending toward the corresponding first cutting edge portion of the opposite jaw and each first cutting edge portion is curved concavely inward toward the proximal end. 
     In one example, a longitudinal axis of the instrument extends in a direction from the proximal end to the free end of the jaws. The curvature or arc of the first cutting edge portion of each jaw tip end is symmetrically arranged relative to the longitudinal axis such that the axis bisects the arc of the first cutting edge portion of each jaw. 
     In another example, the first cutting edge portion of each jaw tip end is arranged asymmetrically relative to the longitudinal axis. A line that bisects the arc of curvature of each cutting edge portion is disposed at an angle or offset relative to the axis such that the arc is slanted or canted more to one side of the axis. 
     In one example, the rongeur surgical instrument can also have a resilient spring disposed between the handles. The spring can be arranged to bias the handles away from one another and to bias the jaws toward the open position. In another example, the rongeur surgical instrument can be constructed from a stainless steel material. 
     In another example constructed according to the teachings of the present invention, a rongeur surgical instrument includes a pair of handles extending from a first pivot that are moveable toward and away from one another. Each handle has a drive arm that extends beyond the first pivot opposite the respective handle. A pair of opposed jaws extend from a second pivot and are constructed and arranged to open and close relative to one another. Each jaw has a proximal end with a lever arm extending beyond the second pivot opposite the respective jaw. Each lever arm is pivotally coupled to a corresponding one of the drive arms between the first and second pivots. Each jaw also has an opposite free jaw tip end and a confronting surface arranged facing the opposite jaw. A perimeter defines a boundary of the confronting surface and jaw tip end of each respective jaw. At least a first cutting edge portion is provided on a part of each jaw perimeter wherein that part of the perimeter defines the jaw tip end. Each first cutting edge portion is oriented extending toward the corresponding first cutting edge portion of the opposite jaw and is curved concavely inward toward the proximal end of the respective jaw. 
     In one example, a longitudinal axis of the instrument extends in a direction from the proximal end to the free end of the jaws. The curvature or arc of the first cutting edge portion of each jaw tip end is symmetrically arranged relative to the longitudinal axis such that the axis bisects the arc of the first cutting edge portion of each jaw. 
     In another example, the first cutting edge portion of each jaw tip end is arranged asymmetrically relative to the longitudinal axis. A line that bisects the arc of curvature of each cutting edge portion is disposed at an angle or offset relative to the axis such that the arc is slanted or canted more to one side of the axis. 
     These and other objects, features and advantages of the present invention will become apparent upon a review of the detailed description and accompanying drawing figures set forth herein. There is a need for an improved surgical instrument that overcomes the deficiencies in the prior art described above. The detailed description and drawings herein provide one example of such an improved surgical instrument. Changes and modifications can be made to the disclosed examples and yet fall within the scope of the teachings of the present invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of one example of a surgical instrument constructed according to the teachings of the present invention showing the jaws of the instrument in an open position. 
     FIG. 2 is a bottom view of prior art jaws utilized on a surgical instrument such as that shown in FIG.  1 . 
     FIG. 3 is a side elevation view of the surgical instrument shown in FIG. 1 with the jaws in a closed position. 
     FIG. 4 is a top view of the closed jaws of the surgical instrument shown in FIG.  3 . 
     FIG. 5 is a top view of the lower jaw of the jaws shown in FIG. 4 wherein the upper jaw has been removed. 
     FIG. 6 is a lateral cross section taken along line VI—VI of the upper jaw shown in FIG.  4 . 
     FIG. 7 is a top view of the closed jaws of a surgical instrument similar to that shown in FIG. 3, but having an alternative example of a jaw tip configuration constructed according to the teachings of the present invention. 
     FIG. 8 is a top view of the lower jaw of the jaws shown in FIG. 7 wherein the upper jaw has been removed. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     One example of a surgical instrument constructed according to the teachings of the present invention is described herein. The invention is generally directed to a concave inwardly curved jaw tip end for a surgical instrument having a pair of jaws which open and close relative to one another in order to cut or shear a material such as bone. FIG. 1 generally illustrates a double action bone rongeur as the disclosed example. The jaw tip ends of the rongeur of FIG. 1 are shown as having a concave inward curve according to the present invention. FIG. 2 illustrates a prior art convex jaw tip end construction for such a surgical instrument. Though the exemplary instrument set forth herein is a double action bone rongeur, a single action rongeur, biopsy rongeur or other surgical instrument utilizing a pair of opposed jaw elements to cut or shear material can also utilize the teachings of the present invention. 
     Referring now to the drawings, FIG. 1 illustrates a surgical instrument in the form of a double action bone rongeur constructed according to the teachings of the invention. Orientation and arrangement terminology is utilized herein to simplify the description of the surgical instrument  10 . Terms such as “upper”, “lower”, “front”, “side”, “distal”, and “proximal” are utilized herein in order to describe relationships of certain components only. Use of these terms is not intended in any way to limit the construction of the described surgical instrument or the orientation of the instrument and components in any way. 
     With that in mind, the surgical instrument  10  includes an upper handle  12  and a lower handle  14  interconnected at one corresponding end by a first pivot  16 . The handles  12  and  14  can pivot toward and away from one another about the first pivot  16  in order to operate the instrument. As an option, the exterior surface  18  of either of the handles  12  or  14  can include a surface treatment in order to improve the grip characteristics of the instrument. Knurling, bumps, grooves, high friction material, or the like can be added to either or both of the handles in order to accomplish an improved grip. 
     In the present example, a drive arm  20  extends from the upper handle  12  on the opposite side of the first pivot  16 . The drive arm  20  terminates at a distal end  22 . Similarly, a drive arm  26  extends from the lower handle on the opposite side of the first pivot and which terminates at a distal end  28 . Movement of the handles  12  and  14  toward one another in this example moves the drive arm distal ends  22  and  28  away from one another. In an alternative example, the handles and drive arms can be configured similar to a pair of pliers, wherein the drive arms crisscross at the first pivot whereby movement of the handles toward one another moves the distal ends of the drive arms toward one another. 
     As illustrated in FIG. 1, the surgical instrument  10  also has a pair of jaws including an upper jaw  30  and a lower jaw  32  pivotally connected to one another at a second pivot  34  spaced from the first pivot  16 . The upper and lower jaws  30  and  32  move about the second pivot  34  toward and away from one another. 
     In the present example, an upper lever arm  36  extends from the upper jaw  30  on the opposite side of the second pivot  34  and terminates at a proximal free end  38 . Similarly, a lower lever arm  40  extends from the lower jaw  32  on the opposite side of the second pivot  34  and terminates at a proximal free end  42 . Again, in this example, movement of the upper and lower jaws  30  and  32  toward one another moves the upper and lower lever arms  36  and  40  away from one another. 
     A pair of intermediate pivots, including an upper intermediate pivot  44  and a lower intermediate pivot  46 , are provided to couple the jaws to the handles. The distal ends  22  and  28  of the drive arms  20  and  26  are coupled to the proximal ends  38  and  42  of the lever arms  36  and  40  at the intermediate pivots  44  and  46 , respectively. This type of surgical instrument construction is known as a double action bone rongeur. Movement of the handles toward one another spreads the drive arms away from one another which also spreads the lever arms away from one another. This movement in turn draws the jaws to a closed position toward one another. 
     As discussed above, a pliers-type single action bone rongeur can also be utilized in conjunction with the teachings of the present invention. In such a construction, the handles  12  and  14  can be directly connected at a single pivot to the jaws  30  and  32 . The upper handle can extend beyond the pivot and define a lower jaw and the lower handle can extend beyond the pivot and define an upper jaw, whereby the two components would crisscross. In the pliers configuration, movement of the handles toward one another moves the jaws toward one another as well. The double action construction as shown in FIG. 1 enables a manufacturer or designer to better manipulate the mechanical advantage characteristics of the surgical instrument. 
     The handles and jaws of the present invention can be provided or fabricated from any number of suitable materials. One preferable material is a high-quality stainless steel utilized for many surgical quality instruments. Surgical instruments typically require high precision, tight tolerance control during the manufacturing process and during use. However, the components of the invention are not to be limited to any particular material. 
     As an optional element, the surgical instrument  10  can also be provided with a resilient spring  48  or other suitable biasing element that is utilized to bias the handles away from one another. In the present example, one end of a spring section  48   a  is fixed to the upper handle  12  and one end of a spring section  48   b  is fixed to the lower handle  14 . The free ends of spring sections  48   a  and  48   b  are coupled to one another between the handles. Movement of the handles toward one another flexes the resilient spring sections toward one another by overcoming the spring force of each section and closes the jaws. The resilient spring  48  returns the handles to an open jaw configuration when the handles are released. FIG. 1 illustrates the surgical instrument in the open jaw or at-rest position. FIG. 3 illustrates the surgical instrument  10  in the closed jaw configuration. 
     In the disclosed surgical instrument  10 , the upper jaw  30  includes a proximal end  50  and the lower jaw  32  includes a proximal end  52  positioned nearer the second pivot  34 . The opposite free end of each jaw defines an upper jaw tip end  54  and a lower jaw tip end  56 , respectively. An upper confronting surface  58  (shown in FIG. 6) is provided on the upper jaw  30  and a lower confronting surface  60  (shown in FIG. 5) is provided on the lower jaw  32  arranged such that the upper and lower confronting surfaces  58  and  60  face one another. 
     An upper perimeter  62  of the upper jaw  30  defines a boundary of the upper confronting surface  58  and upper jaw tip end  54 . Similarly, a lower perimeter  64  defines a boundary of the lower confronting surface  60  and lower jaw tip end  56  of the lower jaw  32 . When the jaws are brought to the closed position as shown in FIG. 3, the confronting surfaces  58  and  60  and perimeters  62  and  64  move toward one another. A forward part of the upper perimeter  62  that defines the upper jaw tip end  54  is honed to provide an upper first cutting edge. Similarly, a forward part of the lower perimeter  64  that defines the lower jaw tip end  56  is honed to define a lower first cutting edge  72 . When the jaws  30  and  32  are moved to the closed position, the upper and lower first cutting edges  70  and  72  contact one another or otherwise cooperate to provide a cutting or shearing action as determined by the particular surgical instrument characteristics. 
     A substantial remaining portion of the upper perimeter  62  on either side of forward part is also honed to provide a pair of upper second cutting edges  74   a  and  74   b  that continue from the upper first cutting edge  70 . The second cutting edges are spaced apart on the sides of the upper jaw  30 . The second cutting edge portions  74   a  and  74   b  flank the confronting surface  58  of the upper jaw. Similarly, a substantial remaining portion of the lower jaw perimeter  64  is honed or sharpened to define a pair of spaced apart lower second cutting edges  76   a  and  76   b  that flank the lower jaw confronting surface  60 . The lower second cutting edges  76   a  and  76   b  continue from the lower first cutting edge  72  of the lower jaw. 
     As is known in the art of these types of surgical instruments, one or both of the confronting upper and lower surfaces  58  and  60  can be hollowed, curved or recessed into the jaw to define a space between the two jaws when in the closed configuration of FIG.  3 . In the present example, the upper jaw  30  has a hollow  78  and the lower jaw  32  has a hollow  80 . The two hollow portions  78  and  80  of the jaws cooperate when the jaws are closed to define a cavity for holding material cut when utilizing the surgical instrument. As illustrated in FIG. 6 (upper jaw only), either one jaw or both jaws can include a significant depression or hollow to provide a substantial cavity between the closed jaws  30  and  32  for retaining a relatively large amount of cut-away material. When a surgical instrument such as the double action bone rongeur is utilized during surgery, it is preferable that when material is cut away, it remains captured in the instrument until removed from the body of the patient so that none of the material is lost within the wound or body cavity. 
     As discussed briefly above, FIG. 2 illustrates a prior art jaw tip end configuration for the upper and lower jaws  30  and  32  of such an instrument. The jaw tip ends are shown as being curved convexly or outward from the instrument. FIGS. 4 and 6 illustrate an improved and novel concave inwardly curved jaw tip end construction according to the teachings of the present invention. As shown in FIGS. 4 and 5, both of the jaws  30  and  32  have a corresponding concave curvature. The jaw tip end and the first cutting edges  70  and  72  are concavely curved inward toward the proximal end of the respective jaws. In one example as illustrated in FIGS. 1 and 4, each jaw tip end has an end face  82  (upper jaw  30 ) and  84  (lower jaw  32 ). In this example, the end faces  82  and  84  are concavely curved inward in such a manner. The first cutting edges  70  and  72  of the upper and lower jaws, respectively, generally follow the same concave contour of the end faces  82  and  84  as illustrated. 
     In one example, the concave inward curvature of the jaw tip ends  54  and  56  and first cutting edges  70  and  72  of the surgical instrument are only slightly curved. As an example, the tip ends can have a curvature defining an arc for a two-inch radius. As will be evident to those of ordinary skill in the art, the particular width of the jaw tip ends  54  and  56  and the particular curvature of the first cutting edges  70  and  72  can vary according to the needs of a particular surgical instrument. As shown in FIG. 6, a plane “A” of the cutting edges  70  and  72  and the cutting edges  74   a ,  74   b  and  76   a ,  76   b  remains consistent. 
     In the disclosed example of FIGS. 4 and 5, the curved first cutting edges  70  and  72  have an arc that is arranged symmetrically relative to the jaws. A tangent to the center of the curve is essentially perpendicular to a line “R” that bisects the arc of the edges  70  and  72 . The instrument  10  and each of the jaws  30  and  32  has a longitudinal axis “X” that is parallel to and at the centerline of the instrument. The line “R” of each arc is defined as extending from a center point of a circle on which the arc would lie and bisects the arc of the curved cutting edges. In this example, the line “R” and the longitudinal axis “X” of the instrument are co-linear, thus positioning the arc of the curved cutting edges  70  and  72  symmetrically relative to the instrument axis “X”. Therefore, each side of the curved cutting edges is a mirror image of the side opposite the axis “X” and the line “R” of the instrument. The geometry, curvature, and orientation of the arc of the inwardly curved cutting edges can vary from that disclosed in the example of FIGS. 4 and 5. 
     Referring to FIGS. 7 and 8, another example of a curved jaw tip end is shown and is constructed according to the teachings of the present invention. A surgical cutting instrument  110  is essentially the same as the instrument  10 . Most parts of the instrument  110  are essentially the same as the instrument  10  except as described below. In this example, a pair of upper and lower jaws  130  and  132 , respectively, have slightly different first cutting edges  170  and  172 . The first or forward tip end cutting edges  170  and  172  of the disclosed instrument  110  are not symmetrically oriented relative to the instrument longitudinal axis. Instead, the inward concave arc of each cutting edge  170  and  172  is slanted or angled relative to the axis “X” as shown in FIGS. 7 and 8. The line “R” that extends from the center point of the arc and that bisects the arc of each cutting edges  170  and  172  is offset at an angle “β” relative to the longitudinal axis “X” of the instrument  110 . In this disclosed example, the line “R” is offset or oriented at a 20° angle relative to the axis “X”. The offset or slant angle “β” of the concavely curved cutting edges can also vary and yet fall within the scope of the invention. 
     The offset angle “β” permits the surgical instrument  110  to be used for smoothly cutting along a curved side of a bone surface while reducing or eliminating the degree to which the instrument must be manually angled by the surgeon. For the example of FIGS. 4 and 5, the instrument  10  must generally be held normal or perpendicular to the surface to be cut. If cutting on a side of a bone, the surgeon must hold the instrument  10  normal to the bone surface, which can be difficult or impossible. 
     For example, a surgeon often can only open a relatively small incision during surgery to perform certain operations. The incision is retained open and spread apart by clamps or retractors which typically stay in place until the invasive part of a procedure is completed. The retractors can inhibit or impede side to side movement of the surgeon&#39;s hands as well as any instruments and can also reduce the overall working area around the incision. If side to side movement is required, such as for cutting and smoothing curved bone surfaces, the retractor can become dislodged or repositioned. This can cause undesired problems, delays, or even errors during a procedure. 
     As an example, during a spinal operation, the incision to work on one or two vertebra may typically be only about 1 to 3 inches long. When the skin is spread open and held by retractors, the work opening is limited. If the surgeon is to cut bone from a curved surface of a vertebrae using the instrument  10  to cut around the curved side, the surgeon must hold the instrument at an angle, normal to the bone surface. This can be difficult or virtually impossible with such a small incision and with retractors in place. 
     The angled jaw tip ends of the instrument  110  permit the instrument to be held closer to normal to the patient incision and yet cut along the side of the curved bone. The instrument  110  can be held at a shallower, more comfortable angle relative to the bone surface while the jaw tip ends are essentially positioned normal to the surface. The offset or slant angle “β” can be either to the right of the axis “X” (as shown) for a right handed surgeon or to the left of the axis for a left handed surgeon, depending upon the needs of a particular tool or surgeon. The instrument  110  can also be of such a design that it can simply be inverted so that either a right or left handed use is possible. The instrument  10  may be suitable for many procedures. However, the instrument  110  may be provide better results where cutting around or along the sides of curved bone surfaces. 
     The inward or concave curvature of the jaw tip ends of the surgical instruments  10  and  110  described herein permits material such as bone spurs or bone material to be removed while simultaneously leaving a relatively smooth surface on the bone. For example, during certain types of back surgery, bone spurs or osteophytes are cut away from vertebrae. Utilizing a surgical instrument according to the prior art of FIG. 2, the convex curvature of the jaw tip end leaves tiny grooves in the bone that mirror the curvature of the jaw tip end. In contrast, the surgical instruments  10  and  110  disclosed herein will not leave such grooves or indents in the cut away bone surface and will instead leave a relatively smooth and slightly outwardly curved bone surface. 
     Although certain surgical instruments constructed in accordance with the teachings of the present invention have been described herein, the scope of coverage of this patent is not limited thereto. On the contrary, this patent covers all embodiments of the teachings of the invention that fairly fall within the scope of the appended claims, either literally or under the doctrine of equivalents.