Patent Description:
A relevant part of such procedures is obtaining sufficient securement between the glenoid implant and the glenoid. Doing so not only ensures that the implant is properly positioned, but also increases the likelihood that the implant will last for a longer period of time. This is an ongoing challenge not only for implants in the shoulder, but also for implants in joints more generally. Further, the characteristics of an optimal articular surface of the implant may vary widely among patients. Thus, problems may arise if an articular surface part of a glenoid implant cannot be dimensioned in an optimal manner for a particular patient.

Thus, a need exists for glenoid implants with greater versatility, load bearing capacity and longevity once implanted in a patient.

According to the present invention, there is provided a glenoid implant as defined in appended claim <NUM> and the corresponding dependent claims. Further, the present disclosure addresses challenges extant with glenoid implants by providing an implant with an anatomically shaped keel for improved securement with bone and improved methods of securing such implants, the methods not forming part of the present invention. These methods may also be advantageous when employed in other joints of the body. Additionally, the present disclosure contemplates an articular surface part of a glenoid implant with a bump on a non-exposed surface opposite the articular surface to allow for a greater range in the depth and radius of the articular surface. This may be accomplished by having a bottom side that protrudes away from the articular surface to allow such articular surface to extend deeper into a central region of the implant.

The present disclosure will be better understood on reading the following detailed description of non-limiting embodiments thereof, and on examining the accompanying drawings, in which:.

As used herein, the term "medial" when used in reference to a prosthetic implant refers to a position closer to the mid-line of the patient's body when the prosthetic implant is implanted in an intended position and orientation, whereas the term "lateral" means farther away from the mid-line of the patient's body. As used herein, the term "superior" when used in reference to a prosthetic implant refers to a position closer to the top or head of the patient's body when the prosthetic implant is implanted in an intended position and orientation, whereas the term "inferior" means closer to the bottom or feet of the patient's body. As used herein, the term "anterior" when used in reference to a prosthetic implant refers to a position closer to the front of the patient's body when the prosthetic implant is implanted in an intended position and orientation, whereas the term "posterior" means closer to the rear of the patient's body.

The present disclosure is directed to mammalian joint implants and methods related to same, including methods of bone preparation and methods of implant placement. None of the methods of the present disclosure forms part of the present invention.

The present disclosure relates to a glenoid implant. One embodiment of the glenoid implant and its constituent parts is shown in <FIG>. In this embodiment, the glenoid implant is designed for TSA, although it should be appreciated that the concepts described herein may be applied in either TSA or RSA. Similarly, other embodiments of the present disclosure that are explicitly directed to RSA may be modified for use in TSA procedures and vice versa. Glenoid implant <NUM>, as shown in <FIG>, includes a medial part <NUM> and a lateral part <NUM>. Medial part <NUM> is the anchor component of the implant for placement into the glenoid, while the lateral part includes an articulating surface that interfaces with the humerus. As shown in <FIG>, medial part <NUM> includes an engagement feature <NUM> that interfaces with a complementary engagement feature <NUM> of the lateral part <NUM>. The lateral part <NUM> is preferably polymeric and has capacity for flexure so that engagement feature <NUM> may flex or be bent around the corresponding engagement feature <NUM> on medial part <NUM> to snap fit the parts with one another. However, it should be understood that materials other than polymers may be suitable, particularly those that provide a suitable level of flexibility. Specific examples of material usable for lateral part <NUM> includes polycarbonate urethane and silicone rubber, both of which are biocompatible. Any imposed deformation of the lateral part <NUM> is elastic such that the snapping action results in the return of the lateral part to its original shape. In some arrangements, the fit between the lateral part <NUM> and medial part (<NUM>) may be a press fit, although other types of fit may be suitable. Each engagement feature <NUM>, <NUM> may be a dovetail connection, as shown, though other types of engagement features are also contemplated.

<FIG> show the medial part <NUM> in isolation. Medial part <NUM> includes a medial surface <NUM> that is generally convex in shape, and has a keel <NUM> extending medially therefrom. An outer layer of medial part <NUM> including medial surface <NUM> preferably has a porous structure that facilitates bone ingrowth. On an opposite side of medial part <NUM> is a lateral surface <NUM>, shown in <FIG>. Lateral surface <NUM> is generally planar and includes engagement feature <NUM> around its perimeter. Extending through lateral surface <NUM> are three separate slots 120A-C that surround a central opening <NUM>. Central opening <NUM> has a tear drop shape and extends through medial part <NUM>. In some arrangements, central opening <NUM> may extend through an entire length of keel <NUM>. In other embodiments, central opening <NUM> may have a pear shape. Slot 120A is shorter than slots 120B, 120C and is located superior to opening <NUM>. Each slot 120B, 120C is positioned on an opposite side of the central opening <NUM> and extends approximately parallel to lateral sides of opening <NUM>. All three slots 120A-C may have slightly curved edges along their lengths to generally follow a shape of keel <NUM> and opening <NUM>, as best shown in <FIG>. Inclusion of the slots 120A-C may provide access to the bone, for example via a bone-cutting tool, when the implant is in place to simplify a revision procedure. In other words, instead of cutting around the exterior perimeter of medial part <NUM> to remove the medial part from the bone, the bone may be cut through slots 120A-C to allow keel <NUM> to be removed from the bone, sparing a relatively large amount of bone.

An overall perimeter of medial part <NUM> is pear-shaped, as best shown in <FIG>, the shape being generally similar to an outer edge of the glenoid surface. In other embodiments, the overall perimeter of medial part <NUM> may be tear-drop shaped. In particular, the illustrated pear shape is narrower toward a superior end and wider toward an inferior end. Outer dimensions of medial part <NUM> are guided by an outer dimension of the glenoid surface (glenoid fossa) itself. In particular, medial part <NUM> is designed to have a footprint similar to, but smaller than, a total surface area of the glenoid. In some examples, a first dimension of medial part <NUM> from a superior end to an inferior end may be from about <NUM> to about <NUM>. And, a second dimension from an anterior end to a posterior end, substantially orthogonal to the first dimension, may be from about <NUM> to <NUM>.

Keel <NUM> is hollow with central opening <NUM> passing therethrough, as mentioned above. Keel <NUM> may also include a graft window <NUM> as shown in <FIG> and <FIG> passing laterally therethrough. A shape of graft window <NUM> may be rectangular with one or more rounded corners as shown in <FIG>, although it is contemplated that the shape may be square, obround, circular or other similar shapes. Along an outer surface <NUM> of keel <NUM> are grooves or notches <NUM> spaced apart from one another and oriented approximately parallel to lateral surface <NUM> in an inferior-superior alignment. The inclusion of notches <NUM> gives the keel <NUM> a larger surface area to increase contact with bone when implanted, which may provide better anchoring to the bone. The notches may have a U or V shaped profile. In some examples, the notches may be oriented orthogonally to the orientation of notches <NUM> shown in <FIG> and <FIG>. The structure of keel <NUM> itself may be anatomically shaped. That is, the keel <NUM> may have a shape that is consistent with that of the perimeter of medial part <NUM> as defined by outer edge <NUM>. For medial part <NUM> as shown in <FIG>, keel <NUM> is pear shaped when viewed in a medial or lateral direction. Inclusion of a keel <NUM> with an anatomical shape, such as a pear shape, improves bone remodeling potential, e.g., renewal of bone tissue, post-implantation when compared to implants that include a keel with a non-anatomical shape. Keel <NUM> includes a superior part <NUM>, an inferior part <NUM>, and opposite side parts 138A-B that bridge a distance between the superior and inferior parts. The combined superior part <NUM>, opposite side parts 138A-B and inferior part <NUM> define a continuous enclosed loop, as shown in <FIG>. Keel <NUM> is wider nearer to inferior part <NUM> and has an inner surface <NUM> with a larger first radius of curvature at inferior part <NUM>, measured about a medial-to-lateral axis through a length of the keel, than a second radius at superior part <NUM>. Each side part 138A-B has slight curvature so that inner surface <NUM> is concave in those parts, but the side parts have much less curvature than the respective end parts <NUM>, <NUM>. Side parts 138A-B become closer together moving toward superior part <NUM>. A rim <NUM> at a terminal or free end of keel <NUM> may have a rounded edge, as shown in <FIG>.

<FIG> show lateral part <NUM> in isolation. Lateral part <NUM> includes articular surface <NUM> and medial surface <NUM> opposite the articular surface. Lateral part <NUM> has a varying depth (in the medial-to-lateral direction) along its length and width as a function of the concave shape of articular surface <NUM>. A length of lateral part <NUM> extends from inferior apex <NUM> to superior apex <NUM>. Articular surface <NUM> has a width (in the anterior-to-posterior direction) with a maximum closer to inferior apex <NUM> than superior apex <NUM>. From a location with the maximum width, a width of the lateral part <NUM> tapers toward superior apex <NUM>, as shown in <FIG>. In this manner, from a front view, lateral part <NUM> has a pear-shape consistent with a shape of medial part <NUM>. The shape of the articular surface <NUM> is bounded by edge <NUM>. Further, because articular surface <NUM> is concave, the surface has low edge points 164A, 164B in between apices <NUM>, <NUM>. A radius of curvature of the concavity of articular surface <NUM> may be in a range from about <NUM> to about <NUM>. In some examples, the range may be from about <NUM> to about <NUM>. In further examples, the range may be from about <NUM> to about <NUM>. In further examples, the range may be from about <NUM> to about <NUM>. In yet another example, the radius of curvature may be about <NUM>. In other examples, the radius may be greater than about <NUM>.

Turning to the other side of lateral part <NUM>, medial surface <NUM> has a central region <NUM> and a peripheral region <NUM> radially outward of the central region. An outer bound of peripheral region <NUM> includes a rim as shown in <FIG> and <FIG>, the rim including engagement feature <NUM>. Central region <NUM> protrudes medially relative to peripheral region <NUM>, as best shown in <FIG> and <FIG>. An outer extent of central region <NUM> interfaces with peripheral region <NUM> at edge <NUM>, as shown in <FIG>. As depicted, central region <NUM> includes a convex surface. In some alternative arrangements, the surface may be partially convex. In further arrangements, the surface of central region <NUM> may have planar parts. A size of the protrusion of central region <NUM> is preferably such that articular surface <NUM> extends to a depth at its lowest point that is close to a plane through peripheral region <NUM>. This is best shown in <FIG>. In some alternative arrangements, the central region <NUM> protrudes sufficiently relative to peripheral region <NUM> so that articular surface <NUM> crosses the plane through the peripheral region. Central region <NUM> provides extra material or structure to increase a minimum thickness of lateral part <NUM> in a portion of the lateral part that would otherwise be the thinnest part of the structure. Without the protruding surface of central region <NUM>, a curvature of the articular surface <NUM> would be limited to one that would preserve a minimum thickness between an articular surface and a generally planar medial surface. With the protrusion of central region <NUM> included in lateral part <NUM>, the lateral part may have a constant thickness <NUM> at or above a minimum threshold value at all locations of lateral part <NUM> within a perimeter of central region <NUM> defined by edge <NUM>. A minimum threshold thickness value may be at least about <NUM> if lateral part <NUM> is formed of a polymer, such as polyethylene. Outside of edge <NUM>, a thickness of lateral part <NUM> increases toward edge <NUM>. This is shown, for example, in <FIG>. Further to the depicted embodiment, at one extreme, a surface area of peripheral region <NUM> may be close to zero while a surface area of the central region <NUM> may occupy all or nearly all of the medial surface <NUM> of the lateral part <NUM>. Conversely, a surface area of the central region <NUM> may be such that the surface area of peripheral region <NUM> is about <NUM>% of the surface area of the central region. In this respect, the surface area of the central region <NUM> may be anywhere from about <NUM>% to about <NUM>% of a total surface area of the medial surface <NUM>.

Implant <NUM> preferably utilizes a material combination such that medial part <NUM> is a metal material and lateral part <NUM> is a polymeric material. The metal may be a metal or metal alloy such as cobalt-chromium (CoCr) or Ti64. The polymeric material may be polyethylene such as X3 polyethylene by Stryker®. In some examples, the lateral part <NUM> may be ceramic or pyrolytic carbon instead of a polymer. It is contemplated that the aforementioned materials may be used in the respective medial and lateral parts of the glenoid implants of other embodiments of the present disclosure, including those illustrated in <FIG>, for example.

Another embodiment of a glenoid implant is shown in <FIG>. Unless otherwise stated, like reference numerals refer to like elements of implant <NUM>, but within the <NUM>-series of numerals. Glenoid implant <NUM> is an augmented implant and includes a medial part <NUM>, a central part <NUM> and a lateral part <NUM>. Medial part <NUM> is preferably metallic while central part <NUM> and lateral part <NUM> are preferably polymeric. In some examples, the material of the central part may be more rigid than the material of the lateral part. Lateral part <NUM> functions as a labrum part and may have flexural properties similar to that of rubber. Through the distinguishing characteristic of the central part, the central part may function as an insert to bridge the differences between the metallic material of the medial part and the flexible polymeric material of the lateral part. Medial part <NUM> includes engagement feature <NUM> on a periphery of lateral surface <NUM>. Central part <NUM> includes engagement features <NUM> that are engageable with engagement feature <NUM>. As shown in <FIG>, the respective engagement features <NUM>, <NUM> form a dovetail connection, though other connection types are contemplated, such as a snap fit connection. Lateral part <NUM>, a flexible component, includes a peripheral wall <NUM> that forms a closed loop or ring sized so that when placed over central part <NUM>, the lateral part engages with the central part through an interference fit. In some examples, a ring-shaped inward protrusion (not shown) on the peripheral wall of the lateral part engages with a ring-shaped groove on the central part, thereby establishing a compression fit.

Lateral part <NUM> includes an articular surface <NUM> and a medial surface <NUM>, although unlike implant <NUM>, medial surface <NUM> is a single convex surface throughout and does not have a protrusion or other distinctive sub-surface that deviates from the convex shape. Central part <NUM> may function as an insert between the medial part and the lateral part and includes a lateral surface <NUM> that is concave and sized and shaped such that when lateral part <NUM> is placed over and against lateral surface <NUM>, as shown in <FIG>, medial surface <NUM> of lateral part <NUM> and lateral surface <NUM> of central part <NUM> are flush with one another. Opposite the lateral surface of central part <NUM> is medial surface <NUM>, <NUM>. The medial surface of central part <NUM> includes a peripheral region <NUM> and a central region <NUM> that protrudes medially relative to peripheral region <NUM>. The structure of the medial surface <NUM>, <NUM> of central part <NUM> is similar to medial surface <NUM> of lateral part <NUM> in implant <NUM>. Central region <NUM> as shown in <FIG> has a convex protrusion that is entirely surrounded by peripheral region <NUM>. As with lateral part <NUM>, central region <NUM> provides a thickness <NUM> of the lateral part at or above a set minimum, while also providing space so that lateral surface <NUM> has a deeper low point in a central area of the implant and a smaller radius of curvature than otherwise possible, if desired. In some examples, including that shown in <FIG>, lateral surface <NUM> crosses a plane through peripheral region <NUM>, a depth that, without the central protrusion, would result in a void in central part <NUM> toward its center.

Medial part <NUM> includes lateral surface <NUM> with engagement feature <NUM>. As shown in <FIG>, engagement feature <NUM> extends peripherally in a closed loop around an outer boundary of lateral surface <NUM>. Opposite lateral surface <NUM> is medial surface <NUM>. Medial surface <NUM> includes shallow portion 219A and wedged portion 219B. Wedged portion 219B extends along one side of keel <NUM> while shallow portion 219A extends along an opposite side, thereby roughly dividing medial surface <NUM> evenly between the two portions. Wedged portion 219B may be positioned on a posterior or an anterior side of the glenoid. For TSA applications, posterior-inferior wear tends to be very common, so in those circumstances, posterior positioning is typical. Wedged portion 219B protrudes relative to shallow portion as shown in <FIG> and has a slight convex contour. Surfaces of portions 219A-B are characteristic of augmented glenoid implant structures for use with patients having eccentric glenoid erosion, in which the wedged portion 219B is adapted to contact a neoglenoid surface and the shallow portion 219A is adapted to contact a paleoglenoid surface. Augmented glenoid surfaces, which may be used in place of those illustrated in <FIG>, are described in greater detail in <CIT>. Keel <NUM> of medial part <NUM> includes grooves, ribs or notches <NUM> which have extensions thereon, as shown in <FIG>. The extensions may have a "<NUM>"-shaped or "V"-shaped profile. Notches <NUM> with extensions function to compress bone upon impaction of implant <NUM> into bone. Although extensions on the notches <NUM> are not shown for implant <NUM>, it is contemplated that such extensions may be included on the keel of any one of the implants of the present disclosure.

In another embodiment, a complete glenoid implant may include medial part <NUM> and central part <NUM> alone, without the lateral part. With an implant assembled in such a manner, central part <NUM> functions as an articulation surface with the humeral implant head, e.g., an implant made of a metallic material such as cobalt-chromium (CoCr). In yet another embodiment, shown in <FIG>, a complete glenoid implant <NUM>' may include medial part <NUM>', central part <NUM>', and a lateral part <NUM>' in the form of a flexible ring, which has a length that extends around a perimeter of central part <NUM>'. Lateral part <NUM>' includes an inward facing protrusion <NUM>' that is engageable with a complementary recess <NUM>' on central part <NUM>', the engagement being in the form of a compression fit. Lateral part <NUM>' is hollow so that when implant <NUM>' is fully assembled, an articular surface of central part <NUM>' is exposed. In this manner, the articular surface of central part <NUM>' is exposed to contact with a humeral implant post-surgery. In use, wear between the exposed surface of the glenoid implant <NUM>' and the humeral head is minimized through the inclusion of lateral part <NUM>'. Less wear results in less buildup of debris.

Glenoid implant <NUM> is yet another embodiment of the glenoid implant and is illustrated in <FIG>. Unless otherwise stated, like reference numerals refer to like elements of implants <NUM> and <NUM>, but within the <NUM>-series of numerals. Glenoid implant <NUM> includes many of the same features as implant <NUM>, with distinctions as shown in the Figures and as described in the following. Glenoid implant <NUM> includes medial part <NUM>, central part <NUM>, and lateral part <NUM>, each engageable with one another as shown in <FIG> and having engagement features that are the same as those described for glenoid implant <NUM>. Lateral part <NUM> includes articular surface <NUM> with an outer part <NUM> curved as shown in <FIG>. Medial part <NUM> includes lateral surface <NUM> and medial surface <NUM>. Medial surface <NUM> includes a first portion 319A and a second portion 319B, shown in <FIG>. Second portion 319B tapers from an outer surface of medial part <NUM> toward keel <NUM> and first portion 319A tapers from the keel toward the outer surface. In this manner, medial part <NUM> is thicker in second portion 319B than in first portion 319A. As shown, medial surface <NUM> is generally convex, though the medial surface includes slots 320A-C therein. The shape of medial part <NUM> provides additional versatility for the glenoid implants contemplated by the present disclosure in that it may be used to accommodate different anatomy or surgical conditions than implants <NUM>, <NUM>, for example. This may be desirable if the labrum in the shoulder has a shape that is best accommodated by implant <NUM>.

<FIG>, <FIG> illustrate yet another embodiment of the implant, glenoid implant <NUM>. Unless otherwise stated, like reference numerals refer to like elements of implant <NUM>, but within the <NUM>-series of numerals. Implant <NUM> includes medial part <NUM> and lateral part <NUM>. Medial part <NUM> includes a medial surface <NUM>, a lateral surface <NUM> opposite the medial surface, and a keel <NUM> extending from the medial surface. Medial part <NUM> includes a central opening <NUM> through keel <NUM> and slots 420A-C. Medial surface <NUM> is convex in shape, with lateral surface <NUM> being generally parallel to the medial surface and thus having a concave shape. As shown in <FIG>, lateral surface <NUM> includes a superior ridge 425A and lateral ridges 425B-C, the ridges defining a protruding central region interior to the ridges. Lateral part <NUM> includes a medial surface <NUM> and an articular surface <NUM> opposite the medial surface. As shown in <FIG>, medial surface <NUM> includes a superior ridge 455A and lateral ridges 455B-C, the ridges defining a recessed surface interior to the ridges. Ridges 455A-C are complementary to ridges 425A-C. Through these respective surface features, lateral part <NUM> is engageable with medial part <NUM> by sliding lateral part <NUM> over medial part <NUM> from a position superior to the medial part and moving in an inferior direction until ridge 455A makes contact with ridge 425A. In implant <NUM>, lateral part <NUM> has a generally uniform thickness throughout, so that a curvature of medial surface follows that of articular surface <NUM>. The relatively thin structure of implant <NUM>, as compared to implant <NUM>, for example, improves the ability to place the implant into the glenoid through an inlay technique.

<FIG> illustrate a glenoid implant <NUM> according to an embodiment of the disclosure. Unless otherwise stated, like reference numerals refer to like elements of implant <NUM>, but within the <NUM>-series of numerals. A medial part <NUM> of implant <NUM> is shown in <FIG>. On a medial surface <NUM> of the medial part <NUM>, and centrally disposed, is keel <NUM>. Also on medial surface <NUM> are pegs <NUM>, <NUM>, disposed on respective superior and inferior sides of the keel. As shown, medial part <NUM> has two pegs. Each peg has a cylindrical main body with a tapered tip. The tip as shown is partially spherical. In alternative arrangements, medial surface <NUM> may have any number of pegs. For example, medial surface <NUM> may have four, five or six pegs. The pegs may be arranged at equal spacing, in a pattern, or in another arrangement. In some arrangements, the pegs may have a different shape. For example, the pegs may include one or more planar surfaces and tips with shapes varying from that shown. Medial surface <NUM> may include surface characteristics for bone ingrowth, as is shown in <FIG>.

<FIG> illustrate a glenoid implant <NUM> according to an embodiment of the disclosure. In <FIG>, glenoid implant <NUM> is shown implanted into bone. Unless otherwise stated, like reference numerals refer to like elements of implant <NUM>, but within the <NUM>-series of numerals. Implant <NUM> includes medial part <NUM> and lateral part <NUM>. Medial part <NUM> includes a keel <NUM> that extends from a central part of medial surface <NUM>. Keel <NUM> is hollow and is pear-shaped when viewed along an axis <NUM> through the hollow part. Keel <NUM> is defined by a wall with an inner surface <NUM> and an outer surface <NUM>. Keel <NUM> has a depth that extends from a base 637A-B of the keel to a lip <NUM> of the keel at the open end of the keel. Lip <NUM> extends around a length of the free end of keel <NUM> and includes an outward facing protrusion. From base 637A-B to lip <NUM>, a thickness of the wall tapers as shown in <FIG>. Punctuated at intervals along the wall around its peripheral dimension are slits 639A-F, six in total. As shown in <FIG>, each slit extends from a first end at the lip to a second end adjacent to outer base 637A external to the wall or inner base 637B internal to the wall. At the second end, each slit 639A-F includes a bulge in size. The inclusion of the slits 639A-F and their position around the keel <NUM> render the keel flexible to an extent sufficient for implant installation into bone. In particular, the wall of keel <NUM> may bend toward or away from axis <NUM>. In some arrangements, a greater or smaller number of slits may be included in the keel, and the shape of the slits may vary from that shown. Lateral part <NUM> is engageable with medial part <NUM> as described in other embodiments of the disclosure. Further, lateral part <NUM> includes a medial surface <NUM> with a protrusion <NUM> thereon. When assembled, protrusion <NUM> fits through a corresponding opening in inner base 637B of keel <NUM>.

<FIG> illustrate a glenoid implant <NUM> according to an embodiment of the disclosure. In <FIG>, glenoid implant <NUM> is shown implanted into bone. Unless otherwise stated, like reference numerals refer to like elements of implants <NUM> and <NUM>, but within the <NUM>-series of numerals. Implant <NUM> includes medial part <NUM> and lateral part <NUM>. A keel <NUM> extends medially from medial surface <NUM> of medial part <NUM>. Keel <NUM> is hollow with an opening <NUM>. The wall of keel <NUM> defines a pear-shape when viewed on axis <NUM> through a center of opening <NUM>, and is solid throughout, as shown in <FIG>. From a base <NUM> of the keel <NUM> to a rim <NUM> of the keel, the wall tapers, as shown in <FIG>. Lateral part <NUM> is engageable with medial part <NUM> as described in other embodiments of the disclosure. In some arrangements, keel <NUM> may be a relatively solid metallic material while in other arrangements the keel maybe a relatively porous metallic material.

<FIG> illustrate a glenoid implant <NUM> according to an embodiment of the disclosure. Unless otherwise stated, like reference numerals refer to like elements of implant <NUM>, but within the <NUM>-series of numerals. Implant <NUM> includes a medial part <NUM> and a lateral part (not shown) that attaches to a lateral surface <NUM> of medial part <NUM>. Medial part <NUM> includes hollow keel <NUM> within opening <NUM> therein. Keel <NUM> has a thin wall with notches <NUM> on an outside surface. Keel <NUM> is a hard metallic material with strength sufficient so that bone may be compacted within the keel as it is implanted. The outer surface of keel <NUM>, over its depth from base <NUM> to rim <NUM>, is parallel to an axis <NUM> through the opening, as shown in <FIG>. Inner surface <NUM> of keel <NUM>, however, tapers from base <NUM> to rim <NUM>. In this manner, a thickness of a wall of keel <NUM> tapers from the base to the rim. The tapered profile of the keel wall improves compaction of bone when the implant is impacted and otherwise placed onto the glenoid. Between base <NUM> of the keel <NUM> and medial surface <NUM> of the medial part is a transition surface <NUM> that encloses keel <NUM>. The transition surface is recessed relative to medial surface <NUM> and is included to simplify the manufacturing process. In some arrangements, if implant <NUM> is formed through an additive manufacturing technique, medial surface <NUM> may be formed to abut keel <NUM> without a recess surrounding the keel.

<FIG> illustrates yet another embodiment of a glenoid implant, but for a reverse shoulder implanted for a RSA procedure. Glenoid implant <NUM> includes a medial part <NUM> and a glenosphere <NUM> configured to be disposed in the medial part <NUM>. Preferably, the medial part <NUM> and glenosphere <NUM> are both formed of a metal or metal alloy. Medial part <NUM> includes keel <NUM>. Keel <NUM> includes two openings <NUM>, <NUM> extending in parallel directions along a depth of the keel. Opening <NUM> is round and forms a cylindrical path through the keel <NUM> sized to receive an engagement portion <NUM> of glenosphere <NUM>. Opening <NUM> is triangular such that a path defined through the keel <NUM> is a triangular prism and functions to receive bone graft or other bony ingrowth during implant use. Keel <NUM> has an outer surface that is pear shaped and includes notches 1thereon. Through medial part <NUM> and on opposite sides of the keel <NUM> are slots 1020B, 1020C. Glenosphere <NUM> includes a hemispherical surface <NUM> and a medial surface <NUM> that presses onto or toward medial part <NUM> when engaged thereto.

Glenoid implant <NUM> illustrated in <FIG>, another embodiment of the disclosure, is also for a RSA procedure. Unless otherwise stated, like reference numerals refer to like elements of implant <NUM>, but within the <NUM>-series of numerals. Both medial part <NUM> and glenosphere <NUM> are preferably metallic. In implant <NUM>, however, while keel <NUM> has two parallel openings <NUM>, <NUM>, opening <NUM> is cylindrical and sized to receive a fastener <NUM>. Fastener <NUM> has surface characteristics for engagement with bone, in furtherance of the purpose of implant <NUM>. In medial part <NUM>, opening <NUM> is defined by an inner wall that is tapered in toward a lateral surface of medial part. This is sometimes referred to as a Morse taper and is shown in <FIG>. The inclusion of the Morse taper enhances engagement between engagement portion <NUM> of glenosphere <NUM> and medial part <NUM>.

<FIG> illustrates an embodiment of a glenoid implant <NUM> that utilizes a metallic medial part <NUM> that is the same as medial part <NUM>, but includes a polymeric lateral part <NUM> attached thereto. This allows a lateral part with a concave articular surface to be substituted with a glenosphere such as that described for <FIG> and vice versa. Unless otherwise stated, like reference numerals refer to like elements of implants <NUM>, <NUM>, but within the <NUM>-series of numerals. <FIG> illustrates an embodiment of a glenoid implant <NUM> that includes medial part <NUM> and lateral part <NUM>. Unless otherwise stated, like reference numerals refer to like elements of implants <NUM>, <NUM>, but within the <NUM>-series of numerals. Medial part <NUM> is preferably metallic and lateral part <NUM> is preferably polymeric. Medial part <NUM> includes a keel <NUM> extending medially from medial surface <NUM>. Keel <NUM> has a structure consistent with keel <NUM>. Lateral part <NUM> includes a glenosphere with a hemispherical surface <NUM> at an inferior end on top of a base <NUM>. Base <NUM> is pear-shaped to be commensurate in size with medial part <NUM>. In this manner, complementary engagement features of the medial part and the lateral part, <NUM>, <NUM>, line up for engagement between the two parts.

The keel is ovoid in shape when viewed in a medial to lateral direction, such that it is symmetric about a single plane. In some examples, a rim of the keel may have a lip or it may have a sharp edge. The keel may also have openings varying from the specific variations shown in the depicted embodiments. For instance, a side of the keel may have two separate openings therethrough, or the hollow part of keel extending along its depth may have two separate compartments.

In some examples, the lateral part may have a medial surface with a protruding central region that has planar surfaces thereon or has a surface that only includes part that is partially convex. The central region may be proportionally larger or smaller than what is shown in <FIG>. Further, the height of the protrusion may be greater or lesser proportional to a size of the implant than that shown in <FIG>. In some examples, the height of the protrusion will be <NUM>, a thickness of the lateral part in the central region, combined with a minimum distance between a plane of the peripheral region and a maximum depth of the articular surface.

In some examples, a medial part of the implant may exclude slots or may have a quantity of slots greater or lesser than three. In some examples, the keel may have no notches or have another structural feature in their place. In some examples, the central part of implants <NUM>, <NUM> may be included as a part of another contemplated implant. In some examples, a single-component glenoid implant may include a keel such as keel <NUM>. For instance, a monolithic single-component glenoid implant may be formed from molding the medial part to the lateral part.

In another aspect, the implant may form part of a kit. In one example, a kit includes a set of at least two implants. In some examples, the set includes two or more implants of the same size. In some examples, the set includes at least two different sizes of implants. In some examples, the set includes some implants that are the same and at least one that is different. In some examples, a set may include two or more different types of implants. In another example, a kit may include robotic cutting tools or a complete robot along with one or more implants. Any combination of implants may also be included in a single package or in separate packages which may be later brought together as a kit.

The kit may be varied in many ways. For example, it is contemplated that any combination of particular implants and tools as described herein may further include other tools or instruments not otherwise described as part of a kit. Some or all of the various combinations of elements of any contemplated kit may be included in a single package or distributed among multiple packages. In other examples, the kits contemplated herein may be accompanied by an instruction manual on how to perform one or more of the methods of using the contents of the kit.

In another aspect, the present disclosure relates to a method of assembly of an implant. The method does not form part of the present invention. In one example, implant <NUM> as shown in <FIG> is assembled by bringing lateral part <NUM> to medial part <NUM> with medial surface <NUM> of the lateral part facing lateral surface <NUM> of the medial part. Engagement feature <NUM> is then snapped onto engagement feature <NUM>, positioning an outer rim of lateral part <NUM> over the medial part, as shown, for example, in <FIG>. In another example, implant <NUM> is assembled in the same manner as implant <NUM> to bring central part <NUM> together with medial part <NUM>. Then, lateral part <NUM> is slid over central part <NUM> by placing peripheral wall <NUM> over an outer surface of central part <NUM>. In this manner, an interference fit is created between the parts. Similar methods of assembly may be employed for implants contemplated in the disclosure.

In another example, implant <NUM> as shown in <FIG> is assembled by advancing engagement portion <NUM> of glenosphere <NUM> through opening <NUM> in medial part <NUM> to obtain an interference fit, e.g., via a Morse taper. A method of assembly of implant <NUM> is similar, with an additional step of advancing fastener <NUM> into opening <NUM>. In yet another example, implant <NUM> is assembled. Engagement features <NUM> of lateral part <NUM> are snap fit onto corresponding engagement feature <NUM> of medial part <NUM>.

In yet another exemplary aspect, the present disclosure relates to a method of implantation of an implant in a joint, however, said method does not form part of the present invention and is described for illustrative purposes only. The joint may be a shoulder, but may be other joints in the body as well, such as a hip, knee or ankle. According to one exemplary aspect of the present disclosure, a method of implanting a glenoid implant into a shoulder is as shown in <FIG>. The method may be performed autonomously or semi-autonomously with the assistance of a robotic manipulator for the implantation of the glenoid implant. Throughout the disclosure, the term "robotic manipulator" is used interchangeably with "robot. " The robot may form part of a larger system (not shown) that includes a computer, memory, controller, inputs and outputs, and/or a navigation system, which may be interconnected with one another. The inputs may include a keyboard or other user interface and the output may include at least a display that outputs images and/or data associated with the three-dimensional model and the surgical plan, among other information pertinent to the surgery. One function of the robot is to store data that relates to the location of various elements involved in the performance of the method. These include data for the location of the implant, the surface features on the implant, the cutting tool and the planned bone cuts. The robot may be configured to operate with haptic guidance, may be set up for connection to a cutting tool, such as a bur, and may be set up for connection to a rotatable driver for seating of the glenoid implant. Through the combination of the programmable robot and haptics, the system is configured to provide force feedback and visual guidance during surgery, as described in greater detail below.

The robot with haptics may be as described in <CIT> (the '<NUM> Publication). The robot of the '<NUM> Publication is shown in <FIG> as robot <NUM> and includes a base <NUM>, platform <NUM> and arms <NUM>, <NUM> that extend from base <NUM>. Arm <NUM> extends to a haptic device tracker <NUM> while arm <NUM> includes a plurality of linkages and extends to an end effector <NUM> that connects to a tool. Here, the tool is a bur tool <NUM>, though in some arrangements, other tools may be attached. Another example of a robot is described in <CIT>. In alternative approaches, the method may be fully automatic or may include certain steps performed manually by a user. The term "user" refers to an individual that performs the surgical method. This may include an operator of the robot or a surgeon, for example.

In some variations, the system used for the method may employ a robot that includes both a cutting instrument and imaging hardware. Such a robot is advantageous in that it streamlines workflow and reduces the need to move around the various parts of the system during the procedure and/or reduces the need for repeated registrations of one or more elements of the system. One example of such a robot is described in <CIT>.

With the anatomy registered, surgical planning, also referred to herein as planning, for the surgery surrounding shoulder <NUM> is performed. In short, planning involves establishment of the particular bone structure, including location, size and shape, to be cut with the robot. Because the glenoid implant is already manufactured at this stage and thus has a predetermined keel shape for engagement with bone, the dimensions of the glenoid implant are used as a guide to determine or confirm how the glenoid will be cut.

Turning to the details of the required bone cut or cuts, the robot may optionally be used to prepare an overall surface <NUM> of the glenoid to receive the medial part of the glenoid implant. The surface <NUM> is prepared as necessary to receive medial surface <NUM> of medial part <NUM>. Such surface preparation is in accordance with known practices for shoulder replacement surgery and typically involves resection of bone to expose subchondral bone. Further, the bone surface is resected to refine its curvature to match that of medial surface <NUM> of medial part <NUM>. Once any required glenoid surface preparation is complete, a deeper cut is made into the glenoid, as shown in <FIG>. In particular, a closed loop groove <NUM> is cut with a size and shape to receive keel <NUM>. The groove is cut to a size so that an interference fit may be achieved when the keel is received in the groove. To render the surgical plan executable, data for the bone cuts is saved into the memory linked to the computer and incorporated into the three-dimensional model described above. With the precise identification of anatomical locations already in the model, this approach allows for very precise cutting of the bone so that when the implant is inserted into the glenoid, a close fit will result. In some variations of the method, the computer is used to generate boundary volumes for disposal of the implant into the resected bone as part of the planning process. In particular, the model may generate a range of acceptable cut volumes and/or cut paths in the bone that will allow for a satisfactory seating of the implant. Some examples describing the details of these planning steps are provided in <CIT>.

It should be appreciated that the exact dimensions of the planned cut may be varied based on results of an optional bone density review that may warrant deeper or shallower cuts. Some examples of how bone density of a particular patient may be used to optimize implant geometry are described in <CIT>. Similarly, the depth of the cuts may be slightly shallower to increase friction between the keel and the bone or deeper to reduce friction.

Turning to the operation of the robot and the bur, the robot, such as robot <NUM>, is connected to the controller and/or computer, along with the navigation system, to ensure data from the robot including the bur location is overlaid with the three-dimensional model. The bur is then connected to the robot if not already connected. It should be appreciated that although the method is described with the use of a bur as a cutting tool, it is contemplated that other cutting tools may also be used. Through the connection of the robot to the overall system, advancement of the bur into the glenoid will be visible on the display showing the three-dimensional model. As shown in <FIG>, bur tool <NUM>, e.g., a ball bur tool, is then advanced to glenoid while the navigation system tracks the coordinates of the bur and relays such information to the computer to show a location of bur tool <NUM> on the display that shows the three-dimensional model. During this step, the model is viewable via the display and the surgical site is also viewable via direct visualization.

As referenced above, in some circumstances, when the robot is used to prepare the glenoid surface, the user references the cut plan on the model to guide bur <NUM> to glenoid surface <NUM> to make the first cut, which is the initial surface cut that corresponds to the size and shape of the convex medial surface <NUM> of glenoid implant <NUM>. This cut may be performed to expose subchondral bone on the glenoid. As the user performs the cut, the location of the bur tip is fed back to the computer and associated with the three-dimensional model information. The model has a predetermined cut depth based on the surgical plan programmed as noted above. As bur <NUM> reaches the bounds of such depth or the outer limits of the cut near a perimeter <NUM> of the glenoid surface, the haptics of the robot generate increasing feedback, such as vibration, resistance, or a combination of the two, among others, to prevent the user from cutting outside of the predetermined limits of the planned cut volume. In this manner, the bone cut is precise and does not deviate from the surgical plan. Further detail regarding how haptics may be used to control cutting limits and volume are described in <CIT>. When this step is complete, glenoid surface <NUM> is sized and shaped to closely fit, e.g., be flush with a size and shape of the convex medial surface <NUM> of the implant. However, prior to insertion of the implant onto the glenoid, a further cut to create the closed loop groove may be completed.

Similarly to the preparation of the glenoid surface <NUM> for receipt of the implant, bur tool <NUM> is used to cut closed loop groove <NUM> in surface <NUM> in accordance with the three-dimensional model parameters as established during the planning stage of the procedure described above. The application of bur tool <NUM> to the glenoid surface to cut the grooves is shown in <FIG>. The user directs the bur tool along the surface of the glenoid within a predetermined cut path for the tool to create closed loop groove <NUM>. The cut path follows what may be described as a tear-drop shape as shown in <FIG>. Through this cut, the remaining bone left intact interior to the groove, bone core <NUM>, also has a tear-drop shape. The predetermined limits of the cut, including width, depth and cross-sectional shape, are programmed in the three-dimensional model and are associated with coordinates that are continuously compared with coordinates of the bur tool. In this manner, when the bur tool reaches the limits of the predetermined cut path during use, the haptics of the robot provide increasing feedback in the same manner as occurs during execution of the first cut. Again, as with the first cut, the robot-assisted bur tool forms the groove with exacting tolerances as established through the three-dimensional model. Upon completion of the cut required to create closed loop groove <NUM>, the remaining glenoid is split into two regions, an outer surface region external to closed loop groove <NUM>, and bone core <NUM> interior to closed loop groove <NUM>, as shown in <FIG>. Bone core <NUM> is undisturbed bone and preserves the original integrity of the bone to promote engagement between the implant and the bone.

At this juncture, the glenoid is ready to receive glenoid implant <NUM>. Confirmation that the lateral part and the medial part of the implant are assembled is done prior to implantation, and assembly completed if required. Then, implant <NUM> is advanced onto the glenoid, and in particular, keel <NUM> is advanced into closed loop groove <NUM>, as shown in <FIG>. This step may be done manually by the user or with the robot. When the robot is used, planning and controls as described above are utilized to obtain accurate placement. Further, the closed loop groove is sized with a high degree of accuracy such that once it receives keel <NUM>, a secure fit should be expected with resistance to removal more than sufficient to hold the glenoid implant in place on the bone. As shown in <FIG>, keel <NUM> occupies a volume of closed loop groove <NUM>, with bone core <NUM> occupying the hollow interior of keel <NUM>. Thus, one advantage of this method is that no separate bone substitute material, e.g., bone graft is required. This simplifies the method of implantation and renders it more efficient in terms of the time required for its performance. Further, without the need for bone graft, the possibilities for error during the method are reduced, another advantage. Once implantation is complete, bone ingrowth is promoted through the inclusion of porous material on medial surface <NUM>.

The method of implantation described for glenoid implant <NUM> may also be performed to implant glenoid implants <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> shown in <FIG>. Such a method may be performed with the same steps as described above. For implant <NUM> in particular, use of such method may involve formation of a wider closed loop groove in the glenoid so that when the implant is inserted, there is space to flex the keel in order to allow the protrusion of the keel to snap into the outward facing step in the removed material. According to another aspect of the present disclosure, a method of implantation of implant <NUM> shown in <FIG> is performed as described above for implant <NUM>, with additional steps as follows. When the glenoid is prepared, a central region <NUM> of the bone is removed and the robot is used to further remove an outward facing step <NUM> at a terminal depth of the cut, all shown in <FIG>, where the implant is shown positioned within the space left subsequent to the removal of the bone material. This outward facing step may also be referred to as an undercut. When implant <NUM> is advanced onto the glenoid for implantation, keel <NUM> flexes inward to pass through the opening in the bone, and once the keel reaches the plan depth, lip <NUM> snaps into the undercut.

According to another exemplary aspect of the present disclosure, a method of implantation of glenoid implant <NUM> involves preparation of an opening within the glenoid surface with a volume sufficient to receive keel such that when keel <NUM> is received in the bone, opening <NUM> within keel <NUM> remains unoccupied by bone. That is, a full volume of bone is removed for receipt of the keel and there is no bone core left in place once the cut in the glenoid is made. In this manner, such method may be performed with placement of bone graft in keel <NUM>, then placement of keel <NUM> into the glenoid opening to position implant <NUM> in the implanted position. Bone graft may be received through graft opening <NUM> and opening <NUM>. Because opening <NUM> includes two openings located on opposite sides of keel <NUM>, this arrangement provides for bone ingrowth from three separate openings. Examples of bone graft that may be used include natural bone graft and a porous structure that acts as an allograft, such as a porous titanium. When natural bone graft is used, the humerus cut head may be used as a source. Once implanted, the porous material on medial surface <NUM> promotes bone ingrowth. Such a method may also be performed for the other contemplated implants, including glenoid implants <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>.

According to yet another exemplary aspect of the present disclosure, a reverse shoulder implant with glenoid implant <NUM> is implanted as part of an RSA. With keel <NUM>, implant <NUM> may be implanted with methods that correspond to those described above for glenoid implant <NUM>. A completed implantation, inclusive of reverse humeral implant <NUM> and polymeric inner cup <NUM>, is shown in <FIG>. In this configuration, contacting surfaces of the humeral part and the glenoid part are both polymeric.

According to yet another exemplary aspect of the present disclosure, another reverse shoulder implant is implanted into the shoulder as shown in <FIG>. A cavity is formed in the glenoid to receive keel <NUM>. The keel has notches <NUM> to aid in engagement with the bone once the keel is in place. Additionally, a fastener element <NUM> is receivable through opening <NUM> in keel and thus may be advanced into bone to aid in the fixation of implant <NUM> onto the glenoid. The fastener may be a locking and compression based screw. A complete assembly of the shoulder implant is shown in <FIG>, with reverse humeral implant <NUM> in the humerus, the humeral implant having a polymer articular surface and the glenosphere having a metallic articular surface for polymer-metal contact.

In another exemplary aspect, the disclosure relates to a method of revision surgery to replace an existing glenoid implant, however, said method does not form part of the present invention and is described for illustrative purposes only. According to one exemplary aspect of the present disclosure, glenoid <NUM> is replaced. An existing glenoid implant <NUM> is removed with a focus on removal of the keel through tool access provided by slots 120A-C. Such access allows for removal of bone ingrowth around the keel and for the preservation of the glenoid. Tools that may be used to perform such removal include osteotomes, for example. Once the existing implant is removed, a new implant is implanted according to a method as set forth elsewhere in the present disclosure or according to methods known to those of ordinary skill where other varieties of implants are used.

Claim 1:
A glenoid implant (<NUM>, <NUM>, <NUM>', <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) comprising:
a body (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) with an articulation surface (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) and a bone facing surface (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>); and
a keel (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) having a depth extending from the bone facing surface to a free end (<NUM>) of the keel remote from the bone facing surface, the keel having a first length and a first width both measured in a plane perpendicular to a direction of the depth, the first width being perpendicular to the first length,
wherein a first distance from an inferior end (<NUM>) of the keel to a superior end (<NUM>) of the keel defines the first length,
and wherein the first width is measured at a first location adjacent to the inferior end,
the keel having a tapering width along a first portion of the keel from the first location to the superior end and measured in the plane, the tapering width tapering from the first location to the superior end,
the glenoid implant being characterized in that:
the keel has an ovoid shape in a cross-section in the plane, the ovoid shape being symmetric about a single plane, and in that
sides (138A-B) of the keel remote from the inferior end and the superior end have less curvature than the inferior end and the superior end.