US20040162619A1 - Tibial augments for use with knee joint prostheses, method of implanting the tibial augment, and associated tools - Google Patents

Abstract

A tibial augment for use with a knee joint prosthesis, composed of annular members of different stock sizes, each size being configured to fit within a cavity formed in a human tibia. The augment may include a stepped distal surface. A provisional (temporary) tibial augment used to ensure a proper fit for the permanent augment is also provided. The provisional may include grooves configured to cooperate with a set of ribs on a tong-like holder used for removing the provisional from the cavity. A pusher for use implanting the tibial augment is also provided. In addition, a system for creating a cavity in a human tibia is also described. The system preferably includes a guide with a slot therein and a set of osteotomes that are inserted within different portions of the slot. Methods for using the tools and/or implanting the prosthetic devices discussed above are also described.

Description

• This application is a continuation-in-part of prior application Ser. No. 10/225,774, filed Aug. 22, 2002, which claims the benefit of Provisional Application No. 60/315,148, filed Aug. 27, 2001, both of which are hereby incorporated by reference.[0001]
• The present invention relates generally to a bone augmenting member used to reinforce damaged bone, and more particularly to an augment for the proximal portion of a human tibia, where the augment is intended to be implanted in the proximal portion of the tibia, just slightly below the tibial portion of a knee joint prosthesis. The present invention also relates to the tool used for implanting the tibial augment, and the tools used for making the cavity in the bone to receive the augment. In addition, the invention also relates to a provisional augment used temporarily to ensure that the permanent augment will be seated within the bone correctly, as well as to a holder used for holding, inserting and removing the provisional augment.[0002]
BACKGROUND OF THE INVENTION
• Knee replacement surgery methods and knee joint prostheses are known in the art. A typical knee joint prosthesis includes a rounded femoral component that is attached to the distal portion of the femur, and a tibial component, which may be formed of a single piece or from two separate pieces that are joined together, that is attached to the proximal portion of the tibia. The femoral component rides on the exposed surface of the tibial component, replicating natural knee movement as closely as possible. When such knee replacement surgery is performed, an incision is made to expose the knee joint in order to enable removal of both the proximal portion of the tibia and the distal portion of the femur, which creates surfaces upon which the tibial and femoral components of the knee prosthesis can be attached.[0003]
• In certain situations, additional portions of the tibia, other than the relatively narrow proximal portion being removed during knee replacement surgery, it may also be damaged by arthritis or other problems. In such situations, a relatively thick proximal portion of the tibia is often removed, and it is replaced with an augment block shaped like the bone that has been removed. However, such previously known methods often result in the removal of an unnecessary amount of healthy bone, along with the damaged bone. Thus, for example, even in cases where the peripheral bone was healthy, and only the internal bone was damaged, prior art methods often removed both the healthy peripheral bone and the damaged internal bone[0004]
BRIEF SUMMARY OF THE INVENTION
• The present invention is intended for situations in which the proximal portion of the tibia is defective, and it provides a method and devices that allow for preservation of healthy peripheral bone, while still providing the necessary augmentation to the proximal portion of the tibia. Preservation of the healthy peripheral bone provides for early onset of bony ingrowth into the tibial augment and allows the bone to infiltrate the augment, restoring the bony platform upon which other implants can reside.[0005]
• More specifically, the present invention provides a tibial augment for use with a knee joint prosthesis that is made of an annular member with a proximal surface, a distal surface, an outer anterior surface, an inner anterior surface, an outer posterior surface, an inner posterior surface, an inner lateral surface, an outer lateral surface, an inner medial surface and an outer medial surface. Preferably, the outer lateral surface is curved to define a continuous surface connecting the outer posterior surface and the outer anterior surface; and the outer medial surface is also curved to define a continuous surface connecting the outer posterior surface and the outer anterior surface. In addition, the outer anterior surface is slightly curved and the outer posterior surface is a generally planar surface. The annular member can be made in a variety of different stock sizes, with each size being configured to fit within a cavity formed in a proximal portion of a different sized human tibia.[0006]
• In certain embodiments, the tibial augment of the present invention can include a stepped distal surface, thereby defining a first distal surface and a second distal surface with a transition surface therebetween, where the first distal surface is located at a greater distance from the proximal surface than the second distal surface. The transition surface can be located at different portions of the augment, such as: (1) midway between the outer lateral surface and the outer medial surface; (2) closer to the outer lateral surface than to the outer medial surface; or (3) closer to the outer medial surface than to the outer lateral surface.[0007]
• The present invention also includes a provisional or temporary tibial augment that is used to ensure a proper fit for the permanent augment. The provisional augment is preferably composed of a material that is substantially transparent to allow visualization of the bony contact surfaces that will likely contact the augment. In addition, in the preferred embodiment, the provisional augment preferably includes at least one set of generally lateral/medial extending grooves to facilitate removal of the provisional from the cavity formed in the tibia. The grooves are configured to cooperate with a set of ribs on a tong-like holder used for inserting and removing the provisional from the cavity.[0008]
• The present invention also relates to a pusher for use in implanting the tibial augment, where the pusher includes a handle portion and an augment seating portion. The augment seating portion is connected to one end of the handle portion, and is configured and arranged to seat a particularly sized tibial augment.[0009]
• In addition, the present invention also relates to a system used for creating a cavity in a proximal portion of a human tibia for use prior to implanting a knee joint prosthesis. The system preferably includes a guide with a slot therein and a set of osteotomes that are configured and arranged to be inserted within different portions of the slot on the guide.[0010]
• Additionally, the present invention also relates to a holder for inserting and/or removing a provisional augment to/from a cavity in a bone. The holder preferably includes a body portion, a pair of legs extending from the body portion, a finger connected to each of the legs, and a rib extending outwardly from each of the fingers. Each of the ribs preferably extends in a direction that is generally perpendicular to the longitudinal axis of the body portion, and the ribs are configured and arranged to correspond to grooves on an inner surface of a provisional augment. In a first preferred embodiment of the holder, the pair of legs comprises a pair of flexible legs, such that application of a force upon outer surfaces of the legs allows for the ribs to be disengaged from the grooves on the inner surface of the provisional augment without significantly altering the location of the provision augment. In the second preferred embodiment of the holder, each of the legs is a relatively rigid member, and each of the fingers is attached to one of the legs such that the fingers are movable with respect to the legs, whereby movement of the fingers with respect to the legs allows for the ribs to be disengaged from the grooves on the inner surface of the provisional augment without significantly altering the location of the provision augment. The second embodiment of the holder is also preferably adjustable to permit a single holder to be used with provisional augments of different sizes.[0011]
• The present invention also relates to the methods of using the tools and/or implanting the prosthetic devices discussed above.[0012]
BRIEF DESCRIPTION OF THE DRAWINGS
• Preferred embodiments of the present invention are described herein with reference to the drawings wherein:[0013]
• FIG. 1 is a perspective view of a preferred embodiment of a tibial augment of the present invention;[0014]
• FIG. 2 is a top view of the tibial augment of FIG. 1;[0015]
• FIG. 3 is an anterior view of the tibial augment of FIG. 1, with the posterior view being identical due to symmetry along the major axis;[0016]
• FIG. 4 is a lateral view of the augment of FIG. 1, with the medial view being a mirror image thereof;[0017]
• FIG. 5 is a perspective view of a tibial augment of a different height than that shown in the FIG. 1 embodiment;[0018]
• FIGS.[0019]6A-6C are anterior views of three different stepped versions of the tibial augment of the present invention;
• FIG. 7 is a view of a tibia, shown with the damaged proximal bone surface removed and also including a cavity within which a tibial augment of the present invention will be implanted;[0020]
• FIG. 8 is a view of a tibial augment of the present invention, shown implanted in place below a knee joint prosthesis;[0021]
• FIG. 9 is a perspective view of a provisional tibial augment of the present invention;[0022]
• FIG. 10 is a top view of a holder of the present invention, where the holder is intended for use with the provisional of FIG. 9;[0023]
• FIG. 11 is a side view of the holder of FIG. 10;[0024]
• FIG. 12 is a perspective view of a second embodiment of a holder of the present invention;[0025]
• FIG. 13 is a front view of the holder of FIG. 12;[0026]
• FIG. 14 is a perspective view of a pusher of the present invention, which pusher is intended to be used to implant the tibial augment;[0027]
• FIG. 15 is a bottom view of the pusher of FIG. 14;[0028]
• FIG. 16 is a side view of the pusher of FIG. 14;[0029]
• FIG. 17 is a front view of the pusher of FIG. 14, and an enlarged view of the augment seating portion upon which a tibial augment has been seated;[0030]
• FIG. 18 is a perspective view of a guide and a curved osteotome of the present invention, which are used for making a cavity for the augment;[0031]
• FIG. 19 is a bottom view of the guide of FIG. 18;[0032]
• FIG. 20 is a side view of the guide of FIG. 18;[0033]
• FIG. 21 is a side view of the osteotome of FIG. 18;[0034]
• FIG. 22 is a rear view of the osteotome of FIG. 18;[0035]
• FIG. 23 is a bottom view of the osteotome of FIG. 18;[0036]
• FIG. 24 is a bottom view of the osteotome of FIG. 25;[0037]
• FIG. 25 is a perspective view of the guide of FIG. 18, shown with a second osteotome of the present invention;[0038]
• FIG. 26 is a perspective view of the guide of FIG. 18, shown with a third osteotome of the present invention;[0039]
• FIG. 27 is a side view of the osteotome of FIG. 26; and[0040]
• FIG. 28 is a rear view of the osteotome of FIG. 26.[0041]
DETAILED DESCRIPTION OF THE INVENTION
• Referring to FIGS. 1 through 4, a first embodiment of the tibial augment of the present invention is shown. The tibial augment is preferably an[0042]annular member10, and it is preferably made from a tantalum based porous material, such as Trabecular Metal™. Trabecular Metal™ is desirable because it resembles bone and approximates the physical and mechanical properties of bone better than other materials. Use of such a metal enables increased bonding with the adjacent bone by allowing the bone to grow into its highly porous surface. The tibial augment may also be made of other materials, and it is preferably made of a material that facilitates bony ingrowth.
• The tibial augment[0043]10 is anatomically sized and shaped to fill an existing cavitary defect within the proximal human tibia or a cavity prepared in the proximal portion of a human tibia. In the preferred embodiment, a system of different stock sizes of augments would be available, as discussed more fully below, with different sizes being used for different sized tibias. Further, if desired two augments of different sizes may be stacked upon each other if such stacking is necessary to fill the cavity.
• As shown in FIGS. 1 through 4, the tibial augment[0044]10 includes aproximal surface12, adistal surface14, an outeranterior surface16, an inneranterior surface18, anouter posterior surface20, aninner posterior surface22, an innerlateral surface24, an outerlateral surface26, an innermedial surface28 and an outermedial surface30. Of course, depending on which tibia (right or left) the augment is being implanted into, the surfaces designated as the medial and lateral surfaces will be reversed. However, since the augment is symmetric with respect to its lateral and medial sides, such distinctions are irrelevant, and the terms lateral and medial are being used for convenience of description only.
• To mimic the portion of the tibia bone that the tibial augment is being implanted into, the outer[0045]lateral surface26 is curved to define a continuous surface that connects theouter posterior surface20 and the outeranterior surface16. Likewise, the outermedial surface30 is curved to define a continuous surface that connects theouter posterior surface20 and the outeranterior surface16. The outeranterior surface16 is slightly curved and theouter posterior surface20 is a generally planar surface.
• As best shown in FIGS. 2 through 4, a majority of the[0046]annular member10 is of a substantially uniform thickness, as most readily depicted by the hidden lines of FIGS. 3 and 4. The major exception to the uniform thickness is achannel32, shown in FIGS. 1 and 2, which defines a reduced thickness portion. In the preferred embodiment, the thickness of the majority of the augment is preferably approximately 5 mm thick, and the thickness of the reduced thickness portion is preferably approximately 3 mm at its narrowest point. However, other dimensions are also contemplated as being within the scope of the invention. Although the preferred embodiment includes walls of a substantially uniform thickness, with a reduced thickness portion nearchannel32, it is also contemplated that the walls could be tapered, in either direction, between the proximal and distal surfaces.
• The reduced thickness portion is preferably included to provide a space for the stem of a stemmed tibial base plate of a knee joint prosthesis. One example of such a stemmed tibial base plate is shown in FIG. 8, which shows a knee[0047]joint prosthesis100 that includes stemmedtibial base plate102 with astem104 extending through the tibial augment10. FIG. 8 also shows atibial articulating surface106 and afemoral component108, which are also parts of the kneejoint prosthesis100. Although the present augment10 is shown and described for use with a stemmed tibial base plate and includes a channel for accommodating the base plate's stem, it is contemplated that the present invention could also be used with other forms of base plates without stems, and therefore the channel could be omitted. Further, it is also contemplated that the inner surfaces of the tibial augment of the present invention could be modified to accommodate other designs of tibial base plates, such as pegged base plate designs.
• As shown in FIG. 3, both the outer[0048]medial surface30 and the outerlateral surface26 have a distal taper (i.e. downward slope) of between approximately 8 degrees and approximately 30 degrees, with a taper of approximately 19 degrees being preferred. Such tapers replicate the tapers commonly found in corresponding areas of the proximal portions of human tibias. Since the thickness of theannular member10 is generally uniform from its proximal side to its distal side, the innermedial surface28 and the innerlateral surface24 will also have the same taper as the outer lateral and medial surfaces.
• Referring now to FIG. 4, the[0049]outer posterior surface20 has a distal taper of less than approximately 17 degrees, with a taper of approximately 12 degrees being preferred. The outeranterior surface16 is an essentially normal surface relative to theproximal surface12. Like the tapers of the lateral and medial surfaces, those of the anterior and posterior surfaces were also chosen to mimic the tapers of the appropriate portions of a human tibia. Once again, due to the relatively uniform thickness, the tapers of the inner posterior and anterior surfaces (22 and18, respectively) will be the same as those of the corresponding outer posterior and anterior surfaces (20 and16, respectively).
• The present invention also comprises a system of a plurality of differently sized augments that can be held on hand in order to accommodate tibias of different sizes. It is contemplated that three or four different sizes in the anterior/posterior-medial/lateral direction should suffice for most applications. For example, the lateral/medial dimension could range from about 40 mm to about 80 mm, when measured from its widest point (which is at the proximal surface). Thus, if four sizes were to be used, the lateral/medial dimension of the smallest tibial augment (at its widest point) would be 48 mm for an extra small augment, 52 mm for a small augment, 59 mm for a medium augment and 67 mm for a large augment. Additionally, the anterior/posterior dimension could range from about 30 mm to about 40 mm, when measured from the widest point in the anterior/posterior direction (which is at the proximal surface). Thus, the approximate minimum dimensions for extra small, small, medium, and large augments would be 33 mm, 34 mm, 36 m and 38 mm, respectively.[0050]
• Further two different heights of augments should be available, where the height is measured from the[0051]proximal surface12 to thedistal surface14. In cases where the decay has only extended a small distance into the tibia, a shorter augment can be used than that needed where the decay has extended to a greater depth of the bone. As a general rule, as much healthy bone should be preserved as possible. However, if the decay is relatively deep, two augments of different sizes may be stacked upon each other. For example, a small augment may be stacked upon an extra small augment; a medium augment may be stacked upon a small augment; or a large augment may be stacked upon a medium augment. Due to the shapes of the outer peripheries of the augments, stacking essentially creates extensions of the outer lateral, medial, posterior and anterior surfaces.
• It is believed that two different heights should be sufficient to remedy most tibial bone decay situations that are suitable for correction by implantation of a tibial augment. For example, augments could be available in 15 mm and 30 mm heights. However, more than two heights may also be produced, if desired. The tibial augment[0052]10 shown in FIGS. 1 through 3 is one example of an augment of the 30 mm height, and the tibial augment40 shown in FIG. 5 is one example of an augment of the 15 mm height. The augment40 of FIG. 5 is essentially the same as the augment10 of FIGS. 1 through 4, except for the height thereof. Accordingly, the same index numbers have been used in FIG. 5 as those used in FIGS. 1 through 4.
• In order to accommodate the requirements of most situations, multiple sizes and shapes of augments may be desired. In the preferred embodiment of a set of augments, six different sizes of augment are believed to be sufficient—extra small, small, medium and large in a short height (such as 15 mm) and medium and large in a tall height (such as 30 mm). Thus, in a system including these basic sizes, there is no tall height (such as 30 mm) augments in the extra small size or the small size. It is believed that defective bone portions corresponding to these two sizes are better suited to be corrected by other methods.[0053]
• Of course, all of the dimensions discussed above (and below) are being provided by way of example only, and other dimensions are also contemplated as being within the scope of the invention. However, the dimensions provided, as divided into four different increments, are believed to be able to accommodate the needs of the majority of patients. Accordingly, only a limited stock of differently sized augments would need to be kept on hand. Thus, for example, a kit of augments would only need to contain four different sizes of augments of the 15 mm height, and two different sizes of augments of the 30 mm height.[0054]
• Turning now to FIGS. 6A through 6C, three different stepped versions of a tibial augment are shown. More specifically, FIG. 6A shows stepped augment[0055]50, FIG. 6B shows stepped augment60 and FIG. 6C shows stepped augment70. Since only the distal surface of the stepped augments is different from the augment of FIGS. 1 through 4, only that portion needs to be discussed. In addition, the same index numbers as those used in FIGS. 1 through 4 will be used for similar features found in FIGS. 6A through 6C.
• FIG. 6A shows tibial augment[0056]50, which includes a stepped distal surface14a/14bwith atransition surface52 therebetween. As shown in the figure, distal surface14ais located at a greater distance from theproximal surface12 thandistal surface14b. In this embodiment, thetransition surface52 is located approximately midway between the outermedial surface30 and the outerlateral surface26.
• A second embodiment of a stepped tibial augment is shown in FIG. 6B, as represented by tibial augment[0057]60. In this embodiment, as in the FIG. 6A embodiment, distal surface14ais located at a greater distance from theproximal surface12 thandistal surface14b. The main difference between this embodiment and the FIG. 6A embodiment is the location of thetransition surface52. In this embodiment, thetransition surface52 is located closer to the outerlateral surface26 than to the outermedial surface30.
• FIG. 6C shows a third embodiment of a stepped tibial augment[0058]70. In this embodiment, as in the embodiments of FIG. 6A and 6B, distal surface14ais located at a greater distance from theproximal surface12 thandistal surface14b. The main difference between this embodiment and the other two embodiments is the location of thetransition surface52. In this embodiment, thetransition surface52 is located closer to the outermedial surface30 than to the outerlateral surface26.
• The embodiments of FIGS. 6A through 6C are especially useful where there has been uneven tibial decay, i.e., where there is more decay on either the lateral side or the medial side than on the other side. By using one of the stepped tibial augments shown in FIGS. 6A through 6C, more healthy bone, if it exists on one side or the other, can be preserved, and mostly only defective bone will end up being removed when forming a stepped cavity to implant the tibial augment. In other words, the base of the cavity into which the stepped tibial augment will be implanted will be stepped to correspond to the stepped distal surface of the augment. Such a stepped-base cavity provides for preservation of more healthy bone on the shallower side, as compared with a flat-based cavity where bone has been removed to a depth equal to the depth of the lowest damaged area of bone.[0059]
• Suggested heights for the stepped tibial augments of FIGS. 6A through 6C are 15 mm and 30 mm (as measured from the[0060]proximal surface12 to thedistal surfaces14band14a, respectively). Of course, other heights are also contemplated as being within the scope of the invention.
• FIG. 7 shows an example of a[0061]human tibia80 into which acavity82 has been prepared or formed in a proximal portion thereof. Thecavity82 of this example has aflat base84, so it is suitable for tibial augments with flat distal surfaces, such as those depicted in FIGS. 1 through 5. However, those of ordinary skill in the art should be able to adapt theflat base84 into a stepped base using the cavity forming techniques described hereinbelow.
• The[0062]tibia80 of FIG. 7 is shown in a state prior to implantation of a tibial augment and a knee joint prosthesis. More specifically, the extreme proximal portion of thetibia80 has been removed. Normally, most, if not all, of the removed proximal portion will be damaged tibial bone. However, a small amount of healthy bone may also need to be removed at the same time in order to provide a relatively flat surface upon which the flat-bottomed tibial base plate102 (FIG. 8) can be seated.
• Either prior to removing the extreme proximal portion[0063]86, or immediately after removing it (depending upon which surgical techniques are used), anintramedullary rod88 may be inserted and used to define the relationship between the knee prosthesis stem and the tibial augment.
• An example of a tibial augment[0064]10 that has been implanted into a human tibia is shown in FIG. 8. This figure shows how the tibial augment10 that is seated within a cavity, such ascavity82 of FIG. 7, is positioned directly distal of the stemmedtibial base plate102. Preferably, thetibial base plate102 is cemented to the tibial augment10. The remainder of the components of the knee joint prosthesis100 (the articulatingsurface106, thefemoral component108, etc.) are all implanted in the customary manner. It should be noted that although only one form of knee joint prosthesis has been shown and described, the tibial augments of the present invention can be used with other types of knee joint prostheses.
• FIG. 9 shows an example of a provisional tibial augment[0065]90, which is a temporary augment used as a test to ensure that the permanent augment will fit properly within the cavity. Although only one size provisional is shown and described, provisional augments should be made to correspond to every size of tibial augment, including the stepped augments. There are two main differences between the provisional augment90 and the permanent augments of FIGS. 1 through 6C.
• First, the provisional augment[0066]90 may be made of a material which indicates the bony areas of the provisional so that the surgeon can visualize how the augment fits within the cavity. For example, the provisional may be made of a transparent or photo-elastic material. One example of a suggested material for the provisional is polyphenylsulfone, although other materials are also contemplated.
• Second, provisional augments preferably include a set of[0067]grooves92/94 on the innermedial surface28 and the innerlateral surface24. Thesegrooves92 and94 extend in the generally lateral/medial direction, and are configured to cooperate withribs96 onholder110 shown in FIG. 10. Theholder110 is designed to facilitate insertion and removal of the provisional augment90 to/from the cavity82 (FIG. 7) in order to determine that there is a proper fit between the cavity and the provisional augment (and therefore there is necessarily a proper fit with the permanent augment also, since both the provisional and the permanent augment are the same size and shape).
• The[0068]holder110 includes twoflexible legs112 that extend in one direction (to the left, as shown in FIGS. 10 and 11) to abody portion114 that is topped with acrown portion116. As shown towards the right-hand sides of FIGS. 10 and 11, eachleg112 connects with ashoulder portion118. Eachshoulder portion118 in turn extends into afinger portion120, upon which theribs96 are situated. The lowermost surfaces of theshoulders118 each include astop surface122, which is used to align theholder110 with theproximal surface12 of the provisional90 (FIG. 9) to facilitate the mating of theribs96 of theholder110 with thegrooves92 and94 of the provisional90.
• The[0069]holder110 is preferably made of stainless steel, but it is contemplated that it may also be fabricated from plastic. A key consideration when selecting material is that thelegs112 must be flexible enough to be able to be biased inwardly towards each other with light force applied from the surgeon's thumb and forefinger, but they must also be resilient enough to return to their original positions when the force is removed.
• In use, the[0070]legs112 of theholder110 are flexed inwardly by the surgeon, and thefingers120 are inserted into the interior of the provisional90 (which is an annular member). Once thestops122 contact theproximal surface12 of the provisional, theribs96 of the holder should be face to face with thegrooves92 and94 of the provisional90. Pressure on thelegs112 can now be released, and thelegs112 will flex outwardly until theribs96 mate with thegrooves92 and94. At this point, theholder110 can be moved (such as by holding thecrown portion116 and/or by the body portion114), and the provisional90 will remain attached to theholder110, for inserting/removing the provisional90 to/from the cavity82 (FIG. 7).
• One important feature of the[0071]holder110 is that it can be disengaged from the provisional without affecting the position of the provisional. Thus, once the provisional is seated in the desired position, thelegs112 can be squeezed together, and theholder110 can be removed without disrupting the position of the provisional.
• Only one[0072]size holder110 has been shown, but it should be understood that since the ribs of the holder are specifically configured to make contact with the grooves on the inner surfaces of a provisional tibial augment, a different sized holder is necessary for each different sized provisional. However, since the grooves are near the proximal surface of the each provisional, no additional holder needs to be fabricated for a provisional that has the same sized proximal surface as another provisional. In the preferred set of augments and provisionals, there are six basic sizes—(1) extra small with 15 mm height; (2) small with 15 mm height; (3) medium with 15 mm height; (4) medium with 30 mm height; and (5) large with 15 mm height and (6) large with 30 mm height. However, in the preferred embodiment, the 30 mm height medium-sized provisional (or augment) is essentially a 15 mm height medium-sized provisional (augment) stacked upon a 15 mm height small-sized provisional (augment). Similarly, in the preferred embodiment, the 30 mm height large-sized provisional (or augment) is essentially a 15 mm large-sized provisional (augment) stacked upon a 15 mm medium-sized provisional (augment). Thus, the 30 mm height medium-sized provisional can employ the same holder as the 15 mm medium-sized provisional (since they have the same proximal dimensions), and the 30 mm large-sized provisional can employ the same holder as the 15 mm large-sized provisional. Accordingly, in the preferred set of six differently sized provisionals, only four holders are utilized because one holder does double duty for both the 30 mm medium provisional and the 15 mm medium provisional, and another holder does double duty for both the 30 mm large provisional and the 15 mm large provisional.
• Further, if extra small, small, medium and large stepped provisionals are also included, the number of holders does not need to be increased because the rib spacing on a stepped provisional is the same as that of a similarly sized flat-bottomed provisional. Thus, the extra small holder can be used with the extra small stepped provisional, the small holder with the small stepped provisional, the medium holder with the medium stepped provisional, and the large holder with the large stepped provisional.[0073]
• Turning now to FIGS. 12 and 13, a second embodiment of the holder will be shown and described. The second embodiment of the holder, which will be designated as[0074]holder111, is adjustable so that it can be used with provisionals of a variety of different sizes, as well as with provisionals other than tibial augment provisionals, such as femoral provisionals.Holder111 includes abody portion113 that serves as a handle and may optionally include aribbed surface115 that allows for a more secure grip. Thebody portion113, which defines a longitudinal axis (a vertical axis as shown in FIGS. 12 and 13), is connected to a pair oflegs117. Theselegs117 are each preferably L-shaped, and are preferably attached to the lower portion of thebody portion113 by welding (although other attaching means, such as screws, may be used instead). On the other hand, if desired, thelegs117 and thebody portion113 may be formed as a single unit, such as by casting, which will eliminate the need for any attaching means for connecting the legs with the body portion. When viewed together, thebody portion113 and thelegs117 define a generally fork-shaped component, as shown in FIG. 13.
• Each of the[0075]legs117 includes afinger119 connected thereto. Thefingers119 are preferably connected to thelegs117 via an externally threadedshaft121. The threadedshaft121 is divided in half such that one half is threaded in one direction and the other half is threaded in the opposite direction. Each of the fingers includes an internally threadedaperture123 that is configured to mate with the associated portion of the threadedshaft121. Thus, whenknob125 is turned in one direction, the threadedshaft121 will rotate within threadedapertures123, which will cause thefingers119 to separate from each other, and when the knob is turned in the other direction, thefingers119 will move towards each other. For example, the threadedshaft121 could be configured such that clockwise rotation of theknob125 will cause thefingers119 to move closer together and counterclockwise rotation will cause the fingers to move farther apart (or, if desired, it could be configured in the opposite manner, where clockwise rotation causes greater separation and counterclockwise rotation reduces the separation distance). As shown in FIG. 13, each of thefingers119 preferably includes a thickenedportion129, which serves to increase the contact area between the threadedaperture123 and the threadedshaft121.Thickened portions129 also provide stops that prevent thefingers119 from coming too close together.
• For the purpose of connecting the threaded[0076]shaft121 to thelegs117, each of the legs preferably includes an open-endedslot127 for receiving the ends of the shaft, which are preferably not threaded. After one end of the threadedshaft121 has been inserted into eachslot127, a small metal block is welded to each slot to close its open-end, which serves to maintain the threaded shaft in position, while still allowing rotation of the threaded shaft with respect to the legs. Of course, other methods of attaching the threadedshaft121 to thelegs117 are also contemplated as being within the scope of the invention.
• A[0077]secondary shaft131 is also provided in parallel with the threadedshaft121. Thesecondary shaft131 is preferably not threaded, and is provided in order to prevent thefingers119 from rotating with respect to thelegs117 when the threadedshaft121 is rotated. Thefingers119 are connected to thesecondary shaft131 via a pair of apertures133 (where one aperture extends through each finger), which allows the fingers to slide along, as well as rotate with respect to, thesecondary shaft131. Optionally, in order to alleviate possible binding as thefingers119 travel along thesecondary shaft131, the secondary shaft may be slightly tapered from the center thereof. For example, thecenter portion135 may be made of full diameter, and extending outwardly therefrom towards thelegs117, thesecondary shaft131 may include a one degree taper (although tapers of different degrees may also be provided), with the ends seated withinapertures133 preferably being of the same diameter as thecenter portion135. Preferably, thesecondary shaft131 is welded in place at theapertures133, although other ways of attaching the secondary shaft to the legs may also be used. Additionally, other means of preventing thefingers119 from rotating with respect to the threaded shaft are also contemplated as being within the scope of the invention. For example, the legs and/or the body portion may include some form of protrusion extending therefrom for preventing rotation of thefingers119 with respect to thelegs117, but which still permits the fingers to move sideways (i.e., towards and away from each other) with respect to the legs. As another example, the upper portions of thefingers119 may be configured to include forks that extend upwardly to straddle thelegs117 and/or the lower portion of thebody portion113.
• Each of the[0078]fingers119 also includes arib137, and they also each preferably include astop surface139. As withholder110 of FIGS. 10 and 11, theribs137 ofholder111 are configured to mate with thegrooves92 and94 of the provisional90 (FIG. 9) for inserting and removing the provisional to/from the cavity, and the stop surfaces139 are used to align theholder111 with theproximal surface12 of the provisional90 to facilitate mating the ribs of the holder with the grooves of the provisional.
• The[0079]holder111 is preferably made of stainless steel or of another metal, but other materials may be used for all or for only some of the components. For example, plastic may be used for certain parts such as thebody portion113, theknob125 and thesecondary shaft131, while a metal or other different material may be used for the remaining components.
• In order to accommodate many different sizes of tibial augment provisionals, as well other types of provisionals (such as femoral provisionals), the spacing of the[0080]fingers119 should be able to be adjusted so that the fingers are far enough apart to enable theribs137 to engage with the grooves of the largest provisional, as well as to be adjusted to be close enough together for use with the smallest provisional. For example, a distance of approximately two inches between the outer surfaces of thefingers119 when separated at the maximum distance and a distance of approximately three quarters of an inch when separated at the minimum distance should be sufficient for most uses. Of course, these dimensions are only provided as a suggestion, and other dimensions may also be used.
• In use, the[0081]knob125 is rotated to separate thefingers119 by a distance that is less than the distance that separates the grooves of the provisional being acted upon (such asgrooves92 and94 of provisional90 in FIG. 9). Thestop surface139 is positioned upon the proximal surface of the provisional, and theribs137 of the holder are aligned with thegrooves92 and94 of the provisional90 (FIG. 9). Theknob125 is again rotated to make theribs137 engage thegrooves92 and92, and the provisional90 is inserted into the cavity82 (FIG. 7). Theholder111 can be disengaged from the provisional90 by rotating theknob125 to bring thefingers119 closer together, separating theribs137 from thegrooves92 and94. One important feature of theholder111 is that is allows the ribs to be disengaged from the grooves without significantly altering the location of the provisional within the cavity. When the provisional90 is to be removed from thecavity82, theholder111 is again used in the manner described above.
• The preferred embodiments of the provisional and holder combination have been shown and described with grooves on the inner lateral and medial surfaces. However, it is also contemplated that the grooves could be placed on the inner anterior and posterior surfaces, and that the spacing of the fingers on the holder could be adjusted accordingly. Further, detents could be substituted for the grooves, and a spring loaded holder for mating with the detents could also be used.[0082]
• It is also contemplated that other means for inserting the provisional may also be used. For example, the provisional may include a threaded circular holder into which a threaded handle member can be inserted and removed.[0083]
• Turning now to FIGS. 14 through 17, these figures show an example of a tibial augment[0084]pusher130, which is used to seat a tibial augment within the cavity of the proximal portion of the tibia. The pusher130 (or one of the holders) may also be used in conjunction with the provisional tibial augment as a tamp. In situations where a bone graft is necessary to fill a void within the tibia in preparation for receiving the provisional tibial augment within the cavity, the void could be filled with morselized bone and the provisional tibial augment (in combination with a holder or pusher) could be used to tamp the morselized bone into place.
• The[0085]pusher130 includes ahandle portion132 and an augmentseating portion134. The augmentseating portion134 is further divided into ahead portion136 and aplatform portion138. Thehead portion136 is preferably shaped to mimic the interior surfaces of the tibial augment10 (FIG. 1), except thehead portion136 is slightly smaller than the corresponding surfaces of the tibial augment10 associated therewith, which permits thehead portion136 to be easily seated within (and easily withdrawn from) the tibial augment10. More specifically, there is preferably approximately 0.030 inches (0.762 mm) clearance between the outer surface of thehead portion136 and the inner surfaces of the tibial augment10, as represented by distance “X” in FIG. 17, which includes (in the main view) a front view ofpusher130 and a magnified view of part of thehead portion136 of the same pusher, but with a tibial augment10 seated thereon. That is, the magnified view of FIG. 17 shows thehead portion136 in hidden lines to represent that the head portion is hidden behind the augment10, with the inner surface of the augment (also in hidden lines) spaced from the outer surface of thehead portion136 by distance “X.”
• As also shown in the magnified portion of FIG. 17, the[0086]proximal surface12 of the augment10 contacts theplanar surface140 of theplatform portion138, which provides a surface from which the surgeon can apply light pressure to the augment10 to align, locate, and to seat it within the cavity82 (FIG. 7). As can be seen in FIGS. 16 and 17, theplanar surface140 is provided upon theplatform portion138 at the interface between theplatform portion138 and thehead portion136.
• Since the shape of the[0087]head portion136 mimics the shape of the interior surfaces of the augment10, it follows that thehead portion136 should have a taper of approximately 19 degrees (+/−3 degrees) at the surface that corresponds to the inner medial and lateral surfaces (as shown in FIG. 17), and that it should have a taper of approximately 12 degrees (+/−3 degrees) at the surface that corresponds to the inner posterior surface (as shown in FIG. 16). Further, as also shown in FIG. 16, the surface of thehead portion136 that corresponds to the inner anterior surface is not tapered, but is instead substantially perpendicular to theplatform portion138.
• In order to properly orient a tibial augment[0088]10 within a cavity, thepusher130 must have ahead portion136 that is appropriately shaped, as discussed above, and the head portion must also be appropriately sized. Thus, as with theprovisional holders110 discussed earlier, a number of pushers may be provided for the set of augments. For example, if there are four sizes of augments (extra small, small, medium and large), with two heights available (15 mm and 30 mm) for the medium and the large sizes only, then there is a total of six differently sized augments. Accordingly, as with theprovisional holders110, there should also be four differently sized pushers—one pusher for the 15 mm extra small augment; one for the 15 mm small augment; one for the 15 mm medium augment, the 30 mm medium augment, and the medium stepped augments; and one for the 15 large augment, the 30 mm large augment, and the large stepped augments.
• In its preferred form, each[0089]pusher130 is preferably made with analuminum handle portion132 and anacetyl seating portion134. However, other materials can also be used. For example, the seating portion could be made from various polymers or metals and the handle portion could be made of a different metal or from plastic.
• Turning now to FIGS. 18 through 28, a guide and several associated osteotomes that are all used to create a cavity in the tibia are shown and will be described next. One important aspect of the present invention is that the cavity formed in the tibia (such as[0090]cavity82 of FIG. 7) must be carefully created so that the tibial augment fits as precisely as possible. Among the advantages of a precise fit is that the more precise the fit, the greater the stability of the implant. Accordingly, the present invention includes tools and a method of creating a cavity of the proper size and shape. Although only one method of creating the cavity will be shown and described, other methods may also be used as a supplement to or in place of the method described. For example, a rasp technique may be used to either create the cavity or to make fine adjustments to a cavity created by another method. With such a technique, a rasp shaped like a tibial augment (with a rasp-like outer surface and a handle) is used to remove the bone and form the cavity (or to make fine adjustments to the shape of the cavity).
• FIG. 18 shows a preferred embodiment of a[0091]guide142 with a firstcurved osteotome144 inserted into a portion of aslot146 formed within theguide142. FIG. 25 shows a second curved osteotome148 (inserted into the guide142), and FIG. 26 shows a straight osteotome150 (also inserted into the guide142). As the following description will show, all three different osteotomes (144,148 and150) are required to form the cavity82 (FIG. 7) because of the configuration of theslot146, which is specifically configured to properly orient the osteotomes to create a cavity that corresponds to the tibial augment being implanted therein. Theosteotomes144,148 and150 are preferably made of stainless steel, although other materials are also contemplated.
• As with several of the other components, the osteotomes and guides are preferably configured in a variety of different sizes. In the preferred embodiment, there are four sets of osteotomes (extra small, small, medium and large) and four guides (extra small, small, medium, and large). As described more fully below, these four sets of osteotomes and four guides can be used to create a cavity in the tibia for any of the 15 mm, 30 mm or stepped augments of the preferred embodiment.[0092]
• Turning first to FIGS. 18, 21 and[0093]22, the firstcurved osteotome144 includes ahandle152 with acrown154 at the top end thereof. Thecurved osteotome144 also includes a cuttingportion156 attached to thehandle152, and the cutting portion includes atapered edge158 at its far end and a plurality of first (or distal) stops160 for hindering the cutting portion from extending into theslot146 of theguide142 past a predetermined distance. The cuttingportion156 of theosteotome144 also includes at least one second (or proximal)stop162. As described more fully below, theslot146 in theguide142 preferably includes a plurality of cutouts147 (FIG. 19), which allow thedistal stops160 to pass through in order to use theproximal stop162.
• The[0094]proximal stop162 is placed at a greater distance from the taperededge158 than thedistal stops160, as can be seen in FIGS. 21 and 22. The use of such staggered stops allows a single osteotome to be used to make two different cavities of two different depths, depending upon which stop is used and also depending upon which size guide is used. Thus, for example, assuming that tibial augments are provided in two different heights (such as 15 mm and 30 mm), accommodations must be made to provide cavities of two different depths (15 mm and 30 mm) so that the depth of the cavity coincides with the height of the tibial augment being placed therein. When a shallow cavity is needed, the set of osteotomes is inserted into the same sized guide (e.g., the set of small osteotomes is used with the small guide, etc.) whereby the exterior stops160 contact a planartop surface143 of the guide, hindering the cuttingportion156 from extending further into the guide, and accordingly hindering further extension into the bone. By inserting the set of osteotomes into the same sized guide,distal stops160 do not mate withcutouts147, and therefore stops160 do not pass throughcutouts147. On the other hand, if a deep cavity is needed, the same set of osteotomes are inserted into the incrementally larger guide (e.g. the small osteotomes are used with the medium guide), whereby thedistal stops160 pass throughcutouts147 and theproximal stop162 contacts the planartop surface143 of the guide, hindering the cuttingportion156 from extending further into the guide, and accordingly hindering further extension into the bone. The distal and proximal stops of the other osteotomes function in a similar manner. Although in the examples provided the distal and proximal stops have been shown and described as being on the radially exterior sides of the osteotomes, some or all of the stops may be provided on the radially interior sides of the osteotomes. Of course, if all stops are provided on the radially interior sides of the osteotomes, then thecutouts147 on theguide142 would have to be changed to be on the radially interior side of theslot146. Additionally, if the distal stops are provided on the radially exterior side of the osteotome and the proximal stops are provided on the radially interior side (or vice versa), then the cutouts17 could be omitted, if desired, as long as the slot was made wide enough to accept the cuttingportion156 including the stops.
• As mentioned above, FIG. 25 shows an example of a second[0095]curved osteotome148. The secondcurved osteotome148 is very similar to the firstcurved osteotome144 in that it also includes ahandle164, acrown166, and a cuttingportion168 with atapered edge170 and a plurality of distal stops172, as well as at least one proximal stop174.
• Although it appears as though the first[0096]curved osteotome144 and the secondcurved osteotome148 are identical to each other, but are just shown in different orientations, in actuality, they are mirror images of each other. More specifically, thefront cutting area176 of the firstcurved osteotome144 and thefront cutting area178 of the secondcurved osteotome148 each have no inclination, which corresponds to the outeranterior surface16 of the tibial augment10 (FIG. 4) that also has no incline. Similarly, since theouter posterior surface20 preferably has an incline of approximately 12 degrees (although inclines within the range of between about 0 to about 17 degrees may also be used), as shown in FIG. 4, the posterior cutting area184 of the firstcurved osteotome144 and theposterior cutting area186 of the secondcurved osteotome148 is also provided with an incline of 12 degrees (or a corresponding incline within the range of about 0 to about 17 degrees, depending upon the exact degree of incline provided to the anterior surface of the tibial augment). Likewise, the outermedial surface30 and the outerlateral surface26 of the tibial augment10 are preferably inclined at 19 degrees (or within the range of between about 8 to about 30 degrees), as shown in FIG. 3, theside cutting area180 of firstcurved osteotome144 and theside cutting area182 of secondcurved osteotome148 are also inclined at 19 degrees (or at whatever selected angle between 8 and 30 degrees that the outer lateral and outer medial surfaces of the augment are provided at). FIGS. 23 and 24 also show how cuttingportion156 is a mirror image of cuttingportion168. Accordingly, the secondcurved osteotome148 is not interchangeable with the firstcurved osteotome144.
• FIGS. 26 through 28 show[0097]straight osteotome150. Like the other osteotomes, the straight osteotome includes ahandle188, acrown190, and a cuttingportion192 with atapered edge194,distal stops196, and at least oneproximal stop198. As shown in FIG. 27, the cuttingportion192 is preferably inclined with respect to the handle. This degree of incline corresponds to the degree of incline of theouter posterior surface20 of the tibial augment10 (FIG. 4). Thus, in the preferred embodiment, there is an incline of approximately 12 degrees. However, inclines of between approximately 0 degrees and approximately 17 degrees are also contemplated as being within the scope of the invention, as well as other degrees of incline. The orientation of the cuttingportion192 with respect to thehandle188 of this osteotome, as well as the other osteotomes, is intended to allow for the proper cutting angle when the handle is held perpendicular to the tibial surface within which the cavity82 (FIG. 7) has been formed.
• Moreover, as shown in FIGS. 18 through 20,[0098]25 and26, theguide142 is also provided so that the proper cutting orientation of the osteotomes is maintained, which thereby aids in making a cavity with sidewalls of inclines that correspond to the inclines on the outer surfaces of the tibial augment. As mentioned earlier, theguide142 includes aslot146 for guiding the cutting portions (156,168,192) of the osteotomes (144,148,150). Each portion of theslot146 is made with a particular incline that matches the incline of the corresponding outer surface of the tibial augment associated therewith. Thus, for example, as shown in hidden lines in FIG. 18, the slot'slateral portion200 and the slot'smedial portion202 are inclined, respectively, to match the slopes of the outerlateral surface26 and the outermedial surface30 of the tibial augment10, which in the preferred embodiment is a 19 degree incline. Likewise, the slot'sposterior portion204 and itsanterior portion206 are also configured to correspond of the incline of, respectively, theouter posterior surface20 and the outeranterior surface16 of the tibial augment10. Thus, in the preferred embodiment, the slot'sposterior portion204 will be inclined at approximately 12 degrees and the slot'santerior portion206 will have no incline.
• The[0099]guide142 also includes a securing arrangement that is used to secure the guide to the bone within which the cavity is being formed. The securing arrangement includes anaperture208 that is configured to receive the intramedullary rod88 (FIG. 7), which serves as both a reference point for the guide and as the stable member that the guide is secured upon. The securing arrangement also includes a threaded hole210 (FIG. 18) that is configured to receive a setscrew212 (FIG. 19), which is comprised of ahead214 and a threadedshaft216. Alternately, the setscrew could also be replaced with a thumbscrew or the head could be replaced with a lever or small handle to facilitate tightening without the need for a screwdriver. The threadedhole210 is preferably made within acollar218, which allows for additional length of thesetscrew212, and also allows for also easier access to the head of the setscrew, which may be necessary, especially if a thumbscrew of other similar component is used in place of the setscrew.
• The[0100]slot146 of theguide142 is not annular, but instead includes a gap near itsanterior portion206, as best shown in FIG. 19. This gap is where the threadedshaft216 of the setscrew extends through the guide. If this gap in theslot146 were not present, there is a chance that the threadedshaft216 of the setscrew could accidentally be damaged if an osteotome were inserted into the slot at this area. Damaging the setscrew could result in misalignment of the guide with respect to the bone, or it could make it difficult to remove the guide from theintramedullary rod88.
• With regard to sizing, there should be one guide and one set of three osteotomes (two curved and one straight osteotome) for each 15 mm sized tibial augment. Further, additional guides and osteotomes need not be provided for the 30 mm sized or for the stepped augments. Thus, if four sizes of augments (extra small, small, medium and large) are provided, there should be four different sizes of guides and four sets of osteotomes, with three osteotomes in each set, for a total of twelve different osteotomes. To make cavities for any of the 15 mm augments, the same sized set of osteotomes and guide are used. For example, to make a cavity for a 15 mm extra small augment, the extra small set of osteotomes and the extra small guide is used. However, to make a cavity for one of the 30 mm augments, the same sized guide is used, but the set of osteotomes for the next smaller size is used. For example, to make a cavity for a 30 mm medium augment, the medium guide is used along with the small set of osteotomes. In other words, no matter what depth cavity is being created (15 mm or 30 mm), the guide that is the same size as the augment being inserted (extra small, small, medium or large) will always be used. However, when 30 mm depth cavities are being created, the set of osteotomes of one size smaller than the augment are used, otherwise (for 15 mm depth cavities), the set of osteotomes of the same size as the augment are used.[0101]
• To further clarify this point, the following specific examples are provided. Assume that one intends to prepare a cavity suitable for the medium sized augment (of either 15 mm height or 30 mm height). First, for either case (15 mm or 30 mm), the medium[0102]sized guide142 is affixed to theintramedullary rod88. For creating a 15 mm depth cavity for the medium augment,medium osteotome144 is inserted into the correspondingly sized medium guide, whereby thedistal stop160 contacts the planartop surface143 of the guide, hindering the cuttingportion156 from extending further into the guide, past the desired 15 mm depth. The other medium osteotomes are also used in the same manner, with the stops operating in a similar manner to create a 15 mm depth cavity for the 15 mm medium augment.
• To create a 30 mm depth cavity for the 30 mm medium augment, the set of small osteotomes (i.e., the osteotomes of one incremental size smaller than the augment) would be inserted into the appropriate position of the[0103]slot146, instead of using the medium osteotomes discussed above. Whensmall osteotome144 is appropriately inserted into the incrementally larger medium guide, thedistal stop160 passes through themedium guide cutout147, allowing the cuttingportion156 of the osteotome to extend further into the bone until theproximal stop162 contacts the planartop surface143 of the guide. The contact of theproximal stop162 with the top planar surface hinders the cutting portion from extending further into the guide than the desired 30 mm, and accordingly hinders further extension into the bone. (On the other hand, ifsmall osteotome144 is inserted into the correspondingly sized small guide, thedistal stop160 contacts the planartop surface143 of the guide, hindering the cutting portion of the156 from extending further into the guide so that a 15 mm deep cavity can be created). The distal and proximal stops of the other small osteotomes function in a similar manner, and a 30 mm depth cavity for the medium augment is created by using all three small osteotomes with the medium guide.
• To form a cavity in the proximal portion of the tibia, an appropriately[0104]sized guide142 and an appropriately sized set of osteotomes are selected. After the intramedullary rod88 (FIG. 7) has been implanted within thetibia80, theaperture208 of theguide142 is slid over theintramedullary rod88, and theguide142 is secured in place by tightening thesetscrew212. It should be noted that theaperture208 is preferably triangular, as best shown in FIG. 19, which allows for theintramedullary rod88 to have an increasingly secure fit as the setscrew is tightened because of the way the rod is seated at the apex of the triangle.
• Once the[0105]guide142 is securely attached tointramedullary rod88, one of the appropriately sized osteotomes, such as the firstcurved osteotome144, is inserted into the appropriate position of theslot146. More specifically, the firstcurved osteotome144 is inserted intoportion200 of theslot146. It should be noted that the osteotomes may be used in any desired order.
• As discussed above, the desired depth of cavity is formed by using the appropriate combination of a particularly sized set of osteotomes with an appropriately sized guide, whereby either[0106]proximal stops198 ordistal stops196 are utilized to result in a cut of an appropriate depth. Also, if one of the stepped tibial augments shown in FIGS. 6A through 6C is intended to be implanted, cuts of one depth may be made at one area of the cavity and cuts of another depth may be made at another area in order to form an appropriate cavity with a stepped bottom to accommodate the stepped distal surface14a/14bof FIGS. 6A through 6C.
• Next, one of the other osteotomes, such as the straight osteotome[0107]150 (FIGS.26-28), is inserted into the appropriate portion of the slot. As shown in FIG. 26, thestraight osteotome150 is inserted into the slot's posterior portion204 (best seen in FIG. 19). As described above, the appropriate stop, or stops, (eitherproximal stop198 or distal stops196) is/are utilized to result in a cut of the appropriate depth.
• Finally, the remaining osteotome, which in this case is the second curved osteotome[0108]148 (FIG. 25), is inserted into the appropriate portion of theslot146, which in this case is the medial portion202 (FIG. 19). As with the other osteotomes, the appropriate stop, or stops, (either proximal stop174 or distal stops172) is/are utilized to result in a cut of the appropriate depth. After all three osteotomes have been used, theguide142 may be removed from theintramedullary rod80 by loosening thesetscrew218 and sliding the guide upwardly and off of the intramedullary rod. At this point, the bone to be removed should be cut to the desired depth, and it merely needs to be taken from the site to form the cavity82 (FIG. 7). If necessary, an additional cut may need to be made with thestraight osteotome150, or one of the other osteotomes, at the area below the gap in theslot146, between the two edges of the anterior portion206 (FIG. 19). However, the decayed bone at that area may is simply fall from the peripheral bone without requiring an additional cut. Once the bone is completely removed from within the cut area formed by the osteotomes, a cavity that corresponds to the tibial augment being inserted therein should result.
• After forming the cavity, which alternatively could be formed using the rasp technique mentioned earlier, as well as by other known techniques, the provisional augment[0109]90 (FIG. 9) may be temporarily implanted to determine whether the cavity is properly sized, or if additional bone needs to be removed. The provisional may be inserted either with the aid of one of theholders110 or111 (FIGS. 10 and 12) or by using one of the pushers130 (FIG. 14), or with a combination of both a holder and a pusher. At this point, the provisional90 may also be used to trial the locations of the tibial base plate provisionals (or the provisionals of the tibial tray and stem). After the fit is adequately tested with the provisional90, it can be removed by using theprovisional holder110 or111 in the manner previously described. Then, the permanent tibial augment, such as augment10 of FIG. 1, is inserted using the pusher130 (FIG. 12). After properly seating the augment within the cavity, cement is applied to theproximal surface12 of the augment, and the stemmed tibial base plate102 (FIG. 8) is attached to the augment and to the peripheral bone remaining around the cavity. Then, the remainder of the kneejoint prosthesis100 is attached using any desired method, and the surgical procedure continues in the customary manner.
• While various embodiments of the present invention have been shown and described, it should be understood that other modifications, substitutions and alternatives may be apparent to one of ordinary skill in the art. Such modifications, substitutions and alternatives can be made without departing from the spirit and scope of the invention, which should be determined from the appended claims.[0110]
• Various features of the invention are set forth in the appended claims.[0111]

Claims (55)

What is claimed is:

1. A tibial augment for use with a knee joint prosthesis, comprising:

an annular member with a proximal surface, a distal surface, an outer anterior surface, an inner anterior surface, an outer posterior surface, an inner posterior surface, an inner lateral surface, an outer lateral surface, an inner medial surface and an outer medial surface;

said outer lateral surface being curved to define a continuous surface connecting said outer posterior surface and said outer anterior surface;

said outer medial surface being curved to define a continuous surface connecting said outer posterior surface and said outer anterior surface;

said outer anterior surface being a slightly curved surface; and

said outer posterior surface being a generally planer surface.

2. The tibial augment defined inclaim 1, wherein said annular member is sized to fit, at least partially, within a cavity formed in a proximal portion of a human tibia.

3. The tibial augment defined uniform thickness, whereby each outer surface of said substantially uniform inclaim 1, wherein at least a majority portion of said annular member is of a substantially thickness majority portion is spaced a substantially constant distance from each associated inner surface.

4. The tibial augment defined inclaim 3, wherein said inner anterior surface includes a distal/proximal extending channel therein, thereby defining a reduced thickness portion.

5. The tibial augment defined inclaim 4, wherein said majority portion of a substantially uniform thickness is approximately 5 mm thick and said reduced thickness portion is approximately 3 mm thick at the narrowest point thereof.

6. The tibial augment defined inclaim 1, wherein said inner anterior surface includes a distal/proximal extending channel therein, thereby defining a reduced thickness portion.

7. The tibial augment defined inclaim 1, wherein said annular member is composed of a tantalum based porous metal.

8. The tibial augment defined inclaim 1, wherein said outer posterior surface has a distal taper of less than approximately 17°.

9. The tibial augment defined inclaim 1, wherein said outer medial surface and said outer lateral surface each have a distal taper of between approximately 8° and approximately 30°.

10. The tibial augment defined inclaim 1, wherein said outer anterior surface has essentially no distal taper.

11. The tibial augment defined inclaim 1, further comprising a stepped distal surface, thereby defining a first distal surface and a second distal surface with a transition surface therebetween, wherein said first distal surface is located at a greater distance from said proximal surface than said second distal surface.

12. The tibial augment defined inclaim 11, wherein said transition surface is located midway between said outer lateral surface and said outer medial surface.

13. The tibial augment defined inclaim 11, wherein said transition surface is located closer to said outer lateral surface than to said outer medial surface.

14. The tibial augment defined inclaim 11, wherein said transition surface is located closer to said outer medial surface than to said outer lateral surface.

15. The tibial augment defined inclaim 1, wherein said annular member is composed of a material that is substantially transparent to provide an indication of bony contact when said annular member is used as a provisional.

16. The tibial augment defined inclaim 1, wherein said annular member is made of a photo-elastic material that provides an indication of bony contact when said annular member is used as a provisional.

17. The tibial augment defined inclaim 1, further comprising at least one set of generally lateral/medial extending grooves formed on at least two opposing inner surfaces of said annular member to facilitate insertion and removal of the tibial augment when used as a provisional.

18. The tibial augment defined inclaim 17, wherein said at least one set of generally lateral/medial extending grooves are formed on said inner lateral surface and said inner medial surface; and further wherein said annular member is composed of a material that is substantially transparent.

19. An implant system for use with a knee joint prosthesis, said implant system comprising:

a plurality of differently-sized tibial augments, wherein each said tibial augment is an annular member that is substantially shaped as a truncated cone with a generally oblongated oval cross-section that is symmetric about its minor axis, each of said annular members being sized to fit within a cavity of a corresponding size formed in a proximal portion of a human tibia of an appropriate size.

20. The implant system as defined inclaim 19, further comprising:

a plurality of differently-sized tibial augment pushers, with at least one pusher configured for use with each size of tibial augment, said pushers being configured and arranged for implanting each of said differently-sized tibial augments within a human tibia

21. The implant system as defined inclaim 20, wherein at least one pusher of said plurality of pushers is configured for use with more than one size of said differently sized tibial augments.

22. The implant system as defined inclaim 20, wherein each of said pushers includes:

a handle portion; and

an augment seating portion, connected to one end of said handle portion, wherein said augment seating portion is configured and arranged to seat a tibial augment of at least one particular size.

23. The implant system as defined inclaim 19, further comprising:

a plurality of differently-sized guides, with one guide being configured for use with each size of tibial augment; and

a plurality of osteotomes configured and arranged to cooperate with each of said guides, said osteotomes and said guides being configured and arranged to create an appropriately sized cavity within a proximal portion of a human tibia for implanting an appropriately sized tibial augment therein.

24. The implant system as defined inclaim 19, further comprising:

a plurality of differently-sized provisional tibial augments, with one of said provisional tibial augments corresponding in size and shape to each of said tibial augments, and each of said provisional tibial augments being composed of a material that is substantially transparent.

25. The implant system as defined inclaim 24, wherein:

each of said provisional tibial augments includes a plurality of grooves on a plurality of inner surfaces thereof;

a plurality of differently-sized holders, configured for use with said provisional tibial augments, each of said holders including a plurality of ribs, with each of said ribs being configured and arranged to correspond to one of said grooves on said provisional tibial augment, such that an appropriately sized one of said holders is capable of holding one of said provisional tibial augments during removal of said provisional tibial augment from a cavity formed within a proximal portion of a human tibia.

26. A method of correcting for tibial defects during knee replacement surgery:

preparing an existing cavity, or creating a cavity in a proximal portion of a human tibia;

inserting a tibial augment within said cavity; and

attaching a tibial portion of a knee joint prosthesis to said tibial augment.

27. The method of correcting for tibial defects, as defined inclaim 26, further comprising the step of:

selecting an appropriately sized tibial augment from a group of differently sized tibial augments.

28. The method of correcting for tibial defects, as defined inclaim 26, wherein:

during said step of preparing or creating said cavity, a guide and a set of osteotomes are utilized to form said cavity, said guide including a slot with different portions thereof configured for accepting different osteotomes of said set of osteotomes.

29. The method of correcting for tibial defects, as defined inclaim 26, further comprising the step of inserting a second tibial augment within said cavity, wherein said second tibial augment is stacked upon said tibial augment originally inserted within said cavity.

30. The method for correcting for tibial defects, as defined inclaim 26, wherein prior to said step of inserting a tibial augment within said cavity, a provisional tibial augment is temporarily inserted into said cavity.

31. The method for correcting for tibial defects, as defined inclaim 30, further comprising the step of using said provisional tibial augment as a tamp to tamp a bone graft into position.

32. A pusher for use with a tibial augment, said pusher comprising:

a handle portion; and

an augment seating portion, connected to one end of said handle portion, wherein said augment seating portion is configured and arranged to seat at least one particularly sized tibial augment.

33. The pusher as defined inclaim 32, wherein:

said augment seating portion includes a head portion and a platform portion, which are attached together, and wherein said platform portion is attached to said handle portion of said pusher;

said platform portion including a generally planar surface at an interface between said platform portion and said head portion; and

said head portion including a plurality of tapered surfaces, such that a cross-section of said head portion decreases with increasing distance from said generally planar surface of said head portion.

34. An osteotome used for creating a cavity in a bone, said osteotome comprising:

a handle portion; and

a cutting portion attached to said handle portion, wherein said cutting portion includes:

a tapered edge at a distal end thereof;

at least one stop for hindering penetration of said cutting portion into said bone past a predetermined distance.

35. The osteotome as defined inclaim 34, wherein said at least one stop includes two stops, with one of said stops being configured for hindering penetration of said cutting portion into said bone past a first predetermined distance and with the other one of said stops being configured for hindering penetration of said cutting portion into said bone past a second predetermined distance.

36. The osteotome as defined inclaim 35, wherein:

one of said stops is configured to cooperate with a guide of a first size and the other of said stops is configured to cooperate with a guide of a second size, where said second size is different from said first size.

37. The osteotome as defined inclaim 34, wherein said cutting portion is curved into an arc shape.

38. The osteotome as defined inclaim 35, wherein:

said cutting portion is generally planar, with said plane defined by said generally planar cutting portion being situated at an oblique angle with respect to a longitudinal axis of said handle portion.

39. The osteotome as defined inclaim 35, wherein said osteotome is configured and sized to create a cavity in a proximal portion of a human tibia.

40. A guide for use with at least one osteotome when creating a cavity in a bone, said guide comprising:

an upper surface;

a generally planar lower surface;

a generally C-shaped slot extending from said upper surface to said generally planar lower surface; and

a securing arrangement to secure said guide to the bone within which the cavity is being created, said securing arrangement securing said guide such that said generally planar lower surface faces the bone within which a cavity is being created.

41. The guide as defined inclaim 40, wherein said securing arrangement includes:

an aperture with a central axis extending in a direction generally perpendicular to said generally planar lower surface, wherein said aperture is configured to accept an intramedullary rod.

42. The guide as defined inclaim 41, wherein said securing arrangement further includes:

a threaded hole extending in a direction generally transverse to said plane of said generally planar lower surface; and

a setscrew configured to extend through said threaded hole and to contact the intramedullary rod such that said guide is retained in position with respect to the intramedullary rod within said aperture.

43. The guide as defined inclaim 41, wherein said aperture is generally triangular-shaped, and said aperture extends completely through said guide from said generally planar lower surface to said upper surface.

44. The guide as defined inclaim 40, wherein portions of said generally C-shaped slot are tapered inwardly toward said generally planar lower surface.

45. A system used for creating a cavity in a proximal portion of a human tibia for use prior to implanting a knee joint prosthesis, said system comprising:

a guide that includes:

an upper surface;

a lower surface;

a generally C-shaped slot extending from said upper surface to said lower surface; and

a securing arrangement to secure said guide to the bone within which the cavity is being created, said securing arrangement securing said guide such that said lower surface faces the bone within which the cavity is being created; and

a set of osteotomes configured and arranged to be inserted within said generally C-shaped slot of said guide.

46. The system according toclaim 45, wherein each of said osteotomes within said set includes at least one stop for hindering penetration of a cutting portion of said osteotome into said bone past a predetermined distance by contacting a surface of said upper surface of said guide adjacent to said C-chapped slot.

47. The system as defined inclaim 46 wherein said at least one stop on each of said osteotomes within said set includes two stops, with one of said stops being configured for hindering penetration of said cutting portion into said bone past a first predetermined distance and with the other one of said stops being configured for hindering penetration of said cutting portion into said bone past a second predetermined distance.

48. A holder for inserting and/or removing a provisional augment to/from a cavity in a bone, said holder comprising:

a body portion defining a longitudinal axis;

a pair of legs extending from said body portion;

a finger connected to each of said legs; and

a rib extending outwardly from each of said fingers, each of said ribs extending in a direction generally perpendicular to said longitudinal axis of said body portion, wherein said ribs are configured and arranged to correspond to grooves on an inner surface of a provisional augment.

49. The holder as defined inclaim 48, further comprising a pair of stops configured and arranged to be seated upon a proximal surface of the provisional augment, whereby said stops serve as locators for properly locating said ribs of said holder with respect to the grooves of the provisional augment.

50. The holder as defined inclaim 48, wherein said pair of legs comprises a pair of flexible legs, such that application of a force upon outer surfaces of said legs allows for said ribs to be disengaged from the grooves on the inner surface of the provisional augment without significantly altering the location of the provision augment.

51. The holder as defined inclaim 48, wherein:

each of said legs is a relatively rigid member; and

each of said fingers is attached to one of said legs such that said fingers are movable with respect to said legs, whereby movement of said fingers with respect to said legs allows for said ribs to be disengaged from the grooves on the inner surface of the provisional augment without significantly altering the location of the provision augment.

52. The holder as defined inclaim 51, wherein a distance between said fingers is adjustable to permit said holder to be used with provisional augments of different sizes.

53. The holder as defined inclaim 51, wherein said fingers are attached to said legs via a threaded shaft that is threaded in one direction where one of said fingers is connected thereto and in an opposite direction where the other of said fingers is connected thereto, whereby when said threaded shaft is rotated in a first direction with respect to said legs, said fingers are moved towards each other and when said threaded shaft is rotated in an opposite direction with respect to said legs, said fingers are moved away from each other.

54. The holder as defined inclaim 51, further comprising:

a threaded shaft that extends from one of said legs to the other of said legs and is rotatable with respect to said legs and connects said fingers to said legs, said threaded shaft being threaded in one direction where one of said fingers is connected thereto and in an opposite direction where the other of said fingers is connected thereto; and

a secondary shaft that extends from one of said legs to the other of said legs, with said fingers being movably attached thereto.

55. The holder as defined inclaim 54, wherein said secondary shaft includes a slight taper from a center thereof outwardly towards each of said legs.

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