Source: https://patents.justia.com/patent/20060030944
Timestamp: 2020-02-22 19:14:39
Document Index: 755630591

Matched Legal Cases: ['Application No. 60', 'Application No. 60', 'Application No. 60', 'Application No. 60', 'Application No. 60', 'Application No. 60', 'Application No. 60', 'Application No. 60', 'Application No. 60']

US Patent Application for Methods and apparatus for enhanced retention of prosthetic implants Patent Application (Application #20060030944 issued February 9, 2006) - Justia Patents Search
Justia Patents US Patent Application for Methods and apparatus for enhanced retention of prosthetic implants Patent Application (Application #20060030944)
Methods and apparatus for enhanced retention of prosthetic implants
The present invention claims priority to U.S. Provisional Application No. 60/551,096, filed Mar. 8, 2004, entitled, “METHODS AND APPARATUS FOR ENHANCED RETENTION OF PROSTHETIC IMPLANTS,” and U.S. Provisional Application No. 60/551,080, filed Mar. 8, 2004, entitled, “METHODS AND APPARATUS FOR PIVOTABLE GUIDE SURFACES FOR ARTHROPLASTY,” and U.S. Provisional Application No. 60/551,078, filed Mar. 8, 2004, entitled, “METHODS AND APPARATUS FOR MINIMALLY INVASIVE RESECTION,” and U.S. Provisional Application No. 60/551,631, filed Mar. 8, 2004, entitled, “METHODS AND APPARATUS FOR CONFORMABLE PROSTHETIC IMPLANTS,” and U.S. Provisional Application No. 60/551,307, filed Mar. 8, 2004, entitled, “METHODS AND APPARATUS FOR IMPROVED CUTTING TOOLS FOR RESECTION,” and U.S. Provisional Application No. 60/551,262, filed Mar. 8, 2004, entitled, “METHODS AND APPARATUS FOR IMPROVED DRILLING AND MILLING TOOLS FOR RESECTION,” and U.S. Provisional Application No. 60/551,160, filed Mar. 8, 2004, entitled, “METHODS AND APPARATUS FOR IMPROVED PROFILE BASED RESECTION,” and U.S. patent application Ser. No. 11/036,584, filed Jan. 14, 2005, entitled, “METHODS AND APPARATUS FOR PINPLASTY BONE RESECTION,” which claims priority to U.S. Provisional Application No. 60/536,320, filed Jan. 14, 2004, and U.S. patent application Ser. No. 11/049,634, filed Feb. 3, 2005, entitled, “METHODS AND APPARATUS FOR WIREPLASTY BONE RESECTION,” which claims priority to U.S. Provisional Application No. 60/540,992, filed Feb. 2, 2004, entitled, “METHODS AND APPARATUS FOR WIREPLASTY BONE RESECTION,” the entire disclosures of which are hereby fully incorporated by reference.
FIGS. 32-34, 99-115 and 120-129 show various depictions of embodiments and methods in accordance with alternate embodiments of the present invention.
FIGS. 99 through 112 generally represent prosthesis and prosthesis fixation feature embodiments of the present invention.
Alternatively, FIGS. 103 through 112 represent combinations of finned and/or crosspinned implants. It should be noted that the AP Fin Profile of the fin may be linear as shown in FIG. 106 (in other words, the fin may be may be planar), or it could be slightly tapered to achieve an interference fit with the walls of the groove as the implant fixation surfaces are forced into contact with the cut surfaces to which they are mated (see FIGS. 107 through 109), or in could be curved as looked at from the viewpoint of FIG. 106 to further provide stability of fixation (this curve could be a single curve or spline or sinusoidal curve, in one embodiment of the present invention allowing for a multiaxial interference fit between the fin and bone to facilitate fixation and avoid deleterious levels of postoperative micromotion). Interestingly, the fixation aperture created to fix a cutting guide to the bone could be utilized to cross pin a flange or fin of a femoral prosthesis. It should be noted that although the embodiment shown is a Unicondylar femoral prosthesis, this concept could be applied to tibial, femoral, or patellofemoral prostheses in any application, or in other joint, trauma, spine, or oncology procedures, as is generally represented in FIGS. 120 through 127.
In FIGS. 105 through 112, a tapered pin is used to engage the cross pin hole in the fin of the prosthesis. The tapered pin may be utilized to facilitate a resulting press fit between the pin and the fixation surfaces of the implant and/or ease of introducing the pin into the hole in the fin. The pin could be of any known material, but resorbable materials are especially interesting as they are ‘consumed’ by the body leaving minimal hardware within the body after a fairly predictable amount of time has passed. PLA/PGA compositions, Tricalcium Phosphate, allograft and autograft bone, bone substitutes, and the aforementioned slurry type compositions may serve well. Alternatively, bone cement or other liquid or semi-liquid material may be injected into the portals/apertures to achieve intimate interdigitation, and the crosspins optionally inserted thereafter, but prior to complete hardening or curing. Alternatively, the crosspin(s) could be hollow with radially extending holes allowing the pins to be inserted and then have bone cement injected into them and up under the implant. Alternatively, the cross pin could be threaded to engage threads in the fin, or to engage the bone (both for short term stability and to facilitate removal) or both. These embodiments hold significant promise in both providing for intraoperatively stable for cemented or cementless fixation as well as facilitating long-term biological ingrowth. It should be noted that the use of multiple holes, pins, and apertures in the prosthesis could be used and that the holes in the bone need not be fixation holes to which guides are attached. Also it should be noted the condylar sections, and patellofemoral sections of the implant could be wholely separate, modularly joined, be composed of a dual condylar prosthesis and separate patellofemoral prosthesis, or any combination of the above. Although the bone/implant interface shown is curved in two planes, these concepts apply to implants with 3 planar curved geometry (where the cutting path and cutting profiles of the resected surface geometry and therefore the fixation surface geometry do not remain in two planes through the entirety of the cutting path, or where the cutting path is contained within multiple or single curved surfaces), entirely planar geometries, or anything in between.
FIGS. 107 through 112 demonstrate another embodiment of the present invention allowing for benefits well above and beyond those of the prior art. This will be referred to herein as a BMO Prosthesis or BMO Cortical type implant (Biomechanical Optimization Prosthesis). This embodiment has several applications. For instance, if the resected surfaces will to vary significantly from the fixation surface geometries, as may be seen in unguided kinematic resection, it may be advantageous to implement fixation surface geometries that can conform to variation in resection geometry. Most implant materials in joint replacement are thought of as being rigid, and that their rigidity is a desirable characteristic for achieving stable fixation. In the case of surface replacement, that is not necessarily the case. Anecdotally, picture a bar of aluminum 2 inches square and 5 inches long—now picture trying to manually bend it. At these dimensions, aluminum is rigid; however, it is obvious that aluminum foil is not so rigid. The point to this is that very thin (less than 3 mm thick, probably closer to a range of 1.5 to 0.01 mm thick) sections of many metals, including implant grade metals and alloys including cobalt chrome, titanium, zirconium, and liquid metal™, can be processed into very thin forms capable of conforming to variations in the resected surface and yet still have bearing surfaces that are highly polished and provide significant contact area, where desirable, for bearing against the bearing or articular surfaces of the opposing implant. The construct or prosthesis resulting from applying the present invention to a femoral component in Unicondylar knee replacement, for example, may start out being a 1″ wide be 3″ long strip of 1.5 mm thick material curved in a manner to generally look like the curved cutting path and curved cutting profile of a natural, healthy femur. A process such as Tecotex from Viasys Healthcare of Wilmington, Mass. is used to remove material from the strip down to a nominal thickness of perhaps 0.1 mm thick while leaving multiple protruding ‘hooks’ (almost like the hook and eye concept of Velcro) emerging from the thin fixation surface to engage the bone. One or more fins can be attached or be made a continuous part of this construct as shown in FIG. 107. During insertion, the anterior most cross pin could lock that portion of the prosthesis in place, then the prosthesis could be wrapped around the remaining, more posteriorly resected surfaces and the posterior cross pin inserted (see FIG. 111). Alternatively, the fins can be located about the periphery of the articular surfaces of the condyle in the form of tabs and the cross pins or screws or tapered dowels, etc. known in the art inserted through holes in the tabs and into bone to fix the cortical implant. The combination of fins and tabs may also be useful. In using the tabs, it is critical to keep all features of the implanted device ultralow profile to avoid irritating the surrounding soft tissues (perhaps creating recesses in the bone underlying the tabs would be desirable to allow for a form of countersinking of the tabs and/or the pins or screws or other fixation devices).
Another embodiment of the present invention would be to apply the aforementioned principals to tibial implant design and fixation methodologies. It should be obvious to one of ordinary skill in the art that the crosspin and/or tongue and groove configurations would provide for outstanding stability of tibial component fixation to living bone whether for conventional finned tibial components or the AP or ML fin embodiments of the present invention. FIGS. 32 through 34 represent, very generally, some of the basic primary cut surface geometries to which such implants may be attached (although the fin accommodating cuts are not shown). In regards to conventional state of the art tibial component designs, the implementation of the crosspin embodiments of the present invention will provide for attaining sufficiently robust cementless fixation of implant to bone that the currently substandard results of pressfit tibial components may be significantly improved upon.
FIGS. 113 through 115 are an embodiment of the present invention that may prove to be a very usefully alternative to conventional rectilinear based referencing techniques. In essence, conventional alignment techniques, once having established appropriate flexion extension angulation and varus valgus angulation of desired implant location, reference the anterior cortex, distal most femoral condylar surface, and posterior most condylar surface (indicated in FIG. 114 by stars) to dictate the anterior posterior location, proximal distal location (otherwise known as distal resection depth), and appropriate implant size in determining the ‘perfect’ location and orientation for the appropriately sized implant (mediolateral location is normally ‘eyeballed’ by comparison of some visual reference of the mediolateral border surrounding the distal cut surface and some form of visual guide reference). These conventional techniques fail to directly reference the distinctly different anatomic bone features which dictate the performance of distinctly separate, but functionally interrelated, kinematic phenomena, and they also attempt to reference curvilinear articular surfaces by way of rectilinear approximations. The embodiment of the present invention is an alternative alignment technique with an object to overcome the errors inherent in prior art. As shown in FIG. 115, the femur possesses two distinct kinematic features and functions that lend themselves to physical referencing; the patellofemoral articular surface and the tibiofemoral articular surfaces, both of which are curved, more specifically these surfaces represent logarithmic curves that may be effectively approximated by arcs. The one codependency between the two articular functions, and therefore any geometric approximation made of them in referencing, is that they must allow for smooth kinematically appropriate articulation of the patella as it passes from its articulation with the trochlear groove (shown in blue in FIG. 115) to its articulation with intercondylar surfaces between the femoral condyles (shown in red in FIG. 115). Thus, knowing that three points define an arc and may be used to approximate a curve or sections of a curve, what is proposed is to use a referencing device which contacts at least one femoral condyle at three points to determine both an approximation of arc radius and centerpoint location, while independently or simultaneously referencing the trochlear groove at three points to determine both an approximation of arc radius and centerpoint location. The referencing system would further need to provide for the need of the articular surfaces of the trochlear articular surfaces to smoothly transition to those of the intercondylar surfaces. Armed with this information, a surgeon may most appropriately determine appropriate implant location and orientation.
This embodiment of the present invention is especially useful in determining the proper location, orientation, and implant size for the modular tricompartment components shown in FIGS. 120 through 124, the non-modular implants shown in FIGS. 125 through 127, and standard implants where the appropriate size, location, and orientation would be determined by that which best mimics existing articular bone surfaces thus resulting in optimal postoperative kinematic function. FIG. 123 represents one method of fixing the patellofemoral implant with respect to the condylar implant(s) so as to maintain smooth transitional articulation. It should be noted that this crosspin method of interconnecting the separate components could be augmented by tongue and groove interlocking between the medial side of the condylar component shown and the lateral side of the patellofemoral component shown. What is critical is that the transition between the patellofemoral component and the condylar component surfaces responsible for patellofemoral articulation are and remain tangent at at least one point. FIGS. 128 and 129 represent an alignment guide that could be easily modified to accomplish the aforementioned 3 point referencing by addition or inclusion of dedicated or modular referencing means. Alternatively, surgical navigation methods could be implemented in registering these articular surfaces and determining the resulting idealized implant location(s) and orientation(s) as reflected by the geometry and/or kinematics of the joint.
an implant body having a fixation surface facing the bone and an articulation surface adapted to articulate with another surface;
at least one projection structure extending inwardly from the interior surface of the implant body toward the bone; and
means for laterally retaining the at least one projection structure such that a preload force is exerted on the implant body biasing the interior surface of the implant body against the bone.
2. The implantable orthopedic prosthesis of claim 1, wherein the means for laterally retaining comprises at least one lateral projection structure extending outwardly from at least one side of the at least one projection structure, the at least one projection structure adapted to mate with a corresponding channel created in the bone.
3. The implantable orthopedic prosthesis of claim 2, wherein the at least one lateral projection structure includes a pair of lateral projections on opposite sides of the at least one projection structure that together with the at least one projection structure define a generally T-shaped structure.
4. The implantable orthopedic prosthesis of claim 2, wherein the at least one lateral projection structure and the corresponding channel interact to create the preload force by advancing the at least one lateral projection structure relative to the corresponding channel in a direction generally transverse to the force.
5. The implantable orthopedic prosthesis of claim 4, wherein the at least one lateral projection structure defines a ramp relative to the corresponding channel in the direction generally transverse to the force.
6. The implantable orthopedic prosthesis of claim 4, wherein the corresponding channel defines a ramp relative to the at least one lateral projection structure in the direction generally transverse to the force.
7. The implantable orthopedic prosthesis of claim 1, wherein the means for laterally retaining comprises at least one retention aperture defined in the at least one projection structure and a corresponding cross pin adapted to mate with the at least one retention aperture.
8. The implantable orthopedic prosthesis of claim 7, wherein the corresponding cross pin is tapered in a direction of insertion into the at least one retention aperture.
9. The implantable orthopedic prosthesis of claim 7, wherein the at least one retention aperture is tapered in a direction of insertion of the corresponding cross pin.
10. The implantable orthopedic prosthesis of claim 7, wherein the projection structure is a fin structure.
11. The implantable orthopedic prosthesis of claim 11, wherein the means for laterally retaining comprises at least two retention apertures defined in the fin structure and a corresponding cross pin adapted to mate with each retention aperture.
12. The implantable orthopedic prosthesis of claim 1, wherein the means for laterally retaining comprises at least one retention aperture defined in the at least one projection structure and a corresponding aperture created in the bone and extending through the retention aperture into which a filler material is inserted.
13. The implantable orthopedic prosthesis of claim 1, wherein the projection structure is a structure selected from the set comprising: a generally linear peg, a non-linear peg, a generally planar fin, and a non-planar fin.
14. The implantable orthopedic prosthesis of claim 1, wherein the projection structure is comprised of a porous metal capable of lateral fluid communication between generally opposing sides of the projection structure to permit tissue in growth through the projection structure post operatively.
15. The implantable orthopedic prosthesis of claim 1, wherein a depth of the projection structure extends inwardly from the fixation surface of the implant body a distance at least as large as a cross-sectional depth of the implant body measured at a location other than a location of the projection structure.
16. The implantable orthopedic prosthesis of claim 1, wherein the other surface is selected from the set consisting of: another bone, another implantable prosthesis, and an intermediary structure adjacent another bone.
17. A method for implanting an orthopedic prosthesis during arthroplasty surgery comprising:
providing an orthopedic prosthesis having a fixation surface and an articulation surface adapted to articulate with another surface with at least one projection structure extending inwardly from the fixation surface toward the bone and having at least one retention aperture;
preparing a bone to receive the orthopedic prosthesis, including creating a channel in the bone corresponding to each of the at least one projection structures;
positioning the orthopedic prosthesis on the bone;
creating an opening into the bone that extends at least through the retention aperture; and
biasing the interior surface of the implant body against the bone by inserting a cross pin in the opening and through the retention aperture such that a preload force is exerted on the implant body.
18. The method of claim 17 wherein a ratio of the preload force to an insertion force for the cross pin is at least 2:1.
19. The method of claim 17 wherein the step of creating the opening into the bone is accomplished with an opening that is commonly aligned with a hole used to secure a cutting guide for the arthroplasty procedure.
20. A method for implanting an orthopedic prosthesis during arthroplasty surgery comprising:
providing an orthopedic prosthesis having a fixation surface facing a bone and an articulation surface adapted to articulate with another surface with at least one projection structure extending inwardly from the interior surface toward the bone and having at least one lateral projection structure extending outwardly from at least one side of the at least one projection structure;
preparing a bone to receive the orthopedic prosthesis, including creating a channel in the bone corresponding to each of the at least one projection structures, the channel including structure adapted to mate with the corresponding at least one lateral projection structure of the at least one projection structure;
positioning the orthopedic prosthesis on the bone by inserting the at least one projection structure and the corresponding at least one lateral projection structure into the corresponding channel and moving the at least one lateral projection structure relative to the corresponding channel to bias the interior surface of the implant body against the bone such that a preload force is exerted on the implant body.
21. The method of claim 20, wherein a ratio of the preload force to an insertion force for the corresponding at least one projection structure relative to the corresponding channel is at least 2:1.
Publication number: 20060030944
Patent Grant number: 8287545
Inventor: Timothy Haines (Seattle, WA)
Application Number: 11/075,836
Current U.S. Class: 623/20.140