Stem centralizer devices and methods

Abstract

In some embodiments, a stem centralizer for a stemmed implant, configured to be implanted within an intramedullary canal of a bone adjacent to an articulating joint, may include an internal portion configured to receive a distal end of the stemmed implant, and an external portion including a plurality of fins configured to engage an interior cortical wall of the intramedullary canal. Each of the plurality of fins may include a leading angle and a trailing angle. The leading angle may be configured to facilitate insertion of the stem centralizer into the intramedullary canal, and the trailing angle may be configured to facilitate removal of the stem centralizer from the intramedullary canal.

Description

STEM CENTRALIZER DEVICES AND METHODSTECHNICAL FIELD

[0001] The present disclosure relates to the field of devices and methods for joint arthroplasty. More specifically, the present disclosed subject matter is directed towards devices and methods for a removable stem centralizer for a stemmed implant.BACKGROUND

[0002] Humeral stem component designs have evolved from prostheses with relatively long stems that fit within the diaphysis to more modem designs with shorter stems that rely primarily on metaphyseal fixation, where the greatest bone density exists, while avoiding distal contact with the cortical walls in the diaphysis. As such, these stems have a reduced bone filling ratio, meaning there is less total volume of metal within the humerus which allows the metaphyseal bone to react to stresses from the implant and achieve stable bony ingrowth without resorption. Importantly, these stems are not generally cemented so the principles that apply to cemented fixation do not apply to them; the goal is to achieve long term metaphyseal fixation by bony ingrowth or reactive new bone formation that will stabilize the stem.

[0003] Older stem designs are often meant to achieve fixation by filling as much of the bone with metal as possible. Studies have shown that this canal filling technique has resulted in adverse bone adaptations and stress shielding bone resorption around the metaphysis and medial calcar.

[0004] While contemporary humeral stem implants aim to preserve humeral bone in the short and long term, they are potentially subject to malalignment during either (a) initial implantation of the stem, or (b) after surgery as the stem is settling into the final position before bony ingrowth occurs and secures the stem in its position. There are two major concerns with malpositioning of these stems in the humeral canal: 1) die tip of the stem may cut out of the diaphyseal bone over time and may lead to loosening or fracture or 2) the malalignment of the stem may change the neck shaft angle or the version in the glenohumeral joint, potentially leading to catastrophic dislocation. Currently, there is no method to centralize humeral stem implants without using cemented fixation and associated cement centralizers.SUMMARY

[0005] The various systems and methods of the present disclosure have been developed in response to the present state of the art, and in particular, in response to the problems and needs in the art that have not yet been fully solved by currently available stem centralizer devices and methods.

[0006] In some embodiments, a stem centralizer for a stemmed implant, configured to be implanted within an intramedullary canal of a bone adjacent to an articulating joint, may include an internal portion configured to receive a distal end of the stemmed implant, and an external portion including a plurality of fins configured to engage an interior cortical wall of the intramedullary canal. Each of the plurality of fins may include a leading angle and a trailing angle. The leading angle may beconfigured to facilitate insertion of the stem centralizer into the intramedullary canal, and the trailing angle may be configured to facilitate removal of the stem centralizer from the intramedullary canal.

[0007] In die stem centralizer of any preceding paragraph, die internal portion may further include a removal aperture configured to receive a removal device to facilitate withdrawal of the stem centralizer from the intramedullary canal of the bone.

[0008] In the stem centralizer of any preceding paragraph, the removal aperture may be smaller than the internal portion.

[0009] In the stem centralizer of any preceding paragraph, the external portion may further include a distal end and the removal aperture may extend from the internal portion to the distal end.

[0010] In the stem centralizer of any preceding paragraph, the external portion may further include a distal end including an insertion portion and a proximal end opposite the distal end. The plurality of fins may extend radially outward from the external portion between the proximal end and the insertion portion.

[0011] In the stem centralizer of any preceding paragraph, at least one of the plurality' of fins may include a fin thickness sized so that the at least one of the plurality of fins may be flexible.

[0012] In some embodiments, a stem centralizer for a stemmed implant, configured to be implanted within an intramedullary' canal of a bone adjacent to an articulating joint, may include and internal portion configured to receive a distal end of the stemmed implant and including a removal aperture, and an external portion including a plurality of fins configured to engage an interior cortical bone. Each of the plurality of fins may include a leading angle and a trailing angle. The removal aperture may be smaller than the internal portion, and may be configured to receive a removal device to facilitate withdrawal of the stem centralizer from the intramedullary' canal of a bone.

[0013] In the stem centralizer of any preceding paragraph, the leading angle may be configured to facilitate insertion of the stem centralizer into the intramedullary' canal and the trailing angle may be configured to facilitate removal of the stem centralizer from the intramedullary' canal.

[0014] In the stem centralizer of any preceding paragraph, the external portion may further include a distal end and the removal aperture may extend from the internal portion to the distal end.

[0015] In the stem centralizer of any preceding paragraph, the external portion may further include a distal end including an insertion portion and a proximal end opposite the distal end. tire plurality of fins may extend radially outward from the external portion between the proximal end and the insertion portion

[0016] In some embodiments, a method for centralizing a stemmed implant within an intramedullary canal of a bone may include, inserting a distal end of the stemmed implant into an internal portion of a stem centralizer, inserting the stemmed implant and stem centralizer into the intramedullary canal, and securing the stem centralizer within the intramedullary canal without the use of bone cement.

[0017] In die method of any preceding paragraph, the stem centralizer may include an external portion including a plurality of fins configured to engage an interior cortical wall of the intramedullary canal. Each of the plurality of fins may include a leading angle and a trailing angle.

[0018] In the method of any preceding paragraph, the leading angle may be configured to facilitate insertion of the stem centralizer into die intramedullary canal and the trailing angle may be configured to facilitate removal of the stem centralizer from the intramedullary canal.

[0019] In the method of any preceding paragraph, the internal portion may include a removal aperture configured to receive a removal device to facilitate withdrawal of the stem centralizer from the intramedullary canal of a bone.

[0020] In some embodiments, a method for centralizing a stemmed implant within an intramedullary canal of a bone may include, withdrawing a distal end of the stemmed implant from an internal portion of the stem centralizer. The internal portion may include a removal aperture that is smaller than the internal portion. The method may further include removing the stemmed implant from the intramedullary canal, inserting a removal device with the removal aperture, and withdrawing the stem centralizer from the intramedullary canal.

[0021] In the method of any preceding paragraph, the stem centralizer may further include a distal end and the removal aperture may extend from the internal portion to the distal end.

[0022] In die method of any preceding paragraph, the stem centralizer may include an external portion including a plurality of fins configured to engage an interior cortical wall of the intramedullary canal. Each of the plurality of fins may include a leading angle and a trailing angle.

[0023] In the method of any preceding paragraph, the leading angle may be configured to facilitate insertion of the stem centralizer into the intramedullary canal and the trailing angle may be configured to facilitate removal of the stem centralizer from the intramedullary canal.

[0024] In some embodiments, a method for revising a stemmed implant and a stem centralizer from an intramedullary canal of a bone may include, removing the stemmed implant from the intramedullary canal, removing the stem centralizer from the intramedullary canal, and inserting a revision stemmed implant into the intramedullary canal.

[0025] In the method of any preceding paragraph, the stem centralizer may include an internal portion including a removal aperture configured to receive a removal device to facilitate withdrawal of the stem centralizer from the intramedullary canal.

[0026] In the method of any preceding paragraph, the stem centralizer may include an external portion including a plurality of fins configured to engage an interior cortical wall of the intramedullary canal. Each of the plurality of fins may include a trailing angle wherein the trailing angle is configured to facilitate removal of the stem centralizer from the intramedullary canal.

[0027] These and other features and advantages of the present disclosure will become more fully apparent from the following description taken in conjunction with the accompanying drawings. Understanding that these drawings depict only exemplary embodiments and are. therefore, not to beconsidered limiting of the scope of the present disclosure, the exemplary embodiments of the present disclosure will be described with additional specificity and detail through the use of accompanying drawings.BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Exemplary embodiments of the present disclosure will become more fully apparent from the following description taken in conjunction with the accompanying drawings. Understanding that these drawings depict only exemplary embodiments and are, therefore, not to be considered limiting of the scope of the present disclosure, the exemplary' embodiments of the present disclosure will be described with additional specificity and detail through use of the accompanying drawings in which:

[0029] Fig. 1A is a perspective view of a stem centralizer, according to an embodiment of the present disclosure.

[0030] FIG. IB is a top view of the stem centralizer of FIG. 1A.

[0031] FIG. 1C is a front view of the stem centralizer of FIG. 1A.

[0032] FIG. ID is a side view of the stem centralizer of FIG. 1 A.

[0033] FIG. IE is a side section view' of the stem centralizer of FIG. 1A.

[0034] FIG. IF is a front view of an exemplary stemmed implant.

[0035] FIG. 1G is a front view' of the stemmed implant of FIG. IF in the stem centralizer of FIG.1A.

[0036] FIG. 2 is front view's of three stemmed implants in three stem centralizers with various potential placements of the stem centralizer along stemmed implant according to an embodiment of the present disclosure.

[0037] FIG. 3 is a perspective view of a stem centralizer and front views of the stem centralizer on a stemmed implant according to an embodiment of the present disclosure.

[0038] FIG. 4 is a perspective view and front views of a stem centralizer with fins according to an embodiment of the present disclosure.

[0039] FIG. 5 includes front views of a stem centralizer according to an embodiment of the present disclosure.

[0040] FIG. 6 includes tops views and a front view of an internal portion of a stem centralizer according to an embodiment of the present disclosure.

[0041] FIG. 7 includes front views of a stem centralizer with fins according to an embodiment of the present disclosure.

[0042] FIG. 8 includes tops views and a front view of a stem centralizer with slits according to an embodiment of the presen. t disclosure.

[0043] FIG. 9 includes top views of various cross-sectional shapes of a stem centralizer according to various embodiments of the present disclosure.

[0044] FIG. 10 includes perspective views of a deploy able stem centralizer according to an embodiment of the present disclosure.

[0045] FIG. 11 includes top and side views of a stem centralizer including various concepts to identify different diameters according to an embodiment of the present disclosure.

[0046] FIG. 12 includes top and perspective views of a stem centralizer including uni-directional cross-sectional geometry according to an embodiment of the present disclosure.

[0047] FIG. 13 includes front and top views of a stem centralizer with fins according to an embodiment of the present disclosure.

[0048] FIG. 14 includes top, perspective and section views of a stem centralizer with fins according to an embodiment of the present disclosure.

[0049] FIG. 15 includes front and top views of a stem centralizer with a fin and a stemmed implant according to an embodiment of the present disclosure.

[0050] FIG. 16 includes perspective and top views of the stem centralizer of FIG. 15.

[0051] FIG. 17 includes front section views of a balloon stem centralizer according to an embodiment of the present disclosure.

[0052] FIG. 18 includes perspective views of a collapsible stem centralizer according to an embodiment of the present disclosure.

[0053] FIG. 19 includes top and front views of a stem centralizer according to an embodiment of the present disclosure.

[0054] FIG. 20 includes top and front views of an expandable stem centralizer according to an embodiment of the present disclosure.

[0055] FIG. 21 includes front views of an expandable stem centralizer according to an embodiment of the present disclosure.

[0056] FIG. 22 includes front and detail views of an actuatable stem centralizer according to an embodiment of the present disclosure.

[0057] It is to be understood that the drawings are for purposes of illustrating the concepts of the present disclosure and arc drawn to scale according to certain embodiments. In alternative embodiments, dimensions of the drawings may be varied to provide different features and benefits. Furthermore, the drawings illustrate exemplary embodiments and do not represent limitations to the scope of the present disclosure.DETAILED DESCRIPTION

[0058] Exemplary embodiments of the present disclosure will be best understood by reference to the drawings, wherein like parts are designated by like numerals throughout. It will be readily understood that the components of the present disclosure, as generally described and illustrated in the drawings, could be arranged, and designed in a wide variety of different configmations. Thus, the following more detailed description of the embodiments of the devices, systems, and methods, as represented in the drawings, is not intended to limit the scope of the present disclosure but is merely representative of exemplary embodiments of the present disclosure.

[0059] The word "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any embodiment described herein as "exemplary " is not necessarily to be construed as preferred or advantageous over other embodiments. While the various aspects of the embodiments are presented in the drawings, the drawings are not necessarily drawn to scale unless specifically indicated.

[0060] The following examples have been included to provide guidance to one of ordinary skill in the art for practicing representative embodiments of the presently disclosed subject matter. Considering the present disclosure and the general level of skill in the art, those of skill can appreciate that the following examples are intended to be exemplary only and that numerous changes, modifications, and alterations can be employed yvithout departing from the scope of the presently disclosed subject matter.

[0061] For purposes of interpreting this specification, the following definitions will apply. In the event that any definition set forth below conflicts with any document incorporated herein by reference, the definition set forth below shall control.

[0062] Bone and cartilage are referred to, collectively, as “tissue.” “Proximal” means closer to a user, “distal” means farther away from a user. For example, the handle of a screwdriver is on a proximal end. and the drive tip of a screwdriver is on a distal end. “Parallel” direction means a direction that is parallel to an object such as an instrument longitudinal axis. “Circumferential” direction means in a direction around the circumference of an object, for example, along a circumference encircling an instrument longitudinal axis.

[0063] The phrases “connected to,” “coupled to” and “in communication with” refer to any form of interaction between tyvo or more entities, including mechanical, electrical, magnetic, electromagnetic, fluid, and thermal interaction. Tyvo components may be functionally coupled to each other even though they are not in direct contact yvith each other. The term “coupled” can include components that are coupled to each other via integral formation, as yvell as components that are removably and / or non-removably coupled with each other. The term “abutting” refers to items that may be in direct physical contact with each other, although the items may not necessarily be attached together. The phrase “fluid communication” refers to two or more features that are connected such that a fluid within one feature is able to pass into another feature. As defined herein the term “substantially” means within + / - 10% of a target value, measurement, or desired characteristic.

[0064] The present disclosure relates to devices, systems, and methods for a removable stem centralizer for a stemmed implant. Those skilled in the art will recognize that the following description is merely illustrative of the principles of the technology, which may be applied in various ways to provide many alternative embodiments. For the purposes of illustrating the concepts of the present design, the present disclosure illustrates stem centralizer devices to be used in the proximal humerus for shoulder arthroplasty. However, it will be understood that other variations and uses are contemplated, including, but not limited to. applications in in the bones of the hip. knee, elbow, ankle / foot, wrist / hand. and / or other bone adjacent to an articulating joint.

[0065] Cemented joint replacement is well known in the art. The 2022 American Joint Replacement Registry Annual Report, including data from over 2.8 million hip and knee procedures, states that, regarding Total Hip Arthroplasty, “Cemented femoral component fixation is also gradually growing in popularity for both elective primary THA and arthroplasty for femoral neck fractures, with utilization in primary elective THA increasing by over 75% since 2013." Regarding Total Knee Arthroplasty, the report further states that, “While cemented TKA remains the leading form of fixation, cementless fixation is gaining prevalence, with 18.8% of primary TKA utilizing cementless fixation in 2021." (American Joint Replacement Registry (AJRR), 2022).

[0066] Positioning of the implant stem is considered easier in cemented fixation. The setting time of a common bone cement, polymethylmethacrylate (PMMA), is approximately ten minutes and surgeons often rely on the bone cement to keep the implant stem and a stem centralizer in place. It is also well known in the art that removing cement during a revision procedure is a time-consuming process that adds to the length and complexity’ to the revision procedure. Revision arthroplasty procedures are known to be longer and more complex than primary arthroplasty procedures, and, therefore, have a greater risk of complications. Eliminating the need to remove cement and a cemented stemmed implant may reduce the risk of complications and may improve patient safety.

[0067] Fig. 1 A is a perspective view of a stem centralizer 100 according to an embodiment of the present disclosure. FIG. IB is a top view of the stem centralizer 100. FIG. 1C is a front view of the stem centralizer 100, FIG. ID is a side view of the stem centralizer 100, and FIG. IE is a front section view of the stem centralizer 100. The stem centralizer 100 may be configured to fit onto a distal end 220 of a stemmed implant 200. The stem centralizer 100 may be further configured to prevent stem malalignment of the stemmed implant 200 from occurring in non-cemented fixation. The stem centralizer 100 may be used to maintain a central position of the stemmed implant 200 within an intramedullary canal and avoid contact betw een die distal end 220 of the stemmed implant 200 and an interior cortical wall.

[0068] The stem centralizer 100 may include an internal portion 120 and an external portion 125. The internal portion 120 may include an internal profile 115, a removal aperture 110, and an internal diameter 140. The internal profile 115 may be shaped to be complementaiy to the distal end 220 of the stemmed implant 200 so that the distal end 220 may be received within the internal portion 120.

[0069] The removal aperture 110 may extend along a longitudinal axis of the stem centralizer 100 from the internal portion 120 to a distal end of the external portion 125. The removal aperture 110 may include a removal diameter 145 that is smaller than die internal diameter 140 of the internal portion 120. The removal aperture 110 may be configured to securely receive a removal device (not shown). The removal device may have a threaded tip, an expandable tip, a toggle portion and / or other configuration to securely engage the removal aperture 110. The removal device may engage the internal diameter 140 and / or pass through the removal aperture 110 to engage the external portion 125. Theremoval device may facilitate withdrawal of the stem centralizer 100 from an intramedullary canal of a bone.

[0070] The external portion 125 may include a plurality of fins 105 and an insertion portion 155. The insertion portion 155 may be at the distal end of the external portion 125. The insertion portion 155 may include a radius and / or a lead-in angle to facilitate insertion of tire stem centralizer into the intramedullary canal. A distal end of the insertion portion 155 may be smaller than an opening of the intramedullary canal. The insertion portion 155 may taper from the distal end to the plurality' of fins 105. The plurality of fins 105 may extend radially outward from the external portion 125 between a proximal end of the stem centralizer 100 and the insertion portion 155.

[0071] Each of the plurality of fins 105 may include a fin thickness 160. The fin thickness 160 may be configured to provide a desired degree of flexibility. For example, a thinner fin thickness 160 may be more flexible than a thicker fin thickness 160. Each of the plurality of fins 105 may have a generally equal fin thickness 160. Alternatively, each of the plurality of fins 105 may have a different fin thickness 160. Alternatively, one or more of the plurality of fins 105 may have a fin thickness 160 that may be different than the remaining plurality' of fins 105. Each of the plurality of fins 105 may include a fin thickness 160 based on patient anatomy and / or bone quality.

[0072] The plurality of fins 105 may be equally spaced around the external portion 125. The stem centralizer 100 may include three fins, four fins, five fins, six fins, or more than six fins. Alternatively, the plurality' of fins 105 may be arranged around the external portion 125 in a pattern that is not equally spaced. The spacing of the plurality of fins 105 may' be based on patient anatomy and / or bone quality.

[0073] The plurality of fins 105 may each extend a generally equal distance from the external portion 125, thereby defining a fin diameter 150. The fin diameter 150 may be sized to be generally equal to, or slightly larger than the intramedullary' canal so that the plurality' of fins may engage an interior cortical wall of the intramedullary canal. Alternatively, the plurality' of fins 105 may each extend a different distance from the external portion 125, thereby defining a non-circular fin profile. Each of the plurality of fins 105 may be configured to extend from the external portion 125 a distance sufficient to engage an interior cortical wall of the intramedullary' canal. The distance each of the plurality' of fins 105 extends from the external portion 125 may be based on patient anatomy and / or bone quality.

[0074] Each fin of tire plurality of fins 105 may include a leading angle 130 and a trailing angle 135. The leading angle 130 may be an angle along one of the plurality of fins 105 between a distal end of the external portion 125 and the fin diameter 150. The leading angle 130 may be configured to facilitate insertion of the stem centralizer 100 into the intramedullary canal. The leading angle 130 may be between 10 degrees and 50 degrees. More specifically, the leading angle 130 may be between 15 degrees and 25 degrees.

[0075] The trailing angle 135 may be an angle along one of the plurality of fins 105 between the fin diameter 150 and a proximal end of the external portion 125. The trailing angle 135 may be configured to facilitate removal of the stem centralizer 100 from the intramedullary canal. The trailingangle 135 may be between 30 degrees and 60 degrees. More specifically, the trailing angle 135 may be between 40 degrees and 50 degrees.

[0076] FIG. IF is a front view of an exemplary stemmed implant 200. FIG. 1G is a front view of the stemmed implant 200 in the stem centralizer 100. The stemmed implant 200 may configured for use in a proximal humerus. In other embodiments, the stemmed implant 200 may be configured for use in bones of the hip. knee, elbow, ankle / foot, and / or wrist / hand. The stemmed implant 200 may include an implant head 205 and an implant stem 210. The implant head may be located at a proximal end of the stemmed implant 200 opposite a distal end 220. The implant stem 210 may include a stem diameter 215, and a distal end 220 having a distal profile.

[0077] The implant stem 210 is shown as having a generally circular cross-section, however, other implant stem geometries are known in the art. The internal portion 120 of the stem centralizer 100 may be configured to receive any implant stem cross-section geometry known in the art.

[0078] The implant stem 210 may extend between the implant head 205 and the distal end 220. The internal profile 115 of the stem centralizer 100 may be configured have a shape that is complementary to the distal profile 225. The internal diameter 140 may be generally equal to or slightly larger than the stem diameter 215. Alternatively, the stem centralizer may be manufactured using a flexible and / or compressible material, for example: polymers (such as polyethylene [PE], poly-ether- ether-ketone [PEEK], poly-lactic acid [PLA], poly-lactic-co-glycolic acid [PLGA], poly-glycolic acid [PGA], poly-methyl-methacrylate [PMMA] and silicone), biological materials (such as bone grafts or collagen) and / or other suitable biocompatible material. The internal diameter 140 may be generally equal to or slightly smaller than the stem diameter 215, thereby providing an interference fit between the stemmed implant 200 and the stem centralizer 100.

[0079] The stem centralizer 100 may receive die stemmed implant 200 prior to implantation. Alternatively, the stem centralizer 100 may be implanted within the intramedullary canal first and the stemmed implant 200 may be subsequently inserted into the intramedullary canal and advanced so that the distal end 220 of the stemmed implant 200 is received in the internal portion 120 of the stem centralizer 100.

[0080] The stem centralizer 100 may be configured to centralize the distal end 220 of the stemmed implant 200 within the intramedullary canal without the need for bone cement or another supplemental fixation. The stem centralizer 100 may be secured within the intramedullary canal through engagement of the plurality of fins 105 with an interior cortical bone, thereby eliminating the need for bone cement.

[0081] Without bone cement locking the stem centralizer 100 within the intramedullary canal, the stem centralizer 100 may be removed after implantation, for example during revision surgery. The trailing angle 135 of the stem centralizer 100 may prevent the stem centralizer from catching and / or embedding into the interior cortical wall of the intramedullary canal as the stem centralizer is withdrawn from the intramedullary canal, thereby facilitating removal of the stem centralizer.

[0082] FIG. 2 is front views of a stemmed implants 200 in a stem centralizer 250, the stemmed implant 200 in a stem centralizer 260, and die stemmed implant 200 in a stem centralizer 270 according to an embodiment of the present disclosure. In various embodiment, a stem centralizer may be configured to be placed at various locations along an implant stem.

[0083] The stem centralizer 250 may be configured to be placed at a distal end 220 of a stemmed implant 200. The stem centralizer 250 may include an internal portion 252 configured to receive the distal end 220. The internal portion 252 may have a shape that is complementary with the distal profile 225 of the stemmed implant 200.

[0084] The stem centralizer 260 may be configured to be placed along the implant stem 210 of the stemmed implant 200. The stem centralizer 260 may include an internal portion 262 configured to receive the implant stem 210. The internal portion 262 may extend through the entire stem centralizer 260 so that the distal end 220 may pass through the internal portion 262.

[0085] The stem centralizer 270 may be configured to be placed along the proximal end of the implant stem 210. The stem centralizer 270 may include an internal portion 272 configured to receive the implant stem 210 and a portion of the implant head 205. The internal portion 272 may extend through the entire stem centralizer 270 so that the distal end 220 may pass through the internal portion Til.

[0086] FIG. 3 is a perspective view of a stem centralizer system 300 and front views of the stem centralizer system 300 on a stemmed implant 200 according to an embodiment of the present disclosure. The stem centralizer system 300 may include one or more discs 305 configured to receive tire implant stem 210. Additionally, or alternatively, the one or more discs 305 may be configured as rings, plugs, gaskets, ribs, fins and / or other extension structures that may be inserted onto the distal end 220 of the implant stem 210. Each of the one or more discs 305 may be configured with the same outer diameter 320 or may be offered in a series of different internal portions 310 and / or outer diameters 320 that may be selected based on the size of the implant stem 210 and the patient anatomy and / or bone quality.

[0087] The internal portion 310 of the one or more discs 305 may have an internal geometry that is complementary to the cross-sectional geometry of the implant stem 210 to allow the one or more discs 305 to receive the implant stem 210. Alternatively, the internal portion 310 may include one or more flexible features that may bend and conform to the implant stem 210 geometry.

[0088] The one or more discs 305 may be initially placed in their final orientation on the implant stem 210, or alternatively they may all be placed near the distal end 220 of the implant stem 210 and may slide into different positions along the implant stem 210 based on the cross-sectional dimensions within the intramedullary canal as the stem is impacted into the intramedullary canal. The one or discs 305 may include an outer diameter 320. Alternatively, the one or more discs 305 may be shaped into triangles, squares, rectangles, and / or any other shape that accommodates an intramedullary canal appropriately. The one or more discs 305 may include an internal portion 310 that may be shaped intocircles, triangles, squares, rectangles, and / or any other shape that accommodates an implant stem 210 appropriately.

[0089] The one or more discs 305 may include locking tabs 315. The locking tabs 315 may be configured to engage the implant stem 210 and allow the disc 305 to translate proximally along the implant stem 210 while inhibiting the disc 305 from translating distally along the implant stem 210. The locking tabs 315 may help ensure that the stem centralizer system 300 does not migrate with respect to the stemmed implant 200 after implantation.

[0090] FIG. 4 is a perspective view and front views of a stem centralizer 400 with fins 405 according to an embodiment of the present disclosure. The stem centralizer 400 may include an internal portion 415 and an external portion 410. The internal portion 415 may be configured to receive an implant stem 210. The internal portion 415 may have an internal geometry that is complementary to the cross-sectional geometry of the implant stem 210. Alternatively, the internal portion 415 may include one or more flexible features that may bend and conform to the implant stem 210 geometry.

[0091] The external portion 410 may include a plurality of fins 405 configured to engage an interior cortical wall. Each of fins 405 may be configured with the same outer diameter or may be include a series of different outer diameters 320.

[0092] In an embodiment, the stem centralizer 400 may include three fins 405, a first fin 405 may have a diameter 0A, a second fin 405 may have a diameter 0B, and a third fin 405 may have a diameter 0C, wherein 0A < 0B < 0C. Alternatively, the three fins 405 may be configured so that 0A = 0B = 0C.

[0093] The number of fins 405 may vary from one to more than one. The fins 405 may either be perpendicular to the external portion 410 or angled with respect to the external portion 410 to facilitate easier insertion into the intramedullary canal.

[0094] Each of the plurality of fins 405 may include a fin thickness 460. The fin thickness 460 may be configured to provide a desired degree of flexibility. For example, a thinner fin thickness 460 may be more flexible than a thicker fin thickness 460. Each of the plurality of fins 405 may have a generally equal fin thickness 460. Alternatively, each of die plurality of fins 405 may have a different fin thickness 460. Alternatively, one or more of the plurality of fins 405 may have a fin thickness 460 that may be different than the remaining plurality of fins 405. Each of the plurality of fins 405 may include a fin thickness 460 based on patient anatomy and / or bone quality.

[0095] FIG. 5 includes front views of a stem centralizer 500 according to an embodiment of the present disclosure. The stem centralizer 500 may be configured to receive an implant stem 210. The stem centralizer 500 may include an internal portion 510 and an external portion 515. The internal portion 510 may be configured to receive the implant stem 210. The internal portion 510 may have an internal geometry that is complementary to the cross-sectional geometry of the implant stem 210. Alternatively, the internal portion 510 may include one or more flexible features that may bend and conform to the implant stem 210 geometry.

[0096] The internal portion 510 may have a shape that is complementary with the distal profile 225 of the stemmed implant 200. Alternatively, the internal portion 510 may extend through the entire stem centralizer 500 so that the distal end 220 may pass through the internal portion 510.

[0097] Additionally, or alternatively, the internal portion 510 may be stepped internally to accommodate different stem diameter end geometries. The internal portion 510 may include a first stem receiving portion 530 and a second stem receiving portion 535. The first stem receiving portion 530 may be configured to receive an implant stem from a first sized stemmed implant and the second stem receiving portion 535 may be configured to receive an implant stem from a second sized stemmed implant.

[0098] In an embodiment, the first sized stemmed implant may be a size #36 stemmed implant. The second sized stemmed implant may be a size #41 stemmed implant. In an embodiment, the first sized stemmed implant may include a 05mm distal tip. The second sized stemmed implant may include a 07mm distal tip. In an embodiment, the first sized stemmed implant may include a 09mm distal tip. The second sized stemmed implant may include a 011mm distal tip.

[0099] The external portion 515 may include a plurality of fins 505 configured to engage an interior cortical wall. Each of the plurality of fins 505 may be configured with the same outer diameter or may include a series of different outer diameters. In an embodiment, the plurality of fins 505 may be oriented horizontally with respect to the longitudinal axis of the stem centralizer 500. Alternatively, the plurality of fins 505 may be oriented vertically with respect to the longitudinal axis of the stem centralizer 500 and may extend radially outward from the external portion 515.

[0100] FIG. 6 includes tops views and a front view of an internal portion 605 of a stem centralizer 600 according to an embodiment of the present disclosure. The internal portion 605 may include various internal features to allow for flexibility (for example, w ith flexible tabs) and / or may be sized specifically to various cross-sectional geometries. The internal features may include rounded deformable flaps 610 and / or angled deformable flaps 620. The rounded deformable flaps 610 and / or angled deformable flaps 620 may be configured as bumps, flaps, and / or other shapes that may either be flexible or rigid. The rounded deformable flaps 610 and / or angled deformable flaps 620 may exist along a single axis or may be spaced apart along different axes along the length of the stem centralizer 600. The rounded deformable flaps 610 and / or angled deformable flaps 620 may be present in any embodiment of the present disclosure.

[0101] FIG. 7 includes front views of a stem centralizer 700 with fins according to an embodiment of the present disclosure. The stem centralizer 700 may include an internal portion 705 and an external portion 725. The stem centralizer 700 may be configured to receive an implant stem 210. The stem centralizer 700 may include an internal portion 705 and an external portion 725. The internal portion 705 may be configured to receive the implant stem 210. The internal portion 705 may have an internal geometry that is complementary to the cross-sectional geometry of the implant stem 210. Alternatively.the internal portion 705 may include one or more flexible features that may bend and conform to the implant stem 210 geometry .

[0102] The external portion 725 may include a first fin 710, a second fin 715, and a third fin 720. The first fin 710, the second fin 715 and the third fin 720 may be configured to engage an interior cortical wall.

[0103] Each of the first fin 710, the second fin 715 and the third fin 720 may be configured with the same outer diameter or may include a series of different outer diameters. Each of the first fin 710, the second fin 715 and the third fin 720 may be configured with a same fin thickness 760 or may include a series of different fin thicknesses.

[0104] The fin thickness 760 may be configured to provide a desired degree of flexibility. For example, a thinner fin thickness 760 may be more flexible than a thicker fin thickness 760. Each of the first fin 710, the second fin 715 and the third fin 720 may include a fin thickness 760 based on patient anatomy and / or bone quality.

[0105] The different fin thicknesses may create different degrees of rigidity.

[0106] Additionally, or alternatively, the distal end (base) of the stem centralizer 700 may have an enlarged diameter. Additionally, or alternatively, the stem centralizer 700 may have thinner and more flexible tabs proximally that may have increased diameters relative to each other and / or the base.

[0107] FIG. 8 includes tops views and a front view of a stem centralizer 800 with slits 810 according to an embodiment of the presen.t disclosure. The stem centralizer 800 may include an internal portion 805 and an external portion 815. The internal portion 705 may be configmed to receive the implant stem 210. The internal portion 705 may have an internal geometry that is complementary to the cross-sectional geometry of the implant stem 210. Alternatively, the internal portion 705 may include one or more flexible features that may bend and conform to the implant stem 210 geometry. The external portion 815 may be configmed to engage an interior cortical wall.

[0108] The stem centralizer 800 may include slits 810 (or cutouts) to allow for some flexibility of the external portion 815 so that the stem centralizer 800 may conform to different internal geometries of the bone. Certain portions of the stem centralizer 800 may flex while others may not flex depending on the internal geometries of the bone.

[0109] FIG. 9 includes top views of various cross-sectional shapes of a stem centralizer 900 according to various embodiments of the present disclosure. The stem centralizer 900 may include an internal portion 910 and an external portion 915. The internal portion 910 may be configured to receive the implant stem 210. The internal portion 910 may have an internal geometry that is complementary to the cross-sectional geometry of the implant stem 210.

[0110] The external portion 915 may be configured to engage an interior cortical wall. The external portion may include a series of wings 905 (like flower petals) that may allow for flexibility of the external portion 915. The wings 905 may also be selectively placed on certain regions of the stem centralizer 900 to allow for a combination of rigid and flexible regions. The stem centralizer 900 mayinclude two wings 905, three wings 905, four wings 905, five wings 905, six wings 905, or more than six wings 905.

[0111] FIG. 10 includes perspective views of a deployable stem centralizer 1000 according to an embodiment of the present disclosure. The stem centralizer 1000 may include an internal portion 1005 and an external portion 1010. The internal portion 1005 may be configured to receive the implant stem 210. The internal portion 1005 may have an internal geometry that is complementary to the cross- sectional geometry of the implant stem 210.

[0112] The external portion 1010 may be configured to engage an interior cortical wall. The stem centralizer 1000 may have a disc 1040 that may be cut into a series of flaps 1015. Each of the flaps 1015 may be pushed up and around the implant stem 1035 as the implant stem 1035 is inserted into the intramedullary canal 1025. The flaps 1015 may be created using cuts 1020 that may be straight, arcuate, or have some other organic pattern to achieve the desired amount of flexibility. Alternatively, the disc 1040 may include a flexible material and have no cuts 1020. The flexibility of the material may allow the disc 1040 be pushed up and around the implant stem 1035 as the implant stem 1035 is inserted into the intramedullary canal 1025.

[0113] A broach 1030 may be used to insert the stem centralizer 1000 into the intramedullary canal 1025. After the stem centralizer 1000 is positioned within the intramedullary canal 1025. the broach 1030 may be withdrawn leaving the stem centralizer in place. A stemmed implant having an implant stem 1035 may then be inserted into the intramedullary canal 1025 and received in the internal portion 1005 of the stem centralizer 1000.

[0114] Additionally, or alternatively, the stem centralizer 1000 may be activated using a string, thread, suture, or other flexible member. The string may run up along the length of the intramedullary canal 1025, allowing the stem centralizer 1000 to remain compressed as it is inserted into the intramedullary canal 1025. Once the implant stem 1035 is fully seated within the stem centralizer 1000, the string may be pulled on to actuate the stem centralizer 1000 to expand to a specific diameter of the intramedullary canal 1025 in a particular location. The string may then be cut so that nothing is left sticking out of the bone.

[0115] FIG. 11 includes top and side views of a stem centralizer 1100 including various concepts to identify different diameters according to an embodiment of the present disclosure. The stem centralizer 1100 may include an internal portion 1105 and an external portion 1110. The internal portion 1105 may be configured to receive the implant stem 210. The internal portion 1105 may have an internal geometry that is complementary to the cross-sectional geometry of the implant stem 210.

[0116] The external portion 1110 may be configured to engage an interior cortical wall. The external portion may include a disc portion 1120 having markings 1115. The disc portion 1120 may be trimmable with a pair of scissors (for example) so that the disc portion 1120 may conform to different internal bone geometries. The disc portion 1120 may also have a number of markings 1115 that may indicate different diameters. The markings 1115 may also be configured as perforations within the discportion 1120 to facilitate cutting of the disc portion 1120. Based on pre-operative measurements, the disc portion 1120 may be sized for the specific patient accordingly.

[0117] FIG. 12 includes top and perspective views of a stem centralizer 1200 including unidirectional cross-sectional geometry according to an embodiment of the present disclosure. The stem centralizer 1200 may include an internal portion 1205 and an external portion 1210. The internal portion 1205 may be configured to receive the implant stem 210. The internal portion 1205 may have an internal geometry that is complementary to the cross-sectional geometry of the implant stem 210.

[0118] The external portion 1210 may be configured to engage an interior cortical wall. The external portion may include one or more directional fins 1215. The one or more directional fins 1215 may prevent the stem centralizer 1200 from rotating or moving in one or more particular directions after implantation within the intramedullary canal, while maintaining a lower profile on the rest of the stem centralizer 1200.

[0119] FIG. 13 includes front and top views of a stem centralizer 1300 with fins 1315 according to an embodiment of the present disclosure. The stem centralizer 1300 may include an internal portion 1305 and an external portion 1310. The internal portion 1305 may be configured to receive the implant stem 210. The internal portion 1305 may have an internal geometry that is complementary to the cross- sectional geometry of the implant stem 210.

[0120] The external portion 1310 may be configured to engage an interior cortical wall. The external portion 1310 may include a plurality of fins 1315. The plurality of fins 1315 may extend radially outward from the external portion 1310.

[0121] The plurality of fins 1315 may be equally spaced around the external portion 1310. The stem centralizer 1300 may include three fins, four fins, five fins, six fins, or more than six fins. Alternatively, the plurality of fins 1315 may be arranged around the external portion 1310 in a pattern that is not equally spaced. The spacing of the plurality' of fins 1315 may be based on patient anatomy and / or bone quality.

[0122] The plurality of fins 1315 may each extend a generally equal distance from the external portion 1310. Alternatively, the plurality of fins 1315 may each extend a different distance from the external portion 1310. Each of the plurality of fins 1315 may be configmed to extend from the external portion 1310 a distance sufficient to engage an interior cortical wall of the intramedullary canal. The distance each of the plurality of fins 1315 extends from the external portion 1310 may be based on patient anatomy and / or bone quality.

[0123] The plurality of fins 1315 may vary from one to more than one. The fins 1315 may either be perpendicular to the external portion 1310 or angled with respect to the external portion 1310 to facilitate easier insertion into the intramedullary canal.

[0124] Each of the plurality of fins 1315 may include a fin thickness 1360. The fin thickness 1360 may be configmed to provide a desired degree of flexibility. For example, a thinner fin thickness 1360 may be more flexible than a thicker fin thickness 1360. Each of the plurality of fins 1315 may have agenerally equal fin thickness 1360. Alternatively, each of the plurality of fins 1315 may have a different fin thickness 1360. Alternatively, one or more of the plurality of fins 1315 may have a fin thickness 1360 that may be different than the remaining plurality' of fins 1315. Each of the plurality of fins 1315 may include a fin thickness 1360 based on patient anatomy and / or bone quality.

[0125] FIG. 14 includes top, perspective and section views of a stem centralizer 1400 with fins 1415 according to an embodiment of the present disclosure. The stem centralizer 1400 may include an internal portion 1405 and an external portion 1410. The internal portion 1405 may be configured to receive an implant stem 1420. The internal portion 1405 may have an internal geometry that is complementary to the cross-sectional geometry of the implant stem 1420.

[0126] The external portion 1410 may be configured to engage an interior cortical wall. The external portion 1410 may include a plurality of fins 1415. The plurality of fins 1415 may extend radially outward from the external portion 1410.

[0127] The plurality of fins 1415 may be equally spaced around the external portion 1410. The stem centralizer 1400 may include three fins, four fins, five fins, six fins, or more than six fins. Alternatively, the plurality of fins 1415 may be arranged around the external portion 1410 in a pattern that is not equally spaced. The spacing of the plurality' of fins 1415 may be based on patient anatomy and / or bone quality.

[0128] The plurality of fins 1415 may7each extend a generally equal distance from the external portion 1410. Alternatively, the plurality of fins 1415 may each extend a different distance from the external portion 1410. Each of the plurality of fins 1415 may' be configured to extend from the external portion 1410 a distance sufficient to engage an interior cortical w all of the intramedullary canal. The distance each of the plurality of fins 1415 extends from the external portion 1410 may be based on patient anatomy and / or bone quality'.

[0129] The plurality of fins 1415 may vary from one to more than one. The fins 1415 may angled with respect to the external portion 1310 to facilitate easier insertion into the intramedullary' canal. The plurality' of fins 1415 may extend longitudinally along the lengtir of the external portion 1410. To facilitate easier insertion and the narrowing of the bone distally, the plurality' of fins 1415 may increase in their outer diameter. Alternatively, the external portion 1410 may not have any fins at all, and may just be a cylinder or other continuous shape or a shape that increases in diameter along its length such that it is more conical.

[0130] FIG. 15 includes front and top views of a stem centralizer 1500 with a fin 1515 and a stemmed implant 1520 according to an embodiment of the present disclosure. FIG. 16 includes perspective and top views of the stem centralizer 1500. The stem centralizer 1500 may be configured to clip onto a stem 1525 of the stemmed implant 1520. The fin 1515 may be uni-directional so that one or more stem centralizers 1500 may be placed at one or more different regions along the length of the stem 1525. This may prevent movement in different directions at different locations. The fins may either be rigid or flexible.

[0131] The stem centralizer 1500 may include a clip 1530 having a clip internal portion 1505 and a clip external portion 1510. The clip internal portion 1505 may be configured to receive a stem 1525. The clip internal portion 1505 may have an internal geometry that is complementary to die cross- sectional geometry of the stem 1525.

[0132] The clip external portion 1510 may be configured to engage an interior cortical wall. The clip external portion 1510 may include a fin 1515. The fin 1515 may extend radially outward from the clip external portion 1510. The stem centralizer 1500 may be one of a set of differently -sized stem centralizers, each having a different length clip 1530 size and a different fin size.

[0133] The clip 1530 may not have a continuous diameter as it is engaged around the stem 1525. It may be a discontinuous ring that allows for some flexibility to accommodate varying sizes of stems 1525 without the need to be size-specific. For example, the cross-sectional shape of the clip 1530 may have a c-shaped region to clip onto the stem 1525. Alternatively, the clip 1530 may be configured with other geometric cross-sectional shapes to clip or attach to various features on the stem 1525 that may not have a round cross-sectional shape.

[0134] FIG. 17 includes front section views of a balloon stem centralizer 1700 according to an embodiment of the present disclosure. The balloon stem centralizer 1700 may be placed at some position along the length of the stemmed implant 1715. The balloon stem centralizer 1700 may be inflated and / or fdled with a liquid 1725 or another suitable material (such as air. water, saline, polymethylmethacrylate. and / or some other liquid).

[0135] The balloon stem centralizer 1700 may include an internal portion 1705 and an external portion 1710. The internal portion 1705 may be configured to receive a distal end 1720 of a stemmed implant 1715. The external portion 1710 may be configured to be expandable to engage an interior cortical wall. The balloon stem centralizer 1700 may further be configured to comrect to an inflation device 1730. The inflation device 1730 may introduce a liquid 1725 into the balloon stem centralizer 1700 to expand the balloon stem centralizer 1700 within the intramedullary’ canal. The expansion of the balloon stem centralizer 1700 may cause the external portion 1710 to engage the interior cortical wall and the internal portion 1705 to engage the distal end 1720 of the stemmed implant 1715.

[0136] The balloon stem centralizer 1700 may be a polymer balloon that may be inflated with saline, air. silicone, PMMA, water and / or some other liquid.

[0137] FIG. 18 includes perspective views of a collapsible stem centralizer 1800 according to an embodiment of the present disclosure. The collapsible stem centralizer 12800 may include an internal portion 1805 and a plurality of flexible portions 1815. The internal portion 1805 may be configured to receive a stem 1820 of a stemmed implant.

[0138] The collapsible stem centralizer 1800 may be actuated from a collapsed position to an expanded position prior to or after placement of the device on a stem 1820. The collapsible stem centralizer 1800 may be actuated by compressing, collapsing, twisting, rotating, and / or some othermeans. The plurality of flexible portions 1815 may be configured so that, in the expanded position, the plurality of flexible portion 1815 engage an interior cortical wall.

[0139] The collapsible stem centralizer 1800 may have an internal portion 1805 along the main longitudinal axis to allow for integration with the stem 1820. As the device is actuated it may flex internally against the stem 1820 and / or externally against the interior cortical walls, thus increasing the centering capability of the collapsible stem centralizer 1800 as the stem 1820 is pushed down through it and the collapsible stem centralizer 1800 wedges itself against the interior cortical walls.

[0140] FIG. 19 includes top and front views of a stem centralizer 1900 according to an embodiment of the present disclosure. The stem centralizer 1900 may include an internal portion 1905 and an outer layer 1910. The internal portion 1905 may be configured to receive an implant stem 210. The internal portion 1905 may have an internal geometry that is complementary to the cross-sectional geometry of the implant stem 210.

[0141] The outer layer 1910 may be configured to engage an interior cortical wall. The stem centralizer 1900 may have a rigid or semi-rigid core to affix to the implant stem 210, with a flexible or compressible outer layer 1910. The outer layer 1910 may be hardened once placed in-situ and / or it may be resorbable over time.

[0142] FIG. 20 includes top and front views of an expandable stem centralizer 2000 according to an embodiment of the present disclosure. The stem centralizer 2000 may include an internal portion 2005 and an outer layer 2010. The internal portion 2005 may be configured to receive an implant stem 210. The internal portion 2005 may have an internal geometry’ that is complementary’ to the cross- sectional geometry of the implant stem 210.

[0143] The outer layer 2010 may be configured to engage an interior cortical wall. The stem centralizer 2000 may be made of an expanding material that is set over a period of time, expands at body temperature, and / or is activated or cured using light.

[0144] FIG. 21 includes front views of an expandable stem centralizer 2100 according to an embodiment of the present disclosure. The expandable stem centralizer 2100 may include an internal portion 2105 and an external portion 2110. The internal portion 2105 may be configured to receive an implant stem 210. The internal portion 2105 may have an internal geometry that is complementary to the cross-sectional geometry of the implant stem 210.

[0145] The external portion 2110 may be configured to engage an interior cortical wall. The expandable stem centralizer 2100 may include a compressed position and an expanded position. The expandable stem centralizer 2100 may be loaded onto a stem 2115 in a compressed or collapsed position. The expandable stem centralizer 2100 may be secured in the collapsed position by an actuator 2120. The actuator may be configured as a containment mechanism when the expandable stem centralizer 2100 is in a collapsed position. The actuator 2120 may be removed or released once the expandable stem centralizer 2100 and the stem 2115 are inserted into the intramedullary canal. One possible mechanism by which this may occur is through the use of a string, suture, or other flexiblemember that may release the expandable stem centralizer 2100 and allow the expandable stem centralizer 2100 to expand from the collapsed position to the expanded position.

[0146] FIG. 22 includes front and detail views of an actuatable stem centralizer 2200 according to an embodiment of the present disclosure. The actuatable stem centralizer 2200 may include an internal portion 2205 and an external portion 2210. The internal portion 2205 may be configured to receive an implant stem 2215. The internal portion 2205 may have an internal geometry that is complementary to the cross-sectional geometry of the implant stem 2215.

[0147] The external portion 2210 may be configured to engage an interior cortical wall. The external portion may include a fin 2225 rotatably connected to the external portion 2210 through a pivot 2235.

[0148] The actuatable stem centralizer 2200 may further include an actuator 2220 configured to rotate the fin 2225 from an insertion position to an extended position wherein the fin 2225 engages an interior cortical wall. The actuator 2220 may be configured a string, a suture or other actuation mechanism that may be used to pull or actuate the fin 2225 or lever or other device out and away from the stem 2215 into an extended position.

[0149] The stem centralizers included in this disclosure may be manufactured from a number of different materials or combination of materials including, but not limited to: metals (such as titanium, stainless steel, nitinol or cobalt chrome), polymers (such as polyethylene [PE], poly-ether-ether-ketone [PEEK], poly-lactic acid [PLA], poly-lactic-co-glycolic acid [PLGA], poly-glycolic acid [PGA], poly- methyl-methacrylate [PMMA] and silicone), or biological materials (such as bone grafts or collagen). The materials may be resorbable or non-resorbable.

[0150] An exemplary method for centralizing a stemmed implant within an intramedullary canal of a bone may include the following steps:1. Inserting a distal end of the stemmed implant into an internal portion of a stem centralizer.2. Inserting the stemmed implant and stem centralizer into the intramedullary' canal.3. Seeming the stem centralizer within the intramedullary' canal without the use of bone cement.

[0151] Those of skill in the art will recognize that this is only one of many potential methods that may be used to centralize a distal end of a stemmed implant. In alternative embodiments, different methods may be used to centralize a distal end of a stemmed implant. Further, the methods set forth above may be used to centralize a distal end of a stemmed implant with a stem centralizer besides those stem centralizers specifically disclosed herein.

[0152] An exemplary method for removing a stemmed implant and a stem centralizer from an intramedullary canal of a bone may include the following steps:1. Withdrawing a distal end of the stemmed implant from an internal portion of the stem centralizer, wherein the internal portion comprises a removal aperture that is smaller than the internal portion.2. Removing the stemmed implant from the intramedullary canal.3. Inserting a removal device into the intramedullary canal.4. Engaging the removal device with the removal aperture.5. Withdrawing the stem centralizer from the intramedullary canal.

[0153] Those of skill in the art will recognize that this is only one of many potential methods that may be used to remove a stemmed implant and a stem centralizer from an intramedullary canal. In alternative embodiments, different methods may be used to remove a stemmed implant and a stem centralizer from an intramedullary canal. Further, the methods set forth above may be used to remove a stemmed implant and a stem centralizer besides those stem centralizers specifically disclosed herein.

[0154] An exemplary method for revising a stemmed implant and a stem centralizer from an intramedullary canal of a bone may include the following steps:1. Removing the stemmed implant from the intramedullary canal.2. Removing the stem centralizer from the intramedullary canal.3. Inserting a revision stemmed implant into the intramedullary canal.

[0155] Those of skill in the art will recognize that this is only one of many potential methods that may be used to revise a stemmed implant and a stem centralizer from an intramedullary canal. In alternative embodiments, different methods may be used to revise a stemmed implant and a stem centralizer from an intramedullary canal. Further, the methods set forth above may be used to revise a stemmed implant and a stem centralizer besides those stem centralizers specifically disclosed herein.

[0156] Reference throughout this specification to “an embodiment” or “the embodiment” means that a particular feature, structure, or characteristic described in connection with that embodiment is included in at least one embodiment. Thus, the quoted phrases, or variations thereof, as recited throughout this specification are not necessarily all referring to the same embodiment. Features and / or method steps of the various embodiments set forth above may be combined together to yield new embodiments. The drawings arc drawn to scale, but the shapes and dimensions shown in the drawings are merely exemplary . Various features and / or dimensions may be modified within the understanding of a person of ordinary skill in the art with the aid of the present disclosure.

[0157] Similarly, it should be appreciated that in the above description of embodiments, various features are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the present disclosure. This method of disclosure, however, is not to be interpreted as reflecting an intention that any embodiment requires more features than those expressly recited in that embodiment. Rather, inventive aspects lie in a combination of fewer than all features of any single foregoing disclosed embodiment.

[0158] Recitation of the term “first” with respect to a feature or element does not necessarily imply the existence of a second or additional such feature or element. Elements recited in means-plus-function format are intended to be construed in accordance with 35 U.S.C. §112(1). It will be apparent to thosehaving skill in the art that changes may be made to the details of the above-described embodiments without departing from the underlying principles set forth herein.

[0159] The phrases "connected to," "coupled to," "engaged with," and "in communication with" refer to any form of interaction between two or more entities, including mechanical, electrical, magnetic, electromagnetic, fluid, and thermal interaction. Two components may be functionally coupled to each other even though they are not in direct contact with each other. The term "coupled" can include components that are coupled to each other via integral fonnation, as well as components that are removably and / or non-removably coupled with each other. The term "abutting" refers to items that may be in direct physical contact with each other, although the items may not necessarily be attached together. The phrase "fluid communication" refers to two or more features that are connected such that a fluid within one feature is able to pass into another feature. Moreover, as defined herein the term "substantially" means within + / - 20% of a target value, measurement, or desired characteristic.

[0160] While specific embodiments and applications of the present disclosure have been illustrated and described, it is to be understood that the scope of this disclosure is not limited to the precise configuration and components disclosed herein. Various modifications, changes, and variations which will be apparent to those skilled in the art may be made in the arrangement, operation, and details of the devices, systems, and methods disclosed herein.

Claims

1. A stem centralizer for a stemmed implant configured to be implanted within an intramedullary canal of a bone adjacent to an articulating joint, the stem centralizer comprising: an internal portion configured to receive a distal end of the stemmed implant; and an external portion comprising a plurality of fins configured to engage an interior cortical wall of the intramedullary canal, each of the plurality of fins comprising a leading angle and a trailing angle: wherein: the leading angle is configured to facilitate insertion of the stem centralizer into the intramedullary canal; and the trailing angle is configured to facilitate removal of the stem centralizer from the intramedullary canal.

2. The stem centralizer of claim 1. wherein the internal portion further comprises a removal aperture configured to receive a removal device to facilitate withdrawal of the stem centralizer from the intramedullary canal of the bone.

3. The stem centralizer of claim 2, wherein the removal aperture is smaller than the internal portion.

4. The stem centralizer of claim 2, wherein the external portion further comprises a second distal end and the removal aperture extends from the internal portion to tire second distal end.

5. The stem centralizer of claim 1, wherein the external portion further comprises a second distal end comprising an insertion portion and a proximal end opposite the second distal end. and wherein the plurality' of fins extends radially outward from the external portion between the proximal end and the insertion portion.

6. The stem centralizer of claim 1, wherein at least one of the plurality of fins comprises a fin thickness sized so that the at least one of the plurality' of fins is flexible.

7. A stem centralizer for a stemmed implant configured to be implanted within an intramedullary canal of a bone adjacent to an articulating joint, the stem centralizer comprising: an internal portion configured to receive a distal end of the stemmed implant and comprising a removal aperture; and an external portion comprising a plurality of fins configured to engage an interior cortical bone, each of the plurality of fins comprising a leading angle and a trailing angle; wherein the removal aperture is smaller than the internal portion and is configured to receive a removal device to facilitate withdrawal of the stem centralizer from the intramedullary canal of the bone.

8. The stem centralizer of claim 7. wherein the leading angle is configured to facilitate insertion of the stem centralizer into the intramedullary canal and the trailing angle is configured to facilitate removal of the stem centralizer from the intramedullary canal.

9. The stem centralizer of claim 7, wherein the external portion further comprises a second distal end and the removal aperture extends from the internal portion to tire second distal end.

10. The stem centralizer of claim 7, wherein the external portion further comprises a second distal end comprising an insertion portion and a proximal end opposite the second distal end, and wherein the plurality of fins extends radially outward from the external portion between the proximal end and the insertion portion.

11. A method for centralizing a stemmed implant within an intramedullary canal of a bone, the method comprising: inserting a distal end of the stemmed implant into an internal portion of a stem centralizer; inserting the stemmed implant and the stem centralizer into the intramedullary canal; and securing the stem centralizer within the intramedullary canal without the use of a bone cement.

12. The method of claim 11. wherein the stem centralizer comprises an external portion comprising a plurality of fins configured to engage an interior cortical wall of the intramedullary canal, each of the plurality of fins comprising a leading angle and a trailing angle.

13. The method of claim 12, wherein the leading angle is configured to facilitate insertion of the stem centralizer into the intramedullary canal and the trailing angle is configured to facilitate removal of the stem centralizer from the intramedullary canal.

14. The method of claim 11, wherein the internal portion comprises removal aperture configured to receive a removal device to facilitate withdrawal of the stem centralizer from the intramedullary canal of the bone.

15. A method for removing a stemmed implant and a stem centralizer from an intramedullary canal of a bone, the method comprising: withdrawing a distal end of the stemmed implant from an internal portion of the stem centralizer, wherein the internal portion comprises a removal aperture that is smaller than the internal portion; removing the stemmed implant from the intramedullary canal; inserting a removal device into the intramedullary canal; engaging tire removal device with the removal aperture; and withdrawing the stem centralizer from the intramedullary canal.

16. The method of claim 15, wherein the stem centralizer further comprises a second distal end and the removal aperture extends from the internal portion to the second distal end.

17. The method of claim 15, wherein the stem centralizer comprises an external portion comprising a plurality of fins configured to engage an interior cortical wall of the intramedullary canal, each of the plurality of fins comprising a leading angle and a trailing angle.

18. The method of claim 17, wherein the leading angle is configured to facilitate insertion of the stem centralizer into the intramedullary canal and the trailing angle is configured to facilitate removal of the stem centralizer from the intramedullar}' canal.

19. A method for revising a stemmed implant and a stem centralizer from an intramedullary canal of a bone, the method comprising: removing the stemmed implant from the intramedullary canal; removing the stem centralizer from the intramedullary canal; and inserting a revision stemmed implant into the intramedullary canal.

20. The method of claim 19, wherein the stem centralizer comprises an internal portion comprising a removal aperture configured to receive a removal device to facilitate withdrawal of the stem centralizer from the intramedullary canal.

21. The method of claim 19 wherein, the stem centralizer comprises an external portion comprising a plurality of fins configured to engage an interior cortical wall of the intramedullary canal, each of the plurality of fins comprising a trailing angle wherein the trailing angle is configured to facilitate removal of the stem centralizer from the intramedullary’ canal.

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