Patent Application
20050240197
The present invention is directed to a device and method for inserting, positioning and/or removing an implant from bone and, in particular, a device having a portion which can be selectively fixed or freely pivotable and/or rotatable with respect to a body portion of the device.
Intramedullary rods or nails can be used for internal fixation and reduction of a fractured bone, such as for example a long bone. The intramedullary rod is generally inserted into the marrow canal of a long bone, such as the femur, and across the fracture so that the fracture portions are properly aligned in close apposition. The rod is typically inserted in one end of the long bone and extends into the shaft of the bone. Moreover, the rod may be designed to be backed-out of the bone to adjust the rod, remove the rod, or pull two halves of a fracture together. Various devices can aid in the insertion and/or backing-out and/or removal of the intramedullary rod.
The implant insertion and positioning device chosen by a surgeon depends on the technique the surgeon desires to use, the desired results, the implant, and parameters of the operation. If a surgeon desires to freely hammer an implant into a bone and the surgical procedure so allows, a surgeon can use a hammer-type insertion device having a head and a shaft. The head on such devices has an orientation which is fixed with respect to the shaft. A rod inserter having an enlarged portion is attached to the intramedullary rod. The surgeon repeatedly strikes the enlarged portion of the rod inserter with the head of the hammer-type insertion device to drive the rod into the marrow canal.
On the other hand, if a surgeon desires or the surgical procedure so requires and/or allows, the surgeon can use a hammer-type insertion device where the head pivots about the shaft. This hammer-type insertion device may be used with a rod inserter, which is attached to the rod and consists of an elongated shaft having proximal and distal ends. The shaft may also have an enlarged portion at its proximal end, which is closest to the surgeon, and/or an enlarged portion at its distal end, the end closest to, and typically attached to the intramedullary rod. The hammer-type device is positioned on the shaft and travels along the shaft as it undergoes a reciprocating motion that allows a surgeon to repeatedly strike either enlarged portion. A pivotable head allows for ease of movement as the device is reciprocated along the shaft. To drive a rod into the bone, the surgeon strikes the enlarged portion at the distal end of the shaft with the head of the hammer-type device. To back-out or remove a rod from the bone, an operator strikes the enlarged portion at the proximal end of the shaft.
The present invention relates to a device for impacting or inserting an implant into bone, and/or backing-out, extracting or removing the implant from the bone, and/or repositioning an implant in bone. In particular, the device can be used to insert a rod into a bone, back-out and/or remove a rod from a bone, or reposition a rod in a bone. The device comprises a shaft, a head, optionally a channel through the head, and a locking mechanism. The locking mechanism may engage the head so that the head does not pivot and/or rotate relative to the shaft. In addition, the locking mechanism may be disengaged from the head, thereby enabling the head to pivot and/or rotate freely with respect to the shaft. Preferably, the locking mechanism is associated with the shaft of the device. The device may also have means for retaining a guide in the optional channel. Additionally, the locking mechanism may have means for tightening the locking mechanism on the shaft.
The present invention also relates to methods for impacting or inserting an implant into bone, backing-out, extracting, or removing an implant from a bone, and/or repositioning an implant in a bone. In one method of impacting, repositioning or backing-out a rod from a bone, the device may be used with an implant inserter which is attached to the rod. The inserter may have an aiming arm and an enlarged portion proximate its end. One exemplary method of using the device includes the steps of: moving the locking mechanism so that it engages the head, thereby fixing the head relative to the shaft (i.e., the head does not pivot, rotate, or translate relative to the shaft); and striking the rod or the enlarged portion of the inserter (if an inserter is used) with the head of the device.
Another alternative method of using the device involves the steps of: attaching an implant inserter, which comprises a guide to an implant (such as, for example, an intramedullary rod); adjusting the locking mechanism so that it is disengaged from the head, thereby allowing the head to pivot or rotate relative to the shaft; positioning the device onto the guide; and reciprocating the device along the guide. The inserter used with this method may have an enlarged portion at one end of the guide proximate the rod and/or an enlarged portion at the other end of the guide. An operator can strike the rod or the enlarged portion proximate the rod to insert the rod into the bone. Alternatively, an operator can strike the enlarged portion proximate an operator to back-out, remove or reposition the rod from the bone.
In another embodiment, the head of the device may also contain a slot, which communicates with the channel of the head, preferably intersecting the channel at an angle, most preferably perpendicular to the channel. The head can be positioned on a guide by moving the slot of the head onto the guide shaft until the shaft reaches the channel. The device is then rotated to align the longitudinal axis of the guide shaft with the longitudinal axis of the channel. In yet another embodiment, the head may have a helical slot, which intersects the channel of the head. The helical slot is inserted onto the guide shaft and, as the helical slot is advanced onto the guide shaft, the head threads, rotates or twists until the longitudinal axis of the guide is aligned with the longitudinal axis of the channel.
The present invention can be better understood by reference to the following drawings, wherein like references numerals represent like elements. The drawings are merely exemplary to illustrate certain features that may be used singularly or in combination with other features and the present invention should not be limited to the embodiments shown.
Handle 2 permits an operator to grab and hold tool 1 during use. Handle 2 is preferably ergonomically contoured for use by the operator and may contain grip enhancing surfaces, materials and/or projections. It should be noted that handle 2 is not necessary to the functioning of tool 1 since an operator can grab shaft 4 instead. Handle 2 may be made of plastic, rubber, metal, wood, a composite material (i.e., made of at least two materials), or any other suitable material. For example, handle 2 may be made of an impregnated linen or a phenolic resin. Alternatively, handle 2 can be made from a molded polymer (e.g., Delrin®). Handle 2 may also have a core material surrounded by another material. For instance, an aluminum core may be surrounding by a silicon jacket. Various factors can be considered when determining the material used to make handle 2, including ability to withstand sterilization/cleaning (e.g., using an autoclave; cleaning products used for sterilization in hospitals), feel (e.g., a molded material gives a softer feel in a operator's hand), weight, durability (e.g., ability to withstand impact/load forces, ability to be dropped), resistance to staining (e.g., from blood or substances used in surgery or to clean tool 1), the ability to withstand heat, and the ability to grip the handle, particularly with latex gloves which are generally used during surgery. Other factors, not listed, may also be relevant.
The handle 2 can be any shape or size. For example, it may be desirable for handle 2 to be shaped to fit the contours of a hand (i.e., ergonomic). Moreover, the end 3 of handle 2 can be flared to prevent handle 2 from slipping from an operator's hand during use. Additionally, to allow for enhanced gripping of handle 2 by an operator, handle 2 may have a grip (not shown), which covers or is positioned in a least a portion of handle 2.
The grip may be made out of the same materials as handle 2. The grip may have indents or protrusions. And, the factors used to select the material for handle 2 are also applicable to choosing material(s) for the grip. The grip may be a separate piece from handle 2, for example, the grip may be positioned as an inset (not shown) in the handle. The grip may also be over-molded (i. e., formed by molding a material over handle 2). A grip made of rubber may be used. Alternatively, the grip may be integral or monolithic with handle 2 (i.e., the handle and grip are made of one piece of material). In such a configuration, the grip portion of handle 2 can be textured.
Shaft 4 can be attached to handle 2 or be one integral piece with handle 2. Shaft 4 can be made from, for example, a hardened material such as stainless steel. However, shaft 4 may be made of any suitable material. Various factors may be used to determine the material of shaft 4, including ability to withstand sterilization/cleaning, weight, durability, resistance to staining, and heat treatable. Other factors, not listed, may also be relevant. A stainless steel shaft 4 can have a diameter between about approximately 5 mm and about approximately 20 mm, preferably between about approximately 6 mm and about approximately 15 mm, and most preferably between about approximately 7 mm and about approximately 10 mm. It should be understood that the diameter of shaft 4 depends on the material used and can be any diameter so long as the diameter of shaft 4 is sufficient enough so that shaft 4 will not break or bend from repetitive use of tool 1. Moreover, shaft 4 may have a length measured from handle 2 to head 8 between about approximately 20 mm and about approximately 150 mm, preferably between about approximately 50 mm and about approximately 140 mm, and most preferably between about approximately 100 mm and about approximately 130 mm. The length of shaft 4 is one factor, amongst others, enabling an operator to properly swing tool 1, and ensuring proper leverage and momentum of tool 1 for hammering. Furthermore, as shown in
Shaft 4 may abut handle 2 or extend through a portion or the entire length of handle 2. Shaft 4 can be attached to handle 2 in numerous ways, including friction fitting, welding, chemical or molecular bonding, or gluing. In another embodiment, shaft 4 can have an external thread (not shown) engaging an internal thread (not shown) of handle 2. In an alternative embodiment, handle 2 may have an opening 5 which receives a pin, screw, set screw, rod, bar or other retaining means which attaches shaft 4 to lock handle 2 and shaft 4 relative to each other.
Head 8 is connected to shaft 4. Head 8 may be preferably pivotally and/or rotationally connected to shaft 4. In one embodiment, as shown in
It should be understood that open area 8a is not required. For example, head 8 may have an extension 8b (
Shaft 4 and head 8 can be configured so that head 8 has an angle 20 of pivot of about 360° (e.g., where the shaft 4 is attached to the side of head 8 (
In another embodiment, shaft 4 may have a ball (not shown) at distal end 18 and head 8 may have a socket (not shown) to receive the ball of shaft 4. Alternatively, shaft 4 and head 8 may be connected by a swivel joint (not shown) so that head 8 can be rotated about shaft 4. Any other means of connecting shaft 4 and head 8 can also be used in a manner so that head 8 can pivot and/or rotate with respect to shaft 4 in at least one direction or about at least one axis.
A locking mechanism 7 may be provided to fix shaft 4 and head 8 with respect to each other, thereby preventing pivotal or rotational movement of head 8 about shaft 4. It should be understood that a locking mechanism includes any mechanism which functions to lock shaft 4 and head 8 relative to each other and which also allows the shaft 4 to be unlocked so that shaft 4 and head 8 can pivot with respect to each other. The locking mechanism may be associated with, or may be attached to shaft 4, or may be attachable to shaft 4 (i.e., capable of being attached/detached from shaft 4). The locking mechanism can consist of a single piece or more than one piece.
It should be noted that the portion of locking member 6 that engages the handle 2 or head 8 can be configured to assist in holding the locking member 6 against the handle 2 or help in fixing the head 8 relative to shaft 4. For example, locking member 6 can have a flat portion for engaging a corresponding flat portion of handle 2 and/or head 8. Locking member 6 may also have a textured portion, for example teeth, which engages a corresponding textured or smooth portion, for example teeth, on handle 2 and/or head 8.
Locking member 6 may have internal threads (not shown) to engage proximal threads 12 or distal threads 16. Threads 16 may be located proximate head 8 and function to hold locking member 6 against head 8 at distal end 18 of shaft 4. Threads 12 function to hold locking member 6 at a position on shaft 4 such that locking member 6 does not engage head 8. In
By threading locking member 6 on proximal threads 12 or by tightly fastening locking member 6 against an enlarged portion, locking member 6 is restrained from moving as the operator uses the insertion, positioning, removing tool 1. More specifically, locking member 6 will not move along shaft 4 as the device is swung by an operator. Locking member 6 can be tighten on shaft 4 by manually twisting member 6 on threads 12 or 16 (i.e., an operator uses his/her fingers/hand). Member 6 may also have a grip (e.g., diamond knurl 17 as shown in
In addition, to allow for further tightening, locking member may 6 have one or more opening 15, which can be any shape or size, positioned about the periphery of member 6. A device such as a spanner or pin wrench, rod, or bar (not shown) can be positioned in opening 15 and used to twist locking member 6 on shaft 4. The spanner or pin wrench, rod, bar, or other device provides an operator with leverage to further tighten locking member 6 on threads 12, 16. It should be understood that locking member 6 may be tightened only manually or, alternatively, there can be no manual tightening and the entire tightening step can be performed using a device such as a spanner or pin wrench, rod, bar or other device (not shown), or the member 6 can be manually tightened by the operator turning the member 6 and then further tightened using a tightening tool. In addition to or in place of using devices such as the spanner or pin wrench, rod, bar, or other device, an operator may use, for example, a plier, wrench, or similar device to grab the outer surface of locking member 6 and twist member 6 on threads 12 and 16. Moreover, to prevent member 6 from loosening on threads 12 and 16, a screw, set screw, bolt, pin, or other retaining member can be positioned to extend through member 6 and contact the surface and/or extend into threads 12, 16 and/or shaft 4.
In an alterative embodiment, threads 12 may be located at any location along the length of shaft 4. To lock locking member 6 tightly to shaft 4, a portion of threads 12 may be deformed and/or enlarged portion 13 may be positioned adjacent threads 14. In yet another embodiment, there may be only one threaded portion on shaft 4. The threaded portion preferably would cover enough of shaft 4 so that locking member 6 can be moved from a position adjacent head 8 to a position where member 6 disengages head 8. In still another embodiment, the entire shaft 4 may be threaded. In another embodiment, the shaft 4 may taper from a smaller diameter at distal end 18 to a larger diameter at proximal end 14 or have an enlarged portion. Locking member 6 can be force fitted over a portion of the taper or enlarged portion to hold it on shaft 4 at a sufficient distance from head 8 so that head 8 can pivot about shaft 4. Also, in any embodiment, locking member 6, in its disengaged position, may be moveable along shaft 4 (i.e., not locked to shaft 4) or may be designed to be removed all together from shaft 4 upon disengagement from head 8. The locking mechanism 7 may not comprise any threads at all.
In an alternative embodiment, a pin, screw, set screw, bolt, or other retaining means, can extend through member 6 and into or through shaft 4. The pin, screw, set screw, bolt or other retaining means may extend through opening 15 or some other opening that forms a through hole. The through hole may be threaded to engage corresponding threads on the pin, screw, set screw, bolt, or other retaining means. This configuration can be used to hold member 6 on shaft 4 anywhere along the length of shaft 4.
In yet another alternative embodiment, the locking mechanism may incorporate a bayonet fitting. For example, there can be one or more protrusions (not shown) around the periphery of shaft 4. The protrusion(s) may be a single prong, or may extend a portion or the entire length of shaft 4. Locking member 6 of this embodiment may have internal groove(s) along its length to receive the protrusion(s). Such a configuration allows for axial, but not rotational, movement of member 6 on shaft 4 where member 6 engage the protrusion(s). A pin, screw, set screw, bolt or other retaining means may be used to hold member 6 against head 8 or at any position along the length of shaft 4. Alternatively, a spring (not shown) can be positioned around shaft 4 and bias locking member 6 towards head 8. It should be appreciated that any combination of the embodiments and features disclosed herein can be used as a locking mechanism.
In an alternative embodiment, there may be no locking member 6. Such an embodiment may use a pin, set screw, screw, rod, bar, bolt or other means to fix shaft 4 so that shaft 4 does not pivot with respect to head 8. One of ordinary skill in the art can readily appreciate that other means of temporarily fixing shaft 4 and head 8 relative to each other is envisioned by the present invention.
As shown in
Head 8 can be any shape or size so long as head 8 can function to impact/strike an implant and/or portion of an insertion device, such as inserter 29 (
Head 8 may be made of stainless steel, but other materials can also be used. Any of the various factors discussed above with regard to choosing a material for shaft 4 or member 6 can be used to determine the material of head 8. In addition, other factors that may be considered is resistance to dents from hammering and impact strength. Moreover, head 8 can have a length between about approximately 30 mm and about approximately 150 mm, preferably between about approximately 40 mm and about approximately 100 mm, and most preferably between about approximately 50 mm and about approximately 75 mm. And, head 8 can have a diameter of between about approximately 30 mm and about approximately 100 mm, preferably between about approximately 35 mm and about approximately 75 mm, and most preferably between about approximately 38 mm and about approximately 60 mm. Various factors can be considered when determining the dimensions of head 8, including the weight and/or mass of the head 8 which is necessary for generating the energy needed to insert an implant.
Head 8 may also have a channel 23 and a slot 23a intersecting the channel 23. Head 8 and channel 23 may share a longitudinal axis 9, however, head 8 and channel 23 may each have a separate axis, which can be parallel or at any angle with respect to each other. Slot 23a communicates with channel 23 and outer surface 37 of head 8, thereby providing a path for inserting a guide 30, such as longitudinal member 30a shown in
Head 8 may have one or more ball plungers 25. Ball plunger 25 may have a housing 28 containing spring 27 and ball bearing 31. The housing is configured to prevent ball bearing 31 from falling out of the housing while, at the same time, allowing a portion of ball bearing 31 to protrude from the housing into channel 23. Ball bearing 31 may also be held in the housing by being fixed to spring 27. Ball bearing 31 is permitted to move up and down in the housing in response to a force thereon, for example, by insertion of rod 30 into channel 23. Ball plunger 25 may be positioned in hole 33 (or an opening) of head 8. Plunger 25 can have external threads (not shown) to engage threads (not shown) in the perimeter of hole 33, thus keeping plunger 25 in place. Alternatively, plunger 25 may be connected to head 8 in various ways, including force fitting, welding, chemical or molecular bonding, or gluing. The position of plunger 25 in channel 23 or slot 23a (i.e., the extent to which plunger 25 extends into channel 23 or slot 23a) depends on the guide that is used and the size of the channel 23. It should be understood that ball bearing 31 can be any shape, such as for example a sphere, sloped triangular (
To position the head 8 on a guide 30, such as longitudinal member 30a, component 40 (by itself, by rotating/pivoting component 40 along with shaft 4, or by moving component 40 straight up and down with shaft 4) can be rotated, pivoted, or moved straight down into slot 48. Finger 42 can be entirely positioned within the slot 48 so that no portion of finger 42 is within the channel 23. However, finger 42 only needs to be positioned as far into slot 48 as necessary so that guide 30 can enter channel 23. It is desirable that when head 8 is positioned on a guide 30, such as longitudinal member 30a, and reciprocated thereon, the component 40 does not rotate or pivot to such a degree that the head 8 becomes disengage from the guide 30.
Moreover, head 8 can have multiple holes 33 (or opening) to allow an operator to adjust the position of the holding member, such as plunger 25, in head 8. Also, head 8 and plunger 25 can be configured to allow an operator to adjust the extent to which ball bearing 31 extends into channel 23. It should be noted that any mechanism that can be used to temporarily retain a guide 30, such as longitudinal member 30a, in channel 23 is envisioned.
Turning now to
In the fixed position, head 8 can be used to strike or hammer an implant, such as intramedullary rod 24, into bone 26. To assist in hammering rod 24 into bone 26, an implant inserter, such as inserter 29, may be provided. Tool 1, however, can be used to hammer the implant directly. Inserter 29 is attached to rod 24 and includes a mushroom-shaped head portion 28 and an aiming arm 22. In use, an operator and/or an assistant holds aiming arm 22 by hand and the operator and/or the assistant strikes portion 28 with head 8 of tool 1. By swinging tool 1 in direction 32a and striking portion 28, rod 24 is driven in bone 26. It should be understood that head 8 preferably may be fixed with respect to shaft 4 when tool 1 is used with an inserter 29 shown in
Alternatively,
In the toggle position, head 8 may be used with an implant inserter device, such as inserter 29, to hammer an implant, such as rod 24, into and/or out of bone 26. Inserter 29 is attached to rod 24 and includes an aiming arm 22, a distal mushroom-shaped head portion 28, a guide 30 (e.g., a longitudinal member 30a,), and a proximal mushroom-shaped head portion 34. One of ordinary skill in the art would appreciate that guide 30 may be any shape, including round, oval, square, rectangular, or other polygon, and can have any thickness so long as head 8 can fit over guide 30 and move therealong. Head 8 of tool 1 is positioned on guide 30 by moving slot 23a over guide 30 until guide 30 enters channel 23. Guide 30 may be retained in channel 23 using a holding member as described above. To insert rod 24 into bone 26, an operator and/or an assistant holds arm 22 by hand and the operator and/or the assistant reciprocates head 8 on guide 30 in direction 32, repeatedly striking portion 28 with head 8 of tool 1. In this manner, rod 24 is driven in bone 26. To back-out or remove rod 24 from bone 26 or reduce a fracture (i.e., pull two bone fragment together) using rod 24, or reposition rod 24 in the bone, the operator and/or the assistant reciprocates head 8 on guide 30 in direction 32, repeatedly striking portion 34 with head 8 of tool 1.
The tool of
While the foregoing description and drawings represent the preferred embodiments of the present invention, it will be understood that various additions, modifications and substitutions may be made therein without departing from the spirit and scope of the present invention as defined in the accompanying claims. In particular, it will be clear to those skilled in the art that the present invention may be embodied in other specific forms, structures, arrangements, proportions, and with other elements, materials, and components, without departing from the spirit or essential characteristics thereof. One skilled in the art will appreciate that the invention may be used with many modifications of structure, arrangement, proportions, materials, and components and otherwise, used in the practice of the invention, which are particularly adapted to specific environments and operative requirements without departing from the principles of the present invention. The presently disclosed embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims, and not limited to the foregoing description.
