Surgical Bone Punch

Abstract

A surgical instrument for punching holes in bone or other substantially solid matter such as cartilaginous tissue. A relatively easy to operate trigger mechanism permits a very large force to be applied to the punch to penetrate the bone. The punch is advanced incrementally by means of a ratchet mechanism, and a reversible floating ratchet assembly permits the instrument to supply substantially the same force to an elongated surgical punch for both driving and retracting purposes. The device may also be used for cutting hard tissue or shaping other materials such as surgical metal plates due to the large forces which it is capable of developing.

Description

FIELD OF THE INVENTION

This invention relates to a bone punch and more particularly to a surgical instrument for converting lever action to longitudinal motion having a great deal of force. The instrument also provides substantially the same force for driving a surgical punch through solid fibrous material and for retracting it therefrom.

BACKGROUND OF THE INVENTION

Surgical operations within the cranium normally require that a portion of the skull be removed. It is usually desirable after such operations to replace and anchor the removed bone portion at the site of its removal. Such replacement and positioning of bone or other cartilaginous tissue facilitates the process of healing to fuse the bone with surrounding tissue and dispenses with the requirement of artificial plates or foreign matter for the protection of vital organs. Replacement of the original tissue requires maintaining its position securely in the location from which it was removed in order to promote the desired physiological healing. In some cases an artificial plate is necessary and it too must be firmly anchored in place. Securing such natural or artificial member in the site of the operation requires the formation of small holes in the cranium surrounding the opening and the formation of matching holes in the covering member so that surgical wires may be used for connecting and anchoring purposes.

The fibrous nature of bone and other rigid body tissue has been particularly troublesome in punching holes because prior punches have required excessive force to penetrate the bone and have tended to become wedged in the tissue making removal quite difficult. Such wedging of the surgical punch in tissue sometimes required the use of a second instrument to rongeur the punch out. The application of such forces could result in the possibility of cracking or breaking of the surrounding bone causing brain damage, shock and possibly even death to the patient.

SUMMARY OF THE INVENTION

In accordance with the present invention, a surgical instrument is provided for punching holes in or through bone or other tissue wherein a relatively easily operated mechanism provides a large force to the punch itself by the use of a lever and ratchet assembly. Furthermore, this instrument provides a force substantially equal yet opposite in direction to the driving force to remove the surgical punch from the fibrous tissue. An adjustable gap between bearing surfaces of the surgical punch is provided to accommodate bone thickness against which a punch moves in either direction through the bone. The adjustable bearing surfaces and the mechanism of the surgical punch permits the force of the punch to be controlled and absorbed within the instrument.

A reversible floating ratchet assembly is provided for selection of ratchet rods for either driving or retracting the surgical punch with substantially the same mechanical force and similar effort. A simple pistol grip structure is employed where the trigger is squeezed toward the handle several times to drive the punch through the bone and a substantially equal number of times to remove the punch from the bone when the ratchet mechanism is reversed. A selector lever is employed to determine whether the punch moves in a forward or reverse direction. This instrument, by providing a similar mechanical advantage for incrementally driving and after the formation of the hole, incrementally retracting the surgical punch, allows holes to be made rapidly, efficiently and safely, thereby decreasing operation time and providing important time advantage to the patient.

BRIEF DESCRIPTION OF THE DRAWING

The invention will be more fully understood from the following detailed description taken in conjunction with the accompanying drawing in which:

FIG. 1 is a perspective view of a surgical bone punch constructed according to the invention and illustrating its operation;

FIG. 2 is a partial cutaway side view of the bone punch of FIG. 1 with the mechanism in an intermediate position;

FIG. 3 is a partial cutaway view similar to FIG. 2 depicting the operative arrangement of parts in driving the surgical punch;

FIG. 4 is a view similar to FIG. 3 showing the arrangements of parts in retracting the surgical punch; and

FIG. 5 is a partially exploded cutaway perspective view of a bone punch of FIG. 1 depicting various parts of the ratchet selection mechanism.

DETAILED DESCRIPTION OF THE INVENTION

The surgical bone punch 10 as shown in FIG. 1 includes a body 12 of a generally rectangular cross-sectional configuration with a handle 14 extending downwardly therefrom. A hand restraining and leverage directing guide 16 projects rearwardly from handle 14 below body 12. The body is shaped at its forward end 18 for a dovetail connection with the rearward end 20 of punch guide 22. A forwardly projecting key 24 is provided on the lower front face of body 12 for mating with a slot 26 in the bottom of guide 22 to assure proper orientation of the guide when mounting it to the body.

Trigger lever 27 of bone punch 10 is coupled with selectable ratchet rods and a punch rod for punching holes through bone tissue as will be described in more detail hereinafter. FIG. 1 also illustrates an incision showing retracted tissue 28 from an operation incision site 30 from which bone has been removed. Cranial bone 32 is shown having holes 34 formed therein by the surgical instrument of the present invention.

As illustrated in FIG. 2, punch guide 22 contains a bore 36 therethrough forming a passage through which bit 38 of elongated punch rod 40 moves. The forward end 42 of bore 36 is threaded for mating with external threads 44 of hollow bolt 46 having a knurled head 45 and forming an adjustable base member 48. Punch guide 22 at its forward end has a projecting arm 50 terminating in a foot plate or anvil 52 orientated at a right angle to the axis of arm 50. Anvil 52 has a positioning pin 54 and a cone-shaped bore 56 in alignment with cutting end 39 of bit 38, the apex of the bore being of a diameter sized to receive the cutting end of the bit therewithin.

Three bores 58, 60 and 62, each a different size, are provided longitudinally through body 12 of the bone punch. Passage 58, the smallest of the bores, receives a longitudinally movable retracting ratchet rod 72 having a series of forward facing annular teeth 74, a slot 78 and a cylindrical portion 81 at the forward portion thereof. Similarly, bore 62, which is the largest of the three, is formed to receive a longitudinally movable driving ratchet rod 80 having a series of rearwardly facing annular teeth 82, a slot 84 and a cylindrical portion 86 at the forward portion thereof. Intermediate size bore 60 is formed to receive elongated punch rod 40 which has bit 38 at the forward end and a knob shaped projection 90 at the rearward end. Punch rod 40 has flat surfaces 92 on opposite sides of a portion of its length and a slot 94 therethrough parallel to the flat surfaces.

Trigger lever 27 having a ribbed grip 98 and a hand restraining and leverage directing guide 100 is coupled to body 12. The trigger is formed with a flat portion 102 adapted to extend through slot 84 of the driving ratchet rod 80, slot 94 of punch rod 40 and slot 78 of retracting ratchet rod 72. In the area adjacent forward end 18 and in the vicinity of the aforementioned bores, body 12 has a reduced thickness from one side as indicated by reference numerals 104, 108, 110 and 112 upon which the flat portion 102 of the trigger lever slides during operation. A hole 114 of appropriate size is formed in trigger lever 27 at a point between leverage guide 100 and flat portion 102 for receiving guide pin 116. The guide pin 116 has a knurled head 118 at the forward end and is threaded to engage a tapped hole in handle 14. Return spring 124 surrounds guide pin 116 between the handle and the trigger lever to normally bias the trigger away from handle 14.

FIGS. 1, 2 and 5 best illustrate the floating ratchet selector mechanism. Rocker arm 130 has a loop 132 formed thereon for disposition and pivoting around the rearward portion of punch rod 40. A pawl 134 (FIG. 2) is provided adjacent the end of arm 130 below loop 132 for individually engaging the rearward facing teeth 82 on ratchet rod 80. The pawl is formed with a beveled rearward face and a forward face which is substantially perpendicular to the axis of the ratchet rod. A similarly shaped but oppositely facing pawl 136 is formed adjacent the end of rocker arm 130 above loop 132 for individually engaging the forward facing teeth 74 on ratchet rod 72. Rocker arm 130 may be positioned to selectively engage one or the other of ratchet rods 72 and 80 to retract or drive punch rod 40 respectively.

A slot 140 is provided in body 12 for receiving rocker arm 130. A key guide 142 for receiving key pin 144 projecting rearwardly from the rocker arm is formed as a notch along the rear side of slot 140. The purpose of the key pin and guide is to assure proper orientation of rocker arm 130 when the instrument is assembled. Selector lever 150 having a projecting handle 152 thereon is pivoted to body 12 and slides over concave edge 138 of rocker arm 130 to cause the appropriate pawl to engage the teeth of the selected ratchet rod. As shown in FIG. 1, driving ratchet rod 80 has been selected and engaged by pawl 134. Lever 150 is pivotally connected to body 12 by means of a bolt 154 having a vane 156 projecting therefrom, the vane being provided to assist in assembling and disassembling the instrument. The bolt is provided with a bearing surface (not shown) which is larger than the threaded portion and is adapted to fit in hole 153 in the forward end of selector lever 150. Restraining stops 158 and 160 project outwardly from the rocker arm at either end of concave edge 138 to act as positive positioning means for selector lever 150. Bolt 154 in addition to securing selector lever 150 to body 12 also secures resilient drag spring 162 in opening 164 in the body to frictionally engage flat surface 92 of punch rod 40. This spring is captured by lever 150 and its function will be explained hereinbelow.

In using the instrument of this invention for punching, cutting or shaping purposes as previously described, anvil 52 is placed under the working surface and bolt 46 is adjusted until base member 48 is securely positioned above the working surface, herein referred to as bone tissue. Thus the distance between base 48 and anvil 52 is adjusted to accommodate the thickness of the bone. Selector lever 150 is set in the position as shown in FIG. 1 and surgical punch 40 is advanced forward by pressing against knob 90 or by repeatedly squeezing trigger lever 27 until bit end 39, passing through hollow bolt 46, becomes flush with base 48 or comes in contact with the surface of the bone. Advancing punch rod 40 results in teeth 82 sliding by pawl 134 with a snapping sound as the pawl disengages from each succeeding tooth. It should be noted that selector lever 150 is formed to act as a relatively stiff leaf spring to permit the pawls of the rocker arm to ride over the ratchet teeth.

Squeezing of trigger 27 toward handle 14 causes pawl 134 to positively engage one of the teeth 82 on driving ratchet rod 80. At this time trigger 27 pivots about the rearward end of slot 84 of the ratchet rod, thereby applying forward pressure against the forward end of slot 94 of punch rod 40 and driving the punch rod 40 in the direction indicated by arrow 163 (FIG. 3). Each time the trigger is squeezed, the punch rod moves forward a distance substantially equal to the distance between the ratchet teeth. Upon release of trigger 27, spring 124 urges the trigger to return to its normal position. The pivot point then shifts to the rearward end of slot 94 in punch rod 40, applies forward force to the forward end of slot 84 in ratchet rod 80 urging the ratchet rod forward so that pawl 134 slides to the next tooth. All the while, ratchet rod 72 is disengaged and floating freely in bore 58 under the influence and control of the upper end of the trigger in slot 78. Punch rod 40 does not float freely because of the friction engagement of spring 162 against the flat side of the punch rod, permitting the punch rod to act as a pivot for the trigger on its return to normal position. This action is repeated in an oscillating manner until the punch fully penetrates the bone and cutting end 39 enters into bore 56 in the anvil. A small plug of bone cut out by the punch is forced through bore 56. While the punch is penetrating the bone, positioning pin 54 engages the underside thereof, assuring positive placement of the instrument. As an alternative embodiment, the cutting tip of the punch may be hollow and the anvil may be flat so that the bone plug is forced into the hollow punch. Enlarged knob 90 of punch rod 40, in cooperation with the forward ends 86 and 81 of the ratchet rods 80 and 72, respectively, prevent damage to the instrument and the patient which might otherwise result from the continued driving of punch 40 after bit 38 has penetrated the bone or other material and has entered recess 56.

After the desired holes is punched, removal of punch bit 38 often requires the application of a significant retracting force. Such a retracting force is provided by setting selector lever 150 in the position shown in FIG. 4 so that pawl 134 disengages from ratchet rod 80 and pawl 136 engages the teeth of ratchet rod 72. Upon squeezing trigger 27, pawl 136 positively engages one of the teeth 74 on rod 72 and the pivot for the trigger becomes the forward end of slot 78 of retracting rod 72, thereby providing a rearward force against the rearward end of slot 94 of punch rod 40 moving the punch rod in the direction indicated by arrow 168 (FIG. 4). With adjustable base 48 resting against the outer surface of the bone, the punch pin pulls against the base, preventing anvil 52 from being driven inward, resulting in the punch being withdrawn from the bone and thereby providing an added measure of safety for the patient. Upon release of the trigger and under the influence of spring 124, the pivot point shifts to the forward end of slot 94 of punch rod 40 and with drag spring 162 acting against surface 92 of the punch rod, ratchet rod 72 is pushed backward and pawl 136 slips over one of teeth 74 to engage the next succeeding tooth. The intermittent retracting action is then continued until the punch pin is removed from the hole which it has made. Surgical instrument 10 is then removed from the incision and the small plug of bone falls out of or is easily removed from bore 56 before additional holes are punched in the bone. When retracting, the instrument operates substantially the same way as when driving, only ratchet rod 80 floats freely at that time.

It will be noted that in FIG. 3 an alternative embodiment is shown where mound 170 is substituted as a positioning device in place of pin 54. In FIG. 4, base 48 is also shown with such a mound 172 as an alternative structure.

It can be seen that the surgical instrument of the present invention is easily disassembled for cleaning by simply removing guide pin 116 from the handle and trigger and removing trigger 27 from the slots in the rods so that all of the rods may be removed. Punch guide 22 is slid off the end of the body and bolt 154 is removed to complete the dismantling process. Different size punch rods and punch guides and a wide variety of foot plates may be provided for various purposes such as punching, cutting or shaping. The ratchet rods and the punch rod are each of different diameters which fit in the different size passages to prevent accidental misassembly. Typical dimensions for the bone punch shown in the drawing include 1 mm. diameter for the cutting bit and approximately 3 mm. longitudinal movement for each trigger motion, the trigger may move as much as 50 mm.

The present invention can also be embodied in surgical instruments for obtaining samples of tissue for biopsy or further study by slight modification of the size, shape and function of the punch and punch guide.

While the complete description of this surgical bone punch as been directed to a dual reversible ratchet mechanism, it should be recognized that the driving ratchet mechanism is novel in itself and that there are likely to be instances where large retracting forces are not necessary. Specifically contemplated are alternative embodiments such as where the tip of the cutting bit is slightly larger in diameter than the shaft of the bit and is made to separate therefrom after the hole is formed. The anvil could have an opening of sufficient size to receive such a separable cutting bit element.

It will be appreciated that the invention can be implemented in different ways by those skilled in the art to suit particular requirements which are within the scope of this invention.

Claims

What is claimed is:

1. A surgical instrument for shaping or penetrating bone or other substantially solid material, said instrument comprising:

a body having a forward end, a rearward end and a handle projecting transversely of said rearward end;

a rearward facing foot plate mounted to the forward end of said body;

an elongated rod longitudinally movable in said body and having its forward end provided with a cutting edge, said forward end being arranged for confronting engagement with said foot plate;

a lever pivotally mounted to said body; and

first ratchet means in said body coupled to said lever for incrementally driving said rod toward said foot plate in response to oscillating movement of said lever.

2. The surgical instrument of claim 1 and further comprising a second ratchet means in said body coupled to said lever for incrementally retracting said rod from said foot plate in response to said oscillating movement of said lever.

3. The surgical instrument of claim 2 and further comprising selector means for selectively actuating one of said ratchet means for moving said rod in response to said oscillating movement of said lever.

4. The surgical instrument of claim 1 and further comprising:

guide means formed with said foot plate and mounted between said foot plate and said body; and

a base member mounted to said guide means in confronting relationship and spaced from said foot plate, said base member being adjustable so as to vary the distance between said foot plate and said base member.

5. The surgical instrument of claim 4 wherein the forward end of said rod passes through said base member and said guide means.

6. The surgical instrument of claim 1 and further comprising:

a handle projecting from said body;

a spring for normally biasing said lever away from said handle.

7. The surgical instrument of claim 3 wherein the non-actuated ratchet means remains coupled to said lever and floats freely in said body with said oscillating movement of said lever.

8. The surgical instrument of claim 3 and further comprising a resilient member mounted to said body for frictional engagement with said rod to hold said rod in place during each return motion of said lever, said return motion of said lever to normal position moving said actuated ratchet means to a new position.

9. The surgical instrument of claim 3 wherein;

each said ratchet means comprises a ratchet rod having a plurality of annular teeth thereon, one said ratchet rod having said teeth facing rearwardly, the second said ratchet rod having said teeth facing forwardly;

said selector means including a rocker arm pivotally and slidably mounted to said rod, said rocker arm having a pawl at either end adapted to engage the adjacent ratchet rod.

10. The surgical instrument of claim 9 wherein said selector means further comprises a selector lever pivotally connected to said body and engaging said rocker arm for positioning said rocker arm to selectively engage said ratchet rods.

11. The surgical instrument of claim 1 wherein said foot plate is formed with a projection for engaging a surface of said material opposite the side engaged by said rod when said rod is driven toward said foot plate.

12. A surgical instrument for penetrating bone or other substantially solid tissue, said instrument comprising:

a body having a handle projecting therefrom;

a foot plate mounted to said body and adapted for placement against a surface of bony structure facing away from said body;

an elongated surgical punch rod longitudinally movable in said body and having a cutting edge directed toward a surface of said bony structure facing said body and in alignment with said foot plate;

a reversible ratchet assembly in said body; and

a lever pivotally interconnecting said ratchet assembly and said punch rod, said lever causing intermittent longitudinal motion of said punch rod when moved in an oscillating manner.

13. The surgical instrument of claim 12 wherein said foot plate is formed with a projection extending therefrom for preventing sliding movement of said foot plate with respect to said bone.

14. The surgical instrument of claim 12 and further comprising selector means for selectively actuating a portion of said ratchet assembly to move said punch rod in a predetermined longitudinal direction in response to said an oscillating motion of said lever.

15. The surgical instrument of claim 14 and further comprising:

guide means formed with said foot plate and mounted between said body and said foot plate; and

a base member mounted to said guide means in confronting relationship with and spaced from said foot plate, said base member being adjustable so as to vary the distance between said foot plate and said base member;

said punch rod passing through said guide means and said base member.

16. The surgical instrument of claim 15 wherein:

said foot plate provides a bearing surface for the end of said punch rod when said punch rod is driven through said bone; and

said base member is adjusted to contact the interior surface of said bony structure and provide a bearing surface when said punch rod is retracted from said bone.