Patent Description:
Knee arthroplasty, often called a knee replacement, is a surgical procedure used to reconstruct and resurface a knee that has been damaged, such as by arthritis. Total knee arthroplasty devices replace both the tibiofemoral joint and the patellafemoral joint. The tibiofemoral joint is where the tibia and the femur articulate. The patellafemoral joint is where the patella and the femur articulate. To replace the tibiofemoral joint, knee arthroplasty includes a femoral trial (or implant) secured to the distal end of the femur, a tibial tray (or implant) secured to the proximal end of the tibia, and an insert disposed therebetween. The femoral implant and tibial implant cap the ends of the femur and tibia, respectively, which form the knee joint, thereby reconstructing the knee. To replace the patellafemoral joint, knee arthroplasty includes a patella prosthesis (or implant) to replace the backside of the patella and form a replacement articulating surface which interfaces with the femoral trial.

<CIT> describes a patella implant known in the art. <CIT> which is a document forming the state the art according to Art. <NUM>(<NUM>) discloses a patella implant for knee implant according to the art, comprising a cap including an articulating surface, the cap having a plurality of first connection members, and a base configured to be attached to the backside of a patella of a patient, the base including a cap support mounted to the cap, the cap support including a plurality of first connection recesses, wherein each first connection member of the cap is disposed in a corresponding one of the first connection recesses of the cap support to mount the cap to the base, wherein the cap includes a plurality of second connection members and the cap support of the base includes a plurality of second connection recesses, wherein each second connection member of the cap is disposed in a corresponding one of the second connection recesses of the cap support to mount the cap to the base, wherein the second connection members have a different shape than the first connection members and the second connection recesses have a different shape than the first connection recesses.

According to the invention it is provided patella implant according having the features set out in independent claim <NUM>. Further advantageous features are set forth in the dependent claims.

Other objects and features of the present disclosure will be in part apparent and in part pointed out hereinafter.

Various different systems for carrying out and performing knee arthroplasty are disclosed here. The different systems for knee arthroplasty disclosed herein include implants (e.g., tibial implants, femoral implant, patella implants), installation or arthroplasty tools for installing the implants; and position verification systems for determining and verifying the position of the implants relative to the bone. The different methods for knee arthroplasty disclosed herein include methods for installing implants (which do not form part of the invention) and methods for verifying the position of an installed implant relative to the bone.

Referring to <FIG>, one example of a tibial tray or implant for knee arthroplasty is generally indicated at reference numeral <NUM>. The tibial implant <NUM> includes a tibial plate <NUM> sized and shaped for placement on a proximal end PE of a tibia T of a patient (<FIG>). The tibial plate <NUM> can have generally any size and shape to match the particular size and shape of the proximal end PE of the tibia T the tibial implant is attached to. The tibial plate <NUM> includes opposite proximal and distal surfaces <NUM>, <NUM>. The distal surface <NUM> of the tibial plate <NUM> is configured to engage the proximal end PE of the tibia T. The tibial plate <NUM> has a perimeter edge margin <NUM>. In the illustrated example, the tibial plate <NUM> includes a perimeter wall <NUM> extending proximally from the proximal surface <NUM>. The perimeter wall <NUM> includes the perimeter edge margin <NUM>. The perimeter wall <NUM> defines an insert receiving space <NUM> sized and shaped to receive an insert (not shown). The perimeter wall <NUM> may include one or more recesses or notches <NUM> used to receive a portion of the insert to hold the insert in the insert receiving space <NUM>. The proximal surface <NUM> defines the distal or bottom end of the insert receiving space <NUM>.

The tibial implant <NUM> may include at least one (e.g., a plurality of) positioning guides <NUM> configured to be engaged by a position verification system <NUM> (<FIG>), as discussed in more detail below, to verify the position of the tibial implant relative to the proximal end PE of the tibia T after the tibial implant is implanted (e.g., placed) on the proximal end of the tibia. The positioning guides <NUM> are used to locate or register the position verification system <NUM> relative to the tibial implant <NUM>, as discussed in more detail below. The positioning guides <NUM> are sized and shaped to mate with an element or component (e.g., position indicator <NUM>) of the position verification system <NUM>. Thus, the positioning guides <NUM> are touch points for the position verification system <NUM>. The one or more positioning guides <NUM> are disposed on the tibial implant <NUM> in positions that will be accessible after the implant is attached to the tibia T. In the illustrated example, the positioning guides <NUM> are disposed on the tibial plate <NUM>. Specifically, the positioning guides <NUM> are disposed on the perimeter edge margin <NUM> of the tibial plate <NUM> and, desirably on a forward portion of the perimeter edge margin so that the positioning guides are easily accessible after the tibial implant <NUM> is implanted. Other positions of the positioning guides <NUM> are within the scope of the present disclosure. For example, the positioning guides <NUM> may be disposed on the proximal surface <NUM>. The positioning guides <NUM> may be positive elements, such as projections, or negative elements, such as depressions. In the illustrated example, the positioning guides <NUM> are depressions or recesses. Thus, the positioning guides <NUM> of the illustrated example are configured to receive or be engaged by the position verification system <NUM>. The recesses <NUM> may have generally any shape such as, but not limited to, a conical shape (e.g., an inverted cone) as shown in <FIG>, a conical shape with a flat bottom, a partially spherical shaper, a semi-spherical shape, a cylindrical shape, a rectangular shape, a square shape, a pyramidal shape, etc. The positioning guides <NUM> are spaced apart from one another. In one example, the positioning guides <NUM> are configured to indicate identification data of the tibial implant <NUM> such as, but not limited to, the size of the tibial implant, the part number of the implant, etc. The position of the positioning guides <NUM> on the tibial implant <NUM> and/or distance between the positioning guides can be used to indicate or encode the identification data. When the position verification system <NUM> registers with the positioning guides <NUM>, the system can match the position of the positioning guides and/or the distance between the positioning guides to an implant database containing a list of possible implants to determine the specific type of tibial implant <NUM> and/or confirm that the correct tibial implant has been implanted on the tibia T. For example, the distance between the positioning guides <NUM> can represent (e.g., encode) the size of the tibial implant <NUM> (e.g., the spacing between positioning guides <NUM> varies by the size of the implant) and the position verification system <NUM> can determine the size of the implant tibial implant by referencing the implant database to confirm the correct size of tibial implant was implanted.

The tibial implant <NUM> includes a tibial stem or keel <NUM>. The tibial keel <NUM> is configured to be inserted into the proximal end PE of the tibia T. The tibial keel <NUM> is attached to the tibial plate <NUM>. The tibial keel <NUM> extends generally distally from the distal surface <NUM> of the tibial plate <NUM>. In the illustrated example, the tibial keel <NUM> is generally straight. The tibial keel <NUM> may be solid or hollow (e.g., have a solid or hollow core). The tibial keel <NUM> may include coronal fins <NUM> (e.g., two coronal fins). The coronal fins <NUM> extend outward from the center of the tibial keel <NUM> in a direction that is generally parallel to a coronal plane of the patient (e.g., a vertical side-to-side extending plane). In the illustrated example, the coronal fins <NUM> are at a slight angle relative to the coronal plane, such as about <NUM> degrees or less to form a slight V-shape. The tibial keel <NUM> may also include sagittal fins <NUM> (e.g., two sagittal fins). The sagittal fins <NUM> extend outward from the center of the tibial keel <NUM> in a direction that is generally parallel to a sagittal plane of the patient (e.g., a vertical front-to-rear extending plane). The coronal fins <NUM> and the sagittal fins <NUM> taper inwardly as the fins extend distally. The width of the sagittal fins <NUM> may also taper inwardly (e.g., in a direction generally parallel to the coronal plane) as the fins extend distally. The fins <NUM>, <NUM> have rounded edges. The nose or tip of the tibial keel <NUM> is tapered (e.g., curved) in the coronal plane. In other examples, the nose of the tibial keel <NUM> may also be tapered in the sagittal plane. Other configurations of the tibial keel are possible, some of which are disclosed herein.

Referring to <FIG>, the tibial implant <NUM> may include at least one anchoring projection <NUM>. In the illustrated example, the tibial implant <NUM> includes four anchoring projections <NUM>, although more or fewer anchoring projections are possible. The anchoring projections <NUM> are spaced apart from one another over the distal surface <NUM> of the tibial plate <NUM>. In the illustrated example, the four anchoring projections <NUM> are arranged in generally an X-arrangement about the tibial keel <NUM>, with the tibial keel at the center of the X. Other arrangements of the anchoring projections <NUM> are possible.

Each anchoring projection <NUM> is configured to be inserted into the proximal end PE of the tibia T. Each anchoring projection <NUM> is generally identical and thus, one anchoring projections will be described in further detail with the understanding the other anchoring projections have essentially the same construction (e.g., are disposed at different locations on the tibial plate <NUM>). The anchoring projection <NUM> is attached to the tibial plate <NUM>. The anchoring projection <NUM> extends generally distally from the distal surface <NUM> of the tibial plate <NUM>. The anchoring projection <NUM> has a distal end or tip <NUM>. In this embodiment, the distal tip <NUM> includes a recess. The recess may have generally any shape such as, but not limited to, a conical shape (e.g., an inverted cone), although other shapes are within the scope of the present disclosure, such as a conical shape with a flat bottom, a partially spherical shaper, a semi-spherical shape, a cylindrical shape, a rectangular shape, a square shape, a pyramidal shape, etc. The recess maximizes the press fit of the anchoring projection <NUM> with the bone when the tibial implant <NUM> is implanted into the tibia T to increase the compression between the anchoring projection and the bone to stimulate healing of the bone. In addition, the recess facilitates the formation of a sharp, leading distal edge at the distal tip <NUM> to facilitate the insertion of the anchoring projection <NUM> into the proximal end PE of the tibia T. In the illustrated example, the anchoring projection <NUM> has a generally rounded, conical shape (e.g., a bullet shape), although other shapes such as rounded, blade or hollow shaped are possible. The anchoring projection <NUM> includes a plurality of ribs <NUM> that extend proximally from the distal tip <NUM>. The ribs <NUM> extend proximally to the distal surface <NUM> of the tibial plate <NUM>. In the illustrated example, the anchoring projection <NUM> includes six ribs <NUM>, although more (e.g., <NUM>) or fewer (e.g., <NUM>) ribs are possible. The ribs <NUM> are circumferentially disposed about the anchoring projection <NUM>. The ribs <NUM> have beveled edges, but in other examples can have rounded, chamfered, sharp, fillet, etc. edges. In this example, the ribs <NUM> curve (e.g., slightly curve) about a longitudinal axis of the anchoring projection <NUM>. The longitudinal axis extends proximally and distally through the distal tip <NUM> of the anchoring projection <NUM>. In other words, the ribs <NUM> curve helically or partially helically about the longitudinal axis. In the illustrated example, each rib <NUM> includes a proximal portion extending generally distally straight from the distal surface <NUM> and a distal portion extending distally in a curved manner, about the longitudinal axis, from the proximal portion to the distal tip <NUM>. The ribs <NUM> taper inward (e.g., toward the longitudinal axis) toward the distal tip <NUM> as the ribs extend distally. The taper may be straight or curved. Other configurations of the ribs <NUM> are possible. Adjacent ribs <NUM> define a groove <NUM> therebetween. The groove <NUM> extends from the distal surface <NUM> to the distal tip <NUM> and the shape of the groove generally corresponds to the shape of the ribs <NUM>. Accordingly, the groove <NUM> also curves about the longitudinal axis. The design of the ribs <NUM> (broadly, anchoring projection <NUM>) minimizes bone displacement, minimizes risk of fracture and increases the surface area of the anchoring projection for bone ingrowth. Other configurations of the anchoring projection are possible, some of which are disclosed herein. The anchoring projection <NUM> may be solid or hollow (e.g., have a solid or hollow core).

The tibial implant <NUM> may include one or more porous regions. The porous regions are disposed at positions on the tibial implant that engage the tibia T (broadly, bone). The porous regions enable ingrowth of the bone into the tibial implant <NUM> after the tibial implant is placed on the bone to form a strong connection between the implant and the bone. This allows the tibial implant <NUM> to be inserted into the tibia T without the cement conventionally used in knee arthroplasties, reducing procedural times, cement related complications and surgeon stress. The porous regions may have a porosity within the inclusive range of about <NUM>%-<NUM>%, or more preferably within the inclusive range of about <NUM>%-<NUM>%. The porous regions may have a thickness of about <NUM> to <NUM>. In the illustrated embodiment, the distal surface <NUM> of the tibial plate <NUM> is porous (e.g., is a porous region). Other parts of the tibial implant <NUM> may include porous regions. For example, at least a portion of tibial keel <NUM> and/or anchoring projection(s) <NUM> may be porous to enable ingrowth of bone into the tibial keel and/or anchoring projection(s) <NUM>, respectively, after the tibial implant <NUM> is inserted into or implanted on the proximal end PE of the tibia T. Any surface of the tibial keel <NUM> and anchoring projection(s) <NUM> may be porous. Preferably, the porous regions extend distally along the tibial keel <NUM> and anchoring projection(s) <NUM> from the distal surface <NUM> of the tibial plate <NUM>. Preferably, the porous regions of the tibial keel <NUM> and/or anchoring projection(s) <NUM> extend distally from the distal surface <NUM> over a distance up to and including about <NUM>. This allows the bone to grow into the tibial keel <NUM> and/or anchoring projection(s) <NUM> while still allowing the tibial implant <NUM> to be easily removed in the future should adjustment or replacement of the implant be required. The porous regions of the tibial keel <NUM> and/or anchoring projection(s) <NUM> can extend over (e.g., cover) more of the tibial keel and/or anchoring projection(s) <NUM>, including the entirety thereof, to enable a stronger connection to be formed between the tibial keel and/or anchoring projection(s) <NUM> but it will be more difficult to remove and replace such a tibial implant from the bone, if removal is ever needed. In one example, the porous regions comprise hexagonal struts coupled together to form a lattice (<FIG> and <FIG>), although any suitable porous structure is possible.

The tibial implant <NUM> can be made using conventional manufacturing processes and methods and/or additive manufacturing processes and methods (e.g., three-dimensional (3D) printing). In one method of manufacture, the entire tibial implant <NUM> is constructed using additive manufacturing. In this method, the tibial implant <NUM> is built by an additive manufacturing machine (e.g., a 3D printer) which generally constructs the implant on a base plate and post processes the implant before the implant is removed from the base plate. In another method of manufacture, the tibial implant <NUM> is constructed using hybrid manufacturing, which combines conventional manufacturing methods with additive manufacturing. In this hybrid method, the tibial plate <NUM> of the implant <NUM> can first be created by conventional manufacturing methods, such as cold forming (e.g., stamping, cutting, deforming) a metal blank or by forging the tibial plate. The tibial plate <NUM> is then placed in an additive manufacturing machine which builds the additional elements (e.g., keel <NUM>, anchoring projection(s) <NUM>, porous regions, etc.) on the tibial plate. Preferably, the porous regions of the tibial implant <NUM> are constructed using additive manufacturing. The additive manufacturing machine builds (e.g., is configured to build) the porous regions (e.g., the lattice of hexagonal struts) on the components (e.g., tibial plate <NUM>) of the tibial implant. Additive manufacturing enables more complex porous structures to be built than possible with conventional methods. For example, conventional manufacturing methods cannot construct the porous regions comprised of a lattice of hexagonal struts. Various different additive manufacturing processes may be used to create the porous regions such as 3D printing, direct metal laser sintering (DMLS), titanium deposition spray, etc. Other methods of constructing the porous regions are possible. For example, porous regions can be constructed using a subtractive manufacturing process such as laser etching or acid etching.

Other configurations of the tibial implant are possible. For example, the tibial implant can have one or more of the tibial keels and/or anchoring projections described below.

Referring to <FIG>, an anchoring projection for a tibial implant <NUM> according to another example is generally indicated at reference numeral <NUM>. In this embodiment, the ribs <NUM> of the anchoring projection <NUM> are generally straight and extend parallel to and toward the longitudinal axis (e.g., do not curve about the longitudinal axis). In this example, the distal tip <NUM> of the anchoring projection <NUM> includes a point (e.g., a conical shaped point).

Referring to <FIG> and <FIG>, an anchoring projection for a tibial implant <NUM> according to another example is generally indicated at reference numeral <NUM>. In this embodiment, the anchoring projection <NUM> includes four ribs <NUM>, which are arranged in generally an X-shape (<FIG>). The ribs <NUM> are also generally straight and extend parallel to and toward the longitudinal axis. The distal tip <NUM> also includes a point, similar to anchoring projection <NUM>. In this example, the ribs <NUM> are spaced apart from the distal surface <NUM> of the tibial plate <NUM>. The ribs <NUM> extend proximally from the distal tip <NUM> to a location intermediate of the distal tip and the distal surface <NUM>. Each rib <NUM> includes a proximal surface that faces and is spaced apart from the distal surface <NUM>. Together, the proximal surface of the ribs <NUM>, the distal surface <NUM> of the tibial plate <NUM> and a base (not shown) of the rib define a space for the bone (e.g., tibia T) to grow into and surround the ribs. In other examples, the ribs <NUM> may extend all the way to the distal surface <NUM>, such as ribs of the anchoring projections 234A in <FIG>, <FIG>, <FIG>.

Referring to <FIG>, an anchoring projection for a tibial implant <NUM> according to another example is generally indicated at reference numeral <NUM>. In this embodiment, the anchoring projection <NUM> is cylindrical (e.g., has a cylinder shape). The anchoring projection <NUM> includes a cylindrical outer surface <NUM> and a leading or distal surface <NUM>. The distal surface is generally planar (e.g., the distal end <NUM> is generally blunt) and has a circular shape. The edge or corner between the outer surface <NUM> and the distal surface <NUM> is rounded, but in other examples can have beveled, chamfered, sharp, fillet, etc..

Referring to <FIG>, an anchoring projection for a tibial implant <NUM> according to another example is generally indicated at reference numeral <NUM>. In this example, the anchoring projection <NUM> is generally cylindrical with a cylindrical outer surface <NUM>. The distal end <NUM> includes a recess which, in the illustrated example, is an inverted cone, although other configurations as described herein are possible. In this example, the width or diameter of the base of the inverted cone recess at the distal end <NUM> is generally equal to the width or diameter of the cylindrical outer surface <NUM>, although the base of the recess having a smaller width is possible. The anchoring projection <NUM> includes a sharp leading or distal edge at the distal end <NUM> between the recess at the distal end <NUM> and the cylindrical outer surface <NUM>.

Referring to <FIG>, an anchoring projection for a tibial implant <NUM> according to another example is generally indicated at reference numeral <NUM>. In this example, the anchoring projection <NUM> has a generally polygonal (e.g., hexagonal) shape that tapers inward as the anchoring projection extends distally. The surfaces <NUM> of the polygonal shape are concave. As a result, the edges between the surfaces generally define spines <NUM> of the anchoring projection <NUM> with a sharp edge. In this example, the distal end <NUM> has a generally planar distal surface.

Referring to <FIG>, an anchoring projection for a tibial implant <NUM> according to another example is generally indicated at reference numeral <NUM>. In this example, the anchoring projection <NUM> has a generally polygonal (e.g., hexagonal) shape that tapers inward as the anchoring projection extends distally. The surfaces <NUM> of the polygonal shape are concave. As a result, the edges between the surfaces generally define spines <NUM> of the anchoring projection <NUM>. In this example, the spines <NUM> are rounded. The distal end <NUM> has a recess, such as an inverted cone.

Referring to <FIG>, an anchoring projection for a tibial implant <NUM> according to another example is generally indicated at reference numeral <NUM>. In this example, the anchoring projection <NUM> has a generally polygonal (e.g., hexagonal) shape that tapers inward as the anchoring projection extends distally. The surfaces <NUM> of the polygonal shape are concave. As a result, the edges between the surfaces <NUM> generally define spines <NUM> of the anchoring projection <NUM> with a sharp edge. The spines <NUM> generally curve about the longitudinal axis LA of the anchoring projection as the spines extend distally. Accordingly, the polygonal cross-sectional shape generally rotates about the longitudinal axis LA as the anchoring projection extends distally. The distal end <NUM> has a recess, such as an inverted hexagonal pyramid, although other shapes, such as those described herein, are possible. The anchoring projection <NUM> includes a sharp leading or distal edge <NUM> at the distal end <NUM> between the recess at the distal end and the surfaces <NUM>. The distal edge <NUM> has a polygonal (e.g., hexagonal) shape made out of a plurality of linear segments. The linear segments of the distal edge <NUM> are generally coplanar.

Referring to <FIG>, an anchoring projection for a tibial implant <NUM> according to another example is generally indicated at reference numeral <NUM>. In this example, the anchoring projection <NUM> has a generally polygonal (e.g., hexagonal) shape that tapers inward as the anchoring projection extends distally. The surfaces <NUM> of the polygonal shape are concave. As a result, the edges between the surfaces <NUM> generally define spines <NUM> of the anchoring projection <NUM> with a sharp edge. The spines <NUM> generally curve about the longitudinal axis LA of the anchoring projection as the spines extend distally. Accordingly, the polygonal cross-sectional shape generally rotates about the longitudinal axis LA as the anchoring projection extends distally. The distal end <NUM> has a recess, such as an inverted hexagonal pyramid, although other shapes, such as those described herein, are possible. The anchoring projection <NUM> includes a sharp leading or distal edge <NUM> at the distal end <NUM> between the recess at the distal end and the surfaces <NUM>. The distal edge <NUM> has a generally polygonal (e.g., hexagonal) shape made out of a plurality of segments. In this example, the line segments of the distal edge <NUM> are arcuate or curved (e.g., generally curved about an axis (e.g., horizontal axis) extending generally perpendicular to the longitudinal axis LA). As a result, the distal edge <NUM> has a generally saw-tooth configuration with a tooth or point being disposed at (e.g., defined by) the intersection of the two curved segments and a spine <NUM>.

Referring to <FIG> and <FIG>, an anchoring projection for a tibial implant <NUM> according to another example is generally indicated at reference numeral <NUM>. In this example, the anchoring projection <NUM> includes a cylindrical wall <NUM> extending distally from the distal surface <NUM> to a distal end <NUM>. The cylindrical wall <NUM> includes a generally cylindrical outer surface <NUM> and a generally cylindrical inner surface <NUM>. The cylindrical inner surface <NUM> defines a cavity or recess <NUM> of the anchoring projection, similar in function to the other recesses of the anchoring projections described herein. The cavity <NUM> extends from the distal surface <NUM> to the distal end <NUM>. The distal end <NUM> includes a generally planar distal surface. The inner and/or outer circumferential edge of the distal surface may be beveled, rounded, chamfered, sharp, fillet, etc. In the illustrated example, the inner edge of the distal surface of the distal end <NUM> is beveled. The outer and inner surfaces <NUM>, <NUM> each include one or more (e.g., a plurality of) circumferential spines <NUM> defined by circumferential, generally concave grooves extending into the cylindrical wall <NUM>. The spines <NUM> are space apart longitudinally along cylindrical wall <NUM>.

Referring to <FIG> and <FIG>, a tibial keel for a tibial implant <NUM> according to another example is generally indicated at reference numeral <NUM>. In this example, the tibial keel <NUM> is arcuate or curved. The tibial keel <NUM> curves about a transverse axis of the patient (e.g., a lateral or side-to-side axis that is generally parallel to the distal surface <NUM> of the tibial plate <NUM>) as the tibial keel extends distally from the distal surface of the tibial plate. In other words, the tibial keel <NUM> curves towards the front (e.g., in a forward direction) of the tibial implant <NUM>. As a result, the tibial keel <NUM> curves toward the tibial tubercle of the patient when the tibial implant <NUM> is implanted on the tibia T. The tibial tubercle is a cortical prominence commonly used as a landmark in orthopedic surgery. Aiming the nose of the tibial keel <NUM> at the tibial tubercle ensures additional cortical purchase and reduces the chance of lift off by being disposed closer to the cortical bone, as opposed to other keel designs. In addition, the curved tibial keel <NUM> has a larger surface area than straight keel designs. The larger front or anterior surface and rear or posterior surface of the tibial keel <NUM> provides greater resistance to lift off of the tibial implant <NUM> from the tibia T. In addition, due to the curved design, a portion of the posterior surface of the tibial keel <NUM> faces distally, increasing the overall amount of distal facing surface area, which increases the ability of the tibial implant <NUM> to resist subsidence. In addition to the tibial keel <NUM> being curved, the coronal and sagittal fins <NUM>, <NUM> of the tibial keel include piercing edges. The edges of the fins <NUM>, <NUM> may be tapered, sharp and/or serrated. Conventional insertion techniques require keel features to be drilled and/or broached into the tibia T before insertion the implant. The piercing edges of the tibial keel <NUM> facilitate insertion of the tibial implant <NUM> without any or minimal prior bone preparation. In addition, in this example, the tibial keel <NUM> also includes anchoring projections or spikes <NUM>. The anchoring projections <NUM> are configured to be inserted into the proximal end PE of the tibia T to further secure the tibial implant <NUM> to the tibia. In the illustrated example, the anchoring projections <NUM> are disposed on the posterior side of the tibial keel <NUM>, adjacent the edges of the coronal fins <NUM>.

Referring to <FIG>, an installation tool assembly for installing a curved keel tibial implant, such as the implant <NUM>, on the proximal end PE of the tibia T of the patient is generally indicated at reference numeral <NUM>. The installation tool assembly <NUM> includes a tibial trial handle <NUM> and an impaction guide <NUM>. The handle <NUM> includes a footprint template <NUM> used to determine the size of the tibia implant <NUM> to be implanted on the tibia T. The footprint template <NUM> may include one or more holes or spaces <NUM> to allow the tibial keel and/or anchoring projections to be inserted into the proximal end PE of the tibia T while the footprint template overlies the tibia. The footprint template <NUM> is releaseably coupled to one end of a shaft <NUM>. The shaft <NUM> has a generally circular cross-sectional shape. As explained in more detail below, the shaft <NUM> includes positioning recesses or depressions <NUM> used to position the impaction guide <NUM> on the handle <NUM>.

The impaction guide <NUM> is configured to insert the tibial implant <NUM> in a curved manner (e.g., in a curved or arcuate path CP) into the proximal end PE of the tibia T. The impaction guide <NUM> includes a mounting portion <NUM> and a driving portion <NUM>. The mounting portion <NUM> is configured to be coupled (e.g., releaseably coupled) to the handle <NUM>. The mounting portion <NUM> defines a handle opening <NUM> sized and shaped to receive the shaft <NUM> of the handle. The handle opening <NUM> has opposite open ends to allow the mounting portion <NUM> to slide over the end of the shaft <NUM> and along the shaft of the handle <NUM>. The handle opening <NUM> has a cross-sectional shape that matches or corresponds to the cross-sectional shape of the shaft <NUM> of the handle <NUM>. Thus, in the illustrated example, the handle opening <NUM> has a circular cross-sectional shape. The mounting portion <NUM> includes a detent or catch <NUM> configured to position and secure the mounting portion on handle <NUM>. The detent <NUM> is sized and shaped to be inserted into one of the recesses <NUM> along the handle to position and lock the impaction guide <NUM> in place on the handle <NUM>. In a locked position (<FIG>), the detent <NUM> generally extends into the handle opening <NUM>. When the impaction guide <NUM> is mounted on the handle <NUM>, the detent <NUM> extends into a recess <NUM> when the detent is in the locked position. The detent <NUM> may be reliantly biased toward the locked position, such as by a spring or a living hinge. Moving the detent to a release position (not shown), such that the detent <NUM> is spaced from the recess <NUM> (e.g., the handle opening <NUM>) permits the impaction guide <NUM> to move or slide along the handle <NUM>.

The driving portion <NUM> of the impaction guide <NUM> is configured to hold the tibial implant <NUM> and drive the tibial implant into the proximal end PE of the tibia T. The driving portion <NUM> is pivotably coupled to the mounting portion <NUM>. In the illustrated example, the driving portion <NUM> is coupled to the mounting portion <NUM> by a hinge <NUM> (e.g., shafts extending through aligned openings in the mounting and driving portions). Thus, the driving portion <NUM> generally rotates about an axis of rotation AR to drive the tibial implant <NUM> into the tibia T. The driving portion <NUM> includes a coupling head <NUM> configured to releasably couple to the tibial implant <NUM>. In particular, the coupling head <NUM> extends into the insert receiving space <NUM> and recesses <NUM> and engages the interior surface of the perimeter wall <NUM> to couple to the tibial implant <NUM>. The coupling head <NUM> is configured to form a snap-fit or compression fit with the tibial implant <NUM> to releasably coupled to the tibial implant. The coupling head <NUM> includes mounting inserts <NUM>, <NUM> (e.g., an anterior mounting insert and a posterior mounting insert). The mounting inserts <NUM>, <NUM> are configured to be inserted into the insert receiving space <NUM> and/or recesses <NUM>. The mounting inserts <NUM>, <NUM> generally conform to a portion of the perimeter wall <NUM> of the tibial implant <NUM>. The mounting inserts <NUM>, <NUM> are resiliently biased away from one another. The mounting inserts <NUM>, <NUM> move away from one another and engage the perimeter wall <NUM> of the tibial implant <NUM> to secure the tibial implant to the impaction guide <NUM>. To attach or release the tibial implant <NUM> from the coupling head <NUM>, the mounting inserts <NUM>, <NUM> are pushed toward one another to allow the inserts to move into or out of the insert receiving space <NUM>. In the illustrated example, resiliently deflectable arms <NUM> couple the mounting inserts <NUM>, <NUM> together. The arms <NUM> also define a portion of the hinge <NUM>. The illustrated arms <NUM> generally have a U-shape. The coupling head <NUM> also includes a contact surface <NUM> configured to be engaged or hit by a hammer (not shown) to rotate the driving portion <NUM> about the axis of rotation AR and drive the tibial implant <NUM> into the proximal end PE of the tibia T. The driving portion <NUM> is configured such that when the tibial implant <NUM> is attached to the coupling head <NUM>, the axis of curvature about which the curved tibial keel <NUM> curves about is generally collinear with the axis of rotation AR. The allows the driving portion <NUM> to move the tibial implant <NUM> along a curved path that generally corresponds to and matches the curve of the tibial keel <NUM>.

In one method of operation using the installation tool assembly <NUM>, a surgeon uses the handle <NUM> to select the appropriate size of tibial implant <NUM>. The surgeon uses the footprint template <NUM>, a procedure that is generally known in the art, to determine the size of the tibial implant <NUM> to be implanted on the proximal end PE of the tibia T. The handle <NUM> is also secured in place relative to the tibia T using conventional means known in the art. Once the size of the tibial implant <NUM> is determined, the surgeon selects the correct size of tibial implant and attaches it to the coupling head <NUM> of the impaction guide <NUM>. The tibial implant <NUM> is attached to the coupling head <NUM> by moving the mounting inserts <NUM>, <NUM> toward one another so that they can be inserted into the insert receiving space <NUM>. Once in the insert receiving space <NUM>, the mounting inserts <NUM>, <NUM> move away from one another and engage the perimeter wall <NUM> to secure the implant to the impaction guide <NUM>. The surgeon then inserts the shaft <NUM> of the handle <NUM> through the handle opening <NUM> of the mounting portion <NUM> and slides the impaction guide <NUM> along the handle. The surgeon aligns the detent <NUM> with the desired recess <NUM> to set and secure the impaction guide <NUM> at the desired position along the handle <NUM>. After, the surgeon uses a hammer to impact the contact surface <NUM> and drive the tibial implant <NUM> into the tibia T. The hammer rotates the driving portion <NUM> and tibial implant <NUM> about the axis of rotation AR, moving the tibial implant <NUM> along the curved path. In one example, surgeon may hammer the tibial implant <NUM> entirely into the proximal end PE of the tibia T before removing the installation tool assembly <NUM>. In another example, the surgeon may partially hammer the tibial implant <NUM> into the proximal end PE of the tibia T and then remove the installation tool assembly <NUM>. After the installation tool assembly <NUM> is removed, the surgeon drives the tibial implant <NUM> the rest of the way into the tibia T. For example, the surgeon may drive the tibial implant to an intermediate position such as about half way into the tibia T. In this example, the curved tibial keel <NUM> continues to guide the tibial implant <NUM> along the curved path as the implant is further driven into the tibia T. To detach the tibial implant <NUM> from the tibial implant <NUM>, the surgeon moves the mounting inserts <NUM>, <NUM> toward one another and then out of the insert receiving space <NUM>. As mentioned above, the tibial keel <NUM> of tibial implant <NUM> has sharp edges which allows the tibial implant <NUM> to be implanted without some prior bone preparation required to implant conventional tibial implant. Specifically, the step of preparing the tibia T for the tibia keel (e.g., predrilling a hole) is eliminated. In addition, the implanting of the curved keel tibial implant <NUM> as described herein reduces the dislocation, distraction and clearance needed to install the tibial implant over conventional straight keel implantation techniques.

Referring to <FIG>, a tibial keel for a tibial implant <NUM> according to another example is generally indicated at reference numeral <NUM>. In this example, the tibial keel <NUM> with coronal fins <NUM> and sagittal fins <NUM>. In this example, the edges of the fins and the nose of the tibial keel <NUM> is generally blunt (e.g., generally planar). In addition, the sagittal fins <NUM> of the tibial keel <NUM> include concave sides <NUM>. Other configurations of the tibial keel are within the scope of the present disclosure. For example, in one embodiment a tibial implant includes a tibial keel (not shown) at an angle to the vertical, such as slanted forward (instead of curved forward). The slanted angle of the tibial keel makes it easier to implant the tibial implant on the proximal end PE of the tibia T. The slanted tibial keel allows the tibial implant to start at a more forward or anterior position and then move rearward or posteriorly due to the slanted keel as the implant is driven into the proximal end PE of the tibia T. Being able to start the implantation of the tibia implant at a more anterior position, compared to straight keels, provides more clearance between the implant and other parts of the patient's body (such as the femur) and/or other surgical tools, making it easier to insert the implant into the tibia T.

It is understood that the elements, features and methods of and relating to the tibial implants <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> described herein can be applied to other bone implants, including but not limited to femoral implants and patella implants. For example, the porous regions of the tibial implant and be incorporated in other bone implants such as patella implant. An example of such a patella implant is generally indicated by reference numeral <NUM> in <FIG>. The patella implant <NUM> is sized and shaped to be implanted on the backside of the patella. The patella implant <NUM> includes a proximal or articulating surface <NUM> and an opposite distal surface <NUM>. The distal surface <NUM> is configured to engage the backside of the patella. The articulating surface <NUM> has a partial dome shape. The patella implant <NUM> includes a porous region, as discussed above. In particular, the distal surface <NUM> is porous (e.g., is a porous region). In the illustrated example, a portion of the distal surface <NUM> is porous, although in other examples the entire distal surface <NUM> may be porous. The portion of the distal surface <NUM> that is porous is generally centrally located on the distal surface and spaced apart the peripheral edge of the distal surface. The porous region has a generally circular shape disposed within the larger circular shape of the distal surface <NUM>. As shown in the illustrated example, the porous region comprises generally hexagonal struts coupled together to form a lattice, although any suitable porous structure is possible. As mentioned above the porosity of the distal surface <NUM> allows the patella implant <NUM> be inserted into or implanted on the patella without the cement conventionally used in knee arthroplasties, reducing procedural times, cement related complications and surgeon stress.

The patella implant <NUM> includes a cap <NUM> and a base or anchor <NUM> coupled together. The cap <NUM> defines (e.g., includes) the articulating surface <NUM> and a portion of the distal surface <NUM>. In the illustrated example, the portion of the distal surface <NUM> defined by the cap <NUM> is not porous. The cap <NUM> can be made out of a polymeric material or any other suitable material. The base <NUM> defines a portion of the distal surface <NUM>. In the illustrated example, the portion of the distal surface <NUM> defined by the base <NUM> is porous. The base <NUM> also includes at least one (e.g., a plurality of) anchoring projections <NUM>, similar to the anchoring projections discussed above. In the illustrated example, the patella implant <NUM> includes three anchoring projections <NUM>, although more or fewer anchoring projections are within the scope of the present disclosure. Each anchoring projection <NUM> extends generally distally from the distal surface <NUM>. In this example, each anchoring projection <NUM> is cylindrical (e.g., has a cylinder shape) with a shallow conical distal tip <NUM>. The anchoring projection <NUM> is also solid (<FIG>), although in other examples the anchoring projection can be hollow. The base <NUM> may be made out of a metal or any other suitable material.

The cap <NUM> and base <NUM> are configured to be coupled together to form the patella implant <NUM>. In the illustrated example, the cap <NUM> and the base <NUM> are configured to form a snap-fit connection. The base <NUM> includes a support ring <NUM> with opposite inner and outer circumferential edge margins or surfaces. As shown in <FIG>, the inner and outer edge margins of the support ring <NUM> are tapered away from one another as the edge margins extend generally upward. As a result, the proximal end of the support ring <NUM> is wider than the distal end of the support ring (e.g., a generally dovetail cross-sectional shape). The cap <NUM> includes a generally circumferential channel <NUM> or recess sized and shaped to receive the support ring <NUM>. The support ring <NUM> and the channel <NUM> have corresponding sizes and shapes. The cap <NUM> includes opposite inner and outer circumferential surfaces defining the sides of the channel <NUM>. The inner and outer surfaces of the cap <NUM> correspond to the taper of the inner and outer edge margins of the support ring <NUM>. As shown in <FIG>, the inner and outer surfaces of the cap <NUM> also tapper away from one another as the surfaces extend generally upward. As a result, the channel <NUM> has a mouth that is narrower than its base (e.g., a generally dovetail cross-sectional shape). To assemble the patella implant <NUM>, the support ring <NUM> of the base <NUM> is inserted into the channel <NUM> of the cap <NUM>. The cap <NUM> is resiliently deformable and may deform to enlarge the mouth of the channel <NUM> to allow the support ring <NUM> to pass therethrough before returning or snapping back toward its initial or at rest state, thereby securing the cap and base <NUM> together. The cap <NUM> engages the support ring <NUM> to secure the base <NUM> to the cap. The tapered inner and outer surfaces of the cap <NUM> and support ring <NUM> engage each other, respectively, to secure the cap and base <NUM> together. The support ring <NUM> also provides rigidity for the patella implant <NUM> and a mounting platform for the porous structure (e.g., hexagonal struts).

The base <NUM> may be constructed using the manufacturing techniques and processes discussed herein. For example, the base <NUM> can be constructed using hybrid manufacturing, as mentioned above. In a hybrid manufacturing process, the support ring <NUM> and anchoring projections <NUM> can first be created by conventional manufacturing methods, such as cold forming (e.g., stamping, cutting, deforming) a metal blank or by forging. The partially formed base <NUM> is then placed in an additive manufacturing machine which builds the porous regions thereon. The cap <NUM> is then attached to the base <NUM> to complete the construction of the patella implant <NUM>. The polymeric cap <NUM> may be formed by conventional methods such as compression molding.

Referring to <FIG>, various different systems and methods for verifying the implantation of an implant relative to the bone of a patient are disclosed. The following descriptions describe the different systems and methods for verifying the position or placement of knee arthroplasty implants relative to the bone. For example, these systems and methods can be used to verify the position of a tibial implant <NUM>, or any of the implants disclosed herein, relative to the proximal end PE of the tibia T of a patient. However, it is understood that these systems and methods for verifying the position of an implant can be used in other surgical applications besides knee arthroplasties.

Total knee arthroplasty relies on the proper placement of femoral and tibial implants. In conventional knee arthroplasty surgeries, the final placement of the implants depends on the surgical skill in both placing the implant on the bone and performing the saw cuts in the bone upon which the implant sits. There are a variety of different systems for creating the saw cuts in the bone. For example, the saw cuts for the implant can be driven by manual, non-computer assisted instruments, or with the aid of navigation instruments which provide computer assisted feedback on the saw cut positioning, or with a surgical robot which provides robotically-assisted guidance on saw cut positioning. Further details on surgical robots and robotically-assisted guidance on saw cut positioning may be found in <CIT>. While the implants generally follow the saw cuts, in conventional knee arthroplasties the final position of the implants is still dependent on surgical experience, skill, feel and eye. The follow systems and methods provide verification and confirmation on the position of the implant on the bone of the patient.

It is understood that the systems (e.g., surgical robots, tracking systems, etc.) and methods of performing knee arthroplasties disclosed in <CIT> may be used to perform, to guide, to assist in and/or in conjunction with knee arthroplasties using the systems (e.g., implants, position verification system, etc.) and methods (e.g., implant implantation, position verification, etc.) described herein.

Referring to <FIG>, a position verification system according to one example is generally indicated at reference numeral <NUM>. The position verification system <NUM> is configured to verify or determine the position of the tibial implant <NUM> relative to the proximal end PE of the tibia T. The position verification system <NUM> can be used during and/or after the implantation of the tibial implant <NUM> on the proximal end PE of the tibia T. The position verification system <NUM> includes a position indicator <NUM> and a tracker <NUM> (e.g., a tracking system). The position indicator <NUM> is configured to indicate the position of the tibial implant <NUM>. The tracker <NUM> is configured to track or locate, in real time, the position of the position indicator <NUM> (in 3D space) in order to determine the position of the of the tibial implant <NUM>. The position indicator <NUM> is configured to be positioned relative to the tibial implant <NUM> to indicate the position of the tibial implant. The position indicator <NUM> includes a plurality of (e.g., four) tracking markers or indicators <NUM> that are tracked by the tracker <NUM>. The indicators <NUM> are visual or optical markers that are recognized by the tracker <NUM>. In the illustrated example, the indicators <NUM> are spheres or balls, although any suitable optical marker is within the scope of the present disclosure. The position indicator <NUM> has a fixed geometry and the tracker <NUM> knows the geometry of the position indicator. Accordingly, by tracking the position of the indicators <NUM> on the position indicator <NUM>, the tracker <NUM> can determine or extrapolate the position of what the position indicator is touching or coupled to. In the example illustrated in <FIG>, the position indicator <NUM> comprises a stylus. The stylus <NUM> has a tip. In one example, the tip of the stylus <NUM> is a ball or sphere. As will be explained in more detail below, the surgeon may engage the tip of the stylus <NUM> with different components (e.g., the tibial implant <NUM>, arthroplasty tools, etc.) to determine the position of the tibial implant. The tracker <NUM> knows the position of the tip of the stylus <NUM> relative to the indicators <NUM>. The tracker <NUM> can determine the position of the tip of the stylus <NUM> using the indicators <NUM> and the known geometry of the stylus, and thereby the position of what the tip of the stylus is touching or is engaged with. Other configurations of the position indicator <NUM> are possible, some of which are described herein. For example, the position indicator <NUM> may be a dynamic reference array as described in <CIT>.

The tracker <NUM> tracks or locates the position indicator <NUM> to determine the position of the position indicator in the 3D space. The tracker <NUM> may be a camera based tracker (e.g., camera tracking system) such as the one described in <CIT>. The tracker <NUM> includes one or more cameras <NUM> wired or wirelessly coupled (e.g., in communication with) a tracking computer <NUM>. The cameras <NUM> are configured to capture images (e.g., pictures, video, etc.) of the position indicator <NUM> and the tracking computer <NUM> determines the position of the position indicator and the tibial implant <NUM> based on the indicators <NUM> in the images from the cameras. The tracking computer <NUM> may include a display (e.g., a video display) to output information to the surgeon, such as the position of the tibial implant <NUM> relative to the proximal end PE of the tibia T. The tracker <NUM> may also determine the position of the bone (e.g., tibia T) in the 3D space, as described in <CIT>, although other ways of determining the position of the bone are possible. In general, the tracker <NUM> compares the position of the tibia T to the position of the tibial implant <NUM> to determine the position of the implant relative to the tibia. The tracker <NUM> then outputs or displays this information to the surgeon. It is understood that the position verification system <NUM> may be part of a larger surgical system (e.g., larger robotic surgical system).

The position verification system <NUM> can be used in a variety of different ways to determine the position of the tibial implant <NUM> relative to the proximal end PE of the tibia T. In one method of operation as shown in <FIG>, the position verification system <NUM> is configured to mate or register with the one or more positioning guides <NUM> of the tibial implant <NUM> to determine the position of the tibial implant. In this embodiment, the position indicator <NUM> (e.g., tip of the stylus) mates or registers with the one or more positioning guides <NUM> of the tibial implant <NUM>. For example, the tip of the stylus <NUM> is inserted into the recesses <NUM> of the tibial implant <NUM>. The tracker <NUM> then determines the position of the one or more positioning guides <NUM> (e.g., recesses) to determine the position of the tibial implant <NUM> relative to the proximal end PE of the tibia T. For example, in one exemplary method, the surgeon positions the tibial implant <NUM> relative to the proximal end PE of the tibia, such as by placing the tibial implant on the proximal end of the tibia. After, the surgeon positions the position indicator <NUM> relative to the tibial implant <NUM>. The tracker <NUM> tracks the position indicator <NUM> to determine the position of the tibial implant <NUM> (e.g., the position of the tibial implant in the 3D space). In this example, the surgeon uses the stylus <NUM> to register or engage (e.g., touch), with the tip, the various positioning guides <NUM> (e.g., the position indicator directly engages the implant). The tracker <NUM> tracks the position of the position indicator <NUM> as the position indicator is positioned relative to the tibial implant <NUM>. In particular, the tracker <NUM> tracks the stylus <NUM> to determine the position of the positioning guides <NUM> and to extrapolate or determine the position of the tibial implant. In one example, the surgeon tells the tracker <NUM> when the stylus <NUM> is registered with a positioning guide <NUM> via a user interface of the tracker so the tracker knows what positions of the position indicator correspond to positions of the tibial implant <NUM> (e.g., positioning guides). As with the position indicator <NUM>, in this example, the tracker <NUM> knows the geometry of the tibial implant <NUM> and can determine the position of the tibial implant based on the known geometry of the tibial implant and the positions of the positioning guides <NUM>. In one example, the tracker <NUM> accesses the implant's geometry based on the position of the positioning guides <NUM>. As mentioned above, the positions of the positioning guides <NUM> can be used to encode information unique to that style (e.g., type, size, etc.) of implant. After determining the positions of the positioning guides <NUM>, the tracker <NUM> can access the implant database and use the positioning guide information (e.g., distances between positioning guides) to locate the specific implant in the database and associated implant information, such as the name, type, size, geometry, etc. In other examples, the surgeon may provide this information manually, via the user interface, to the tracker or enter information allowing the tracker to access the correct implant entry in the implant database.

Continuing with the method, at some point, the tracker <NUM> determines or is informed of the position of the tibia T (e.g., the position of the tibia in the 3D space). This can be before, during or after the position of the tibial implant <NUM> is determined. The position of the tibial implant <NUM> in the 3D space is then compared relative to the position of the tibia T in the 3D space in order to verify whether or not the tibial implant is correctly positioned on the proximal end PE of the tibia. The tracker <NUM> provides feedback to the surgeon regarding the position of the tibial implant <NUM> relative to the tibia T. The tracker <NUM> may compare the positions of the tibia T and the tibial implant <NUM> or may display information to allow the surgeon to compare the positions of the tibia and tibial implant. The tracker <NUM> or surgeon may compare the position of the tibial implant <NUM> relative to (e.g., on) the tibia T to a baseline or ideal position to determine if the tibial implant is correctly positioned. Ideal position is previously determined, such as by the surgeon, and is the theoretically perfect position of the tibial implant <NUM> on the tibia T (e.g., relative to the proximal end PE of the tibia). If the position of the tibial implant <NUM> relative to the tibia T aligns with the ideal position (or is within an appropriate margin of error), the tibial implant is correctly position and the surgeon can proceed with the rest of the surgery. If the position of the position of the tibial implant <NUM> relative to the tibia T does not align with the ideal position, the surgeon adjusts the position of the implant as needed before proceeding with the surgery. After the tibial implant <NUM> is repositioned, the surgeon can repeat the steps of above to determine the whether the new or adjusted position of the tibial implant is correct. This same process can be used to determine the position of other implants relative to a bone. For example, as shown in <FIG>, the same process can be used to verify the position of a femoral implant <NUM> by registering the position indicator <NUM> of the position verification system <NUM> with the one or more positioning guides <NUM> of the femoral implant.

Referring to <FIG>, in another method of operation, the position verification system <NUM> is configured to mate or register with the one or more positioning guides <NUM> on an arthroplasty tool <NUM> (e.g., a tibial installation tool, a femoral installation tool) to determine the position of the tibial implant <NUM>. The arthroplasty tool <NUM> is configured to releasably attach to the tibial implant <NUM>. When the arthroplasty tool <NUM> and tibial implant <NUM> are coupled together, the arthroplasty tool is rigidly and immovably secured to the tibial implant. The arthroplasty tool <NUM> can be any suitable tool, such as an implant (e.g., tibial implant, femoral implant) holder. The arthroplasty tool <NUM> includes one or more positioning guides <NUM>, as described above. In this example, the position indicator <NUM> (e.g., tip of the stylus) mates or registers with the one or more positioning guides <NUM> of the arthroplasty tool <NUM> (e.g., the position indicator indirectly engages the implant via the tool). The tracker <NUM> then determines the position of the one or more positioning guides <NUM> (e.g., recesses) to determine the position of the arthroplasty tool <NUM> and then determine the position of the tibial implant <NUM>. For example, in one exemplary method, the surgeon positions the tibial implant <NUM> relative to the proximal end PE of the tibia, such as by placing the tibial implant on the proximal end of the tibia. In one embodiment, the surgeon may place the tibial implant <NUM> using the arthroplasty tool <NUM> and leave the tool attached to the implant. In another example, the surgeon attaches the arthroplasty tool <NUM> to the tibial implant <NUM> after the tibial implant is implanted on the tibia T. After, the surgeon positions the position indicator <NUM> relative to the tibial implant <NUM>. The tracker <NUM> tracks the position indicator <NUM> to determine the position of the tibial implant <NUM>. In this example, the surgeon uses the stylus <NUM> to register or engage (e.g., touch), with the tip, the various positioning guides <NUM> of the arthroplasty tool <NUM>. The tracker <NUM> tracks the position of the position indicator <NUM> as the position indicator registers with the positioning guides <NUM> of the arthroplasty tool <NUM>. The tracker <NUM> tracks the stylus <NUM> to determine the position of the positioning guides <NUM> and to extrapolate or determine the position of the arthroplasty tool <NUM> and of the tibial implant <NUM>. As with the position indicator <NUM>, in this example, the tracker <NUM> knows the geometry of the tibial implant <NUM>, the geometry of the arthroplasty tool <NUM> and the relative orientation and position of the tibial implant and arthroplasty tool when the arthroplasty tool is attached to the tibial implant. The tracker <NUM> uses this information to determine the position of the tibial implant based the positions of the positioning guides <NUM>. As discussed above, the positioning guides <NUM> can be used to access the relevant information (e.g., geometry, orientation and location of a tibial implant attached to the tool) regarding the arthroplasty tool.

After the tracker <NUM> determines the position of the tibial implant <NUM>, the process is generally the same as above. The tracker <NUM> determines or is informed of the position of the tibia T. The position of the tibial implant <NUM> is then compared relative to the position of the tibia T in order to verify whether or not the tibial implant is correctly positioned on the proximal end PE of the tibia. If the position of the tibial implant <NUM> relative to the tibia T is correct, the surgeon can proceed with the rest of the surgery. If the position of the position of the tibial implant <NUM> relative to the tibia T is incorrect, the surgeon adjusts the position of the implant as needed before proceeding with the surgery. This same process can be used to determine the position of other implants relative to a bone. For example, as shown in <FIG>, the same process can be used to verify the position of a femoral implant <NUM> by registering the position indicator <NUM> of the position verification system <NUM> with the one or more positioning guides <NUM> of an arthroplasty tool <NUM> coupled to the femoral implant.

Referring to <FIG>, in another method of operation, the position verification system <NUM> is configured to engage the tibial implant <NUM> at a plurality of different locations on the tibial implant to determine the position of the tibial implant. In this embodiment, the surgeon brushes or moves the position indicator <NUM> (e.g., the tip of the stylus) over all or a portion of the tibial implant <NUM>. The tracker <NUM> tracks the position indicator <NUM> as the position indicator engages and moves over the tibial implant <NUM> to generate information (e.g., cloud points or cloud point data) corresponding to the size, shape and position of the tibial implant. For example, in one exemplary method, the surgeon positions the tibial implant <NUM> relative to the proximal end PE of the tibia, such as by placing the tibial implant on the proximal end of the tibia. After, the surgeon positions the position indicator <NUM> relative to the tibial implant <NUM>. The tracker <NUM> tracks the position indicator <NUM> to determine the position of the tibial implant <NUM>. In this example, the surgeon brushes or moves the tip of the stylus <NUM> over the tibial implant <NUM> or a target region thereof. For example, the surgeon may move the stylus back and forth over the tibial implant <NUM>. In this embodiment, the tip of the stylus <NUM> is configured to not damage (e.g., scratch) the tibial implant <NUM> as the tip slides over the implant. The tracker <NUM> tracks the position of the position indicator <NUM> as the position indicator brushes the tibial implant. The tracker <NUM> tracks the stylus <NUM> to determine the position of the tibial implant <NUM>. As the tacker <NUM> track the stylus cloud point data is generated corresponding to the size, shape (e.g., contours), and position of the tibial implant <NUM>. As with the position indicator <NUM>, in this example, the tracker <NUM> knows the geometry of the tibial implant <NUM> and uses this information to determine the position of the tibial implant based the cloud point data. Similar to the positioning guides <NUM> discussed above, in one embodiment, the cloud point data can be used to access the relevant information (e.g., geometry) regarding the tibial implant <NUM> from an implant database. The tracker <NUM> can align the geometric information or data from the implant database for the tibial implant <NUM> with the cloud point data, using surface matching algorithms, to determine the position of the tibial implant <NUM>.

After the tracker <NUM> determines the position of the tibial implant <NUM>, the process is generally the same as described in the embodiments above. The tracker <NUM> determines or is informed of the position of the tibia T. The position of the tibial implant <NUM> is then compared relative to the position of the tibia T in order to verify whether or not the tibial implant is correctly positioned on the proximal end PE of the tibia. If the position of the tibial implant <NUM> relative to the tibia T is correct, the surgeon can proceed with the rest of the surgery. If the position of the position of the tibial implant <NUM> relative to the tibia T is incorrect, the surgeon adjusts the position of the implant as needed before proceeding with the surgery. This same process can be used to determine the position of other implants relative to a bone. For example, as shown in <FIG>, the same process can be used to verify the position of a femoral implant <NUM> by brushing the position indicator <NUM> of the position verification system <NUM> over the femoral implant.

Referring to <FIG>, another example of a position indicator of the positioning system <NUM> is generally indicated a reference numeral <NUM>. In this example, the position indicator <NUM> is an array that is mounted (e.g., coupled) to an arthroplasty device, such as a tool, accessory or implant. The array <NUM> includes a frame supporting the indicators <NUM>. The position indicator <NUM> may be releasably coupled to the arthroplasty device or fixed to the arthroplasty device. When the position indicator <NUM> is mounted on the arthroplasty device, the position indicator is rigidly and immovable secured to the arthroplasty device. The position indicator <NUM> includes indicators <NUM>, as discussed above. In this example, the position indicator <NUM> is rigidly coupled to an arthroplasty tool <NUM>, such as the implant holder. As discussed above, the arthroplasty tool <NUM> is configured to releasably attach to the tibial implant <NUM>.

In an exemplary method of operation, the position verification system <NUM> is configured to track the position indicator <NUM> coupled to the arthroplasty tool <NUM> to determine the position of the tibial implant <NUM>. In this example, the position verification system <NUM> can provide feedback to the surgeon regarding the placement of the tibial implant <NUM> both during the implantation and after the implantation is completed. By being able to determine the position of the tibial implant <NUM> relative to the tibia T during implantation of the implant, the quality and quantity of available bone stock is enhanced. It can also eliminate the extra steps of checking the position of the implant after implantation. In one exemplary method, the position verification system <NUM> is used during implantation to guide the tibial implant <NUM> into position on the tibia T. The surgeon attaches the arthroplasty tool <NUM> with the position indicator <NUM> to the tibial implant <NUM> (e.g., the surgeon positions the position indicator relative to the tibial implant). The surgeon then positions the tibial implant <NUM> relative to the proximal end PE of the tibia. The surgeon moves the tibial implant <NUM> into place on the proximal end PE of the tibia T (e.g., moves the tibial implant toward the tibia) using the arthroplasty tool <NUM>. The tracker <NUM> tracks the position indicator <NUM> to determine the position of the tibial implant <NUM>. The tracker <NUM> tracks the position of the position indicator <NUM> as the position indicator moves with the arthroplasty tool <NUM> and tibial implant <NUM> toward the tibia T. The tracker <NUM> determines or extrapolates the position of the tibial implant <NUM> based on the position of the position indicator <NUM>. In this example, the tracker <NUM> knows the geometry of the tibial implant <NUM>, the geometry of the arthroplasty tool <NUM> (including the location of the position indicator <NUM> relative to the arthroplasty tool) and the relative orientation and position of the tibial implant and arthroplasty tool when the arthroplasty tool is attached to the tibial implant. The tracker <NUM> uses this information to determine the position of the tibial implant based the position of the position indicator <NUM>.

In one example, the relevant information to determine the position of the tibial implant <NUM> (e.g., the geometry of the tibial implant, the geometry of the arthroplasty tool <NUM> (including the location of the position indicator <NUM> relative to the arthroplasty tool) and the relative orientation and position of the tibial implant and arthroplasty tool when the arthroplasty tool is attached to the tibial implant) can be stored in an implant database. In this example, the surgeon may tell the tracker <NUM> which tibial implant <NUM> and arthroplasty tool <NUM> are being used via the user interface and access the appropriate information from the implant database. In another example, the relevant information to determine the position of the tibial implant <NUM> is taught to the tracker <NUM>. In this embodiment, the tibial implant <NUM> is attached to the arthroplasty tool <NUM> and then shown to the tracker <NUM> which then determines (e.g., gathers) the necessary information. For example, the surgeon can calibrate the location of the tibial implant <NUM> relative to the arthroplasty tool <NUM> using a variable region of the tibial implant. In this example, the tacker <NUM> may prompt to the surgeon to touch specific points on the tibial implant <NUM> and/or arthroplasty tool <NUM> using the stylus <NUM> to calibrate the tracker <NUM> using surface matching algorithms.

After the tracker <NUM> determines the position of the tibial implant <NUM>, the process is generally the same as described in the embodiments above. The tracker <NUM> determines or is informed of the position of the tibia T. The position of the tibial implant <NUM> is then compared relative to the position of the tibia T in order to verify whether or not the tibial implant is moving toward the correct position on the proximal end PE of the tibia. When using the position verification system <NUM> during placement or implantation of the tibial implant <NUM> on the tibia T, the tracker <NUM> or surgeon may compare the position of the tibial implant relative to the ideal position to verify that the tibial implant is moving toward (e.g., is inline with) the ideal position (as the tibial implant is implanted on the proximal end PE of the tibia T). If the tibial implant <NUM> is moving toward the ideal position, the surgeon can continue moving (e.g., inserting) the tibial implant <NUM> toward and into the tibia T, without making any adjustments. If the tibial implant is not moving toward the ideal position (e.g., is off track), the surgeon can make the necessary adjustments and corrections while moving the tibial implant <NUM> toward and into the tibia T. In this manner, the position verification system <NUM> guides the tibial implant <NUM> toward the ideal position.

In another exemplary method, the arthroplasty tool <NUM> is coupled or recoupled to the tibial implant <NUM> after the tibial implant is implanted on the tibia T to verify the position of the tibial implant relative to the tibia. In this example, the surgeon attaches the arthroplasty tool <NUM> with the position indicator <NUM> to the tibial implant <NUM> implanted in the tibia T (e.g., the surgeon positions the position indicator relative to the tibial implant). The tracker <NUM> tracks the position indicator <NUM> to determine the position of the tibial implant <NUM>. The tracker <NUM> tracks or locates the position of the position indicator <NUM> mounted on the arthroplasty tool <NUM> that is coupled to the tibial implant <NUM>. The tracker <NUM> locates the position indicator <NUM> to determine or extrapolate the position of the tibial implant <NUM>. As explained above, the tracker <NUM> knows the geometry of the tibial implant <NUM>, the geometry of the arthroplasty tool <NUM> (including the location of the position indicator <NUM> relative to the arthroplasty tool) and the relative orientation and position of the tibial implant and arthroplasty tool when the arthroplasty tool is attached to the tibial implant. The tracker <NUM> uses this information to determine the position of the tibial implant <NUM> based the position of the position indicator <NUM>.

After the tracker <NUM> determines the position of the tibial implant <NUM>, the process is generally the same as described in the examples above. The tracker <NUM> determines or is informed of the position of the tibia T. The position of the tibial implant <NUM> is then compared relative to the position of the tibia T in order to verify whether or not the tibial implant is correctly positioned on the proximal end PE of the tibia. When using the position verification system <NUM> to verify the position of the tibial implant <NUM> relative to the tibia T after the implant is implanted, the tracker <NUM> or surgeon may compare the position of the tibial implant relative to the ideal position to verify or confirm that the tibial implant is in the correct position on the tibia. If the position of the tibial implant <NUM> relative to the tibia T aligns with the ideal position, the tibial implant is correctly position and the surgeon can proceed with the rest of the surgery. If the position of the position of the tibial implant <NUM> relative to the tibia T does not align with the ideal position, the surgeon adjusts the position of the implant as needed before proceeding with the surgery. After the position of the tibial implant <NUM> is verified, the arthroplasty tool <NUM> can be removed or detached from the implant. These same processes can be used to determine the position of other implants relative to a bone. For example, as shown in <FIG>, the same process can be used to verify the position of a femoral implant <NUM> by tracking the position indicator <NUM> of the position verification system <NUM> mounted on an arthroplasty tool <NUM> coupled to the femoral implant.

Referring to <FIG>, in one example, the position verification system <NUM> includes an implant cover <NUM>. The implant cover <NUM> is configured to releasably couple to the implant. The implant cover <NUM> is sized and shaped to couple to the type of implant the cover corresponds to. For example, an implant cover <NUM> for a tibial implant <NUM> (<FIG>) may be similar to an insert and be sized and shaped to be secured in the insert receiving space <NUM> of the implant. In another example, the implant cover <NUM> is for a femoral implant <NUM> (<FIG>) and is sized and shaped to be secure over the implant. When the implant cover <NUM> is coupled to the implant, the implant cover is rigidly and immovable secured to the implant. Preferably, the implant cover <NUM> generally fits over the articulation surface of the implant. Generally, the tracker <NUM> uses the position of the implant cover <NUM> to determine the position of the implant. In this example, the position indicator <NUM>, <NUM> is rigidly coupled to the implant cover <NUM>. <FIG> shows one type of position indicator <NUM>, the stylus, coupled to the implant cover <NUM> for a tibial implant <NUM> and <FIG> shows another type of position indicator <NUM>, the array, coupled to the implant cover for a femoral implant <NUM>. Other types of position indicators may be coupled to the implant covers. In one example, the implant cover <NUM> may be coupled to the implant after the implant is placed on the bone to verify the position of the implant. In another example, the implant cover <NUM> may be coupled to the implant while the implant is being implanted on the bone to guide the implantation.

Still referring to <FIG>, in an exemplary method of operation, the position verification system <NUM> is configured to track the position indicator <NUM> coupled to the implant cover <NUM> to determine the position of the tibial implant <NUM>. In this example, the position verification system <NUM> can provide feedback to the surgeon regarding the placement of the tibial implant <NUM> both during the implantation and after the implantation is completed. In one exemplary method, the position verification system <NUM> is used during implantation to guide the tibial implant <NUM> into position on the tibia T. The surgeon attaches the implant cover <NUM> with the position indicator <NUM> to the tibial implant <NUM> (e.g., the surgeon positions the position indicator relative to the tibial implant). The surgeon also attaches the arthroplasty tool <NUM> to the tibial implant <NUM>. In one embodiment, the implant cover <NUM> is disposed between the tibial implant <NUM> and the arthroplasty tool <NUM> and moves with the arthroplasty tool. The surgeon then positions the tibial implant <NUM> relative to the proximal end PE of the tibia. The surgeon moves the tibial implant <NUM> into place on the proximal end PE of the tibia T (e.g., moves the tibial implant toward the tibia) using the arthroplasty tool <NUM>. The tracker <NUM> tracks the position indicator <NUM> to determine the position of the tibial implant <NUM>. The tracker <NUM> tracks the position of the position indicator <NUM> as the position indicator moves with the implant cover <NUM>, the arthroplasty tool <NUM> and the tibial implant <NUM> toward the tibia T. The tracker <NUM> tracks the position indicator <NUM> to determine the position of the implant cover <NUM> and to determine or extrapolate the position of the tibial implant <NUM> coupled thereto. In this example, the tracker <NUM> knows the geometry of the tibial implant <NUM>, the geometry of the implant cover <NUM> (including the location of the position indicator <NUM> relative to the implant cover) and the relative orientation and position of the tibial implant and implant cover when the implant cover is attached to the tibial implant. The tracker <NUM> uses this information to determine the position of the tibial implant <NUM> based the position of the position indicator <NUM>. This relevant information to determine the position of the tibial implant <NUM> known by the tracker <NUM> may be stored in an implant database and/or taught to the tracker, as explained above.

After the tracker <NUM> determines the position of the tibial implant <NUM>, the process is generally the same as described in the examples above. The tracker <NUM> determines or is informed of the position of the tibia T. The position of the tibial implant <NUM> is then compared relative to the position of the tibia T in order to verify whether or not the tibial implant is moving toward the correct position on the proximal end PE of the tibia. When using the position verification system <NUM> during placement or implantation of the tibial implant <NUM> on the tibia T, the tracker <NUM> or surgeon may compare the position of the tibial implant relative to the ideal position to verify that the tibial implant is moving toward (e.g., is inline with) the ideal position (as the tibial implant is implanted on the proximal end PE of the tibia T). If the tibial implant <NUM> is moving toward the ideal position, the surgeon can continue moving (e.g., inserting) the tibial implant <NUM> toward and into the tibia T, without making any adjustments. If the tibial implant is not moving toward the ideal position, the surgeon can make the necessary adjustments and corrections while moving the tibial implant <NUM> toward and into the tibia T. In this manner, the position verification system <NUM> guides the tibial implant <NUM> toward the ideal position.

In another exemplary method, the implant cover <NUM> is coupled to the tibial implant <NUM> after the tibial implant is implanted on the tibia T to verify the position of the tibial implant relative to the tibia. In this example, the surgeon attaches the implant cover <NUM> with the position indicator <NUM> to the tibial implant <NUM> implanted in the tibia T (e.g., the surgeon positions the position indicator relative to the tibial implant). The tracker <NUM> tracks the position indicator <NUM> to determine the position of the tibial implant <NUM>. The tracker <NUM> tracks or locates the position of the position indicator <NUM> mounted on the implant cover <NUM> that is coupled to the tibial implant <NUM>. The tracker <NUM> locates the position indicator <NUM> to determine or extrapolate the position of the tibial implant <NUM>. As explained above, the tracker <NUM> knows the geometry of the tibial implant <NUM>, the geometry of the implant cover <NUM> (including the location of the position indicator <NUM> relative to the implant cover) and the relative orientation and position of the tibial implant and implant cover when the implant cover is attached to the tibial implant. The tracker <NUM> uses this information to determine the position of the tibial implant <NUM> based the position of the position indicator <NUM>.

After the tracker <NUM> determines the position of the tibial implant <NUM>, the process is generally the same as described in the embodiments above. The tracker <NUM> determines or is informed of the position of the tibia T. The position of the tibial implant <NUM> is then compared relative to the position of the tibia T in order to verify whether or not the tibial implant is correctly positioned on the proximal end PE of the tibia. When using the position verification system <NUM> to verify the position of the tibial implant <NUM> relative to the tibia T after the implant is implanted, the tracker <NUM> or surgeon may compare the position of the tibial implant relative to the ideal position to verify or confirm that the tibial implant is in the correct position on the tibia. If the position of the tibial implant <NUM> relative to the tibia T aligns with the ideal position, the tibial implant is correctly position and the surgeon can proceed with the rest of the surgery. If the position of the position of the tibial implant <NUM> relative to the tibia T does not align with the ideal position, the surgeon adjusts the position of the implant as needed before proceeding with the surgery. After the position of the tibial implant <NUM> is verified, the implant cover <NUM> can be removed or detached from the implant. These same processes can be used to determine the position of other implants relative to a bone. For example, as shown in <FIG>, the same process can be used to verify the position of a femoral implant <NUM> by tracking the position indicator <NUM> of the position verification system <NUM> mounted on an implant cover <NUM> coupled to the femoral implant.

The order of execution or performance of the operations in examples described herein are not essential, unless specifically stated or indicated otherwise. That is, the operations may be performed in any order and/or simultaneously, and the examples may include additional or fewer operations than those disclosed herein. For example, it is contemplated that executing or performing a particular operation before, contemporaneously with, or after another operation is possible.

The tracking systems and methods described herein can also be used to determine the position of other elements and objects besides implants. In one embodiment, the tracking systems and methods described herein are used to determine the position of the bone the implant is attached to. For example, in one example similar to the examples shown in <FIG>, the surgeon may brush or move the position indicator <NUM> (e.g., the tip of the stylus) over all or a portion of the tibia T or proximal end PE thereof to determine the position of the tibia.

Referring to <FIG>, a patella implant according to the invention is generally indicated at reference numeral <NUM>. The patella implant <NUM> is sized and shaped to be implanted on the backside of a patella of a patient. The patella implant <NUM> includes a proximal or articulating surface <NUM> (e.g., proximal end) and an opposite distal surface <NUM> (e.g., distal end). The distal surface <NUM> is configured to engage the backside of the patella. The articulating surface <NUM> has a partial dome shape. The patella implant <NUM> includes a porous region, as discussed above. In particular, the distal surface <NUM> is porous (e.g., is a porous region). In the illustrated embodiment, a portion of the distal surface <NUM> is porous, although in other embodiments the entire distal surface <NUM> may be porous. The portion of the distal surface <NUM> that is porous is generally centrally located on the distal surface and spaced apart the peripheral edge of the distal surface. The porous region has a generally circular shape disposed within the larger circular shape of the distal surface <NUM>. As shown in the illustrated embodiment, the porous region comprises generally hexagonal struts coupled together to form a lattice, although any suitable porous structure is within the scope of the present disclosure. As mentioned above the porosity of the distal surface <NUM> allows the patella implant <NUM> be inserted into or implanted on the patella without the cement conventionally used in knee arthroplasties, reducing procedural times, cement related complications and surgeon stress.

The patella implant <NUM> includes a cap <NUM> and a base or anchor <NUM> coupled or secured together. The cap <NUM> is mounted on the base <NUM>. The cap <NUM> defines (e.g., includes) the articulating surface <NUM>. The cap <NUM> also defines a portion of the distal surface <NUM>. In the illustrated embodiment, the portion of the distal surface <NUM> defined by the cap <NUM> is not porous. The cap <NUM> includes a shroud or cover <NUM>. The shroud <NUM> includes the articulating surface <NUM>. The shroud <NUM> has a partial dome shape and defines an interior or cavity sized and shaped to receive a portion of the base <NUM>, as described in more detail below. The shroud <NUM> surrounds (e.g., covers) the proximal end portion of the base <NUM>. The cap <NUM> can be made out of a polymeric material or any other suitable material.

The base <NUM> is configured to be attached to the backside of the patella of the patient. The base <NUM> includes at least one (e.g., a plurality of) anchoring projections <NUM>, similar to the anchoring projections discussed above. The anchoring projections <NUM> are configured to be inserted into the backside of the patella. In the illustrated embodiment, the patella implant <NUM> includes three anchoring projections <NUM>, although more or fewer anchoring projections are within the scope of the present disclosure. Each anchoring projection <NUM> extends generally distally from the distal surface <NUM>. Specifically, the anchoring projections <NUM> extend from the cap support <NUM>, which is described in more detail below. In this embodiment, each anchoring projection <NUM> is cylindrical (e.g., has a cylinder shape) with a shallow conical distal tip <NUM>. The anchoring projection <NUM> is also solid, although in other embodiment the anchoring projection can be hollow. In addition, the base <NUM> defines a portion of the distal surface <NUM>. In the illustrated embodiment, the portion of the distal surface <NUM> defined by the base <NUM> is porous (see <FIG>). This permits the ingrowth of bone into the base <NUM> to further secure the base to the patella after the base is attached to the patella. Accordingly, the distal surface <NUM> faces and engages the patella when the patella implant <NUM> is attached to the patella. Thus, the porous region of the base <NUM> is configured to face the backside of the patella. The base <NUM> may be made out of a metal or any other suitable material.

The cap <NUM> and the base <NUM> are coupled (e.g., configured to be coupled) together to form the patella implant <NUM>. The base <NUM> includes a base support <NUM> mounted to the cap <NUM> (e.g., configured to attach to the cap). Specifically, the base support <NUM> is mounted to the shroud <NUM> of the cap <NUM>. The base support <NUM> is disposed in the interior of the shroud <NUM>, which is sized and shaped to receive the base support. To secure the cap <NUM> and the base <NUM> together, the cap and base includes a plurality of interconnection or interdigitation members. The interconnection members of the cap <NUM> and the base <NUM> mate and interlock with one another to secure the cap and the base to each other. The plurality of interconnection members of the cap <NUM> and the base <NUM> increase the resistance of the cap and the base from dissociation from one another and minimize the occurrence and intensity of micromotion, over conventional patella implants. The cap support <NUM> also provides rigidity for the patella implant <NUM> and a mounting platform for the porous structure (e.g., hexagonal struts) and the anchoring projections <NUM>.

Referring to <FIG>, the interconnection members of the cap <NUM> include a plurality of first connection members <NUM> (e.g., first projections). Likewise, the interconnection members of the base <NUM> include a plurality of first connection recesses <NUM>. Each first connection member <NUM> of the cap <NUM> is disposed (e.g., is configured to be disposed) in a corresponding one of the first connection recesses <NUM> of the base <NUM> to mount and secure the cap to the base (e.g., the first connection recesses receive or are configured to receive the first connection members). The first connection members <NUM> are spaced apart and extend into the interior of the shroud <NUM> from an interior surface thereof. The cap support <NUM> includes (e.g., defines) the first connection recesses <NUM>. The first connection recesses <NUM> extend generally inward from an exterior surface of the cap support <NUM>. The exterior surface of the cap support <NUM> and the interior surface of the shroud <NUM> correspond to and engage one another (<FIG>). In the illustrated embodiment, the exterior and interior surfaces have generally partial dome shapes.

Each first connection member <NUM> of the cap <NUM> interlocks (e.g., is configured to interlock) with a corresponding one of the first connection recesses <NUM> of the base <NUM>. Specifically, the size and shapes of the first connection member <NUM> and the first connection recesses <NUM> correspond to each other. The first connection recesses <NUM> are each undercut (in one or more directions) so as to prevent withdrawal of the first connection members <NUM> disposed therein. In the illustrated embodiment, each first connection recesses <NUM> includes a recess mouth <NUM> and a recess base or floor <NUM> opposite the recess mouth. The recess mouth <NUM> (e.g., an area and/or a diameter thereof) is smaller or narrower than the recess base <NUM> (e.g., an area and/or a diameter thereof). Each first connection recess <NUM> is at least partially defined by at least one cap support tapered surface <NUM> (e.g., first cap support tapered surface). In the illustrated embodiment, the first connection recess <NUM> includes one cap support tapered surface <NUM>, although other configurations are within the scope of the present disclosure. The cap support tapered surface <NUM> tapers outward as the cap support tapered surface extends inward. In the illustrated embodiment, the cap support tapered surface <NUM> extends inward from the recess mouth <NUM> (e.g., exterior surface of the cap support <NUM>). Correspondingly, in the illustrated embodiment, each first connection member <NUM> includes a free or connection end <NUM> opposite an attached end <NUM>. The attached end <NUM> is attached to the shroud <NUM> (e.g., the interior surface thereof). The attached end <NUM> (e.g., a cross-sectional area and/or a diameter thereof) is smaller or narrower than the connection end <NUM> (e.g., a cross-sectional area and/or diameter thereof). The attached end <NUM> of each first connection member <NUM> corresponds to the size and shape of the recess mouth <NUM> of the corresponding first recess member <NUM>. Likewise, the connection end <NUM> of each first connection member <NUM> corresponds to the size and shape of the recess base <NUM> of the corresponding first recess member <NUM>. Each first connection member <NUM> includes at least one connection member tapered surface <NUM> (e.g., first connection member tapered surface). In the illustrated embodiment, the first connection member <NUM> includes one connection member tapered surface <NUM>, although other configurations are within the scope of the present disclosure. The connection member tapered surface <NUM> is disposed between the connection end <NUM> and the attached end <NUM>. The connection member tapered surface <NUM> tapers outward as the connection member tapered surface extends away from the shroud <NUM> (e.g., the interior surface of the shroud). In the illustrated embodiment, the connection member tapered surface <NUM> extends from the shroud <NUM> (e.g., the interior surface thereof). The connection member tapered surface <NUM> and the cap support tapered surface <NUM> engage (e.g., are configured to engage) each other to connect the cap <NUM> and the base <NUM> together and to inhibit the withdrawal of the respective first connection members <NUM> from the respective first connection recesses <NUM>. In the illustrated embodiment, the first connection member <NUM> and the first connection recess <NUM> have generally truncated conical shapes.

Still referring to <FIG>, the interconnection members of the cap <NUM> further include a plurality of second connection members <NUM> (e.g., second projections). Likewise, the interconnection members of the base <NUM> include a plurality of second connection recesses <NUM>. Each second connection member <NUM> of the cap <NUM> is disposed (e.g., configured to be disposed) in a corresponding one of the second connection recesses <NUM> of the base <NUM> to mount and secure the cap to the base (e.g., the second connection recess receive or are configured to receive the second connection members). The second connection members <NUM> are spaced apart and extend into (e.g., extend radially into) the interior of the shroud <NUM> from the interior surface thereof. The second connection members <NUM> are disposed along a peripheral edge (e.g., an interior peripheral edge) of the cap <NUM> (e.g., shroud <NUM>). The second connection members <NUM> are spaced apart circumferentially along the peripheral edge of the shroud <NUM>. Accordingly, the second connection members <NUM> are generally disposed outward (e.g., radially outward) of the first connection members <NUM> (e.g., the first connection members are disposed generally inward of the second connection members). The cap support <NUM> includes the second connection recesses <NUM>. The second connection recesses <NUM> are disposed along a peripheral edge (e.g., an outer peripheral edge) of the cap support <NUM>. The second connection recesses <NUM> are spaced apart circumferentially along the peripheral edge of the cap support <NUM>. Accordingly, the second connection recesses <NUM> are generally disposed outward (e.g., radially outward) of the first connection recesses <NUM> (e.g., the first connection recesses are disposed generally inward of the second connection recesses).

Each second connection member <NUM> of the cap <NUM> interlocks (e.g., is configured to interlock) with a corresponding one of the second connection recesses <NUM> of the base <NUM>. Specifically, the size and shapes of the second connection members <NUM> and the second connection recesses <NUM> correspond to each other. As with the first connection recesses <NUM>, the second connection recesses <NUM> are each undercut (in one or more directions) so as to prevent withdrawal of the second connection members <NUM> disposed therein. As is apparent, the second connection members <NUM> have a different shape than the first connection member <NUM>. Likewise, the.

In the illustrated embodiment, each second connection recesses <NUM> includes a recess mouth <NUM> and a recess base or floor <NUM> opposite the recess mouth. In the illustrated embodiment, the recess mouth <NUM> has a generally hour-glass shape. The hour-glass shape of the recess mouth <NUM> is generally bent at a corner of the cap support <NUM>. Likewise, the recess base <NUM> has a generally hour-glass shape that is also bent. The recess mouth <NUM> (e.g., an area thereof) is smaller or narrower than the recess base <NUM> (e.g., an area thereof). Each second connection recess <NUM> is at least partially defined by a plurality of cap support tapered surfaces <NUM> (e.g., second cap support tapered surfaces). Each cap support tapered surface <NUM> tapers outward as the cap support tapered surface extends inward. The cap support tapered surfaces <NUM> taper outward in multiple different outward directions. In the illustrated embodiment, each cap support tapered surfaces <NUM> extends inward (e.g., generally radially inward) from the recess mouth <NUM> (e.g., exterior surface of the cap support <NUM>). Each cap support tapered surface <NUM> defines a side of the second connection recess <NUM>. Correspondingly, in the illustrated embodiment, each second connection member <NUM> includes a free or connection end <NUM> opposite an attached end <NUM>. The attached end <NUM> is attached to the shroud <NUM> (e.g., the interior surface thereof). The attached end <NUM> (e.g., a cross-sectional area thereof) is smaller or narrower than the connection end <NUM> (e.g., a cross-sectional area thereof). The attached end <NUM> of each second connection member <NUM> corresponds to the size and shape of the recess mouth <NUM> of the corresponding second recess member <NUM>. Likewise, the connection end <NUM> of each second connection member <NUM> corresponds to the size and shape of the recess base <NUM> of the corresponding second recess member <NUM>. Each second connection member <NUM> includes a plurality of connection member tapered surfaces <NUM> (e.g., second connection member taper surfaces). Each connection member tapered surface <NUM> is disposed between the connection end <NUM> and the attached end <NUM>. Each connection member tapered surface <NUM> tapers outward as the connection member tapered surface extends into the cap support <NUM> (e.g., the exterior surface of the cap support). In the illustrated embodiment, each connection member tapered surface <NUM> extends from the exterior surface of the cap support <NUM>. Each connection member tapered surface <NUM> engages a corresponding cap support tapered surface <NUM> to connect the cap <NUM> and the base <NUM> together and to inhibit the withdrawal of the respective second connection members <NUM> from the respective second connection recesses <NUM>.

Referring to <FIG> and <FIG>, the interconnection members of the cap <NUM> further includes a plurality of interconnecting struts <NUM>. Each interconnecting strut <NUM> extends between and interconnects two adjacent second connection members <NUM>. Likewise, the interconnection members of the base <NUM> further include a plurality of interconnecting voids <NUM>. Each interconnecting void <NUM> extends between and interconnects two adjacent second connection recesses <NUM>. Each interconnecting strut <NUM> of the cap <NUM> is disposed (e.g., configured to be disposed) in a corresponding one of the interconnecting voids <NUM> of the base <NUM> to further mount and secure the cap to the base (e.g., the interconnecting voids receive or are configured to receive the interconnecting struts). Accordingly and as illustrated in <FIG>, the interconnecting struts <NUM> and the second connection members <NUM> combine to form a continuous loop at encircles a portion of the base <NUM> (e.g., the cap support <NUM>). The continuous loop formed by the interconnecting struts <NUM> and the second connection members <NUM> is constrained from moving relative to the base <NUM> by the cap support <NUM>. Thus, like the first connection members <NUM> and the second connection members <NUM> alone, the continuous loop formed by interconnecting struts <NUM> and the second connection members secure and interlock the cap <NUM> and the base <NUM> together and inhibit movement of the cap relative to the base.

Other configurations of the interconnecting members of the cap <NUM> and the base <NUM> and other ways of attaching the cap and the base together are within the scope of the present disclosure.

The patella implant <NUM> can be constructed using the manufacturing techniques and processes discussed herein. The base <NUM> can be constructed using hybrid manufacturing. In a hybrid manufacturing process, the cap support <NUM> and the anchoring projections <NUM> can first be created or formed by conventional manufacturing methods, such as cold forming (e.g., stamping, cutting, deforming) a metal blank or by forging. The partially formed base <NUM> is then placed in an additive manufacturing machine which builds the porous regions thereon (e.g., on the cap support <NUM>). In other embodiment, the base <NUM> may be formed entirely by an additive manufacturing process. After the base <NUM> is formed, the cap <NUM> is then attached to (e.g., formed on) the base to complete the construction of the patella implant <NUM>. The polymeric cap <NUM> may be formed by conventional methods such as compression molding.

For example, in one method of forming the patella implant <NUM> involves forming the base <NUM> (and associated elements such as the interconnection members, anchoring projections <NUM>, etc.) and then molding (e.g., compression molding) a material (e.g., a polymeric material) onto the base (e.g., cap support <NUM>) to form the cap <NUM> with the articulating surface <NUM>. The molding includes substantially (if not completely) filling the first connecting recesses <NUM> with the material, to form the first connecting members <NUM>. Likewise, the molding includes substantially (if not completely) filling the second connecting recesses <NUM> with the material, to form the second connecting members <NUM>. Furthermore, the molding includes substantially (if not completely) filling the interconnecting voids <NUM> with the material, to form the interconnecting struts <NUM>.

Referring to <FIG>, another embodiment of a patella implant not according to the present invention is generally indicated at <NUM> (<FIG>). In this example, the configuration of the base <NUM> of the patella implant <NUM> is different from the configuration of the base <NUM> of the patella implant <NUM> of <FIG> (with the configuration of the cap <NUM> being generally the same as the cap <NUM> of <FIG>). In this example, the porous region of the base <NUM> is distally proud of the cap support <NUM>. In other words, the portion 1616A of the distal surface <NUM> defined by the porous region is distally proud of the portion 1616B of the distal surface defined by the cap <NUM>. This ensures maximal contact of the porous region with the bone to facilitate ingrowth of the bone into the porous region. In addition, in this example, the anchoring projections <NUM> each includes a porous region. In the illustrated example, the porous region generally extends over the entire exterior surface of the anchoring projections <NUM>, although other configurations are within the scope of the present disclosure. For example, the porous region may only extend over a portion of the anchoring projection (e.g., only along the sides). In the illustrated example, the porous regions of the anchoring projections <NUM> are continuous with the porous region of the base <NUM> that defines the portion 1616A of the distal surface <NUM>. The porous regions of the anchoring projections <NUM> and the base may have similar constructions and porosities, as illustrated, or different constructions and porosities.

In addition, in this example, the anchoring projections <NUM> are hollow (e.g., have a hollow core). The base <NUM> defines an elongate cavity <NUM> for each anchoring projection <NUM>. Each elongate cavity <NUM> extends from the exterior surface of the cap support <NUM>, through the cap support and into the anchoring projection <NUM>. The distal end of the elongate cavity <NUM> is adjacent the distal end <NUM> of the anchoring projection <NUM>. In the illustrated embodiment, the distal end of the elongate cavity <NUM> is closed. In other examples, the elongate cavity <NUM> may extend through the anchoring projection <NUM> (e.g., have an open distal end). The elongate cavity <NUM> reduces the amount of material needed to construct the base <NUM>, thereby reducing manufacturing costs over solid anchoring projections. In addition, the elongate cavity <NUM> forms another interconnecting member of the base <NUM> for further securing the cap <NUM> to the base <NUM>. In this example, the cap <NUM> may include elongate members or shafts (not shown), with each elongate member disposed (e.g., configured to be disposed) in a correspond one of the elongate cavities <NUM>. The elongate member of the cap <NUM> may be formed by (e.g., during the) molding, as described herein.

Referring to <FIG>, another embodiment a patella implant according to the present disclosure is generally indicated at <NUM>. In this embodiment, the base <NUM> of the patella implant <NUM> is generally the same as the base <NUM> of <FIG>, except that the porous region of the base <NUM> is distally proud of the cap support <NUM>, like the base <NUM> of <FIG>. In addition, each anchoring projection <NUM> includes bone connection structures <NUM> (besides porous regions) on the exterior of the projection to facilitate the connection of the bone to the anchoring projections. The bone connection structure <NUM> generally increase the surface area of the anchoring projections <NUM> to increase the amount of contact between the bone and the anchoring projection, thereby increase the strength of the connection between the bone and the anchoring projection. In the illustrated embodiment, the bone connection structures <NUM> comprise ridges, separated by grooves, extending along the outer surface of each anchoring projections <NUM>. The grooves defining the ridges enhance the press-fit with the bone by providing reliefs for the bone to compress into. The ridges and grooves generally run axially along the anchoring projections <NUM>. The size (e.g., width) of the grooves and/or ridges can be constant along the length of the anchoring projections <NUM>, as shown, or can vary along the length of the anchoring projections. Other dimensions (e.g., depth, diameter, etc.) of the ridges and/or grooves can vary or be constant as well. In the illustrated embodiment, the ridges and grooves are large enough to be visible to the human eye, although in other embodiments the ridges and/or grooves may be significantly smaller such that they cannot be observed by the human eye (e.g., are microscopic). Other configurations of the bone connection structures are within the scope of the present disclosure. For example, the bone connection structures can comprise spherical dimples, similar to golf balls. In still another example, the bone connection structure may comprise a rough exterior surface of the anchoring projections <NUM>.

Referring to <FIG>, another example of a base for a patella implant is generally indicated at <NUM>. In this example, the base <NUM> is generally the same as the base <NUM> of <FIG>, except that the anchoring projections <NUM> do not have porous regions like the anchoring projections <NUM> of <FIG>. As is apparent, a cap, as described herein, may be connected to the base <NUM> to form a patella implant (not shown).

Referring to <FIG>, another embodiment of a patella implant according to the present disclosure is generally indicated at <NUM>. In this embodiment, the base <NUM> of the patella implant <NUM> is generally the same as the base <NUM> of <FIG>, except for the configuration of the bone connection structure. In this embodiment, the bone connection structure <NUM> includes dovetail grooves (e.g., a plurality of dovetail grooves). In one embodiment, each dovetail groove may taper (in one or more directions) along the anchoring projection <NUM>. In the illustrated embodiment, each dovetail groove tapers (e.g., narrows) in depth as the dovetail groove extends along the anchoring projection <NUM>, away from the porous region of the base <NUM>. In addition, in the illustrated embodiment, each dovetail groove tapers (e.g., narrows) in width as the dovetail groove extends along the anchoring projection <NUM>, away from the porous region of the base <NUM>. In another embodiment, each dovetail groove may remain a constant size along the length of the anchoring projection <NUM>. In yet another embodiment, each dovetail groove may taper (e.g., widen) in depth and/or width as the dovetail groove extends along the anchoring projection <NUM>, away from the porous region of the base <NUM>. In yet another embodiment, each dovetail groove may have one or more dimensions (e.g., depth, width, etc.) that remain constant and one or more dimensions (e.g., depth, width, etc.) that taper (e.g., narrows or widens) as the dovetail groove extends along the anchoring projection <NUM>, away from the porous region of the base <NUM>. For example, the depth of the dovetail groove can remain constant while the width tapers, or vice versa. In the illustrated embodiment, the bottom or base of the dovetail groove is rounded or curved. In another embodiment, the bottom of the dovetail groove may be generally flat or planar.

As is apparent, the implants <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> disclosed herein are generally analogous to one another and, thus, for ease of comprehension, where similar or analogous parts are used between the various different implants (or elements thereof, such as bases <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>), reference numerals having the same last two digits are employed. For example, tibial keel <NUM> is analogous to tibial keel <NUM> and, thus, these two tibial keels have the same last two digits of "<NUM>. " In another example, base <NUM> is analogous to base <NUM> and, thus, these two bases have the same last two digits of "<NUM>. " Thus, unless clearly stated or indicated otherwise, the above descriptions regarding the implants and elements thereof apply equally to all the analogous implants and the elements thereof. For example, at least some of the description related to anchoring projection <NUM> may also apply to anchoring projection <NUM> and/or vice versa. In another example, at least some of the description related to base <NUM> may also apply to base <NUM> and/or vice versa.

It is apparent and understood that the elements, features, and/or teachings set forth in each embodiment disclosed herein are not limited to the specific embodiment(s) the elements, features, and/or teachings are described in. Accordingly, it is apparent and understood that the elements, features, and/or teachings described in one embodiment may be applied to one or more of the other embodiments disclosed herein. For example, it is understood that any of the tibial keels disclosed herein may have sharp edges present on tibial keel <NUM>. In another example, the methods and features of one position verification method may be used with another position verification method.

Modifications and variations of the disclosed embodiments are possible without departing from the scope of the invention defined in the appended claims.

When introducing elements of the present disclosure or the embodiment(s) thereof, the articles "a", "an", "the" and "said" are intended to mean that there are one or more of the elements.

Claim 1:
A patella implant (<NUM>) for knee arthroplasty comprising:
- a cap (<NUM>) including an articulating surface (<NUM>), the cap (<NUM>) having a plurality of first connection members (<NUM>); and
- a base (<NUM>) configured to be attached to the backside of a patella of a patient, the base (<NUM>) including a cap support (<NUM>) mounted to the cap (<NUM>), the cap support (<NUM>) including a plurality of first connection recesses (<NUM>), wherein each first connection member (<NUM>) of the cap (<NUM>) is disposed in a corresponding one of the first connection recesses (<NUM>) of the cap support (<NUM>) to mount the cap (<NUM>) to the base (<NUM>), wherein the cap (<NUM>) includes a plurality of second connection members (<NUM>) and the cap support (<NUM>) of the base (<NUM>) includes a plurality of second connection recesses (<NUM>),
wherein each second connection member (<NUM>) of the cap (<NUM>) is disposed in a corresponding one of the second connection recesses (<NUM>) of the cap support (<NUM>) to mount the cap (<NUM>) to the base (<NUM>), wherein the second connection members (<NUM>) have a different shape than the first connection members (<NUM>) and the second connection recesses (<NUM>) have a different shape than the first connection recesses (<NUM>),
wherein the cap support (<NUM>) includes a plurality of interconnecting voids (<NUM>), each interconnecting void (<NUM>) extending between and interconnecting two adjacent second connection recesses (<NUM>), and wherein the cap (<NUM>) includes a plurality of interconnecting struts (<NUM>), each interconnecting strut (<NUM>) extending between and interconnecting two adjacent second connection members (<NUM>), each interconnecting strut (<NUM>) disposed in a corresponding one of the interconnecting voids (<NUM>).