Patent Description:
Hip arthroplasty, often called hip replacement, is a surgical procedure used to reconstruct and resurface a hip joint that has been damaged by disease or injury, such as by arthritis or hip fracture. Total hip arthroplasty devices replace both acetabulum and the femoral head which comprise the hip joint, where the femur articulates relative to the acetabulum. To replace the hip joint, hip arthroplasty includes a femoral implant secured to the end of the femur and an acetabular implant secured to the acetabulum that forms a replacement articulating surface which interfaces with the femoral implant. The femoral implant is pivotably coupled to the acetabular implant, thereby reconstructing the hip joint.

<CIT> and <CIT> both disclose apparatuses for removing liners known in the art.

Further advantageous aspects of the invention are set forth in the dependent claims.

In one aspect of the disclosure, an apparatus for removing a liner attached to an implanted acetabular shell is provided. The apparatus includes a rim plate, a pilot hole drill tip and a removal tool.

The rim plate has a plurality of drill guide openings and is adapted to be placed on top of the implanted acetabular shell. The pilot hole drill tip is sized to be inserted into each of the drill guide openings of the rim plate to create a pilot hole in the attached liner. The removal tool has an elongate shaft and a threaded tip extending from the shaft. The threaded tip is sized to be inserted into the pilot hole for detaching the attached liner from the implanted acetabular shell.

It is further described but does not form part of the invention a method of removing a liner attached to an implanted acetabular shell is provided. A surgical site is accessed where the acetabular shell has already been implanted into a patient. A rim plate having a through opening is placed over the acetabular shell. A pilot hole is then drilled into the attached liner through the opening in the placed rim plate. After the drilling, the rim plate is removed to expose the drilled hole. A removal tool is inserted into the drilled pilot hole. The attached liner is then disengaged from the implanted acetabular shell with the inserted removal tool.

It is further described but does not form part of the invention, an implant removal tool system, preferably for removing a trial femoral head from a trial dual mobility (DM) mobile insert, is provided. The preferred system includes a trial femoral head, a trial mobile insert, a removal instrument and an impactor for removing the trial femoral head from the trial mobile insert. The trial mobile insert having an attached femoral head is placed over the removal instrument. The impactor's impaction tip is inserted through an opening of the trial mobile insert and its distal end is configured to be in contact with an external surface of the attached femoral head. When force is applied to the impactor, the attached trial femoral head disengages from the attached trial mobile insert.

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

Grayscale shading in the drawings indicates a portion of a component that was cut by a section plane.

Various different systems for carrying out and performing hip arthroplasty are disclosed here. The different systems for hip arthroplasty disclosed herein include implants (e.g., acetabular implants and components thereof) and installation or arthroplasty tools for installing the implants. The different methods for hip arthroplasty disclosed herein include methods for installing acetabular implants.

Referring to <FIG>, an acetabular implant for hip arthroplasty is generally indicated at reference numeral <NUM>. In the illustrated embodiment, the implant <NUM> is a fixed-bearing type implant. The implant <NUM> includes an acetabular shell <NUM>, an acetabular liner <NUM> and a femoral head <NUM>. The femoral head <NUM> is generally spherical, with a spherical outer surface. The femoral head <NUM> defines a stem cavity <NUM> sized and shaped to receive a stem (not shown) of a femoral implant (not shown) to couple the femoral head to the femoral implant. In some embodiment, the femoral head <NUM> may be considered part of the femoral implant.

Referring to <FIG>, the shell <NUM> is configured to be attached to an acetabulum (not shown) of a patient. Specifically, the shell <NUM> is implanted in the acetabulum of the patient. The shell <NUM> includes a body (e.g., a generally spherical wall) having an outer surface <NUM> and an inner surface <NUM>. The outer and inner surfaces <NUM>, <NUM> are generally spherically shaped. The outer surface <NUM> of the shell <NUM> is generally semi-spherical. The outer surface <NUM> may be porous to enable ingrowth of the bone into the shell <NUM> after the shell is placed in the bone in order to form a strong connection between the shell and the bone. The shell <NUM> has a proximal end <NUM> and a distal end <NUM>. The distal end <NUM> of the shell is generally located at the apex of the spherical body. The shell <NUM> includes (or defines) a central axis CA (e.g., a shell central axis) extending between the proximal and distal ends <NUM>, <NUM>. The central axis CA generally extends through the apex of the spherical body. The inner surface <NUM> of the shell <NUM> defines a shell cavity <NUM>. The shell cavity <NUM> is sized and shaped to receive the liner <NUM>. The inner surface <NUM> of the shell <NUM> includes a tapered shell section 22A, a spherical shell section 22B and a transition shell section 22C generally extending between the tapered shell section and the spherical shell section. The tapered shell section 22A is proximal of the spherical shell section 22B. The tapered shell section 22A tapers inward toward the central axis CA of the shell <NUM> as the tapered shell section extends distally toward the distal end <NUM>. Thus, the tapered shell section 22A has a generally truncated cone shape. In the illustrated example, the tapered shell section 22A extends distally from the proximal end <NUM>. The tapered shell section 22A tapers at an angle α (as shown in <FIG>) relative to the central axis CA (e.g., a line parallel to the central axis). Preferably, the angle α of the tapered shell section is within the inclusive range of about <NUM> degrees to about <NUM> degrees, and more preferably within the inclusive range of about <NUM> degrees to about <NUM> degrees, and more preferably about <NUM> degrees. For example, in one example, the angle α of the tapered shell section 22A is about <NUM> degrees. The tapered shell section 22A and transition shell section 22C extend circumferentially around the central axis CA. The spherical shell section 22B is generally spherically shaped (e.g., is a partial sphere) with an apex generally aligned with the central axis CA. Other configurations of the shell <NUM> are within the scope of the present disclosure. The proximal end <NUM> and the distal end <NUM> are opposite one to another in relation to the central axis CA. At the proximal end <NUM> it is provided the opening of the shell <NUM> which is almost circular and is delimited by and edge portion <NUM>.

The shell <NUM> includes (or defines) at least one fastener opening <NUM>. Each fastener opening <NUM> is sized and shaped to receive a fastener (not shown), such as a bone screw, to secure the shell <NUM> to the acetabulum. Each fastener opening <NUM> is disposed in the spherical shell section 22B of the inner surface <NUM>. In the illustrated example, the shell <NUM> includes three fastener openings <NUM>. The three fastener openings <NUM> are in a triangle arrangement, although other arrangements are within the scope of the present disclosure. More or fewer fastener openings <NUM> are also within the scope of the present disclosure. For example, the shell can include five fastener openings <NUM>. One example of a shell <NUM> having five fastener openings <NUM> is shown in <FIG> and another example of a shell <NUM> having five fastener openings is shown in <FIG>. The five fastener openings <NUM> of shell <NUM> are arranged in generally an X-shape. The five fastener openings <NUM> of shell <NUM> are arranged in generally two circumferential rows stacked on top of each other, with a first row closest to the apex of the spherical shell section 22B having two fastener openings and a second row furthest from the apex having three fastener opening, radially offset from the two fastener openings in the first row. Other numbers and/or arrangements of the fastener openings are within the scope of the present disclosure. The numerous fastener openings <NUM> give the surgeon flexibility for the placement of the fastener in the acetabulum.

Referring back to <FIG>, the shell <NUM> includes a tool interlocking structure <NUM>. The tool interlocking structure <NUM> is configured to mate with a shell insertion tool <NUM> (<FIG>) to inhibit the shell <NUM> from rotating relative to the shell insertion tool when the shell and shell insertion tool are coupled together. The shell insertion tool <NUM> includes threads that mate with threads of the shell <NUM> (at the apex) to couple the shell and shell insertion tool <NUM> together. The shell <NUM> includes a threaded opening <NUM> disposed at the apex of the spherical shell section 22B, and, thus, is generally aligned with the central axis CA. The shell insertion tool <NUM> threads into the threaded opening <NUM> to couple to the shell <NUM>. In the illustrated example, the tool interlocking structure <NUM> includes an insertion tool recess <NUM>. The insertion tool recess <NUM> is generally disposed at the apex of the spherical shell section 22B, and, thus, is generally aligned with the central axis CA. The insertion tool recess <NUM> is sized and shaped to revive a shell projection <NUM> of the shell insertion tool <NUM>. The insertion tool recess <NUM> includes at least one rotation inhibiting section 34A (e.g., lobe). In the illustrated example, the insertion tool recess <NUM> includes four rotation inhibiting sections 34A, although more or fewer are within the scope of the present disclosure. Each rotation inhibiting section 34A is sized and shaped to receive a rotation inhibiting structure 92A (e.g., projection) of the shell insertion tool to inhibit the shell <NUM> from rotating about the central axis CA when the shell and shell insertion tool <NUM> are coupled together. Each rotation inhibiting section 34A is offset from the central axis CA. When the shell insertion tool <NUM> and the shell <NUM> are coupled together, the shell projection <NUM> extends into (e.g., mates or registers with) the insertion tool recess <NUM> (e.g., each rotation inhibiting structure 92A extends into one of the rotation inhibiting sections 34A). The engagement between the shell projection <NUM> and the shell <NUM> at the insertion tool recess <NUM> (e.g., the rotation inhibiting structure 92A and the shell at the rotation inhibiting section 34A), prevents the shell from inadvertently rotating (e.g., about the central axis CA) and potentially uncoupling (e.g., unthreading) from the shell insertion tool <NUM>, especially if the inserter tool has not been threaded into the central threaded hole of the shell <NUM>.

The insertion tool recess <NUM> may have generally any shape. In the illustrated example, the insertion tool recess <NUM> has a generally circular shape with four rotation inhibiting sections 34A extending radially outward from a circumference of the circle at equally spaced intervals. Other configurations of the tool interlocking structure <NUM> are within the scope of the present disclosure. For example, the insertion tool recess can have other shapes and sizes. It is understood whatever the shape and size of the insertion tool recess, the shell projection of the shell insertion tool <NUM> has a corresponding (e.g., confirming, matching) size and shape.

In one example, referring to <FIG>, an insertion tool recess for a shell <NUM>, <NUM> according to another embodiment of the present disclosure is generally indicated at reference numeral <NUM>. In this embodiment, the insertion tool recess <NUM> has a generally circular shape with two rotation inhibiting sections 134A extending radially outward from a circumference of the circle on generally opposite sides thereof.

Referring to <FIG>, an insertion tool recess for a shell <NUM> according to another example of the present disclosure is generally indicated at reference numeral <NUM>. In this example, the insertion tool recess <NUM> has a generally polygonal (e.g., rectangular, square, etc.) shape with the corners (e.g., rounded corners) forming the rotation inhibiting sections 334A. Other polygonal shapes are within the scope of the present disclosure.

Referring to <FIG>, an insertion tool recess for a shell <NUM> according to another example of the present disclosure is generally indicated at reference numeral <NUM>. In this example, the insertion tool recess <NUM> has a generally triangular shape, with a generally center circle shaped section and three rotation inhibiting sections 434A, having generally triangular or trapezoidal shapes extending radially outward from the circle shaped section at equally spaced intervals.

Referring to <FIG>, an insertion tool recess for a shell <NUM> according to another example of the present disclosure is generally indicated at reference numeral <NUM>. In this example, the insertion tool recess <NUM> has a generally star shape (e.g., rounded star shape) with the points of the star shape forming the rotation inhibiting sections 534A. In the illustrated example, the star shape of the insertion tool recess <NUM> has four points, although more or fewer points are within the scope of the present disclosure.

Referring back to <FIG>, the liner <NUM> of the implant <NUM> is configured to be attached to the shell <NUM>. In particular, the liner <NUM> is sized and shaped to be disposed in the shell cavity <NUM> of the shell <NUM> (e.g., the shell cavity is sized and shaped to receive the liner). The liner <NUM> includes a body (e.g., a generally spherical wall) having an outer surface <NUM> and an inner surface <NUM>. The outer and inner surfaces <NUM>, <NUM> are generally spherically shaped. The inner surface <NUM> defines a liner cavity <NUM>. The liner cavity <NUM> is sized and shaped to receive at least one of a mobile insert, as described in more detail below, or the femoral head <NUM>. In the illustrated example, the liner cavity <NUM> is sized and shaped to receive the femoral head <NUM>. The inner surface <NUM> is generally semi-spherical. The inner surface <NUM> is smooth to permit the mobile insert or femoral head <NUM> received in the liner cavity <NUM> to articulate or pivot relative to the liner <NUM>. Optionally, the inner surface <NUM> may be polished to a mirror finish, especially if the part is metal. The liner <NUM> has a proximal end <NUM> and a distal end <NUM>. The distal end <NUM> of the liner <NUM> is generally located at the apex of the spherical body. The liner <NUM> includes (e.g., defines) a central axis CA1 (e.g., a liner central axis) extending between the proximal and distal ends <NUM>, <NUM>. The central axis CA1 generally extends through the apex of the spherical body. When the liner <NUM> is coupled to the shell <NUM> (e.g., disposed in the shell cavity <NUM>) the central axes CA, CA1 of the liner and shell are generally coextensive with one another.

The outer surface <NUM> of the liner <NUM> includes a tapered liner section 38A, a spherical liner section 38B and a transition liner section 38C generally extending between the tapered liner section and the spherical liner section. The tapered liner section 38A is proximal of the spherical liner section 38B. The spherical liner section 38B generally corresponds (e.g., is generally sized and shaped to conform) to the spherical shell section 22B of the shell <NUM>. Because a snap-fit receiver <NUM> (see <FIG>) and a snap-fit retainer <NUM> (see <FIG>) form a snap-fit connection between the shell and the liner when the liner is inserted into the shell cavity <NUM> of the shell, the liner <NUM> has been designed to have a small clearance between the spherical liner section 38B and the spherical shell section 22B. Specifically, the clearance is at least <NUM> and at most <NUM> in one example. The clearance provides the benefit of less rubbing between the liner <NUM> and the shell <NUM> to reduce the possibility of any shaving which could be detrimental to the patient.

The spherical shell section 38B is generally spherically shaped (e.g., is a partial sphere) with an apex generally aligned with the central axis CA. The transition liner section 38C generally corresponds (e.g., is generally sized and shaped to conform) to the transition shell section 22C of the shell <NUM> such that the transition liner section and the transition shell section generally mate (e.g., engage) when the liner <NUM> is coupled to the shell. In addition, the tapered liner section 38A generally corresponds (e.g., is generally sized and shaped to conform) to the tapered shell section 22A of the shell <NUM> such that the tapered liner section and the tapered shell section generally mate (e.g., engage) when the liner <NUM> is coupled to the shell. The tapered liner section 38A has a taper that corresponds to (e.g., matches) the taper of the tapered shell section 22A of the shell <NUM>. The tapered liner section 38A tapers inward toward the central axis CA1 of the liner <NUM> as the tapered liner section extends distally toward the distal end <NUM>. Thus, the tapered liner section 38A has a generally truncated cone shape. In the illustrated example, the tapered liner section 38A extends distally from the proximal end <NUM>. The tapered liner section 38A tapers at an angle β (<FIG>) relative to the central axis CA1 (e.g., a line parallel to the central axis). Preferably, the angle β of the tapered shell section is within the inclusive range of about <NUM> degrees to about <NUM> degrees, inclusive (<NUM> degrees to about <NUM> degrees exclusive), and more preferably within the inclusive range of about <NUM> degrees to about <NUM> degrees (<NUM> degrees to about <NUM> degrees exclusive), and more preferably about <NUM> degrees (<NUM> degrees exclusive). Preferably, the angle β is slightly greater than the angle α of the taper of the tapered shell section 22A. For example, in one example, the angle β of the tapered liner section 38A is about <NUM> degrees. The slightly larger angle β than the angle α ensures the tapered liner section 38A is received by and engages the tapered shell section 22A in an interference fit. The tapered liner section 38A is configured to engage the tapered shell section 22A to inhibit movement of the liner <NUM> relative to the shell <NUM> when the liner is disposed in the shell cavity <NUM> of the shell. When coupled together, the tapered liner section 38A and the tapered shell section 22A engage each other to inhibit the liner <NUM> from moving relative to the shell <NUM>. Specifically, the engagement of the tapered liner section 38A and the tapered shell section 22A inhibits the liner <NUM> from rotating, about an axis of rotation perpendicular to the central axes CA, CA1, relative to the shell <NUM>. The tapered liner section 38A and transition liner section 38C extend circumferentially around the central axis CA1. Other configurations of the liner are within the scope of the present disclosure.

The liner <NUM> constructed using (e.g., may be made from) any suitable material, such as a plastic, a metal (such as a cobalt-chrome alloy), or a ceramic. In certain applications, such as a dual mobility application (discussed in more detail below), constructing the liner from a ceramic may be preferred because ceramic is harder and smoother than metal, providing a better wear or bearing surface (e.g., inner surface <NUM> and or inner surface <NUM>). Ceramic liners are also better at preventing particles from being generated due to micro-motion between the liner <NUM> and the shell <NUM>, then metal liners.

Referring to <FIG>, <FIG> and <FIG>, the shell <NUM> and the liner <NUM> have corresponding connectors that secure the shell and liner together when the liner is disposed in the shell cavity <NUM> of the shell. In the illustrated example, the shell <NUM> and liner <NUM> form a snap-fit connection therebetween to couple and secure the shell and liner together. The shell <NUM> includes a snap-fit receiver <NUM> and the liner <NUM> includes a snap-fit retainer <NUM> sized and shaped to be received by the snap-fit receiver to form the snap-fit connection between the shell and the liner when the liner is inserted into the shell cavity <NUM> of the shell. The snap-fit receiver <NUM> includes a generally circumferential recess <NUM> and the snap-fit retainer <NUM> includes a generally circumferential lip <NUM> (e.g., detent, catch) that is sized and shaped to be received by (e.g., inserted into) the recess. The circumferential recess <NUM> and the circumferential lip <NUM> extend circumferentially around the central axes CA, CA1. The lip <NUM> is resiliently deflectable to permit the liner <NUM> to be inserted into the shell cavity <NUM> of the shell <NUM>. As the liner <NUM> is inserted distally into the shell cavity <NUM> of the shell <NUM>, the shell (e.g., tapered shell section 22A) deflects or deforms the lip <NUM>. Once the lip <NUM> is aligned with the recess <NUM>, the lip returns or snaps-back to its undeformed state (<FIG>), extending into the recess and forming the snap-fit connection securing the liner to the shell (<FIG>). Other configurations of the connectors securing the shell and liner together are within the scope of the present disclosure.

Referring to <FIG>, <FIG>, <FIG>, <FIG> and <FIG>, the shell <NUM> and the liner <NUM> may include corresponding interlocking structures to inhibit movement (e.g., rotation) of the shell and liner relative to one another. In the illustrated example, the shell <NUM> includes at least one shell interlocking structure <NUM> and the liner <NUM> includes at least one liner interlocking structure <NUM>. Preferably, the shell <NUM> includes a plurality of shell interlocking structures <NUM> and the liner <NUM> includes a plurality of liner interlocking structures <NUM>. In the illustrated embodiment, the shell <NUM> includes twelve shell interlocking structures <NUM> and the liner <NUM> includes twelve liner interlocking structures <NUM>, although more or fewer shell and liner interlocking structures are within the scope of the present disclosure. For example, the shell can include six shell interlocking structures and the liner can include six liner interlocking structures. The plurality of shell interlocking structures <NUM> are circumferentially spaced apart from one another (about the central axis CA of the shell <NUM>). Likewise, the plurality of liner interlocking structures <NUM> are circumferentially spaced apart from one another (about the central axis CA1 of the liner <NUM>). Each shell interlocking structure <NUM> is configured to mate (e.g., interlock) with one of the liner interlocking structures <NUM> to inhibit rotation of the liner <NUM> relative to the shell <NUM> about the central axes CA, CA1 when the liner is disposed in the shell cavity <NUM> of the shell. The shell interlocking structure <NUM> includes an interlocking recess <NUM> and the liner interlocking structure <NUM> includes an interlocking projection <NUM> that is sized and shaped to be received by the interlocking recess. In other words, the interlocking recess <NUM> and interlocking projection <NUM> have corresponding (e.g., matching) shapes and sizes. In the illustrated example, the shell interlocking structures <NUM> are disposed generally adjacent the proximal end <NUM> of the shell <NUM>. Preferably the interlocking features <NUM> are provided closer to the edge portion <NUM> defining the opening of the shell <NUM>. The liner interlocking structures <NUM> are also disposed generally adjacent the proximal end <NUM> of the liner <NUM>. When the shell <NUM> and liner <NUM> are coupled together, each interlocking projection <NUM> extends into (e.g., mates, registers or interlocks with) one of the interlocking recesses <NUM>. The engagement between the interlocking projections <NUM> of the liner <NUM> and the shell <NUM> at the interlocking recesses <NUM>, prevents the liner from inadvertently rotating (e.g., about the central axes CA, CA1) relative to the shell.

Referring to <FIG>, another example of an acetabular implant according to the present disclosure is generally indicated by reference numeral <NUM>. Implant <NUM> is generally analogous to implant <NUM> and, thus, unless clearly stated or indicated otherwise, the descriptions herein regarding implant <NUM> (and elements thereof such as shell <NUM> and liner <NUM>) also apply to implant <NUM>. In this example, the main difference between implant <NUM> and implant <NUM> is that implant <NUM> is a dual mobility type implant. Accordingly, the implant <NUM> further includes a mobile insert <NUM>. The mobile insert <NUM> is disposed between the liner <NUM> and the femoral head <NUM> and can articulate (e.g.. , rotate) relative to both the liner and the femoral head.

The mobile insert <NUM> is configured to couple to both the liner <NUM> and the femoral head <NUM>. In particular, the mobile insert <NUM> is sized and shaped to be disposed (e.g., received) in the liner cavity <NUM> of the liner <NUM>. In this example, the liner cavity <NUM> of the liner <NUM> is sized and shaped to receive the mobile insert <NUM>. The mobile insert <NUM> includes a body (e.g., a generally spherical wall) having an outer surface <NUM> and an inner surface <NUM>. The mobile insert <NUM> has a proximal end <NUM> and a distal end <NUM> (at generally the apex of the spherical body) with a central axis CA2 (e.g., a mobile insert central axis) extending therebetween (and through the apex of the spherical body). In the position shown in <FIG>, the central axis CA2 (see <FIG>) of the mobile insert <NUM> is generally coextensive with the central axes CA, CA1 of the shell <NUM> and the liner <NUM>. The outer and inner surfaces <NUM>, <NUM> are generally spherically shaped. The outer surface <NUM> is smooth to permit the mobile insert <NUM> to articular or pivot relative to the liner <NUM> (e.g., slide on the inner surface <NUM> of the liner). The spherical outer surface <NUM> forms the majority of a sphere. For example, in one example, the height (extending between the proximal and distal ends <NUM>, <NUM>) of the mobile insert <NUM> (e.g., height of the outer surface <NUM>) is within the inclusive range of about <NUM>% to about <NUM>% of an outer diameter of the mobile insert (e.g., diameter of the outer surface), or more preferably within the inclusive range of about <NUM>% to about <NUM>% of the outer diameter, or even more preferably about <NUM>% of the outer diameter. This larger outer surface <NUM> increases the range of motion between the mobile insert <NUM> and the liner <NUM> over conventional mobile inserts that are typically only semi-spherical.

The inner surface <NUM> of the mobile insert <NUM> defines a mobile insert cavity <NUM> sized and shaped to receive the femoral head <NUM>. The inner surface <NUM> is smooth to permit the mobile insert <NUM> to articular or pivot relative to the femoral head <NUM> (e.g., permit the femoral head to slide on the inner surface of the mobile insert). The mobile insert <NUM> is configured to attach to the femoral head <NUM> to prevent the mobile insert and femoral head from decoupling from one another. In the illustrated example, the mobile insert <NUM> is configured to form a snap-fit connection with the femoral head <NUM>. The inner surface <NUM> has a proximal rim <NUM>. The inner surface <NUM> generally extends proximally, in a spherical manner, from an apex of the sphere to the proximal rim <NUM>. In the illustrated example, the proximal rim <NUM> is distal of the proximal end <NUM>. Like the outer surface <NUM>, the inner surface <NUM> forms the majority of a sphere. For example, in one example, the height (between the apex of the spherical inner surface <NUM> and the proximal rim <NUM> and extending parallel to the central axis CA2) of the inner surface <NUM> (e.g., a height of the mobile insert cavity <NUM>) is within the inclusive range of about <NUM>% to about <NUM>% of an inner diameter of the inner surface <NUM>, or more preferably within the inclusive range of about <NUM>% to about <NUM>% of the inner diameter, or even more preferably about <NUM>% of the inner diameter. As a result, a proximal portion of the inner surface <NUM> generally tapers toward the central axis CA2 as it extends proximally toward the proximal rim <NUM>. This proximal portion of the inner surface <NUM> retains the femoral head <NUM> in the mobile cavity <NUM>. Thus, the inner surface <NUM> surrounds a majority of the spherical femoral head <NUM> to retain the femoral head in the mobile insert cavity <NUM>. The mobile insert <NUM> is constructed using a resiliently deflectable material. Accordingly, the mobile insert <NUM> (e.g., proximal rim <NUM>) is resiliently deflectable to permit the femoral head <NUM> to inserted into the mobile insert cavity <NUM>. As the femoral head <NUM> is inserted distally into the mobile insert cavity <NUM>, the mobile insert deflects or deforms (e.g., the proximal rim <NUM> expands radially outward) to enlarge the proximal end of the mobile insert cavity to permit the femoral head to pass therethrough. Once the femoral head <NUM> is in the mobile insert cavity <NUM> (e.g., the widest part of the femoral head has passed the proximal rim <NUM>), the mobile insert <NUM> returns or snaps-back to its undeformed state (<FIG>), forming the snap-fit connection and securing the femoral head to the mobile insert. In one example, an insertion tool or press (not shown) may be required to insert the femoral head <NUM> into the mobile insert cavity <NUM>.

The mobile insert <NUM> may also include a stem relief recess <NUM> at a proximal end of the mobile insert cavity <NUM>. The stem relief recess <NUM> is configured to receive (intermittently receive as need) a stem (not shown) of the femoral implant when the femoral implant (e.g., femoral head <NUM>) rotates relative to the mobile insert <NUM>. This increases the possible range of motion between the femoral implant and the mobile insert <NUM>. In the illustrated example, the stem relief recess <NUM> is generally defined by an inner circumferential chamfer (e.g., a tapered inner surface) of the mobile insert <NUM> extending between the proximal rim <NUM> and the proximal end <NUM> of the mobile insert. Other configurations of the mobile insert <NUM> are within the scope of the present disclosure.

In addition to the mobile insert <NUM>, the implant <NUM> has a liner <NUM> with a different configuration. The liner <NUM> does not includes a snap-fit retainer, such as snap-fit retainer <NUM>, to secure the liner to the shell <NUM>. In this example, the liner <NUM> is preferably made of a ceramic or metallic alloy such as cobalt chrome alloy, which may be generally unsuitable for forming a snap-fit retainer (e.g., the snap-fit retainer may break instead of resiliently deforming when inserted into the shell <NUM>). In the illustrated example, the shell <NUM> still includes a snap-fit receiver <NUM>, although in other examples, the snap-fit receiver may also be eliminated from the shell. In addition, in this example, the liner <NUM> does not include liner interlocking structures <NUM>. In the illustrated example, the shell <NUM> still includes the shell interlocking structures <NUM>, although in other examples, the shell interlocking structures may also be eliminated from the shell. Moreover, in this example, the liner <NUM> includes an alignment projection <NUM>. The alignment projection <NUM> generally extends distally from the apex of the spherical outer surface <NUM> of the liner <NUM>. The alignment projection <NUM> is configured to be inserted into the threaded opening <NUM> (broadly, an alignment recess) of the shell <NUM>. It is understood the alignment projection <NUM> could be configured to extend into a different recess (e.g., opening) of the shell <NUM>. The insertion of the alignment projection <NUM> into the alignment recess <NUM> facilitates the alignment and positioning (e.g., centering) of the liner <NUM> relative to the shell <NUM> when the liner is being coupled to the shell.

In operation, to implant an acetabular implant, such as implant <NUM>, into the acetabulum of a patient, first the surgeon prepares the acetabulum to receive the shell <NUM> of the implant. Preparing the acetabulum may include one or more of reaming, cutting, and the like to shape the acetabulum to receive the shell <NUM>. After, the surgeon couples the shell <NUM> to the shell insertion tool <NUM>. This may be done by threading the shell <NUM> onto the threads of the shell insertion tool. Coupling the shell <NUM> to the shell insertion tool <NUM> includes inserting the shell projection <NUM> of the shell insertion tool into the tool interlocking structure <NUM> (e.g., insertion tool recess <NUM>) of the shell. The mating of the tool interlocking structure <NUM> with the shell insertion tool <NUM> (e.g., shell projection <NUM>) while the shell and shell insertion tool are coupled together inhibits the rotation (and inadvertent decoupling) of the shell relative to the shell insertion tool, in particular while the shell is being implanted. The surgeon then uses the shell insertion tool <NUM> to implant the shell <NUM>. The surgeon generally moves the shell insertion tool <NUM>, with the shell <NUM> thereon, distally into the prepared section of the acetabulum. The surgeon may use a hammer (not shown) to contact the shell insertion tool <NUM> and drive the shell <NUM> into the acetabulum. After the shell <NUM> is in position, the surgeon detaches the shell insertion tool <NUM> from the shell <NUM>. This requires the disengagement (e.g., removal) of the shell projection <NUM> from the tool interlocking structure <NUM> and then unthreading (e.g., rotating) the shell insertion tool <NUM> from the shell <NUM>. If desired, the surgeon can then insert one or more fasteners (not shown) through the one or more fastener openings <NUM> to secure the shell <NUM> to the acetabulum.

The liner <NUM> is then inserted into the shell cavity <NUM> of the shell <NUM>. The liner <NUM> is moved distally into the shell cavity <NUM>. If the liner includes an alignment projection <NUM>, such as liner <NUM>, the surgeon aligns the alignment projection with the alignment recess <NUM>, <NUM> (e.g., the threaded opening in the illustrated example). As the surgeon moves the liner <NUM> distally, the alignment projection <NUM> moves distally into the alignment recess <NUM>, <NUM>. Insertion of the liner <NUM> also includes mating the one or more liner interlocking structures <NUM> with the one or more shell interlocking structures <NUM>. The surgeon rotates the liner <NUM> about the central axis CA1, such that the liner interlocking structures <NUM> align with the shell interlocking structures <NUM>. As the liner <NUM> is moved distally, the liner interlocking structures <NUM> mate with the shell interlocking structures <NUM>. Specifically, each liner interlocking projection <NUM> moves into one of the interlocking recesses <NUM> (through an open proximal side thereof). The mating of the shell and liner interlocking structures <NUM>, <NUM> inhibits the rotation, about the central axes CA, CA1, of the liner <NUM> relative to the shell <NUM>. The mating of the shell and liner interlocking structures <NUM>, <NUM> and the alignment projection <NUM> with the alignment recess <NUM>, <NUM> may occur generally simultaneously. Once the surgeon moves the liner <NUM> fully into the shell cavity <NUM>, the snap-fit connection will form between liner and the shell to secure the liner in the shell cavity of the shell. The tapered portion 38A of the liner <NUM> and tapered portion 22A of the shell <NUM> also create an interference fit to secure the liner in the shell. In fact, the interference fit of the tapered portion due to the difference in angles α and β may secure the liner <NUM> to the shell <NUM> even without the snap-fit connection. As the surgeon moves the liner <NUM> into the shell cavity <NUM>, the lip <NUM> of the liner is compressed and then expands (e.g., snaps-backs) into the recess <NUM> of the shell <NUM>, once they become aligned.

With a fixed-bearing implant, such as implant <NUM>, after the liner <NUM> is coupled to the shell <NUM>, the surgeon then inserts the femoral head <NUM> (which may already be attached to the stem of the femoral implant) into the liner cavity <NUM> of the liner. With a dual-mobility implant, such as implant <NUM>, the surgeon will first attach the mobile insert <NUM> to the femoral head <NUM> before inserting the mobile insert (and femoral head) into the liner cavity <NUM> of the liner <NUM>. The femoral head <NUM> may be attached to the stem of the femoral implant after it is coupled to the mobile insert <NUM>. To attach the mobile insert <NUM> to the femoral head <NUM>, the surgeon moves the femoral head distally into the mobile insert cavity <NUM>. As the femoral head <NUM> moves into the mobile insert cavity <NUM>, the femoral head expands the mobile insert <NUM> (e.g., the proximal end of the mobile insert cavity), which then retracts (e.g., snaps-back) once the femoral head is in the mobile insert cavity. In one embodiment, the surgeon uses a tool or press to couple the mobile insert <NUM> and the femoral head <NUM> together. The surgeon then insertions the mobile insert <NUM>, with the femoral head <NUM>, into the liner cavity <NUM> of the liner <NUM>.

The order of execution or performance of the operations in examples of the aspects of the present disclosure 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 of the aspects of the disclosure 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 within the scope of the present disclosure.

As is apparent, the implants <NUM>, <NUM> and elements thereof disclosed herein are generally analogous to one another and, thus, for ease of comprehension, where similar, analogous or identical parts are used between the various different implants (or elements thereof), reference numerals having the same last two digits are employed (and the same subsequent letter, if applicable). For example, shell <NUM> is analogous to shells <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> and, thus, all these shells have the same last two digits of "<NUM>. " Thus, unless clearly stated 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 insertion tool recess <NUM> may also apply to insertion tool recess <NUM> and/or vice versa. In another example, at least some of the description related to the inner surface <NUM> of shell <NUM> (e.g., the tapered shell section 22A, the spherical shell section 22B and the transition shell section 22C) applies equally to shells <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>.

For the materials of each component of dual-mobility application such as one shown in <FIG>, in one example, the acetabular shell <NUM> may be made of metal such as a Titanium alloy, liner <NUM> may be made of either ceramic material or metal such as a cobalt-chrome alloy. For ceramic materials, a preferred material may be Aluminum oxide (Al<NUM>O<NUM>). Ceramic material for the liner <NUM> may be preferred if the fit between the liner and the shell <NUM> is less than perfect which allows the two materials to rub together. Metal to metal rubbing from micro motion may cause metallic shavings or particles to be dislodged. The mobile insert <NUM> may be made of polyethylene material such as a compression-molded, GUR 1020E material. The femoral head <NUM> may be made of metal such as a cobalt-chrome alloy or ceramic material Aluminum oxide (Al<NUM>O<NUM>) material.

<FIG> disclose an impaction tool system for seating an acetabular shell in the acetabular space. When seating the acetabular shell with a conventional impaction tool whose tip is threaded into the central hole <NUM>, there is a possibility that a user may accidentally disengage the tool while orienting the shell in the acetabular space. Thus, it would be desirable to provide an impaction tool that prevents the user from unthreading and disengaging the tool from the shell.

<FIG> illustrate a shell insertion tool <NUM> with anti-rotation control according to an example of the present disclosure. The tool <NUM> has a hollow outer shaft <NUM> and an internal shaft <NUM> disposed within the outer shaft. The outer shaft <NUM> includes a distal sleeve <NUM>, an impactor sleeve <NUM> extending proximally from a proximal end of the distal sleeve <NUM>. The impactor sleeve <NUM> includes an impactor head <NUM>. In the example shown, the outer shaft <NUM> is a single integral piece which is formed from a single metal piece. In other examples, the distal sleeve <NUM> and the impactor sleeve <NUM> of the outer shaft <NUM> may be made from two separate pieces that are attached together such as by welding. The impactor sleeve <NUM> has an internal flat stop <NUM> which engages a corresponding stop <NUM> of the internal shaft <NUM>.

A distal end of the outer shaft <NUM> as shown in <FIG> has an anti-rotation projection feature <NUM>,<NUM> in the shape which is complementary to the anti-rotation recess <NUM>, <NUM>, <NUM> of the acetabular shell <NUM>. For example, <FIG> has a round projection <NUM> and four uniformly spaced semi-circular projections extending laterally from the round projection. The projection <NUM> of <FIG> is configured to be received in the complimentary anti-rotation recess <NUM> of the acetabular shell <NUM> as shown in <FIG> while the square shaped projection <NUM> of <FIG> is configured to be received in the complimentary anti-rotation recess <NUM> of the acetabular shell <NUM> as shown in <FIG>.

A distal end portion <NUM> of the internal shaft <NUM> has an external threading configured to be threaded into internal threading of the central hole <NUM>, as shown for example in <FIG>. A proximal end portion of the internal shaft <NUM> has a key feature such as a hex key configured to receive a hex driver for threading the internal shaft <NUM> into the acetabular shell <NUM>.

This anti-rotation feature of the present design provides rotational stability and is concentric or centered with the threaded central hole of the shell. The new shell inserter instruments can mate with the shell's rotational control feature and thread into the apical/central hole of the shell for insertion and impaction of the acetabular shell. Ultimately, the rotational control feature allows a fully seated positioning of the shell without the potential of unthreading the inserter from the shell.

<FIG> illustrates an insertion tool <NUM> according to another example. Unlike the insertion tool <NUM> of <FIG>, the impactor head <NUM> is part of the internal shaft <NUM>. An annular stop <NUM> of the internal shaft <NUM> and a flat stop <NUM> of the outer shaft <NUM> captures an internal spring <NUM> to provide a constant bias of an opposing force at all times. At rest, the insertion tool <NUM> is in an unthreaded position. The internal shaft <NUM> is captured in the outer shaft <NUM> by a pin <NUM> in an annular recess defined by a stop <NUM> and <NUM>. The pin <NUM> is permanently attached to the impactor sleeve <NUM> by welding, for example. The distal end portion of the internal shaft <NUM> and outer shaft <NUM> are the same as those of <FIG> and <FIG>.

<FIG> illustrate an insertion tool <NUM> according to another example. Unlike the other insertion tools, the insertion tool <NUM> is made of a single shaft <NUM> with an integrated impaction head <NUM>. The shaft <NUM> includes a distal end portion comprising a distal projection <NUM> having a lower outer surface designed to sit flush against the surface of the recess <NUM> without any rotation control and a threaded tip <NUM> extending distally of the distal projection <NUM>. When the threaded tip <NUM> is threaded into the threaded central hole <NUM>, the distal projection <NUM> does not engage the key feature of the recess <NUM> so that the insertion tool <NUM> may rotate relative to the acetabular shell <NUM> about the longitudinal axis of the central hole <NUM> with perhaps some resistance.

<FIG> is a cross-sectional view of a shell insertion tool <NUM> that attaches to a rim plate according to one aspect of the present disclosure. The use of the rim plate is intended to be an optional secondary step after the initial impaction of the shell <NUM> into the acetabulum. This rim plate method of impaction allows a greater contact surface area in which the force of impaction spreads out uniformly across the shell's exterior surface. This helps ensures proper seating of the shell <NUM> into the acetabulum. Although the rim plate impaction method is intended to be an optional secondary step, it may be a primary step without the initial impaction of the shell <NUM> with the tool <NUM> locked into the central opening <NUM> of the shell <NUM>.

The insertion tool <NUM> of <FIG> is identical to that of <FIG>, except that it attaches to a rim plate as shown in <FIG>. The rim plates are designed to fit over an upper surface of the acetabular shell. Similar to the acetabular shell, a rim plate <NUM> of <FIG> has a center hole <NUM> having an internal threading and an anti-rotation recess <NUM>. Similar to the recess of <FIG>, the recess <NUM> has a round projection and four uniformly spaced semi-circular projections extending laterally from the round projection. A rim plate <NUM> of <FIG> has an anti-rotation recess <NUM> which is square shaped. <FIG> is a bottom perspective view of the rim plate <NUM> of <FIG>. Similar to the liner <NUM> of <FIG>, the rim plate <NUM> has uniformly spaced interlocking tabs <NUM> that rests on corresponding interlocking recesses <NUM> of the shell <NUM>. In the example shown, there are six tabs <NUM> that rest on six of the twelve recesses <NUM> of the shell <NUM>.

Although only the insertion tool <NUM> is shown in conjunction with the rim plates, any of the insertion tools disclosed herein may be used with any of the rim plates.

All insertion tools as disclosed herein may be provided as part of a complete tool kit.

<FIG> illustrate one embodiment of an apparatus, according to the invention, for removing a liner <NUM> attached to an acetabular shell <NUM> that has been implanted into a patient. The apparatus includes a rim plate <NUM>, a pilot hole drill tip <NUM>, and a removal tool <NUM>.

The rim plate <NUM> is similar to the rim plates of <FIG> and is adapted to be placed on top of the attached liner <NUM> and the acetabular shell <NUM>. The rim plate <NUM> is adapted to be placed on the edge portion <NUM> of the acetabular shell <NUM>. The edge portion <NUM> defines the top portion of the acetabular shell <NUM>.

The rim plate <NUM> is provide with coupling elements arranged to cooperate with coupling elements provided in the acetabular shell <NUM> for rotationally coupling the liner <NUM> and the shell <NUM> with the rim plate <NUM>. The rim plate <NUM> has a set of downwardly extending tabs <NUM> having a conical exterior surface such that they extend downwardly and inwardly. The recesses <NUM> of the acetabular shell <NUM> have corresponding conical surfaces to receive and interlock with the tabs <NUM> of the rim plate <NUM>. When the tabs <NUM> are received in the corresponding recesses <NUM>, the rim plate <NUM> is rotationally coupled with the liner <NUM> and the shell <NUM>.

The rim plate <NUM> includes a set of drill guide openings <NUM> (six uniformly positioned circumferentially as shown in <FIG>) that guide the pilot hole drill tip <NUM> for drilling into the liner <NUM>. Each opening <NUM> is angled inwardly, toward the bottom center of the shell <NUM>, to guide the pilot hole drill tip <NUM> into the attached liner <NUM>. The rim plate <NUM> is preferably an almost circular plate and the drill guide openings <NUM> are positioned circumferentially. The drill guide openings <NUM> are preferably through openings and the axis of each drill guide opening <NUM> is radially angled inward, i.e. towards the center of the rim plate <NUM> and it is also inclined in relation to a longitudinal axis X of the rim plate <NUM>.

The angle G of each opening <NUM> relative to the central axis of the acetabular shell <NUM> (or relative to a perpendicular line to a planar upper surface of the rim plate <NUM>) is preferably identical to the taper angle β (see <FIG>) of the liner <NUM>. As shown in <FIG>, the taper angle β and the angle G of the opening <NUM> is in a range of <NUM> to <NUM> degrees and preferably about <NUM> degrees (<NUM> degrees inclusive when considering angles relative to the two opposed openings <NUM>). This ensures that the pilot hole drill tip <NUM> maximizes its engagement with the liner <NUM> and prevents damage to the implanted acetabular shell <NUM>.

The pilot hole drill tip <NUM> includes a threaded portion <NUM>, which is sized to be inserted into the opening <NUM> to create a pilot hole <NUM> in the attached liner <NUM> and a drill stop <NUM> disposed at a predetermined distance proximally of the threaded portion <NUM> configured to contact an upper surface of the rim plate <NUM> so as to prevent the drill tip <NUM> from extending past the attached liner <NUM>.

The removal tool <NUM> includes an elongate shaft <NUM> and a threaded tip <NUM> extending from the shaft <NUM>. The threaded tip <NUM> is sized to be inserted into the pilot hole <NUM>, formed by the pilot hole drill tip <NUM>, for detaching the attached liner <NUM> from the implanted acetabular shell <NUM>. Preferably the diameter of the openings <NUM> of the rim plate <NUM> is smaller than the external diameter of the threaded tip <NUM> of the removal tool <NUM>.

The removal tool <NUM> includes a round end <NUM> at a distal end of the threaded tip <NUM> to minimize damage to an inner surface of the implanted acetabular shell <NUM>.

The thread pitch for the threaded tip <NUM> is finer than that of the pilot hole drill tip <NUM>. The threaded part of the pilot hole drill tip <NUM> has a smaller diameter than the diameter of the threaded tip <NUM> of the removal tool <NUM>.

<FIG> illustrates a method of removing a liner <NUM> attached to an implanted acetabular shell <NUM>. In step <NUM>, a user accesses a surgical site where the acetabular shell <NUM> is implanted into a patient. In step <NUM>, the user places a rim plate <NUM> having an opening <NUM> adapted to be placed on top of the implanted acetabular shell <NUM> so that the tabs <NUM> interlock with the corresponding recesses <NUM> of the acetabular shell <NUM>. In step <NUM>, a pilot hole <NUM> is drilled into the attached liner <NUM> through the opening <NUM> in the placed rim plate <NUM> until the drill stop <NUM> bottoms out on the rim plate <NUM>. In step <NUM>, once the pilot hole <NUM> is drilled into the liner <NUM>, the placed rim plate <NUM> is removed to expose the drilled hole.

In step <NUM>, a removal tool <NUM> is inserted into the drilled pilot hole <NUM> by threading the threaded tip <NUM> through the pilot hole <NUM> until the distal end of the threaded tip <NUM> contacts the acetabular shell <NUM>.

In step <NUM>, the attached liner <NUM> is disengaged from the implanted acetabular shell <NUM> with the inserted removal tool <NUM>. In one aspect, the threaded tip <NUM> of the removal tool <NUM> continues to thread into the liner <NUM> until the attached liner <NUM> disengages from the acetabular shell <NUM>. In the embodiment shown, the liner <NUM> disengages from the acetabular shell <NUM> when the circumferential lip <NUM> pops out of the circumferential recess <NUM>.

<FIG> illustrates another embodiment of an apparatus for removing a liner <NUM> attached to an acetabular shell <NUM> that has been implanted into a patient. The apparatus is similar to that of <FIG>, but also includes a modular dome <NUM> that can fit a liner of particular size. For example, there may be four modular domes <NUM> with outer diameters of <NUM>, <NUM>, <NUM>, and <NUM>. In one aspect, the dome <NUM> is made of plastic material. The rim plate <NUM> of <FIG> is different from that of <FIG> in that it excludes the tabs <NUM> and includes a downwardly extending central projection <NUM> having a male thread through its central axis. The male thread of the projection is adapted to be threadedly received in a central threaded recess <NUM> of the modular dome <NUM>. When the dome <NUM> is threaded onto the rim plate <NUM>, the spherically shaped dome <NUM> is shaped to fit inside the liner <NUM> such that the rim plate <NUM> sits on top of the liner <NUM> and acetabular shell <NUM> to provide proper alignment of the openings <NUM> to the liner <NUM>. The angle of the openings <NUM> in <FIG> is the same as that of <FIG>.

The liner removal steps are the same as those shown in <FIG>, except the step of placing a rim plate. Instead of interlocking the tabs <NUM> with corresponding recesses <NUM>, the rim plate <NUM> with its attached dome <NUM> is placed on the acetabular shell <NUM>.

<FIG> illustrate another example of an apparatus <NUM> for removing a liner <NUM> attached to an acetabular shell <NUM> that has been implanted into a patient. The apparatus <NUM> includes the rim plate <NUM> and a levered removal instrument <NUM> which is placed on the center of the rim plate.

The rim plate <NUM> is identical to the rim plate of <FIG> and has a clearance so that when the attached liner <NUM> disengages from the acetabular shell <NUM>, it can travel upwardly away from the shell <NUM>.

The levered removal instrument <NUM> is somewhat similar to the insertion tool <NUM> of <FIG> in that it includes the cannulated shaft <NUM> having the square key <NUM> that fits the square anti-rotation recess <NUM>. Unlike the shaft <NUM> of <FIG>, however, the shaft <NUM> also includes two pairs <NUM>,<NUM> of lateral extensions with holes <NUM>,<NUM> for rotationally coupling two gears <NUM>,<NUM> of levered arms <NUM>,<NUM>. The removal instrument <NUM> also includes an internal shaft <NUM> received in the outer shaft <NUM> and having a screw tip front-end <NUM> and a Hudson type attachment <NUM> at the proximal end. Directly behind the screw tip <NUM>, the internal shaft <NUM> has a flat stop <NUM> to prevent the screw tip from being inserted into the liner <NUM> past a predetermined distance. The mid portion <NUM> of the internal shaft <NUM> has a threading that threadedly couples to the spur gears <NUM>, <NUM> of the levered arms <NUM>, <NUM>. Two hex cap screws <NUM> are inserted into the lateral extension holes <NUM>, <NUM> to rotationally couple the two levered arms <NUM>,<NUM> to the outer shaft <NUM> with the spur gears <NUM>, <NUM> in engagement with the threading <NUM> of the internal shaft <NUM>.

The outer shaft <NUM> is placed into the anti-rotation control feature <NUM> of the rim plate (See <FIG>). The screw tipped internal shaft <NUM> then travels through the outer shaft <NUM> and threads into the liner <NUM> up to about <NUM> when the flat stop <NUM> engages the liner <NUM> to prevent the screw tip <NUM> from being inserted any further into the liner <NUM> (See <FIG>). As the internal shaft <NUM> travels downwardly, the levered arms <NUM>, <NUM> rotate away from the acetabular shell <NUM> via the spur gears <NUM>,<NUM>. The user then rotates the arms <NUM>, <NUM> towards the shell <NUM> just enough to overcome the engagement mechanism <NUM>,<NUM> of the liner <NUM> and shell <NUM> (See <FIG>). In the example shown in <FIG>, the liner <NUM> disengages from the acetabular shell <NUM> when the circumferential lip <NUM> pops out of the circumferential recess <NUM>.

The example of <FIG> may be advantageous to use as it does not require the additional pilot hole drill tip <NUM>. The openings <NUM> still exits on the rim plate <NUM>. However, they are not used in the embodiment of <FIG>. However, the openings <NUM> allow the rim plate <NUM> to be shared among different embodiments if they are both provided in the removal kits.

<FIG> illustrate an instrument removal tool system <NUM>, and in particular, a system for removing a trial femoral head from a trial DM mobile insert. The system <NUM> includes a trial femoral head <NUM>, a trial mobile insert <NUM>, a removal instrument <NUM> and an impactor <NUM> for removing the trial femoral head <NUM> from the trial mobile insert <NUM>.

Prior to final implantation of total hip arthroplasty implants, the surgeon will often trial different implants to assess stability and leg length, putting the leg through a full trial reduction. This will verify the final implant selection including stem offset and head offset.

As discussed earlier with reference to <FIG>, a dual mobility (DM) construct <NUM> is a growing market for at-risk patients. DM mobile insert trials are required by many surgeons to assess range of motion, stability, and leg length. Trials will need to represent the implant offerings, which match the inner and outer diameters of the DM mobile inserts <NUM>. The DM mobile insert and femoral head implants are separately sterile packaged and require assembly with a press on the back table prior to implantation. The DM mobile insert retains the femoral head to prevent intraprosthesis dislocation. Trials will require easy assembly and disassembly to determine the appropriate head offset of the final implant. The trial mobile inserts <NUM> will still need to retain the trial femoral head <NUM> to allow assessment of the trial reduction.

<FIG> show an exemplary DM trial mobile insert <NUM>. A DM trial femoral head <NUM> can be seen in <FIG>. Both the trial femoral head <NUM> and the trial mobile insert <NUM> are made of sulfone polymer material, and in particular, PPSU (Polyphenylsulfone) that is highly resistant to impaction and high autoclave temperature. PPSU material is available, for example, from Solvay S. in Brussels, Belgium under the trade name Radel.

Shape-wise, the trial mobile insert <NUM> is similar to the mobile insert <NUM> of <FIG>. The trial mobile insert <NUM>, however, includes a central through-hole <NUM> and six V-shaped cuts <NUM> from its face that are circumferentially and uniformly spaced from each other to allow the mobile insert <NUM> to flex and assemble with the trial femoral head <NUM> with simply a user's manual force. The six cuts <NUM> define six legs <NUM> that extend toward the face of the mobile insert <NUM>.

Shape-wise, the trial femoral head <NUM> is similar to the femoral head of <NUM> of <FIG> for attaching to a femoral stem. Once the trial femoral head <NUM> snaps into the trial mobile insert <NUM>, the femoral head can rotate in any direction.

<FIG> shows an exemplary removal instrument <NUM> which is shaped to receive the trial mobile insert <NUM> with the attached trial mobile insert <NUM>. The removal instrument <NUM> has six teeth <NUM> that fits into the corresponding V-shaped cuts <NUM>. The bottom of the legs <NUM> rest on the wide recess areas defined by the teeth of the removal instrument <NUM>.

As shown in <FIG>, the removal instrument <NUM> includes a through opening <NUM> which includes a first opening <NUM> having a larger diameter and a second opening <NUM> with a smaller diameter with a circumferentially tapered region <NUM> therebetween. When the trial mobile insert <NUM> is resting on the removal instrument <NUM>, the face of the trial femoral head <NUM> is resting above the tapered region <NUM> (at approximately midpoint between the proximal and distal end of the first opening) as shown in <FIG>.

<FIG> shows an exemplary impactor <NUM>. The impactor <NUM> includes at its proximal portion an impaction head <NUM>, a shaft <NUM> extending distally from the impaction head, a smaller diameter impaction tip <NUM> adapted to be inserted into the central through-hole <NUM> and an impaction stop <NUM> disposed between the shaft and the impaction tip.

As shown in <FIG>, when a light force is applied to the impaction head <NUM>, the distal end of the impaction tip <NUM> pushes downwardly on the attached trial femoral head <NUM> until it disengages from the trial mobile insert <NUM> and rests on top of the tapered region <NUM>. As shown, the impactor stop <NUM> is positioned to bottom out on an external surface of the mobile insert <NUM> over the through opening <NUM> when no femoral head <NUM> is present. However, in an alternate design, the impactor stop <NUM> can be positioned closer to the distal end of the impactor <NUM> so that once the trial femoral head <NUM> disengages from the trial mobile insert <NUM> and rests on the tapered region <NUM>, the impactor stop <NUM> will bottom out on the mobile insert before the distal end can exert any force on the resting trial femoral head <NUM>. This prevents any chance of damaging the trial femoral head <NUM> from the force applied from the impactor <NUM> while the trial femoral head <NUM> is resting on the tapered region <NUM>.

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 shells disclosed herein may have fastener opening <NUM> arrangement of shell <NUM>.

Modifications and variations of the disclosed embodiments are possible without departing from the scope of the invention, which is defined by 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:
An apparatus for removing a liner (<NUM>) attached to an implanted acetabular shell (<NUM>) the apparatus comprising:
✔ a rim plate (<NUM>) adapted to be placed on top of the acetabular shell (<NUM>), the rim plate (<NUM>) having at least one drill guide opening (<NUM>) having a diameter;
✔ a pilot hole drill tip (<NUM>) sized to be inserted into the at least one drill guide opening (<NUM>) to create a pilot hole (<NUM>) in the attached liner (<NUM>);
✔ a removal tool (<NUM>) having an elongate shaft (<NUM>) and a threaded tip (<NUM>) extending from the shaft elongate (<NUM>), the threaded tip (<NUM>) sized to be inserted into the pilot hole (<NUM>) for detaching the attached liner (<NUM>) from the implanted acetabular shell (<NUM>) characterized in that
✔ the at least one drill guide opening (<NUM>) of the rim plate (<NUM>) includes a plurality of circumferentially spaced drill guide openings (<NUM>) with each being angled to guide the pilot hole drill tip (<NUM>) into the attached liner (<NUM>).