FIELD OF THE INVENTION

[0001] The invention comprises an inserter assembly for use with a room temperature superelastic U-shaped N ^' rtinol staple intended for bone fixation. The inserter assembly has a hand activated vertical slide mechanism that in a first location spreads the staple legs to allow for implantation along the longitudinal axis and in a second location along the longitudinal axis disengages the staple from the inserter. The invention further relates to a drill guide for use with the staple and inserter, which has a retractor aspect, and which accepts a cartridge for the staple leg drill guide so as to allow the drill guide to be used with various configuration and size staples.

[0002] In addition, the drill guide and the inserter have a cooperating relationship which allows the drill guide cartridge to be slid out and the inserter to be slide in its place where the drill guide can be used as a jig for the proper alignment of the staple inserter to place the staple in the pre-drilled holes.

BACKGROUND OF THE INVENTION

[0003] Over 1 .8 million orthopedic trauma fixation procedures were performed in the US in 2016, and the market is expected to reach over $4 billion by 2025. The fastest growing part of the market is the staple fixation segment, which is also expected to remain the fastest growing through to 2025. The primary drivers for growth are reportedly a reduced operating time as compared to screws, and plates.

[0004] While the state of the art has advanced the use of bone staples, there remain issues in the use and design of the deployment instrument or inserter. In particular, the inserter needs to be capable of single-handed use and needs to be able to deform the staple to cause the superelastic deformation and to inhibit over deformation, while permitting easy and reliable deployment of the staple in bone.

[0005]The invention also relates to a distractor that has a roller that spreads the flange ends of the drill guide and makes room for the staple drill guide cartridge that is captured in an appropriate keyed recess in the drill guide body. Upon removal of the drill guide cartridge, the inserter can be vertically slid into that position and the drill guide handle can be used for the proper alignment of the inserter. [0006] This design is intended for multiple or single use so that cost is a consideration, drawing in materials and manufacturing methods that meet economic requirements while presenting a design that is sufficiently strong to reliably accomplish the job. This means that the inserter provides that the staple can be deformed to the insertion position with transverse legs, inserted into pre-drilled pilot holes and tamped into position across a bone divide, all in a design that is quick, reliable, and easy to use, and advantageously single-handedly.

[0007] In addition, the staple can be delivered in a sterile-packed cartridge, and advantageously with the staple in a relaxed position. The cartridge is subsequently loaded on the inserter which is used intraoperatively to activate the staple by spreading the legs to the parallel position. This has the advantage of eliminating the storage and potential early deployment of an energized staple as well as not having a ‘fiddly” loading procedure for a staple that comes pre-packaged with a higher elastic energy.

SUMMARY OF THE INVENTION

[0008] The invention provides an inserter assembly for a superelastic compressive bone staple. The staple has a bridge member that extends a length along an axis and which joins two or more legs spaced apart along the axis and is fabricated in a closed (converging legs) shape and is mechanically deformed or “activated” by the inserter during use to induce the superelastic shape memory properties. This allows the staple to compress bone segments in use. The inserter comprises an assembly having a ram that has a sliding vertical cooperation with ram housing mechanism. The ram housing mechanism has a staple clip having a stop lock and a terminal set of lateral shoulders that form a camming mechanism to splay the staple legs and a set of transverse medial shoulders which are engaged by the bottom surface of the staple bridge to open the staple clip legs and dis-engage the staple. During use, the staple clip is held between the ram housing at upward vertical draw of the staple clip in the housing assembly relative to the ram acts to spread the staple legs on the lateral shoulders into transverse positions to open the legs and induce the superelastic properties for implantation.

[0009] The mechanism uses a hand activated ram or syringe type assembly which presses the ram downward relative to the slide housing mechanism, while the ram housing mechanism has a double set of finger holes which are used to draw the ram housing up-ward on the ram. Further, the ram includes a proximal tamp area (which is the same area contacted by the palm of the user’s hand during the staple activation step) and a set of laterally extending curved draw stops for the finger holes of the ram housing. The finger holes have a first upper interior surface which moves upward relative to the ram as the tamp of the ram is pressed and the finger holes are drawn upward. The finger holes have a slotted upper area to allow the curved stops of the ram to slide through and contact the user’s fingers. This stops the ram housing at the point at which the legs are opened to 90°. The staple is placed with the legs in alignment of a set of pilot holes for the staple legs and the user then grasps the lower exterior surface of the finger holes to draw the ram housing upward on the ram which is being pressed downward at the tamp portion of the ram. In this position, the bottom portion of the staple legs are disengaged from the shoulder ramp of the ram housing mechanism (i.e., specifically from the staple clip) and the staple is disengaged from the inserter.

[0010] The staple of the present invention is configured to accommodate fixation procedures in the forefoot, midfoot, rearfoot and hand, and the inserter (which can be disposable) allows implantation of the staple in bone in a surgical procedure so as to apply a compressive force across a division of bone segments. A preferable configuration for the bone staple is a substantially U-shaped staple, i.e. a staple having a transverse bridge member and downwardly extending legs (one or more pairs), which can be biased into a parallel “activated position” for insertion into the bone, and then released into a compressive configuration.

[0011]The inserter assembly or a portion of it such as the staple clip, is advantageously pre-assembled (i.e. prior to surgery) with a “U-shaped” or modified “table top” style staple in a non-activated state (i.e. in which the legs converge toward each other, each at an angle of from 60° to 88°, and preferably at an angle from 70° to 85° relative to an axis along the bridge member of the staple) and includes an easy to use mechanism for “activating" the staple by deforming the legs to a transverse position and initiating the super elastic properties of the staple material.

[0012] Prior to the deployment of the staple, an inserter sub-assembly, the staple clip, holds the staple so that it is constrained on the bottom side at the edges of the legs which ride against the shoulders of the slide housing mechanism. Prior to deployment, a ram handle is feed into the sliding housing mechanism which is held in a pair of recesses formed on lateral rails on the ram handle. At this point, the staple is also held on the top side by a pair of bosses on the distal end of the ram which advantageously fits within a recess within the bridge member defining separate legs on a lateral side. The staple member is also secured laterally against the inside of the legs of a staple clip member on one edge of the bridge member and against a distal end of the disengagement ram. In particular, the staple securing mechanism of the inserter includes integrated functional components including an expander with shoulders or camming members operatively connected to the disengagement ram which is that is operably held within the ram housing. The assembly includes a staple holding clip member which includes a stop that is configured to lock into a correspondingly shaped opening in the slide housing. The slide housing has a laterally opposed pair of finger holes which can be used to draw the slide housing mechanism proximally on the ram which is simultaneously pressed downward to lock into the lateral lock recesses and pull the staple legs open until the finger holes encounter a pair of curved stop members on the ram side. When the finger holes are drawn upward by engaging the bottom outer surface of the finger holes, the ram housing is moved past the first position until the ram housing mechanism pushes the staple off the inserter as the slide housing disengages the lateral lock recesses and the ram can be pushed downward to activate the staple.

[0013] The ram includes a pair of outwardly extending flange members that are encountered by the user which provides a stop when the ram is being pushed downward on the slide housing mechanism. The ram rails can be pressed medially inward to open the distal end of the staple clip mechanism which opens the arms and disengages the staple from the inserter. As the ram is pressed downward in the slide handle housing the camming surfaces on the distal shoulders of the clip mechanism are drawn upward and the staple legs are caused to splay apart.

[0014] In accordance with the invention, a staple is supplied preassembled (on a disposable inserter or inserter subassembly) as part of a sterile packed procedure kit. The staple is not pre-loaded, which means that the staple is not subjected to the mechanical deformation which initiates the superelastic characteristics of the staple. The staple inserter provides quick and efficient use with minimal user interaction which is accomplished by constraining the staple on the inserter on the pair of cylindrical pins which form a part of an expander component of the inserter and which expands the staple legs to a 90° insertion position. The staple is further captured on the inserter and prevented from inadvertent disassembly from the inserter by a ramp that acts as a cover in the resting or non-energized position.

[0015] The inserter retains the staple in a non-preloaded/non-energized position but interface with the staple in the proximal corners and at the terminal edges of the staple legs. This captures the staple securely on the inserter, and permits the activation of the staple for deployment. The design also enables use of the inserter with both symmetrical and asymmetrical leg staples.

[0016] The invention also relates to a drill guide that expands a set of tips laterally to expose a surgical site, and the drill guide body has a complex opening that forms a clip to secure a drill cartridge in the opening so that various pilot holes can be drilled using a single drill guide body.

BRIEF DESCRIPTION OF THE DRAWINGS [0017] FIG.1 shows a top side perspective view of the staple inserter with a staple in accordance with the present invention;

[0018] FIG. 2 shows a view of the staple inserter with a staple of FIG. 1 ;

[0019] FIG. 3 shows a side cross sectional view about the lateral to medial plane of the inserter in accordance with FIG. 1 ;

[0020] FIG. 4 shows a cross-sectional sagittal side view of the distal portion of the staple inserter of FIG.1;

[0021] FIG. 5 shows the sagittal cross-sectional view of the staple inserter of FIG.1; [0022] FIG. 6 shows a lateral edge detail of the staple inserter of FIG. 1 with a staple in a first position;

[0023] shows the side edge view of the staple inserter of FIG. 1 without the staple;

[0024] FIG. 7 shows the staple inserter of FIG.1 with an activated staple from a front edge view;

[0025] FIG. 8 shows the staple inserter of FIG.7 with a staple in a side view;

[0026] FIG. 9 shows a detail of the staple inserter of FIG.1 with a relaxed staple in a bottom side view; [0027] FIG. 10 shows a bottom side perspective view of the staple inserter drill guide with a four-legged staple in accordance with a second embodiment of the present invention; [0028] FIG.11 shows a bottom detail of the staple inserter and staple of the present invention;

[0029] FIG. 12 shows a bottom side detail of the staple deployment are of the staple inserter of FIG. 10;

[0030] FIG. 13 shows a detail view of the staple inserter ram of FIG. 10 without a staple; [0031] FIG. 14 shows the full assembly of the staple inserter ram and staple clip of FIG.10 and with the ram in a first position relative to the ram housing:

[0032] FIG. 15 shows staple clip of FIG.10;

[0033] FIG. 16 shows a bottom side view of the finger holder of the staple inserter of FIG.

10;

[0034] FIG. 17 shows a top side view of the finger holder of the staple inserter of FIG. 10; [0035] FIG. 18 shows a front side view of the staple ram of FIG.10;

[0036] FIG. 19 shows a side view of the staple ram of FIG. 17;

[0037] FIG. 20 shows a top front view of the staple inserter and drill guide handle assembly of FIG.10;

[0038] FIG. 21 is a front side view of a drill guide/compression device for use with the staple inserter system of the present invention;

[0039] FIG. 22 is a view of the drill guide/compression device assembly with the staple inserter of the present invention; and

[0040] FIG. 23 is detail of the drill guide/staple inserter assembly used together in accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION [0041] The present invention comprises an inserter 50 for use with a room temperature superelastic Nitinol compression staple 10 for bone fixation in the surgical management of fractures and reconstruction of the foot and hand. Typically, the staples used with the present invention have a nominally U-shaped profile with a bridge member 14 spanning a space between opposing legs 12 (and it should be understood that the present inserter is also suitable for use with a staple having four legs in which each end of the bridge member includes a pair of legs, or alternatively, the staple could have three legs with a pair on one end, and a single leg opposing the pair.). The inserter 50 of the invention is illustrated herein with a staple having two opposing pairs of legs 12 that are separated by an opening 13 that extends into the bridge member 14 of the staple. This feature is used for the stabilization of the staple in the inserter 50.

[0042] The staple 10 has two or more, and preferably 2, 3, or 4 transversely extending legs 12 that will engage bones or bone segments through the cortical surfaces. The legs 12 are spaced apart from each other and joined together by bridge member 14 that extends across the area between legs at either end of the bridge member 14. As shown, the legs are joined to transitional extensions 16 which fold or curve at an angle of from 75° to 90°, and preferably from 85° to 90°.

[0043] The bridge member 14 has a top surface 20 and a bottom surface 22 which have corresponding shapes so that they are separated by a constant thickness for at least a portion, and preferably for at least 50%, and more preferably for at least 75% or even 90% of the surface area has a complex curving configuration. It extends along an axis preferably in a straight profile, but with a topography that curves in two dimensions. The shape includes two side edges, which may have an inwardly curving shape or may be represented by straight lines.

[0044] The staple is comprised of a material is elastic and has the ability to recover an original un-deformed shape so as to apply a compressive force. An example of a suitable material is a superelastic material which is activated into the superelastic state by mechanical deformation.

[0045] The inserter 50 comprises an assembly having a ram 60 that has a sliding vertical cooperation with ram housing mechanism 70. The ram housing mechanism has a staple clip 80 having a press point 82 and a terminal set of shoulders 84 that form a camming mechanism. The shoulders also have medial inner edges 81 that hold the staple on the staple clip. The press point 82 of the staple clip 80 is joined to a pair of pronged arms 83 which are held in a corresponding trapezoidal recess 72 in the ram housing mechanism as can be seen in FIG. 1.

[0046] The ram has a pair of longitudinal rail members 61 , having a central slot 62. The rail members 61 also have a pair of laterally extending detent flanges 64 with openings 65 that hold stay members (not shown) on the finger hole portion 72 of the ram housing. The stay members can be drawn laterally out of the openings 65 using the finger holes 72 on the ram housing 70. This allows the ram 60 to be slide downwardly on the ram housing 70. This causes the staple clip 80 to move relative to the ram 60 which includes a pair of bosses 67 which engage the openings 13 in the bridge of the staple 10. The staple clip also includes a pair of legs 86 which terminate in the shoulders 84 that form a camming mechanism to spread the staple legs. When the staple is caught between the bosses 67 of the ram 60 and the shoulders 84 on the legs 86 of the staple clip 80, the staple legs 12 are extended to a transverse position and the staple is ready for insertion [0047] The staple of the present invention is configured to accommodate fixation procedures in the forefoot, midfoot, rearfoot and hand, and the inserter (which can be disposable) allows implantation of the staple in bone in a surgical procedure so as to apply a compressive force across a division of bone segments. A preferable configuration for the bone staple is a substantially U-shaped staple, i.e. a staple having a transverse bridge member and downwardly extending legs (one or more pairs), which can be biased into a parallel “activated position” for insertion into the bone, and then released into a compressive configuration.

[0048] The drill guide/compression instrument 150 of the present invention comprises an assembly of a handle member 160 having an elongated handle 161 which is shaped having straight or scalloped edges to accommodate being grasped while a compression/tension mechanism 170 includes a turn member 172 on a transverse screw 174. The handle member 160 extends into a first drill guide leg member 162 that remains stationary relative to the handle 161 and a second drill guide leg member 164 that opens and closes across a lateral gap by means of the distraction mechanism. More precisely, the user can open and close the gap between the legs by turning the turn member 172 which moves on the transverse screw 174 to drive the second leg closer to or farther away from the first leg.

[0049] Each of the first and the second leg include a transversely extending extension 175, 176 which has a cannulation 177 for a k-wire. Thus, the k-wires can be driven into the bone or bone segments, and the drill guide/distractor can be used to position or apply compression to the bone or bone segments, either before or after the drill guide is used to drill pilot holes for the legs of the associated bone staple. [0050] Accordingly, one of the drill guide legs, here, the first leg, 162 includes a complex recess 178 that allows a drill guide cartridge 180 to be inserted into the drill guide/compression assembly. The drill guide cartridge includes a finger handle 182, and template member 182 that include spaced holes 184 according to various staple configurations. The drill guide cartridge also has a boss that cooperates with the complex recess to securely hold the cartridge in place relative to the handle member 160. The assembly can also include a compression cartridge 180 that can be inserted in place of the drill guide cartridge to help align and stabilize the staple at the user’s discretion. [0051] The operation of the inserter 50 for implantation of the compression staple is described as follows:

[0052] First the bone site is prepped by excising the site to access the relevant bones. Guide wires or more particularly, k-wires, can be placed into the bone segments, and the drill guide 50 is placed over the guide wires and the drill guide cartridge 80 is inserted for the proper placement of the pilot holes for the staple legs after the drill guide cartridge is removed, the drill guide handle and compressor accepts the inserter rails substituted in the position of the drill guide cartridge.

[0053] FIG. 11 shows that the selected staple cartridge 80 is loaded into the ram handle assembly. FIG. 12 shows the inserter ready to bring the staple legs into a parallel position. FIG.13 shows the inserter in an activated position as described. After the bone segments to be fused are prepared for receiving the compression staple 10, the user presses the ram handle 90 using the palm of the hand while engaging the finger holes 72 of the ram housing 70 like a syringe to open the staple legs 12 to the parallel position ready for implantation. The staple is fabricated in the closed (converging legs) shape and is mechanically deformed by the inserter 50 during use to induce the superelastic shape memory properties to compress bone segments and facilitate osteosynthesis. The ram is moved relative to the ram housing by first pressing inward on the flanges of the ram rails to push the rails inward and disengage the ram housing relative to the ram rail stop. Then the user presses against the ram tamp area and draws the housing upward using the inner upper surface 73 of the finger holes 75 and drawing the ram housing 70 upward using the inner upper surface of the finger holes to the point that the fingers meet the bottom surface of the curved stop 63. FIGS. 14 and 15 show the staple inserter aligned with the drill guide handle from differing views and in FIGS. 16 and 17, the system is shown in the positions in which the staple is pushed or tamped into pre-drilled holes. [0054] FIGS. 18 and 19 show differing views with the staple inserter assembly having the ram in a final position in the ram handle housing as is described as follows. The ram/ram housing can be further compressed vertically by placing the fingers on the bottom exterior surfaces of the finger holes 74 and compressing the device further in a vertical direction. The curved stops pass through slots in the finger holes allowing this motion to take place, and the staple bridge engages the transverse medial shoulders 92 on the staple clip legs which spreads these legs apart to fully disengage the staple from the inserter. FIG.20 shows the staple inserter assembly and system when the staple is impacted into the bone, and FIG.21 shows the system as the inserter and drill guide handle are removed, leaving the staple in place.

[0055] Due to the inertial forces as the user squeezes the syringe mechanism, a mechanical lock assembly may be used to ensure that the staple 10 is not inadvertently deployed before being inserted into the bones.

[0056] At this point, the user inserts the staple 10 into the bone segments to be fused, the mechanical lock is then released to permit staple release by squeezing the ramp component 107 with the index finger. (The lock section of the ramp component 108 deflects inward to deflect the staple clip legs 86 outwardly and to dis-engage the staple through the opening between the legs of the staple clip.)

[0057] The staple inserter of the present invention is suitable for manufacture via injection molding but could also be fabricated from other manufacturing techniques such as, but not limited to, machined, 3-d printed or stamped components. The inserter can be fabricated from plastic or metal materials, or a combination of both.

[0058]The staple and inserter are configured to accommodate different fixation procedures in the forefoot, midfoot, rearfoot and hand, and the inserter allows implantation of the staple in bone in a surgical procedure so as to apply a compressive force across a division of bone segments for fracture and osteotomy fixation of the hand and foot, including joint arthrodesis and to stabilize and dynamically compress bone fragments to facilitate osteosynthesis.