Femur and tibia orthopedic implants

Abstract

A femur cone includes an elongated hollow body tapered from an inferior edge to a superior edge. The elongated hollow body forms a bore between the inferior edge and the superior edge. The elongated hollow body has formed therein a window positioned substantially on an anterior side of the femur cone. The window includes a pair of opposing vertical steps connected to one another by a central horizontal connecting region. A tibia cone and a cone reamer are also disclosed.

Description

FEMUR AND TIBIA ORTHOPEDIC IMPLANTSCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This patent application claims priority from and incorporates by reference the entire disclosure of US Patent Application No. 63 / 552,389, filed on February 12, 2024.TECHNICAL FIELD

[0002] The present disclosure relates generally to orthopedic devices and more particularly, but not by way of limitation, to femur and tibia cones and cone reamers related thereto.BACKGROUND

[0003] This section provides background information to facilitate a better understanding of the various aspects of the disclosure. It should be understood that the statements in this section of this document are to be read in this light and not as admissions of prior art.

[0004] In knee arthroplasty surgery, a patient's natural knee joint is partially or totally replaced by a prosthetic knee prosthesis. A typical knee prosthesis includes a tibial tray, a femoral component, and a polymer insert or bearing positioned between the tibial tray and the femoral component. The tibial tray often includes a plate that has a stem extending distally therefrom. The femoral component usually includes a pair of spaced-apart condylar elements, which include surfaces that articulate with corresponding surfaces of the polymer bearing. The stem of the tibial tray is configured to be implanted in a surgically-prepared intramedullary canal of the patient's tibia. The femoral component is configured to be coupled to a surgically-prepared distal end of a patient's femur.

[0005] On occasion, a revision knee surgery may need to be performed on a patient. In a surgery, an implanted knee prosthesis is removed and a revision knee prosthesis is implanted. During a knee-replacement revision surgery, the surgeon typically uses a variety of different surgical instruments such as, for example, cutting blocks, surgical reamers, drill guides, prosthetic trials, and other surgical instruments to prepare the patient's bones to receive the knee prosthesis.

[0006] During a knee -replacement revision surgery, the orthopedic surgeon may use a tibia coneand a femur cone to help to compensate for bone loss associated with removal of the primary knee prosthesis. Tibia cones and femur cones are not directly locked to the revision knee prosthesis before implantation of the prosthesis in the bone of the patient. Instead, a cone is first separately implanted into the bone of the patient. The revision knee prosthesis is then implanted into the bone of the patient through the implanted cone. The implanted revision knee prosthesis may be secured to the previously-implanted cone by use, for example, of bone cement.SUMMARY

[0007] This summary is provided to introduce a selection of concepts that are further described below in the detailed description. This summary is not necessarily intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid in limiting the scope of claimed subject matter.

[0008] A femur cone includes an elongated hollow body tapered from an inferior edge to a superior edge. The elongated hollow body forms a bore between the inferior edge and the superior edge. The elongated hollow body has formed therein a window positioned substantially on an anterior side of the femur cone. The window includes a pair of opposing vertical steps connected to one another by a central horizontal connecting region.

[0009] A tibia cone includes an elongated hollow body tapered from an inferior edge to a superior edge. The elongated hollow body forms a bore between the inferior edge and the superior edge. The elongated hollow body has formed therein a pair of windows separated by a posterior connecting wall positioned substantially on a posterior side of the tibia cone. Each of the pair of windows includes a vertical step.

[0010] A monoblock cone reamer includes a hollow cylindrical shaft and a reamer head fixedly attached to the hollow cylindrical shaft. The reamer head includes a short cone guide and a standard cone guide. The hollow cylindrical shaft includes a plurality of markings that indicate a depth of the reamer head into a patient’s bone.BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The disclosure is best understood from the following detailed description when read with the accompanying figures. It is emphasized that, in accordance with standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of various features may be arbitrarily increased or reduced for clarity of discussion.

[0012] FIGURE 1A is a perspective view of a first embodiment of a femur cone;

[0013] FIGURE IB is an anterior view of a first embodiment of a femur cone;

[0014] FIGURE 1C is a lateral view of a first embodiment of a femur cone;

[0015] FIGURE ID is a posterior view of a first embodiment of a femur cone;

[0016] FIGURE IE is a cross-sectional medial view of a first embodiment of a femur cone;

[0017] FIGURE IF is an inferior view of a first embodiment of a femur cone;

[0018] FIGURE 2A is a perspective view of a second embodiment of a femur cone;

[0019] FIGURE 2B is an anterior view of a second embodiment of a femur cone;

[0020] FIGURE 2C is a lateral view of a second embodiment of a femur cone;

[0021] FIGURE 2D is a posterior view of a second embodiment of a femur cone;

[0022] FIGURE 2E is a cross-sectional medial view of a second embodiment of a femur cone;

[0023] FIGURE 2F is an inferior view of a second embodiment of a femur cone;

[0024] FIGURE 3A is a perspective view of a first embodiment of a tibia cone;

[0025] FIGURE 3B is a posterior view of a first embodiment of a tibia cone;

[0026] FIGURE 3C is a lateral view of a first embodiment of a tibia cone;

[0027] FIGURE 3D is an anterior view of a first embodiment of a tibia cone;

[0028] FIGURE 3E is a cross-sectional medial view of a first embodiment of a tibia cone;

[0029] FIGURE 3F is a superior view of a first embodiment of a tibia cone;

[0030] FIGURE 4A is a perspective view of a second embodiment of a tibia cone;

[0031] FIGURE 4B is a posterior view of a second embodiment of a tibia cone;

[0032] FIGURE 4C is a lateral view of a second embodiment of a tibia cone;

[0033] FIGURE 4D is an anterior view of a second embodiment of a tibia cone;

[0034] FIGURE 4E is a cross-sectional medial view of a second embodiment of a tibia cone; and

[0035] FIGURE 4F is a superior view of a second embodiment of a tibia cone;

[0036] FIGURE 5 illustrates a cone reamer used in knee-replacement revision surgery.DETAILED DESCRIPTION

[0037] Various embodiments will now be described more fully with reference to the accompanying drawings. The disclosure may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

[0038] A standard femur cone, a short femur cone, a standard tibia cone, and a short tibia cone are intended for knee-replacement revision surgery such as revision total knee arthroplasty or primary total knee arthroplasty where the patient’s bone has become compromised. If, for example, the patient has already had a primary knee replacement surgery and the knee replacement implant fails, a surgeon must remove the existing femur and tibia components and replace them with more constraining components because the patient’ s bone is now compromised and the risk of a periprosthetic fracture or implant subsidence is significantly greater. As a result, a stem extension must be placed on each of the back of the femur component and the bottom of the tibia component to provide additional support to thecompromised bone. The cones are used to further augment the compromised bone and further reduce risk of failure.

[0039] FIGURES 1A-F illustrate various aspects of a first embodiment of a femur cone. FIGURE 1A is a perspective view of the first embodiment of the femur cone. FIGURE IB is an anterior view of the first embodiment of the femur cone. FIGURE 1C is a lateral view of the first embodiment of the femur cone. FIGURE ID is a posterior view of the first embodiment of a femur cone. FIGURE IE is a cross-sectional medial view along plane IE- IE of the first embodiment of the femur cone. FIGURE IF is an inferior view of the first embodiment of the femur cone. Those having skill in the art will appreciate that lateral and medial views of the femur cone are mirror images of one another by virtue of the symmetrical nature of the femur cone. As such, the femur cone may be used in the femur of either leg of a patient. Reference numerals of corresponding features are not necessarily indicated in all of FIGURES 1A-F in order to avoid a lack of clarity of features illustrated therein.

[0040] As shown in FIGURES 1A-F, a femur cone 100 includes an elongated hollow body 102 that forms a bore 104. The elongated hollow body 102 is sized and shaped to receive a femoral stem component of a femoral revision prosthesis (not shown). The femur cone 100 is generally frustoconical in shape and is tapered from an inferior edge 106 to a superior edge 108. The femur cone of FIGURES 1A-F may be referred to as a standard femur cone. The femur cone 100 has formed therein a window 110. The window 110 facilitates better interaction between the femur cone 100, a patient’s anterior cortex (not shown), and an anterior flange of a revision femur implant (not shown). In a typical case, this interaction is between a distal (i.e., inferior) end of the femur cone 100 and a stem housing of a knee-revision femoral implant (not shown).

[0041] The window 110 is positioned substantially on an anterior side of the femur cone 100, as best illustrated in FIGURES 1A-1B and includes five primary regions: 1) a pair of opposing angled regions 112a and 112b extending substantially from the inferior edge 106; 2) a pair of opposing vertical steps 114a and 114b extending substantially from corresponding ones of the angled regions 112a and 112b; and 3) a central horizontal connecting region 116 that serves to connect the vertical steps 114a and 114b to one another. In a typical embodiment, the opposingangled regions 112a and 112b mirror one another and are at an acute angle relative to a vertical axis 118 as illustrated in FIGURES IB and IF, while the vertical steps 114a and 114b are substantially parallel to the vertical axis 118. In a typical embodiment, the window 110 curves substantially from the connecting region 116 in a posterior direction toward the inferior edge 106, as best illustrated in FIGURES 1A, IB, and 1C. The vertical axis 118 shown in FIGURES IB and IF is located in a center line of the femur cone 100 and represents a rotational axis of the femur cone 100 that is perpendicular to the superior edge 108 as shown in FIGURE IB. As shown, the femur cone 100 is substantially circular in cross-section perpendicular to the vertical axis 118, a cone angle being formed between a circumference of the inferior edge 106 and a circumference of the superior edge 108.

[0042] The femur cone 100, which may be referred to as a standard femur cone, is in contrast to many prior femur cones, which prior femur cones often feature a solid circumference on a distal (i.e., inferior) end thereof. If the anterior region of a patient’s femur is thin or missing, with such prior femur cones, there is often the potential for destructive metal-on-metal wear. The femur cone 100 reduces the chances of such an undesirable interaction.

[0043] If, for example, the patient has already had already had a knee implant via primary kneereplacement surgery and the knee replacement fails, a surgeon must remove existing components and replace them with more constraining components because the patient’ s bone is now compromised. As a result, a stem must be placed at the back of the femur and on the bottom of tibial components to give additional support to the compromised bone. The femur cone 100 serves to augment that additional support with the patient’s compromised bone.

[0044] Still referring to FIGURES 1A-F, transitions between the inferior edge 106, the respective angled regions 112a and 1 12b, between the respective angled regions 112a and 1 12b and the vertical steps 114a and 114b, and between the vertical steps 114a and 114b and the connecting region 116 are curved in accordance with design considerations to reduce stress risers and facilitate manufacturing of the femur cone 100. In the illustrated embodiment, the vertical steps 114a and 114b are substantially 5.0 mm in length along the vertical axis 118 and the connecting region 116 is located substantially 15.0 mm from the superior edge 108 along thevertical axis 118. In similar fashion, a maximal length between the inferior edge 106 and the superior edge 108 parallel to the vertical axis 218 is substantially 30.0 mm. Those having skill in the art will appreciate that other dimensions may be employed without departing from the principles disclosed herein. The disclosed configuration of the window 110 serves to provide an opening for clearance of various components used during knee-replacement revision surgery while, at the same time, preserving as much material of the femur cone 100, for example, to maintain desirable structural integrity of the femur cone 100. The disclosed configuration of the window 110 also pennits the femur cone 100 to be implanted in a patient’s body at different degrees of rotation about the vertical axis 118. In FIGURE IF, an angle a illustrates a magnitude of opening about the vertical axis 118 along the connecting region 116. In a typical embodiment, a is substantially 60°, although other angular dimensions may be employed as appropriate. It will be apparent that an angular opening of the window 110 about the vertical axis 118 is greater than a by virtue of the geometry of the angled regions 112a and 112b relative to the vertical steps 114a and 114b and the connecting region 116.

[0045] As shown in particular in FIGURE IE, an internal surface of the elongated hollow body 102 may be a metal base 120 that is pitted in order to facilitate integration of a patient’s bony growth into the internal surface. In similar fashion, FIGURE IE shows a porous coating 122 that surrounds a substantial portion of an exterior surface of the metal base 120. The porous coating 122 is adapted to serve a similar function of facilitation of bony growth into the external surface of the femur cone 100.

[0046] FIGURES 2A-F illustrate a second embodiment of a femur cone. FIGURE 2A is a perspective view of the second embodiment of the femur cone. FIGURE 2B is an anterior view of the second embodiment of the femur cone. FIGURE 2C is a lateral view of the second embodiment of the femur cone. FIGURE 2D is a posterior view of the second embodiment of the femur cone. FIGURE 2E is a cross-sectional medial view along plane 2E-2E of FIGURE 2D of the second embodiment of a femur cone. FIGURE 2F is an inferior view of the second embodiment of the femur cone. Those having skill in the art will appreciate that lateral and medial views of the femur cone are mirror images of one another by virtue of the symmetricalnature of the femur cone. As such, the femur cone may be used in the femur of either leg of a patient. Reference numerals of corresponding features are not necessarily indicated in all of FIGURES 2A-F in order to avoid a lack of clarity of features illustrated therein.

[0047] As shown in FIGURES 2A-F, a femur cone 200 includes an elongated hollow body 202 that forms a bore 204. The elongated hollow body 202 is sized and shaped to receive a femoral stem component of a femoral revision prosthesis (not shown). The femur cone 200 is generally frustoconical in shape and is tapered from an inferior edge 206 to a superior edge 208. The femur cone of FIGURES 2A-F may be referred to as a short femur cone, as opposed to the standard femur cone of FIGURES 1A-F. The femur cone 200 has formed therein a window 210. The window 210 facilitates better interaction between the femur cone 200, a patient’s anterior cortex (not shown), and an anterior flange of a revision femur implant (not shown). In a typical case, this interaction is between a distal (i.e., inferior) end of the femur cone 200 and a stem housing of a knee -revision femoral implant (not shown).

[0048] The window 210 is positioned substantially on an anterior side of the femur cone 200, as best illustrated in FIGURES 2A-2B and includes five primary regions: 1) a pair of opposing angled regions 212a and 212b extending substantially from the inferior edge 206; 2) a pair of opposing vertical steps 214a and 214b extending substantially from corresponding ones of the angled regions 212a and 212b; and 3) a central horizontal connecting region 216 that serves to connect the vertical steps 214a and 214b to one another. In a typical embodiment, the opposing angled regions 212a and 212b mirror one another and are at an acute angle relative to a vertical axis 218 as illustrated in FIGURES 2B and 2F, while the vertical steps 214a and 214b are substantially parallel to the vertical axis 218. In a typical embodiment, the window 210 curves substantially from the connecting region 216 in a posterior direction toward the inferior edge 206, as best illustrated in FIGURES 2A, 2B, and 2C. The vertical axis 218 shown in FIGURES 2B and 2F is located in a center line of the femur cone 200 and represents a rotational axis of the femur cone 200 that is perpendicular to the superior edge 208 as shown in FIGURE 2B. As shown, the femur cone 200 is substantially circular in cross-section perpendicular to the vertical axis 218, a cone angle being formed between a circumference of the inferior edge 206 and the acircumference of the superior edge 208.

[0049] The femur cone 200, which may be referred to as a short femur cone, is in contrast to many prior femur cones, which prior femur cones often feature a solid circumference on a distal (i.e., inferior) end thereof. If the anterior region of a patient’s femur is thin or missing, with such prior femur cones, there is often the potential for destructive metal-on-metal wear. The femur cone 200 reduces the chances of such an undesirable interaction.

[0050] If, for example, the patient has already had already had a knee implant via primary kneereplacement surgery and the knee replacement fails, a surgeon must remove existing components and replace them with more constraining components because the patient’ s bone is now compromised. As a result, a stem must be placed at the back of the femur and on the bottom of tibial components to give additional support to the compromised bone. The femur cone 200 serves to augment that additional support with the patient’s compromised bone.

[0051] Still referring to FIGURES 2A-F, transitions between the inferior edge 206, the respective angled regions 212a and 212b, between the respective angled regions 212a and 212b and the vertical steps 214a and 214b, and between the vertical steps 214a and 214b and the connecting region 216 are curved in accordance with design considerations to reduce stress risers and facilitate manufacturing of the femur cone 200. In the illustrated embodiment, the vertical steps 214a and 214b are substantially 5.0 mm in length along the vertical axis 218 and the connecting region 216 is located substantially 10.0 mm from the superior edge 208 along the vertical axis 218. In similar fashion, a maximal length between the inferior edge 206 and the superior edge 208 parallel to the vertical axis 218 is substantially 25.0 mm. Those having skill in the art will appreciate that other dimensions may be employed without departing from the principles disclosed herein. The disclosed configuration of the window 210 serves to provide an opening for clearance of various components used during knee-replacement revision surgery while, at the same time, preserving as much material of the femur cone 200, for example, to maintain desirable structural integrity of the femur cone 200. The disclosed configuration of the window 210 also pennits the femur cone 200 to be implanted in a patient’s body at different degrees of rotation about the vertical axis 218. In FIGURE 2F, an angle a illustrates a magnitudeof opening about the vertical axis 218 along the connecting region 216. In a typical embodiment, a is substantially 60°, although other angular dimensions may be employed as appropriate. It will be apparent that an angular opening of the window 210 about the vertical axis 218 is greater than a by virtue of the geometry of the angled regions 212a and 212b relative to the vertical steps 214a and 214b and the connecting region 216.

[0052] As shown in particular in FIGURE 2E, an internal surface of the elongated hollow body 202 may be a metal base 220 that is pitted in order to facilitate integration of a patient’s bony growth into the internal surface. In similar fashion, FIGURE 2E shows a porous coating 222 that surrounds a substantial portion of an exterior surface of the metal base 220. The porous coating 222 is adapted to serve a similar function of facilitation of bony growth into the external surface of the femur cone 200.

[0053] Various benefits of the femur cone 100 discussed above are also present in the femur cone 200. In similar fashion to the femur cone 100, the femur cone 200 is generally frustoconical in shape; however, in contrast to the femur cone 100, the femur cone 200 has a reduced height relative to the femur cone 200. This reduced height can be advantageous because, in some patients, the anatomy of a transition area (i.e., flare) from where the metaphysis to the diaphysis occurs from wide to narrow can be more abrupt. Since some patients have a so-called steep flare, akin to a champagne flute, the femur cone 100 may not fit the patient’s anatomy.Therefore, in such cases, the femur cone 200 could fit the patient’s anatomy when the femur cone 100 would not; as such, the femur cone 200 would in many cases be able to transfer loads better from a knee implant past compromised bone in the metaphysis to the uncompromised stronger bone in the diaphysis. The windows 110 and 210 may be employed to optimize interaction between a thin cortex, anterior femoral flange, and a stem housing / stem extension. The vertical steps 114a, 114b, 214a, and 214b help to balance mechanical strength and opening of the respective windows 110 and 210 to accommodate a larger constrained femoral stem housing.

[0054] FIGURES 3A-F illustrate a first embodiment of a tibia cone. FIGURE 3A is a perspective view of the first embodiment of the tibia cone. FIGURE 3B is a posterior view of the firstembodiment of the tibia cone. FIGURE 3C is a lateral view of the first embodiment of the tibia cone. FIGURE 3D is an anterior view of the first embodiment of the tibia cone. FIGURE 3E is a cross-sectional medial view along plane 3E-3E of the first embodiment of the tibia cone. FIGURE 3F is a superior view of the first embodiment of the tibia cone. Those having skill in the art will appreciate that lateral and medial views of the tibia cone are mirror images of one another by virtue of the symmetrical nature of the tibia cone. As such, the tibia cone may be used in the tibia of either leg of a patient. Reference numerals of corresponding features are not necessarily indicated in all of FIGURES 3A-F in order to avoid a lack of clarity of features illustrated therein.

[0055] As shown in FIGURES 3A-F, a tibia cone 300 includes an elongated hollow body 302 that forms a bore 304. The elongated hollow body 302 is sized and shaped to receive a tibial stem component of a tibial revision prosthesis (not shown). The tibia cone 300 is generally frustoconical in shape and is tapered from a superior edge 306 to an inferior edge 308. The tibia cone 300 of FIGURES 3A-F may be referred to as a standard tibia cone. The tibia cone 300 has formed therein a pair of windows 310a and 310b. The windows 310a and 310b are mirror images of one another and are separated by a posterior connecting wall 311 of the elongated hollow body 302. The windows 310a and 310b facilitate better interaction between the tibia cone 300, a patient’s bone (not shown), and a keel of a revision tibia implant (not shown). In a typical case, this interaction is between the tibia cone 300 and a stem housing of a knee-revision tibial implant (not shown).

[0056] The posterior connecting wall 311 is positioned substantially on a posterior side of the tibia cone 300, as best illustrated in FIGURES 3A-3C and forms a plurality of regions of the windows 310a and 310b, the regions including: 1) a pair of opposing angled regions 312a and 312b extending substantially from the superior edge 306; and 2) a pair of opposing vertical steps 314a and 314b extending substantially from corresponding ones of the angled regions 312a and 312b. A pair of horizontal connecting regions 316a and 316b serve to connect the vertical steps 314a and 314b to an anterior portion of the elongated hollow body 302. In a typical embodiment, the opposing angled regions 312a and 312b mirror one another and are at an acute angle relativeto a vertical axis 318 as illustrated in FIGURES 3C and 3F, while the vertical steps 314a and 314b are substantially parallel to the vertical axis 318. In a typical embodiment, each of the horizontal connecting regions 316a and 316b extends substantially from one of the vertical steps 314a and 314b in an anterior direction toward a pair of vertical sections 317a and 317b that extend vertically therefrom to the superior edge 306, as best illustrated in FIGURES 3A, 3B, and 3C. The vertical axis 318 shown in FIGURES 3C and 3F is located in a center line of the tibia cone 300 and represents a rotational axis of the tibia cone 300 that is perpendicular to the inferior edge 308 as shown in FIGURE 3C. As shown, the tibia cone 300 is substantially circular in cross-section perpendicular to the vertical axis 318, a cone angle being formed between a circumference of the inferior edge 308 and a circumference of the superior edge 306.

[0057] The tibia cone 300, which may be referred to as a standard tibia cone, is in contrast to many prior tibia cones, which prior tibia cones often feature a solid circumference on a proximal (i.e., superior) end thereof. If, for example, the patient has already had already had a knee implant via primary knee -replacement surgery and the knee replacement fails, a surgeon must remove existing components and replace them with more constraining components because the patient’s bone is now compromised. As a result, a stem must be placed on the bottom of tibial components to give additional support to the compromised bone. The tibia cone 300 serves to augment that additional support with the patient’s compromised bone.

[0058] Still referring to FIGURES 3A-F, transitions between the superior edge 306 and the vertical sections 317a and 317b, the vertical sections 317a and 317b and the horizontal connecting regions 316a and 316b, and the horizontal connecting regions 316a and 316b, and the angled regions 312a and 312b are curved in accordance with design considerations to reduce stress risers and facilitate manufacturing of the tibia cone 300. In the illustrated embodiment, the vertical steps 314a and 314b are substantially 5.0 mm in length along the vertical axis 318 and the horizontal connecting regions 316a and 316b are located substantially 10.0 mm from the inferior edge 308 along the vertical axis 318. In similar fashion, a maximal length between the superior edge 306 and the inferior edge 308 parallel to the vertical axis 318 is substantially 30.0 mm. Those having skill in the art will appreciate that other dimensions may be employed withoutdeparting from the principles disclosed herein. The disclosed configuration of the windows 310a and 310b serve to provide an opening for clearance of various components used during kneereplacement revision surgery while, at the same time, preserving as much material of the tibia cone 300, for example, to maintain desirable structural integrity of the tibia cone 300. The disclosed configuration of the windows 310a and 310b also permits the tibia cone 300 to be implanted in a patient’s body at different degrees of rotation about the vertical axis 318. In FIGURE 3F, an angle P illustrates a magnitude of opening about the vertical axis 318 along each of the horizontal connecting regions 316a and 316b and an angle 5 illustrates an additional magnitude of opening to the vertical sections 317a and 317b. In a typical embodiment, is substantially 50° and 8 is substantially 10°, although other angular dimensions may be employed as appropriate.

[0059] As shown in particular in FIGURE 3E, an internal surface of the elongated hollow body 302 may be a metal base 320 that is pitted in order to facilitate integration of a patient’s bony growth into the internal surface. In similar fashion, FIGURE 3E shows a porous coating 122 that surrounds a substantial portion of an exterior surface of the metal base 320. The porous coating 322 is adapted to serve a similar function of facilitation of bony growth into the external surface of the tibia cone 300.

[0060] FIGURES 4A-F illustrate a second embodiment of a tibia cone. FIGURE 4A is a perspective view of a second embodiment of a tibia cone. FIGURE 4B is a posterior view of the second embodiment of the tibia cone. FIGURE 4C is a lateral view of the second embodiment of the tibia cone. FIGURE 4D is an anterior view of the second embodiment of the tibia cone. FIGURE 4E is a cross-sectional medial view along plane 4E-4E of the second embodiment of the tibia cone. Those having skill in the art will appreciate that lateral and medial views of the tibia cone are mirror images of one another by virtue of the symmetrical nature of the tibia cone. As such, the tibia cone may be used in the tibia of either leg of a patient.

[0061] As shown in FIGURES 4A-F, the tibia cone is generally frustoconical in shape. The tibia cone 400 of FIGURES 4A-F may be referred to as a short tibia cone. The tibia cone 400 is also generally frustoconical in shape and relates to the standard tibia cone in similar fashion to howthe short femur cone relates to the standard femur cone. The short tibia cone is, in a typical embodiment, 5 millimeters shorter to accommodate particular patient anatomy. In the tibia, the transition from the metaphysis to the diaphysis is often very acute, similar to a martini glass. Reference numerals of corresponding features are not necessarily indicated in all of FIGURES 4A-F in order to avoid a lack of clarity of features illustrated therein.

[0062] As shown in FIGURES 4A-F, the tibia cone 400 includes an elongated hollow body 402 that forms a bore 404. The elongated hollow body 402 is sized and shaped to receive a tibial stem component of a tibial revision prosthesis (not shown). The tibia cone 400 is generally frustoconical in shape and is tapered from a superior edge 406 to an inferior edge 408. The tibia cone 400 of FIGURES 4A-F may be referred to as a short tibia cone. The tibia cone 400 has formed therein a pair of windows 410a and 410b. The windows 410a and 410b are mirror images of one another and are separated by a posterior connecting wall 411 of the elongated hollow body 402. The windows 410a and 410b facilitate better interaction between the tibia cone 400, a patient’s bone (not shown), and a keel of a revision tibia implant (not shown). In a typical case, this interaction is between the tibia cone 400 and a stem housing of a knee-revision tibial implant (not shown).

[0063] The posterior connecting wall 411 is positioned substantially on a posterior side of the tibia cone 400, as best illustrated in FIGURES 4A-4C and forms a plurality of regions of the windows 410a and 410b, the regions including: 1) a pair of opposing angled regions 412a and 412b extending substantially from the superior edge 406; and 2) a pair of opposing vertical steps 314a and 314b extending substantially from corresponding ones of the angled regions 412a and 412b. A pair of horizontal connecting regions 416a and 416b serve to connect the vertical steps 414a and 414b to an anterior portion of the elongated hollow body 402. In a typical embodiment, the opposing angled regions 412a and 412b mirror one another and are at an acute angle relative to a vertical axis 418 as illustrated in FIGURES 4C and 4F, while the vertical steps 414a and 414b are substantially parallel to the vertical axis 418. In a typical embodiment, each of the horizontal connecting regions 416a and 416b extends substantially from one of the vertical steps 414a and 414b in an anterior direction toward a pair of vertical sections 417a and 417b thatextend vertically therefrom to the superior edge 406, as best illustrated in FIGURES 4A, 4B, and 4C. The vertical axis 418 shown in FIGURES 4C and 4F is located in a center line of the tibia cone 400 and represents a rotational axis of the tibia cone 400 that is perpendicular to the inferior edge 408 as shown in FIGURE 4C. As shown, the tibia cone 400 is substantially circular in cross-section perpendicular to the vertical axis 418, a cone angle being formed between a circumference of the inferior edge 408 and a circumference of the superior edge 406.

[0064] The tibia cone 400, which may be referred to as a short tibia cone, is in contrast to many prior tibia cones, which prior tibia cones often feature a solid circumference on a proximal (i.e., superior) end thereof. If, for example, the patient has already had already had a knee implant via primary knee-replacement surgery and the knee replacement fails, a surgeon must remove existing components and replace them with more constraining components because the patient’s bone is now compromised. As a result, a stem must be placed on the bottom of tibial components to give additional support to the compromised bone. The tibia cone 400 serves to augment that additional support with the patient’s compromised bone.

[0065] Still referring to FIGURES 4A-F, transitions between the superior edge 406 and the vertical sections 417a and 417b, between the vertical sections 417a and 417b and the horizontal connecting regions 416a and 416b, and the horizontal connecting regions 416a and 416b and the angled regions 412a and 412b are curved in accordance with design considerations to reduce stress risers and facilitate manufacturing of the tibia cone 400. In the illustrated embodiment, the vertical steps 414a and 414b are substantially 5.0 mm in length along the vertical axis 418 and the horizontal connecting regions 416a and 416b are located substantially 5.0 mm from the inferior edge 408 along the vertical axis 418. In similar fashion, a maximal length between the superior edge 406 and the inferior edge 408 parallel to the vertical axis 418 is substantially 25.0 mm. Those having skill in the art will appreciate that other dimensions may be employed without departing from the principles disclosed herein. The disclosed configuration of the windows 410a and 410b serves to provide an opening for clearance of various components used during kneereplacement revision surgery while, at the same time, preserving as much material of the tibia cone 400, for example, to maintain desirable structural integrity of the tibia cone 400. Thedisclosed configuration of the windows 410a and 410b also permits the tibia cone 400 to be implanted in a patient’s body at different degrees of rotation about the vertical axis 418. In FIGURE 4F, an angle 0 illustrates a magnitude of opening about the vertical axis 418 along each of the horizontal connecting regions 416a and 416b and an angle 6 illustrates an additional magnitude of opening to the vertical sections 417a and 417b. In a typical embodiment, 0 is substantially 50° and 6 is substantially 10°, although other angular dimensions may be employed as appropriate.

[0066] As shown in particular in FIGURE 4E, an internal surface of the elongated hollow body 402 may be a metal base 420 that is pitted in order to facilitate integration of a patient’s bony growth into the internal surface. In similar fashion, FIGURE 4E shows a porous coating 122 that surrounds a substantial portion of an exterior surface of the metal base 420. The porous coating 422 is adapted to serve a similar function of facilitation of bony growth into the external surface of the tibia cone 400.

[0067] Features of the tibia are different from features of the femur in a number of ways. Typical tibial implants have a keel to provide rotational stability when a surgeon is implanting a knee implant. Different keels have different angles coming off a stem housing of the implant. Many prior tibia cones are specific to a particular knee implant they were designed to fit with; as such, they have very limited rotational flexibility about the vertical axis 418. In such cases, once a prior tibia cone is placed and impacted into the bone, a tibia baseplate with a stem extension is placed that passes through the tibia cone down into the diaphysis region of the tibia. Such prior tibia cones have very limited flexibility in how to position rotationally the tibia base plate and, as such, restrict where and how a surgeon can position the implant in the tibia.

[0068] In contrast to prior tibia cones and as noted above, the tibia cone 400 has more open windows of substantially 60 degrees on medial and lateral sides and that is oriented more posteriorly relative to most, if not all, prior tibia cones so as to be more universal and better suited to be used with a variety of different revision knee implants. The windows 410a and 410b are oriented more posteriorly and are, as such, able to accommodate a greater variety of revision tibial components. The tibia cone 400 possesses analogous features to those described aboverelative to the femur cones 100 and 200.

[0069] In a typical surgical procedure, a surgeon reams the bone with an intramedullary canal reamer, reams for the tibia cone, then impacts the cone into the desired position. Once the surgeon has implanted the tibia cone, the surgeon will then implant the revision tibia component using bone cement and rotate the revision tibia component internally or externally about axis 418 to optimize coverage of the bone and component alignment with the revision tibia baseplate. In contrast to prior tibia cones, the tibia cone 400 provides more flexibility to the surgeon to adjust the tibia cone 400 rotationally to better match an individual patient’s anatomy.

[0070] In the tibia cones shown in FIGURES 3A-F and 4A-F, a 60 degree keel opening serves to provide significant rotational flexibility about the vertical axis 418 to provide compatibility with a variety of revision implants. Also illustrated is substantially 5.0 mm of additional anterior window utilizing the vertical steps 414a and 414b to balance mechanical strength and window opening. As noted above, the vertical step 414a and 414b are vertical in the sense that they includes at least a portion that is substantially parallel to the vertical axis of the tibia cones as illustrated in FIGURES 3A-F and 4A-F. The short tibia cone shown in FIGURES 4A-F is 5.0 mm less in height relative to the standard tibia cone of FIGURES 3A-F so as to optimize fit of the tibia cone 400 in tibias with a sharper metaphysis-to-diaphysis transition.

[0071] In typical embodiments, the femur cones and tibia cones disclosed herein are porous on the outside and solid on the inside. The porous structure employs a pore size that best matches cancellous bone so that the bone will grow into the cone in question. As the bone grows into the porous structure, the bone is reinforced with a goal of reducing the chances of implant failure following revision knee arthroplasty. In addition, in a typical embodiment of any of the cones disclosed herein, the inner wall is not smooth but is instead relatively rough or pitted so as to allow bone cement to lock into the cone more effectively. In some embodiments, the cone angle of all femur cones and tibia cones disclosed herein is identical irrespective of height, or distance along a vertical axis between the inferior edge and the superior edge of the cone in question.

[0072] FIGURE 5 illustrates a cone reamer used in knee-replacement revision surgery. Duringknee-replacement revision surgery, a surgeon removes all existing implants from the femur and the tibia. Once the implants have been removed, the surgeon uses an intramedullary canal reamer (not shown) to ream down the shaft of the tibia. In FIGURE 5, a cone reamer 500 is illustrated. The cone reamer 500 includes a reamer head 502 and a cylindrical shaft 504 which is hollow. The reamer head 502 is axially aligned with a rotational axis of the cylindrical shaft 504 and is affixed to a distal end of the cylindrical shaft 504.

[0073] The inside of the tibia is cancellous bone, which is a soft spongy bone. Some of this soft spongy bone is removed to allow a stem to contact the cortical bone in the diaphysis, which is more structurally sound. In a typical revision arthroplasty surgical procedure, when the patient has compromised metaphyseal bone and needs augmentation with a cone, the surgeon disconnects a powered handpiece (not shown) while the intramedullary canal reamer is still positioned in the shaft of the tibial canal.

[0074] In a next step of the surgery, the intramedullary canal reamer serves to guide, for example, the cone reamer 500 by maintaining axial alignment with a center of the tibia diaphysis canal. The cone reamer 500 is cannulated and slips over the intramedullary canal reamer. The reamer head, which operates much like an auger, creates a void in the bone that mimics a particular' shape of a tibial cone to be installed in the patient.

[0075] Each specific cone reamer such as the cone reamer 500 matches the dimensions of a particular' tibia or femur cone to be employed in the surgery. As such, dimensions of the reamer head, such as, for example, its diameter, may vary. In order to facilitate such matching, markings 506 on the cone reamer 500 tell the surgeon how deep to take the cone reamer 500 into the bone. For example, the surgeon reams the bone away, pulls out the cone reamer, pulls out the canal reamer, and inserts the tibia cone into the bone. The outside of the tibia cone is porous such that over time the bone will grow into the bone. A similar' procedure using the cone reamer is followed with regard to the femur cone. As illustrated in FIGURE 5, the cone reamer includes a short cone guide 508 and a standard cone guide 510. The short cone guide 508 is illustrated as a series of indentations around a circumference of the reamer head 502 that indicate to the surgeon a depth to which the reamer head should be taken if a short cone is to be installed, while thestandard cone guide 510 is simple the proximal end of the reamer head 502.

[0076] In contrast to many prior cone reamers, the cone reamer 500 is a monoblock such that the reamer head 502 and the cylindrical shaft 504 are fixed to one another rather than being modular in design. The monoblock may be a unitary structure or the reamer head 502 and the hollow cylindrical shaft may be separate parts that are fixedly attached to one another. As such, in either case, a surgeon does not need to assemble various components but rather can instead grab the cone reamer 500 and prepare the bone for a cone, which results in a more efficient revision knee arthroplasty procedure. In a typical embodiment, the cone reamer has a 9.25 mm inner diameter. Many commercial intramedullary canal reamers have a standard outer shaft diameter of 9.0 mm. The 9.25 mm inner diameter of the cone reamer 500 means that the cone reamer 500 will fit over many commercially available intramedullary canal reamers, which improves efficiency during surgery because it is not necessary for the surgical team to pull out another reamer or assemble multiple pails and also decreases the chance of a mistake being made during surgery. In contrast, many currently available systems require intramedullary canal reamers to be exchanged and require multiple steps to prepare the bone. In such prior cases, a surgeon must first ream the bone with a cone reamer and then use a broach to complete the bone preparation. The system disclosed herein uses a single-step bone preparation process.

[0077] The cylindrical shaft 504 includes markings 506 at defined axial distances from the reamer head that may be used to assist a surgeon in operating the cone reamer. The markings 506 are, for example, at axial distances of 30.0 mm, 25.0 mm, and 20.0 mm from a proximal end of the reamer head 502. The markings 506 may be utilized, for example, when cones are to be stacked on top of one another. The markings 506 indicate a depth to which the cone reamer 500 should bore for a particular version of a cone, whether a femur cone or a tibia cone. Stacking of cones is often done when a patient’s anatomy has compromised bone that extends past the metaphysis region and into the diaphysis region of the bone.

[0078] The term "substantially" is defined as largely but not necessarily wholly what is specified (and includes what is specified; e.g., substantially 90 degrees includes 90 degrees and substantially parallel includes parallel), as understood by a person of ordinary skill in the art. Inany disclosed embodiment, the terms “substantially,” “approximately,” “generally,” and “about” may be substituted with “within 10% of’ what is specified.

[0079] Conditional language used herein, such as, among others, "can," "might," "may," “e.g.,” and the like, unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain embodiments include, while other embodiments do not include, certain features, elements and / or states. Thus, such conditional language is not generally intended to imply that features, elements and / or states are in any way required for one or more embodiments or that one or more embodiments necessarily include logic for deciding, with or without author input or prompting, whether these features, elements and / or states are included or are to be performed in any particular embodiment.

[0080] While the above detailed description has shown, described, and pointed out novel features as applied to various embodiments, it will be understood that various omissions, substitutions, and changes in the form and details of the devices or algorithms illustrated can be made without departing from the spirit of the disclosure. As will be recognized, the processes described herein can be embodied within a form that does not provide all of the features and benefits set forth herein, as some features can be used or practiced separately from others. The scope of protection is defined by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.

Claims

What is claimed is:

1. A femur cone comprising: an elongated hollow body tapered from an inferior edge to a superior edge; wherein the elongated hollow body forms a bore between the inferior edge and the superior edge; wherein the elongated hollow body has formed therein a window positioned substantially on an anterior side of the femur cone; and wherein the window comprises a pair of opposing vertical steps connected to one another by a central horizontal connecting region.

2. The femur cone of claim 1, wherein: the window comprises a pair of opposing angled regions extending substantially from the inferior edge; and each of the pair of opposing vertical steps extends substantially from one of the pair of opposing angled regions.

3. The femur cone of claim 2, wherein the pair of opposing angled regions are at acute angles relative to the pair of opposing vertical steps.

4. The femur cone of claim 1, wherein the central horizontal connecting region is positioned substantially halfway between the inferior edge and the superior edge along a vertical axis perpendicular to the superior edge.

5. The femur cone of claim 1 , wherein the central horizontal connecting region is positioned approximately 40% of a distance between the superior edge and the inferior edge from the superior edge along a vertical axis perpendicular to the superior edge.

6. The femur cone of claim 2, wherein the pair of opposing vertical steps mirror one another and the pair of opposing angled regions mirror one another.

7. The femur cone of claim 1, wherein an opening of the central horizontal connectingregion about a vertical axis perpendicular to the superior edge is approximately 60°.

8. The femur cone of claim 1, wherein the elongated hollow body comprises a metal base having a rough internal surface and a porous coating surrounding a substantial portion of an external surface of the metal base.

9. A tibia cone comprising: an elongated hollow body tapered from an inferior edge to a superior edge; wherein the elongated hollow body forms a bore between the inferior edge and the superior edge; wherein the elongated hollow body has formed therein a pair of windows separated by a posterior connecting wall positioned substantially on a posterior side of the tibia cone; and wherein each of the pair of windows comprises a vertical step.

10. The tibia cone of claim 9, wherein: each of the pair of windows comprises an angled region extending substantially from the superior edge; and each vertical step extends substantially from one of the angled regions.

11. The tibia cone of claim 10, wherein each of the angled regions is at an acute angle relative to the vertical step that extends from the angled region.

12. The tibia cone of claim 9, wherein each of the pair of windows comprises a horizontal connecting region that extends anteriorly from one of the vertical steps.

13. The tibia cone of claim 12, wherein each of the horizontal connecting regions connect to a vertical section that extends vertically to the superior edge.

14. The tibia cone of claim 12, wherein each of the horizontal connecting regions is positioned approximately 30% of a distance between the superior edge and the inferior edge from the inferior edge along a vertical axis perpendicular to the inferior edge.

15. The tibia cone of claim 10, wherein the pair of opposing vertical steps mirror one anotherand the pair of opposing angled regions mirror one another.

16. The tibia cone of claim 12, wherein an opening of the each of the horizontal connecting regions about a vertical axis perpendicular to the inferior edge is approximately 50-60°.

17. The tibia cone of claim 9, wherein the elongated hollow body comprises a metal base having a rough internal surface and a porous coating surrounding a substantial portion of an external surface of the metal base.

18. The tibia cone of claim 12, wherein each of the horizontal connecting regions is positioned approximately 20% of a distance between the superior edge and the inferior edge from the inferior edge along a vertical axis perpendicular to the inferior edge.

19. A monoblock cone reamer comprising: a hollow cylindrical shaft; a reamer head fixedly attached to the hollow cylindrical shaft; wherein the reamer head comprises a short cone guide and a standard cone guide; and wherein the hollow cylindrical shaft comprises a plurality of markings that indicate a depth of the reamer head into a patient’s bone.

20. The monoblock cone reamer of claim 19, wherein an inner diameter of the hollow cylindrical shaft is dimensioned to fit over an outer diameter of a canal reamer.

21. The monoblock cone reamer of claim 19, wherein the hollow cylindrical shaft and the reamer head are a unitary structure.

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