US20090210067A1 - Acetabular Cup Fixation - Google Patents

Abstract

An acetabular cup system includes an acetabular cup having a wall with an inner surface and an outer surface. The acetabular cup includes a fixation opening through the wall, the fixation opening including a first wall portion adjacent to the inner surface and a second wall portion adjacent to the outer surface. The acetabular cup system also includes a fixation fastener including a head and a shaft with a bone-anchoring portion. The fastener can be inserted though the fixation opening. The head includes a first head portion engageable with the first wall portion and a second head portion engageable with the second wall portion.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS
• This application claims the benefit of U.S. Provisional Application No. 61/030,027, filed on Feb. 20, 2008. The entire disclosure of the above application is incorporated herein by reference.
INTRODUCTION
• Acetabular cups are used with various fixation fasteners that can secure the cups to the bone in orthopedic procedures.
• The present teachings provide various methods and devices for securing acetabular cups to bone with locking fixation fasteners.
SUMMARY
• The present teachings provide various acetabular cup systems and methods of locking fixation fasteners to acetabular cups and preventing loosening and back out of the fixation fasteners during use.
• The present teachings provide an acetabular cup system that includes an acetabular cup having a wall with an inner surface and an outer surface. The acetabular cup includes a fixation opening through the wall, the fixation opening including a first wall portion adjacent to the inner surface and a second wall portion adjacent to the outer surface. The acetabular cup system also includes a fixation fastener including a head and a shaft with a bone-anchoring portion. The fastener can be inserted though the fixation opening. The head includes a first head portion engageable with the first wall portion and a second head portion engageable with the second wall portion.
• In another aspect, the acetabular cup system includes an acetabular cup having a wall with an inner surface and an outer surface, the acetabular cup including a fixation opening through the wall, the fixation opening including a first wall portion adjacent to the inner surface and a second wall portion adjacent to the outer surface, the first wall portion being internally threaded and the second wall portion being unthreaded and tapered. The acetabular cup system also includes a fixation fastener including a head and a shaft with a bone anchoring portion, the fastener insertable though the fixation opening, the head including a first head portion threadably engageable with the first wall portion and a second head portion tapered for taper lock connection with the second wall portion.
• In another aspect, the acetabular cup system includes an acetabular cup having a wall with an inner surface and an outer surface, the acetabular cup including a fixation opening through the wall, the fixation opening having an unthreaded surface, and a fixation fastener including a head and a shaft with a bone anchoring portion, the fastener insertable though the fixation opening, the head including a threaded portion with self-tapping threads threadably engageable with the fixation opening.
• In a further aspect, the acetabular cup system includes an acetabular cup having a wall with an inner surface and an outer surface, the acetabular cup including a fixation opening through the wall, the fixation opening having a threaded portion, and a fixation fastener including an inner head attached to a bone-anchoring shaft and an outer head pivotably coupled to the inner head, the outer head including a threaded portion threadably engageable with the fixation opening, the inner head including a driver engagement recess.
• Further areas of applicability of the present teachings will become apparent from the description provided hereinafter. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present teachings.
BRIEF DESCRIPTION OF THE DRAWINGS
• The present teachings will become more fully understood from the detailed description and the accompanying drawings, wherein:
• FIG. 1 is a sectional elevation view of an acetabular cup and a fixation fastener according to the present teachings;
• FIG. 2 is a sectional elevation view of an acetabular cup and a fixation fastener according to the present teachings;
• FIG. 3 is a sectional elevation view of an acetabular cup, a fixation fastener and a locking cap according to the present teachings;
• FIG. 4 is a sectional elevation view of an acetabular cup and a fixation fastener according to the present teachings;
• FIG. 5 is a sectional elevation view of an acetabular cup and a fixation fastener according to the present teachings;
• FIG. 6 is a sectional elevation view of an acetabular cup and a fixation fastener according to the present teachings;
• FIG. 7 is a sectional elevation view of an acetabular cup, a fixation fastener and an insert according to the present teachings;
• FIG. 7A is a perspective view of the insert ofFIG. 7;
• FIG. 8 is a sectional elevation view of an acetabular cup and a fixation fastener according to the present teachings;
• FIG. 9 is a sectional elevation view of an acetabular cup, a fixation fastener and a locking cap according to the present teachings;
• FIG. 10 is a sectional elevation view of an acetabular cup, and a two-piece fixation fastener according to the present teachings;
• FIG. 11 is a sectional elevation view of an acetabular cup and a fixation fastener according to the present teachings;
• FIG. 12 is a perspective view of a variable angle locking fixation fastener according to the present teachings;
• FIG. 12A is an exploded and partially sectional view of the fixation fastener ofFIG. 12;
• FIG. 12B is a perspective view of the outer head of the fixation fastener ofFIG. 12;
• FIG. 12C is a plan view of the outer head ofFIG. 12B; and
• FIG. 12D is a side view detail of the fixation fastener ofFIG. 12, showing the inner head of the fixation fastener.
DESCRIPTION OF VARIOUS ASPECTS
• The following description is merely exemplary in nature and is in no way intended to limit the present teachings, applications, or uses. For example, although the present teachings illustrate various fasteners for use with acetabular cups, the present teachings can be used for fixation of fasteners to other prosthetic components.
• The present teachings provide various aspects related to the fixation of acetabular cups to bone through the use of fixation fasteners and preventing loosening or back out of the fasteners during use. Any type of acetabular cups can be used, including, but not limited to, porous metal acetabular cups, such as porous titanium cups, and the Regenerex™ cup, commercially available from Biomet, Inc., of Warsaw, Ind. Methods for fabricating acetabular cups and other implant components from porous metal material are described in co-pending and commonly assigned patent application Ser. No. 11/357,929, filed Feb. 17, 2006, the disclosure of which is incorporated by reference herein.
• Referring toFIGS. 1-10, an exemplaryacetabular cup100 can include awall109 having a concaveinner surface101 and a convexouter surface107. Thewall109 can include one or more fixation holes or other throughopenings102 for receivingcorresponding fixation fasteners200. Anexemplary fixation fastener200 can generally include ahead202 and a shaft orshank204 with a threadedportion208 for anchoring into the acetabular bone.
• Referring toFIGS. 1 and 2, thehead202 of thefastener200 can include a male threadedportion206 and a male taperedportion210. Thetapered portion210 of thehead202 can taper toward theshank204 of thefastener200. The fixation opening102 of thecup100 can similarly have a female threadedportion104 and a femaletapered portion106. Thetapered portion210 of thehead202 of thefastener200 and thetapered portion106 in the opening102 of theacetabular cup100 can have appropriate taper angles to form a taper lock connection. Accordingly, as the threadedportion206 of thehead202 engages the threadedportion104 of the opening102 of thecup100, thetapered portion210 of thehead202 of thefastener200 can mate and taper lock with thetapered portion106 of theopening102, locking thefastener200 to thecup100.
• In the exemplary illustration ofFIG. 1, the tapered portion of thehead202 is adjacent to theshank204, and thetapered portion106 of thecup100 is adjacent the outer convex surface of thecup100. In the exemplary illustration ofFIG. 2, the positions of the tapered and threaded portions are reversed. Specifically, the threadedportion206 of thehead202 is adjacent theshank204 and the threadedportion104 of theopening102 is adjacent the outer convex surface of thecup100. Referring toFIG. 2, the threadedportion206 of thehead202 and the threadedportion104 of theopening102 can be tapered, as shown inFIG. 2, or straight, similarly toFIG. 1.
• Referring toFIG. 3, thehead202 of thefastener200 can include a curved or rounded orspherical undersurface220 and a roundedupper surface222 that can be textured. In addition, theopening102 in theacetabular cup100 can have a similarly curved or rounded or sphericallower portion120 configured to receive theundersurface220 of thehead202 offastener200 adjustably, such that thefastener200 can angulate or pivot in the direction of the curved arrows B relative to an axis A passing through the center of theopening102. Theopening102 of theacetabular cup100 can include a threadedportion104 above thespherical portion120. The threadedportion104 of theopening102 can engage theexternal threads252 of a threaded washer or other locking cap or lockingmember250. The threadedwasher250 can include atextured undersurface254 that can engage the texturedupper surface222 of thehead202 of thefastener200. In operation, thefastener200 can be positioned within theopening102 of theacetabular cup100, adjustably angled relative to the axis A of theopening102 and threaded into the bone. Once thefastener200 is anchored into the bone, the threadedwasher250 can be inserted into theopening102 and rotated such that theundersurface254 of the threadedwasher250 engages theupper surface222 of thehead202 of thefastener200, thereby locking thefastener200 in theacetabular cup100 and the bone and preventing back out of thefastener200 during use.
• Referring toFIG. 4, thehead202 of thefastener200 can include a curved orspherical portion203 and a threadedportion206, which can be cylindrical. The threads of the threadedportion206 can be self tapping. Theopening102 in theacetabular cup100 can include a correspondingspherical portion103 that can engage thespherical portion203 of thehead202 of thefastener200. Theopening102 in theacetabular cup100 can also include acylindrical portion105. During insertion, the self-tapping threadedportion206 on thehead202 of thefastener200 can tap threads into the wall of thecylindrical portion105 of theopening102, until thehead202 of thefastener200 is fully seated in theopening102 and secured to thecup100. In this respect, theacetabular cup100 can be made of porous metal, such as porous titanium, Regenerex™, or other biocompatible material that can be relatively easily tapped.
• Referring toFIG. 5, thehead202 of thefastener200 can include a tapered threadedportion206 with self-tapping threads which can cut into the similarly taperedopening102 of theacetabular cup100. Theacetabular cup100 can be made of porous metal for tapping by the self-tapping threadedportion206 of thehead202 of thefastener200, as discussed above in connection withFIG. 4.
• Referring toFIG. 6, theacetabular cup100 can be made of porous metal that can be peened or otherwise plastically deformed. Thehead202 of thefastener200 is inserted through theopening102 and positioned on a pocket orseat130 defined by theopening102. Anarea132 of theacetabular cup100 immediately surrounding the upper portion of theopening102 adjacent to thehead202 of thefastener200 can be peened or otherwise deformed with a tool such that thedeformed area132 can overlap a portion of thehead202 and trap thehead202 in theseat130 preventing thefastener200 from backing out of theopening102 during use.
• Referring toFIGS. 7 and 7A, theopening102 of thecup100 can be spherically shaped and rotatably receive a spherically shapedinsert300. Theinsert300 can include a throughbore302 havinginternal threads304. Theinsert300 can include meridian slits306 that allow expansion of theinsert300. Thehead202 of thefastener200 can include a taperedportion210, which can be fully or partially threaded withthreads206. Thefastener200 can be inserted through thebore302, and thehead202 of thefastener200 can be threadably engaged with thethreads304 of theinsert300, forcing theinsert300 to expand. The expansion of theinsert300 lockingly engages theinsert300 to theopening102 of theacetabular cup100 and prevents rotational movement between theinsert300 and theacetabular cup100. Before thefastener200 is inserted, theinsert300 can move in a limited manner with respect to theacetabular cup100 so as to permit optimal positioning of thefastener200 with respect to thecup100 before securing thefastener200 to thecup100.
• Referring toFIG. 8, theopening102 in theacetabular cup100 can include a fully threadedportion104 engaging a corresponding threadedportion206 of thehead202 of thefastener200. Theopening102 and thehead202 can be straight or tapered and can be fully threaded or have respective unthreadedportions106 and210.
• Referring toFIG. 9, thefixation fastener200 can include aspherical head202 with a hex or otherwise shapedrecess228 in its upper surface to allow thefastener200 to be rotated by an appropriate driver. Theopening102 of theacetabular cup100 can include an upper internally threadedportion104 and a lower spherical portion defining aseat120. Thefastener200 can be inserted into theopening102 of theacetabular cup100 such that thehead202 of thefastener200 is received in theseat120 of theacetabular cup100. A lockingnut250 havingexternal threads252 and arecess256 for a driver can be threadably engaged with the threadedportion104 of theopening102, thereby locking thehead202 of thefastener200 to theacetabular cup100.
• Referring toFIG. 10, theopening102 of theacetabular cup100 is similar to theopening102 shown inFIG. 9. Thefastener200 can include ahead202 in the form of a spherical cavity. A lockingwasher250 can be pivotably coupled to thehead202 of thefastener202 with apivot pin260 forming a two-piece fixation construct. Thepivot pin260 allows theshank204 of thefastener200 to angulate relative to thewasher250 such that theshank204 can be inserted at various angles relative to the axis A of theopening102, while maintaining the ability to prevent back out by threadably engaging the lockingwasher250 to the internal threadedportion104 of theopening102 of theacetabular cup100.
• Referring toFIG. 11, thefixation fastener200 can include at least a spherical head portion or, alternatively, aspherical head202 having an external threadedportion206. The threadedhead202 of the fastener can be received in a threadedspherical socket104 defined in theopening102 of theacetabular cup100. Further, the threadedhead202 of the fastener can be rotated and inserted at an angle not aligned with the axis of theopening102, such that the threads of thehead202 of thefastener200 and the threads of theopening102 of theacetabular cup100 can cross-thread and lock.
• Referring toFIGS. 12-12D, various aspects of a variableangle locking fastener200 are illustrated. Thefastener200 can include aninner head202 fixedly connected to ashank204 with aneck portion211, and anouter head400 pivotably coupled with theinner head202. Theinner head202 can include adriver engaging recess232. Theshank204 can include a threadedportion208 and an anchoringdistal tip209. Theinner head202 can be pivotably received in anopening406 of theouter head400. Theouter head400 can includeouter threads402 for threadably locking thefixation fastener200 into a threaded opening of an acetabular cup or other implant. Theouter head400 can include adriver engagement feature404 and anend lip408 that can be swaged or otherwise deformed to capture theinner head202. The threadedouter head400 can lock thefixation fastener200 into a similarly threaded hole of anacetabular cup100, or a fixation plate or other implant, preventing back out of thefixation fastener200, while allowing angulation of theshank204 for anchoring thefixation fastener200 at a selected orientation.
• The foregoing discussion discloses and describes merely exemplary arrangements of the present teachings. Furthermore, the mixing and matching of features, elements and/or functions between various embodiments is expressly contemplated herein, so that one of ordinary skill in the art would appreciate from this disclosure that features, elements and/or functions of one embodiment may be incorporated into another embodiment as appropriate, unless described otherwise above. Moreover, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. One skilled in the art will readily recognize from such discussion, and from the accompanying drawings that various changes, modifications and variations can be made therein without departing from the spirit and scope of the present teachings.
• The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms “a”, “an” and “the” may be intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises,” “comprising,” “including,” and “having,” are inclusive and therefore specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed.
• Although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer or section from another region, layer or section. Terms such as “first,” “second,” and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example embodiments.
• Spatially relative terms, such as “inner,” “outer,” “beneath”, “below”, “lower”, “above”, “upper” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. Spatially relative terms may be intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the example term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

Claims (20)

1. An acetabular cup system comprising:

an acetabular cup having a wall with an inner surface and an outer surface, the acetabular cup including a fixation opening through the wall, the fixation opening including a first wall portion adjacent to the inner surface and a second wall portion adjacent to the outer surface; and

a fixation fastener including a head and a shaft with a bone-anchoring portion, the fastener insertable though the fixation opening, the head including a first head portion engageable with the first wall portion and a second head portion engageable with the second wall portion.

2. The acetabular cup system ofclaim 1, wherein the first head portion is externally threaded and the first wall portion is internally threaded.

3. The acetabular cup system ofclaim 2, wherein the second head portion is unthreaded and tapered and the second wall portion is unthreaded and tapered forming a taper lock connection with the second head portion, and wherein the first head portion is contiguous to the second head portion.

4. The acetabular cup system ofclaim 3, wherein the first head portion is cylindrical and the first wall portion is cylindrical.

5. The acetabular cup system ofclaim 3, wherein the first head portion is tapered and the first wall portion is tapered.

6. The acetabular cup system ofclaim 1, wherein the second head portion is externally threaded and the second wall portion is internally threaded.

7. The acetabular cup system ofclaim 6, wherein the first head portion is unthreaded and the first wall portion is unthreaded.

8. The acetabular cup system ofclaim 7, wherein the first head portion is tapered and the first wall portion is tapered.

9. The acetabular cup system ofclaim 1, wherein the first head portion is substantially spherical and unthreaded and the second head portion is cylindrical and threaded with self-tapping threads.

10. The acetabular cup system ofclaim 9, wherein the fixation opening is unthreaded and the first wall portion is substantially spherical and the second wall portion is substantially cylindrical.

11. The acetabular cup system ofclaim 1, wherein the first head portion is substantially spherical.

12. The acetabular cup system ofclaim 11, wherein the first head portion is externally threaded.

13. The acetabular cup system ofclaim 12, wherein the first wall portion is substantially spherical and threaded.

14. An acetabular cup system comprising:

an acetabular cup having a wall with an inner surface and an outer surface, the acetabular cup including a fixation opening through the wall, the fixation opening including a first wall portion adjacent to the inner surface and a second wall portion adjacent to the outer surface, the first wall portion being internally threaded and the second wall portion being unthreaded and tapered; and

a fixation fastener including a head and a shaft with a bone anchoring portion, the fastener insertable though the fixation opening, the head including a first head portion threadably engageable with the first wall portion and a second head portion tapered for taper lock connection with the second wall portion.

15. The acetabular cup system ofclaim 14, wherein the first head portion is substantially cylindrical and the first wall portion is substantially cylindrical.

16. The acetabular cup system ofclaim 14, wherein the first head portion is tapered and the first wall portion is tapered.

17. An acetabular cup system comprising:

an acetabular cup having a wall with an inner surface and an outer surface, the acetabular cup including a fixation opening through the wall, the fixation opening having an unthreaded surface; and

a fixation fastener including a head and a shaft with a bone anchoring portion, the fastener insertable though the fixation opening, the head including a threaded portion with self-tapping threads threadably engageable with the fixation opening.

18. The acetabular cup system ofclaim 17, wherein the threaded portion of the fixation fastener is tapered.

19. The acetabular cup system ofclaim 17, wherein the fixation opening is tapered.

20. An acetabular cup system comprising:

an acetabular cup having a wall with an inner surface and an outer surface, the acetabular cup including a fixation opening through the wall, the fixation opening having a threaded portion; and

a fixation fastener including an inner head attached to a bone-anchoring shaft and an outer head pivotably coupled to the inner head, the outer head including a threaded portion threadably engageable with the fixation opening, the inner head including a driver engagement recess.

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