BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a longitudinal section view of a fixation plate provided with a plurality of threaded guides according to the invention;
FIG. 2 is a side elevation view of a first embodiment of a threaded guide according to the invention;
FIG. 3 is a perspective view of the threaded guide of FIG. 2;
FIG. 4 is a perspective view of a fixation plate provided with a second embodiment of a threaded guide according to the invention;
FIG. 5 is a side elevation view of the second embodiment of a threaded guide according to the invention;
FIG. 6 is a perspective view of the threaded guide of FIG. 5;
FIG. 7 is a view similar to FIG. 4 shown with a guide extension coupled to the threaded guide;
FIG. 8 is a side elevation of the guide extension of FIG. 7;
FIG. 9 is a section view along lines 9-9 in FIG. 8;
FIG. 10 is a distal end view of the guide extension of FIG. 7;
FIG. 11 is an exploded side elevation view of a third embodiment of a guide according to the invention;
FIG. 12 is an exploded perspective view of the third embodiment of a guide according to the invention;
FIG. 13 is a broken partial section view of an assembled guide according to the third embodiment of the invention;
FIG. 14 is an exploded side elevation view of a fourth embodiment of a guide according to the invention; and
FIG. 15 is an exploded perspective view of the fourth embodiment of a guide according to the invention.
DETAILED DESCRIPTION
Turning now to FIG. 1, a system 2 including a fixation plate 10 with guides 30 according to the invention is shown. The plate 10 includes a shaft portion 12 including threaded screw holes 14 and a head portion 16 including holes 18. The holes 18 each define a spherically curved inner surface extending between a bone contacting surface 19 and an upper (opposite) surface 21. A polyaxial bushing 20 is provided in each such hole. The interior surface of each bushing 20 includes a triple lead taper thread 22. Such holes and bushings are described in previously incorporated U.S. Pat. No. 5,954,722 to Bono and U.S. Pub. No. 2005/0049594A1 to Wack et al. A removable guide 30 is provided for the bushings 20.
Referring to FIGS. 1 through 3, according to a first embodiment of the invention, the guide 30 is a relatively short device including a bottom portion 32, a central portion 34, a top portion 36, and an axial passage 38. The bottom portion 32 is tapered with triple lead threads 42 sized for engagement with the triple lead taper threads 22 of the polyaxial bushing 20. The triple lead threads 42 preferably extend through approximately 360°. A distalmost end of the bottom portion 32 preferably includes a non-threaded lead-in portion 44 that facilitates insertion of the guide 30 into the bushing 20. The top portion 36 is preferably tapered to increase clearance between other guides 30 coupled to the plate 10. The axial passage 38 in the embodiment shown approximates the minor diameter of a threaded fastener to be used through the bushing 20 and is thus of suitable dimension to receive a drill bit for drilling a hole in the bone for such threaded fastener. Alternatively, the diameter may be sized substantially smaller than the hole defined by bushing 20 for stably receiving a K-wire or other temporary fastener or another orthopedic instrument. The passage 38 at the top end is preferably provided with tool engagement structure, e.g., six corners 46 for receiving a hex driver. Thus, the same tool used to remove the guide (a hex driver) can be used to insert a fastener having a hex slot into the hole thereafter. The short length of the device, preferably not more than one inch, and more preferably approximately 0.35-0.6 inch, permits multiple guides 30 to be assembled to the plate 10 at once without unnecessarily obscuring and crowding the area of interest at the surgical site. The guides 30 are coupled to the plate in alignment with the axes of the polyaxial bushings, and such alignment can be set by the manufacturer in accord with preferred preset axes or by a medical professional closer to the time of surgery (before or during) in accord with desired anatomical specifications of a particular procedure. The guides are not coupled to the plate as tightly as the threaded fastener that will eventually be positioned in its place and tightened within the bushing. Therefore, the guides 30 may be used as small handles to redirect the axial alignment of the bushing 20. As discussed with respect to other embodiments below, guide extensions can be coupled to the guides to facilitate such redirection and the drilling of holes therethrough.
In a preferred use, a plate with guides pre-assembled therein in preferred axial alignments is provided to the surgeon. The pre-assembled guides are preferably lightly screwed into respective polyaxial bushings of the plating system permitting the surgeon to modify the angle of each guide and bushing to a selected orientation (angular displacement) before locking the bushing at the orientation by tightening of the guide into the bushing. This tightening may occur either before or after positioning the plate on the bone. Once the bone holes have been drilled, the surgeon preferably uses a tool, e.g., a hex driver, or a guide extension, discussed below, to remove each guide before inserting a fastener into the bushing and drilled hole.
Turning now to FIGS. 4 through 6, a second embodiment of the system 102 is shown. The guide 130 has a top end defining a handle 136, preferably with external gripping structure, e.g., longitudinal ridges 150, to facilitate manual manipulation of the axial orientation of bushing or of the plate as whole. In addition, the passage 138 through the guide in the embodiment shown is sized for a K-wire 152. Thus, a screw hole 118 and bushing 120 that under normal circumstances would be too large for stable fixation by K-wire can be used for temporary fixation of the implant on the bone with K-wire.
Referring now to FIGS. 7 through 10, the system 102 is shown with a guide extension 160 coupled to the guide 130 in the plate 110. The guide extension 160 includes a shaft 162 defining a central passage 164, a proximal handle 166, and a distal socket 168 for engagement over the top end of the guide 130. When positioned over the guide, the central passages 138, 168 are aligned and preferably of the same dimension so as to provide a composite guiding passageway of longer length for a K-wire or orthopedic device for which the passageway is sized. The guide extension 160 is rotationally fixed relative to the guide 130 so as to also facilitate insertion of the guide 130 into the bushing 120, axial alignment of the guide 130 and bushing 120 relative to the plate 110, tightening of the guide 130 relative to the bushing 120, and removal of the guide 130 from the bushing 120.
Turning now to FIGS. 11 through 13, a third embodiment of a guide 230 and guide extension 260 are shown. The guide 230 is similar to the above in that it is preferably substantially short, provided pre-assembled to the plate, and includes a central passageway for, e.g., K-wire or instrument guidance. The distal portion of the guide 230 includes a diametric slot 254. In the event the guide 230 is inserted with too much force into the bushing 20 (e.g., FIG. 1), the slot 254 allows compression of such distal portion of the guide 230 within the bushing so as to prevent cross threading. The proximal portion of the guide 230 includes a non-circular head 256, preferably hexagonal in shape, for engagement by the extension 260. The distal end 267 of the extension 260 includes socket 268 that captures at least a portion of the proximal portion of the guide 230 in a rotationally interfering manner. Preferably, the distal socket 268 has a corresponding shape, e.g., hex socket, to the proximal portion of the guide. To eliminate play in the assembly of the guide 230 and extension 260, it is preferred to provide a groove 270 in the socket, and a resilient o-ring 272 in the groove that will contact the guide. Once so assembled, the central passages 238, 264 of the guide and extension are aligned.
Referring to FIGS. 14 and 15, another embodiment substantially similar to the previous embodiment is shown. The distinguishing features between the embodiments are that a socket 368 is provided to the proximal portion of the guide 330, the distal end 367 of the extension 360 includes a head 356 which engages in a rotationally interfering manner within the socket 368, and a groove 370 and o-ring 372 are provided externally about the head 356 to reduce play in the assembly of the guide and extension.
It is also recognized that the guide extension may be provided with a central passageway defining a diameter that is smaller than the diameter of the central passageway of the guide. Such smaller diameter of the guide extension may, e.g., correspond to the diameter of a K-wire, while the diameter of the guide corresponds to a drill for the locking bone fastener. Using the guide and guide extension, the surgeon can first drill a pilot hole with a K-wire and once satisfied with its location within the bone, then remove the extension and drill through the guide with the regular drill bit for the locking bone fastener.
There have been described and illustrated herein several embodiments of a guide and extension therefor and methods of using the same in conjunction with a plate. While particular embodiments of the invention have been described, it is not intended that the invention be limited thereto, as it is intended that the invention be as broad in scope as the art will allow and that the specification be read likewise. Thus, while particular embodiments have been disclosed, it will be appreciated that the embodiments are exemplary and that the present teaching includes combining features of the various embodiments with each other. Also, while it is recognized that the invention has particular application to humoral plates, more generally the guides and extensions therefor may be applied to any other plate capable of accommodating them, with necessary modifications contemplated. It will therefore be appreciated by those skilled in the art that yet other modifications could be made to the provided invention without deviating from its spirit and scope as claimed.
Patent Application
20080015591
