Compression bone staple, apparatus and method
A method and apparatus for interosseous bone fixation uses a compression staple, generally U-shaped, having a pair of legs with sharp front ends and proximal ends interconnect by a bridge portion that is resilient and bowed, the staple having an initial configuration and capable of a tensioned configuration by spreading apart the legs by a certain amount causing the curvature of the bowed bridge to lessen and the legs urged towards each other with certain compressive spring force. A staple applicator supports and guides the staple and positions the tensioned staple with its pointed ends forward, adjacent an ejection port at the front of the applicator. A powered strike member is mounted for longitudinal movement and has a front end that will strike the rear of the tensioned staple with percussive force and eject it in tensioned configuration from the applicator.
1. Field of the Invention
The present invention relates to devices and techniques for securing bone segments across a fracture site, and more particularly relates to a bone stapling method and apparatus for achieving compression between segments.
2. Description of the Prior Art
In treating a bone fracture it is common practice to fasten one bone segment to the other so as to stabilize and immobilize them for the duration of the bone consolidation process. Thus there is the technique of internal fixation or direct mechanical fastening of the bone segments.
Traditionally, fixation has been accomplished by variety of apparatus and techniques, the more common involving the use of metallic fastening devices such as screws, connector plates (secured to the bone by screws), pins and clips. These methods invariably involve the drilling of screw holes in the bone and the use of related equipment such as drill hole templates.
Conventional U-shaped clips have also been used, the clip legs being installed one each in holes in the opposing bone segments. The rigid structure of such clips, like the other fixation devices mentioned above, provide rigid immobilization of the fracture zone. Such devices also served to maintain the distance between segments, which was found however, among other things, to hinder compression induced by contractions of skeletal muscles in some cases, and prevent the establishment of compressive force between the bone segments which is favorable to bone consolidation or knitting. In this regard the concept of creating dynamic compressive force across an osteotomy or bone fracture site has become well recognized as a technique to promote primary bone healing, i.e. consolidation that is faster and of better quality.
Thus there has evolved a number of fastening devices such as clips and the like, designed to deliver compression. Accordingly in U.S. Pat. No. 3,939,294 there is provided a clasp or clip of spring material having a pair of spaced-apart, inwardly inclined legs connected by a Z-shaped upper portion. Sloped holes are drilled in adjoining bone segments and tools are used to manipulate and install one leg, and then the other leg is pulled toward the other hole, spreading the Z-shaped elastic portion, and then inserted in the other hole. Unfortunately this method requires the drilling of specially sloped holes, involves multiple steps and is time-consuming, and like the conventional rigid fastening techniques, requires relatively large surgical opening. Also, the manual installation of the clip using hemostats and the like is difficult, requires meticulous skill and handling.
In U.S. Pat. No. 4,838,254 the legs of a pair of metallic clips are inserted in pairs of specially angled bores in respective opposing bone segments. The exposed tops of the two installed clips then serve as fastening heads for a spring that is connected between the clips.
In U.S. Pat. No. 4,841,960 the disclosed “compression” clip is essentially a clip with opposing legs that are installed in pre-drilled holes and features a crimpable web that joins the top ends of the legs. A crimping tool is used to crimp the web in an effort to set up compression between the embedded legs.
U.S. Pat. No. 4,852,558 also requires manual installation of separate legs in pre-drilled holes, the tops of the install legs then being interconnected with a ratchet mechanism which must be operated to draw the legs together. This design appears inherently limited regarding adjustability and maintenance of constant pressure. In U.S. Pat. No. 5,660,188 the two legs of a clip must also be installed in pre-drilled holes. The clip has a bridge of two side-by-side crimpable elements, and the jaws of a crimping tool must be used on the embedded clip to deformingly spread apart these elements, causing the legs to draw to each other. The foregoing techniques involving crimpable clips all appear to be imprecise in setting up suitable compressive forces, require hole drilling and related problems, and do not lend themselves to minimizing the size of the surgical opening.
In view of the limitations of the afore-mentioned methods, stapling has been looked to as a potentially quick and effective way for fastening bone segments, and as a way to produce compression. Thus in U.S. Pat. Nos. 5,053,038 and 5,662,655 “compression” staples are applied to the bone by a powered stapler. These staples have legs shaped with beveled ends and/or have divergent legs that will be forced apart from each other during implantation, which flexes springy upper parts of the legs thereby tending to set up compression. Unfortunately there is concern for trauma to the bone due to driving of the compound-shaped legs into the bone mass, and there is little apparent precision in establishing the desired compressive forces.
In view of the foregoing it is a general object of the present invention to provide an improved method and for interosseous fastening.
A more particular object is to provide quick and simple, yet effective method for fastening bone segments with compressive force between opposing bone ends.
Another object to provide such a method that minimizes the size of the required surgical opening and associated trauma.
A further object to provide a method of bone stapling that minimizes trauma to the bone tissue during implantation of the staple legs.
Yet another object is to provide a method for stapling that maximizes the capability of establishing a dynamic compression level that is optimal for enhanced osseous healing.
A still further object is to provide simple, effective bone fixation technique that is relatively easy to learn and practice.
Another object is to provide for compression fixation in applications where other techniques would not work or would not deliver compression. For example, conventional fastening techniques for handling a “Jones” fracture, i.e. one that is transverse to the longitudinal extent of the bone segment, is difficult to address using conventional fastening techniques, however the present invention is particularly suitable to provide fastening for such fractures.
Still another object is to provide stapling apparatus and method in which there is enhanced selection capability regarding the level of the compressive forces to be imparted.
There are a number of advantages in exterior bone fixation techniques, where surgical incisions are not required and fasteners are applied through the skin; and thus it is yet another object of the invention to provide a bone stapling method that lends itself well to exterior bone fixation.
These and other objects of the present invention are achievable by way of the present invention of a bone stapling method and apparatus that uses a generally U-shaped staple having pair of spaced apart legs with sharp free ends and proximal ends interconnected by bridge that has at least one resilient curved portion, whereby spreading apart of the parallel legs lessens the curvature of the curved portions which brings the staple to a tensioned configuration in which one leg is resiliently urged towards the other. In a preferred embodiment it is seen that the bridge portion comprises a single bowed spring element, the curvature of which lies in a plane normal to the axes of the staple legs.
The novel fastening method involves first positioning the fractured ends of a first and a second bone segment in proximate, face-to-face relationship. The next step involves spreading apart the staple legs by a certain amount and holding the staple in the resultant tensioned configuration. The extent to which the staple legs are separated can be varied in one preferred embodiment of the invention, the induced compressive forces between the legs being proportional to the amount of displacement of the legs as the bowed portion is moved through range of motion in which elastic behavior is exhibited. In this regard it should be evident that herein lies one of the advantages of the present invention, i.e. the capability of selecting the optimal compressive force for an application by spreading apart the staple legs by a predetermined amount.
Next, as the staple is held in its tensioned configuration, it is positioned with it sharp ends forward and aligned respectively with surfaces of one bone segments and the other. Finally the positioned staple, while maintained in its tensioned configuration, is driven into the bone by percussive force, such quick application being provided by a conventional air-powered striker of a stapler according to the present invention, or by a manually stuck staple applicator according to the invention. The embedded staple legs will cause the opposing bone faces to be pressed into each other with a predetermined amount of force.
Such stapling method lends itself advantageously to a staple with a relatively narrow profile, wherein apparatus according to the present invention include a staple applicator having within its housing means for supporting the staple and guiding its movement with legs pointed ends forwardly disposed, and adapted to receive the staple in its initial untensioned configuration engaging its legs and spreading them apart by certain amount and holding the staple in its tensioned configuration adjacent the front end of the housing, for ejection therefrom. One embodiment, of several, uses opposing first and second grooves for engaging the staple legs and means for adjustably moving one groove from the other. Another embodiment employs grooves that diverge to spread the staple legs as a staple is advanced there-along. Ejection means mounted for longitudinal movement in the housing has a front end adapted to strike the rear of the tensioned staple with percussive force which is provided by air power or electrical power in preferred embodiments.
The invention also includes a staple applicator that is adapted for being manually driven.
Another related bone stapling method for compressively securing adjoining bone segments uses a resilient metallic staple that has legs with an initial convergent configuration with respect to each other, and the legs are resiliently extendible into parallel relationship, in which configuration a predetermined amount of spring force will urge the legs towards their initial convergent orientation. This method includes holding the normally convergent staple in its legs-parallel configuration, positioning the so-tensioned staple with its sharp ends aligned respectively with adjacent bone surfaces; and then driving and embedding the legs of the tensioned staple in the bone segments and releasing the embedded staple, whereby the bone segments are joined, and opposing surfaces of the bone segments are caused to be pressed into engagement with each other with a certain amount of compressive force.
An applicator or tool for such a staple includes staple-engaging means on the front end of the applicator body. Opposing jaws support the staple in a pointed-ends forward position against lateral and rearward movement, and engage inside surfaces of the convergent legs, the jaws being adapted for adjustable movement apart to cause the legs to rotate to a generally parallel orientation. Thus supported on the front end of the tool, the staple can be aligned with the bone segments, and the rear end of the tool stuck with a percussive force to cause the staple legs to be embedded into the bone segments.
Another applicator according to the present invention has a trigger-controlled air-powered staple-driving mechanism, and has a staple feeding mechanism including ramp means that is shaped to receive and support a staple in its initial configuration on one end of said ramp means, the configuration of the ramp means gradually changing to a shape that will hold the staple with its legs generally parallel with each other. Thus the staple can be slidably pushed along the ramp means in a lateral direction, i.e. normal to the plane in which the staple legs and bridge portion lie, to bring it to a terminal position along the ramp means, in which position the rear of the tensioned staple can be struck by the front end of a powered striker.
BRIEF DESCRIPTION OF THE DRAWINGS
Referring now the drawings,
It is preferred that the opposing inside surfaces of legs 13 are provided with serrations or barbs 19. In this regard it is noted that, inasmuch as the insides of legs 13 will be pressed against bone mass when they are embedded in a manner to be described, the size of such serrations or barbs can be advantageously minimized, which minimizes trauma to the bone tissue during their implantation.
It will be evident that there can be several variations of compression staples according to the principles of the invention. For example, staple legs can have various cross sectional configurations, including diamond-shaped, square, triangular and rectangular.
As
In a preferred embodiment, vertically extending gradations are provided at 67 on a forward surface of body 31, adjacent the movable rear end of upper head 45, so as to gauge the displacement of the staple legs when the invention is operated in a manner to be described below.
As
In the operation of staple applicator 29 for osteosynthesis, a staple 11 is mounted to the staple mount 43 which is operated to bring the staple to the desired tensioned configuration. Then bone segments are brought together by manual or mechanical manipulation as close as possible and aligned with each other. The stapler head 41 can then be positioned with its legs straddling the fracture line, and sharp ends 15 adjacent the surfaces of the bone segments. The stapler trigger can then be operated to cause the striker to drive the legs of the tensioned staple into the bone segments.
There is a variant of a staple applicator according to the invention that is identical to the embodiment of
A striker member 95 has upper and lower edges 97 and 99 slidably engagedin slots 101 and 103 so as to mount the striker member for longitudinal movement. The striker front ends 105 and 107 will align with and abut the rear ends of a tensioned staple.
In using tool 113 the sharp ends of a tensioned staple 11 can advantageously be precisely positioned on the target spots on the bone segments, then the tool end 117 struck with a mallet to implant the staple.
Referring now to
The trigger-controlled applicator 271, shown in
The enlarged view of
In operation of applicator 271 it is supported with its front end in close proximity to the relevant bone segments, and with the pointed ends of the staple appropriately aligned therewith. Pulling the trigger will cause the striker end 279 to impact the staple bridge and propel the staple forwardly as the staple legs are held generally parallel by sliding engagement with the generally parallel surfaces of the ramp member 287 during ejection.
The striker will have a stroke sufficient to cause the legs, in their parallel configuration, to be embedded in the bone tissue. The striker will return to its initial position rearward of the ramp member. Then spring force will cause another staple to be positioned in the ejection channel.
Although
The distal end of the ramp 387 receives staples 361 in their untensioned condition, and the walls 391 and 392 gradually diverge from each other such that at the other end 395 of the ramp, a staple 361 will be supported in a legs-parallel tensioned configuration. A spring-powered pusher 399 is adapted to urge a number of nested staples 361 towards the end 395 of the ramp.
The ramp end 395 is spaced a predetermined distance from the guide surface 401 and provides surfaces that engage the opposing surfaces 370 and 374 of staple 361. Thus the rear of a tensioned staple can be struck by the striker 397 and ejected from the applicator.
While particular embodiments of the invention have been described, it should be understood that the invention is not limited thereto, and includes other variants and modifications that will readily occur to those persons of ordinary skill in the art, given the benefit of this disclosure. Thus it is intended that the invention be given its full scope and breath as defined in the claims which follow.
Claims
21. A stapling method for fastening a first bone segment to a second bone segment, said first bone segment having an end to be connected to an end of said second bone segment, said method including the steps of:
- a) positioning the end of said first bone segment in face-to-face adjacent relationship with the end of said second bone segment;
- b) providing a generally u-shaped staple having a pair of spaced apart legs with sharp free ends and other ends interconnected by a bridge portion, and said staple having an initial untensioned configuration in which said legs converge with respect to each other;
- c) moving said staple from its initial configuration to a tensioned configuration in which said legs are held generally parallel to each other and in which said legs are resiliently urged towards their initial configurations;
- d) holding and positioning said tensioned staple with each of the sharp ends of said legs aligned respectively with a spot on the surface of said first and second bone segments; and
- e) driving and embedding the legs of said tensioned staple into said bone segments and releasing said staple, whereby the opposing faces of the bone segments are caused to be pressed into engagement with a predetermined amount of compressive force.
22. A method as defined in claim 21 wherein the step of driving and embedding of said staple legs is effected by percussion.
23. A method as defined in claim 21 wherein said step of moving said staple to its tensioned configuration includes slidably engaging opposing inner surfaces of the legs and bridge portions of said staple in its untensioned configuration with surfaces of a ramp and then moving said staple along said ramp in a direction normal to the plane in which lie said legs and bridge portion, so that said legs slidably follow surfaces of said ramp that are configured to urge said legs into parallel relationship.
24. A method as defined in claim 21 wherein said step of driving and embedding said staple legs includes slidably moving said along parallel surfaces.
25. A compression staple for fastening a first bone segment to a second bone segment, said staple comprised of a resilient material and having a generally U-shaped configuration, and comprising:
- a) first and second spaced-apart longitudinally extending legs with sharp free ends and proximal ends;
- b) a bridge portion interconnecting the proximal ends of said legs; and
- wherein said legs have a convergent orientation, one to the other, and said legs are adapted to be resiliently held in a parallel orientation wherein said legs are urged towards their initial convergent orientation with a predetermined force.
26. A staple as defined in claim 25 wherein said legs are wider than said bridge portion.
27. A staple as defined in claim 26 wherein said bridge portion lies to one side of said legs and the other sides of said legs have opposing generally flat surfaces.
28. A bone staple applicator for a generally U-shaped staple having a first and a second spaced apart legs with sharp free ends and proximal ends interconnected by a bridge portion, and an initial configuration where said legs are convergently oriented, and said staple capable of a tensioned configuration in which said legs are held in parallel relationship, said staple applicator including:
- a) an elongate body with a front end and a rear end, and including: i) means on said body front end for supporting said staple against rearward and lateral movement with the sharp ends of its legs forwardly disposed, and adapted for engaging opposing portions said legs and moving said legs into parallel relationship.
29. A bone staple applicator as defined in claim 28 wherein said tool body has a handle portion, and said rear end is adapted for being struck a percussive blow.
30. A bone staple applicator for a generally U-shaped staple having a first and a second spaced-apart legs with sharp free ends and proximal ends interconnected by a bridge portion, and wherein said legs have an initial convergent orientation one to the other, and said staple capable of a tensioned configuration in which said legs are held in parallel relationship, said parallel legs urged towards their initial convergent orientation by certain spring force; said staple applicator including:
- a) a longitudinally extending body with a front end and a rear end, and including: i) means on said body front end for supporting said staple in its tensioned configuration with the sharp ends of its legs forwardly disposed, and adapted for engaging opposing inside surfaces of said legs and for guiding longitudinal forward movement of said tensioned staple; ii) means for moving said staple from its initial orientation to its tensioned configuration, and for delivering said staple to said staple supporting means; and iii) means mounted to said body for striking the rear end of said tensioned staple with percussive force for driving said tensioned staple forwardly from said staple-supporting means.
31. An applicator as defined in claim 30 wherein said striking means includes an elongate striker mounted to said body for longitudinal movement, and having a front end adapted for impacting the rearward end portion of said staple.
32. An applicator as defined in claim 30 wherein said means for supporting said staple includes opposing first and second supports adapted for engaging respectively the first and second legs of said staple, and mounted for being adjustably spread apart so as to move said legs to a parallel orientation.
33. An applicator as defined in claim 32 wherein said means for adjustably moving said supports comprises drive means, engaging said first and second supports.
34. An applicator as defined in claim 33 wherein said drive means includes drive screw mechanism.
35. An applicator as defined in claim 30 wherein said means for moving said staple and delivering said staple includes elongate ramp means adapted for slidably engaging inner surfaces of said staple legs and bridge portion, and having surfaces configured so that said legs are pushed from their divergent orientation to parallel orientation by virtue of moving said staple in a direction along said ramp in a direction normal to the plane in which said legs and bridge portion lie; and means for pushing said staple along said ramp means.
36. An applicator as defined in claim 35 including means for biasing a staple along said ramp means towards the proximal end of said ramp means.
Type: Application
Filed: Jul 20, 2004
Publication Date: May 5, 2005
Inventor: Drew Allen (San Jose, CA)
Application Number: 10/896,360