Systems and methods for magnetic joints

Abstract

An orthopedic knee prosthesis includes a femoral component configured to couple to a femur, a tibial bearing including a top portion, including one or more concave bearing surfaces, configured to articulate with one or more curved condyle surfaces of the femoral component, a tibial coupler configured to be associated with the tibial bearing and configured to couple to a tibia, a first magnetic portion statically coupled to the tibial coupler and including a first pole having a first pole polarity, and a second magnetic portion statically coupled to the tibial bearing and including a second pole configured to generally face the first pole and having a polarity that is the same as the polarity of the first pole, wherein movement of the tibial bearing in relation to the tibial coupler causes an increase in a magnetic repulsive force between the first magnetic portion and the second magnetic portion.

Description

SYSTEMS AND METHODS FOR MAGNETIC JOINTSBACKGROUND OF THE INVENTIONField of the Invention

[0001] The field of the invention generally relates to prostheses or artificial substitutes or replacements for parts of the body, such as joints, including but not limited to knees, such as total artificial knee prostheses, or the hip, such as hip prostheses.SUMMARY OF THE INVENTION

[0002] In a first embodiment of the present disclosure, an orthopedic knee prosthesis includes a femoral component including a top potion including a femoral coupler configured to couple to a lower portion of a femur, and a bottom portion including a curved medial condyle surface and a curved lateral condyle surface, a tibial bearing including a top portion including a concave medial bearing surface configured to articulate with the curved medial condyle surface and a concave lateral bearing surface configured to articulate with the curved lateral condyle surface, a tibial coupler configured to couple to an upper portion of a tibia, the tibial coupler associated with the tibial bearing, a first magnetic portion associated with the tibial bearing and / or the tibial coupler and including a first pole having a first pole polarity, and a second magnetic portion associated with the tibial bearing and / or the tibial coupler and including a second pole having a second pole polarity, the second pole polarity the same as the first pole polarity, wherein the first pole and the second pole face each other, and wherein at least one of the first magnetic portion and the second magnetic portion is configured to bidirectionally translate with respect to the tibial bearing and / or the tibial coupler.

[0003] In another embodiment of the present disclosure, an orthopedic knee prosthesis includes a femoral component including a top potion including a femoral coupler configured to couple to a lower portion of a femur, and a bottom portion including a curved medial condyle surface and a curved lateral condyle surface, a tibial bearing including a top portion including a concave medial bearing surface configured to articulate with the curved medial condyle surface and a concave lateral bearing surface configured to articulate with the curved lateral condyle surface, a tibial coupler configured to moveably couple to the tibial bearing and configured to couple to an upper portion of a tibia, a first magnetic portion staticallycoupled to the femoral component and including a first pole having a first pole polarity, a second magnetic portion statically coupled to the tibial bearing and including a second pole having a second pole polarity, the second pole polarity the same as the first pole polarity, wherein, when the curved medial condyle surface is articulatably coupled to the concave medial bearing surface and the curved lateral condyle surface is articulatably coupled to the concave lateral bearing surface, the first pole and the second pole are in sufficient proximity to each other such that a first magnetic repulsive force is present, the first repulsive force configured to subtract from compressive forces that are applied between the femoral component and the tibial bearing, the second magnetic portion further including a third pole opposite the second pole and having a third pole polarity that is opposite the first pole polarity and the second pole polarity, the third pole configured to generally face the tibial coupler, and a third magnetic portion statically coupled to the tibial coupler and including a fourth pole configured to generally face the third pole and having a polarity that is the same as the polarity of the third pole, wherein movement of the tibial bearing in relation to the tibial coupler that causes the third pole and the fourth pole to decrease their relative distance from each other causes an increase in a second magnetic repulsive force between the third pole and the fourth pole.

[0004] In yet another embodiment of the present disclosure, a method for performing a total knee arthroplasty includes providing an orthopedic knee prosthesis including a femoral component including a top potion including a femoral coupler configured to couple to a lower portion of a femur, and a bottom portion including a curved medial condyle surface and a curved lateral condyle surface, a tibial bearing including a top portion including a concave medial bearing surface configured to articulate with the curved medial condyle surface and a concave lateral bearing surface configured to articulate with the curved lateral condyle surface, a tibial coupler configured to moveably couple to the tibial bearing and configured to couple to an upper portion of a tibia, a first magnetic portion statically coupled to the femoral component and including a first pole having a first pole polarity, a second magnetic portion statically coupled to the tibial bearing and including a second pole having a second pole polarity, the second pole polarity the same as the first pole polarity, wherein, when the curved medial condyle surface is articulatably coupled to the concave medial bearing surface and the curved lateral condyle surface is articulatably coupled to the concave lateral bearing surface, the first pole and the second pole are in sufficient proximity to each other such that a first magnetic repulsive force is present, the first repulsive force configured to subtract from compressive forces that are applied between the femoral component and the tibial bearing,the second magnetic portion further including a third pole opposite the second pole and having a third pole polarity that is opposite the first pole polarity and the second pole polarity, the third pole configured to generally face the tibial coupler, and a third magnetic portion statically coupled to the tibial coupler and including a fourth pole configured to generally face the third pole and having a polarity that is the same as the polarity of the third pole, wherein movement of the tibial bearing in relation to the tibial coupler that causes the third pole and the fourth pole to decrease their relative distance from each other causes an increase in a second magnetic repulsive force between the third pole and the fourth pole, coupling the femoral coupler to a portion of a femur bone of a patient, coupling the tibial coupler to a portion of a tibia bone of a patient, coupling the tibial coupler to the tibial bearing such that the tibial bearing can move in relation to the tibial coupler, and coupling the femoral component in articulation with the tibial bearing.

[0005] In still another embodiment of the present disclosure, an orthopedic knee prosthesis includes a femoral component including a top potion including a femoral coupler configured to couple to a lower portion of a femur, and a bottom portion including one or more curved condyle surfaces, a tibial bearing including a top portion including one or more concave bearing surfaces configured to articulate with the one or more curved condyle surfaces, a tibial coupler configured to be dynamically coupled to the tibial bearing and configured to couple to an upper portion of a tibia, a first magnetic portion statically coupled to the tibial coupler and including a first pole having a first pole polarity, and a second magnetic portion statically coupled to the tibial bearing and including a second pole configured to generally face the first pole and having a polarity that is the same as the polarity of the first pole, wherein movement of the tibial bearing in relation to the tibial coupler that causes the first pole and the second pole to decrease their relative distance from each other causes an increase in a magnetic repulsive force between the first magnetic portion and the second magnetic portion.BRIEF DESCRIPTION OF THE DRAWINGS

[0006] FIG. 1 is a cross-sectional view of a magnetic total knee prosthesis, according to an embodiment of the present disclosure.

[0007] FIG. 2 is a cross-sectional view of a magnetic total knee prosthesis in a first position, according to an embodiment of the present disclosure.

[0008] FIG. 3 is a cross-sectional view of a magnetic total knee prosthesis in a second position, according to an embodiment of the present disclosure.

[0009] FIG. 4 is a cross-sectional view of a magnetic total knee prosthesis in a third position, according to an embodiment of the present disclosure.

[0010] FIG 5 is a perspective view of a magnetic total knee prosthesis in a partially bent / flexed position as implanted within a patient, according to another embodiment of the present disclosure.

[0011] FIG 6 is a cross-sectional view of a magnetic total knee prosthesis in a first position on a patient, according to an embodiment of the present disclosure.

[0012] FIG. 7 is a cross-sectional view of a magnetic total knee prosthesis in a second position on a patient, according to an embodiment of the present disclosure.

[0013] FIG. 8 is a cross-sectional view of a magnetic total knee prosthesis in a third position on a patient, according to an embodiment of the present disclosure.

[0014] FIG. 9 is a cross-sectional view of an insert molded tibial bearing, according to an embodiment of the present disclosure.

[0015] FIG. 10 is a cross-sectional view of an insert molded tibial coupler according to an embodiment of the present disclosure.

[0016] FIG. 11 is a cross-sectional view of an insert molded tibial coupler according to an embodiment of the present disclosure.DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

[0017] Total knee arthroplasty, or total knee replacement, has undergone many mechanical advancements over the past several decades. However, many problems regarding patient function and patient satisfaction have as yet not been addressed with appropriate solutions. A crucial concept that has not been sufficiently addressed is the transition between the weight bearing surfaces of the femoral and tibial sides of the articulation of total knee prostheses. Experience in joint arthroplasty surgery over several decades, often involving special fellowship training, has enhanced surgeons’ capacity to perform complex joint reconstructive procedures. Many of these procedures are now guided by computer systems and robotic equipment.

[0018] However, despite these advances, a glaring, monumental problem still remains. The normal, natural functioning knee joint has a complex arrangement of surface lining, specialized joint fluid, and multiple cartilaginous structures whose physical characteristics and interplay play an important part in the natural function of the knee. Much of the biomechanical characteristics of these natural elements have not been included in total knee prosthesis designs. In recent years, these functional characteristics have been overlooked, asthe generational improvement of total knee prostheses focuses instead on other, arguably more minor, changes.

[0019] The surface of a natural knee joint is a smooth, glistening layer possessing a complex combination of water, chondrocytes, extracellular matrix, collagens, proteoglycans, and other substances. These and other biological structures of the knee, and their functionality, have been largely ignored in the construction of total knee prostheses. Not surprisingly, most patients receiving total knee prostheses in total knee arthroplasty procedures later opine that their knees “do not feel normal.” Many surgeons tell their patients that about a year after the replacement surgery, the knee will start to feel “normal.” However, it has been reported that this is not truly the case. The memory of the fluid feel during walking, running, dancing, jumping, and even standing, when the person possessed two normal, natural knee joints, remains within the mind of a total knee patient. This memory is longstanding, and serves as a stark comparison to the unnatural feel the patient is suddenly stuck with following total knee replacement surgery. This is true whether the replacement involved one knee, or both knees, and whether it involved one surgery or more than one surgery. Artificial total knee joints often comprise a metal femoral component configured to be coupled to the patient’s femur, a metal tibial component configured to be coupled to the patient’s tibia, and a polymeric tibial bearing configured to be coupled to the tibial component and configured to articulate with the femoral component. The metal components can comprise Cobalt-Chromium (CoCr) alloys, which can comprise nickel. The polymeric bearing can comprise polyethylene, such as ultra-high molecular weight polyethylene (UHMWPE) or highly-cross-linked polyethylene (HXLPE). In some embodiments, the tibial component, the femoral component, and the tibial bearing can all comprise polyethylene. Though these components allow for the flex between the patient’s tibia and femur, as well as a certain amount of torsional freedom, the bearing surfaces are highly rigid, with much less elastic compression or spring action than that provided by the naturally -occurring substances in the knee. The Applicant has determined that many of these somewhat complex mechanical differences are important reasons for the fleeting or entirely absent natural feel of total knee prostheses. It is reported that water makes up between about 65% and about 80% of cartilage. Articular cartilage and meniscal cartilage, as well as viscous joint fluid are some of the naturally-occurring materials that control the fine mechanical performance of a healthy knee. There is no true comparative simulation of this in the metal and polymeric materials of the current total knee prostheses.

[0020] The total knee prostheses presented herein include embodiments comprising a magnetic joint which is configured to add back some of these previously-removed and missing mechanical complexities. By incorporating one or more opposing, distancedependent forces based on magnetic repulsion into the prosthesis, the magnetic total knee prosthesis provides the patient with a more natural feel that was absent in previous total knee prostheses. In some cases, these additional forces may take the place of the viscoelastic “adherence” effect experienced in normal healthy joints having synovial fluid. The natural feel may allow a more comfortable stroll through an uneven or hilly path in some cases, or may even allow running to be possible where it otherwise would not have been. This capability provided by the magnetic total knee prosthesis exists because of the increase in balance, increase in dexterity, and / or reduction in pain. In some cases, a complete removal of pain is possible.

[0021] Further benefits from the addition of the magnetically-provided repulsion (repulsive, repelling) forces include: decreased normal forces, and thus decreased frictional forces, between the components of the prosthesis / implant, for example, between the femoral component and the tibial bearing. As such, wear between the implant components is decreased. As a result, less particulate is created, for example, particulate that may be shed from the polymeric tibial bearing. Furthermore, an overall “gliding” motion between the implant components is created. Along with decreased wear is less generated heat, and less unnatural application of forces on bone, cartilage, tendon, ligament, nerves, and other soft tissue. Other problems associated with joint replacement surgery may also be significantly mitigated, such as fracture of the components, dislocation of the components, asymmetric wear of the components, or fracture of the bones (e.g., tibia, femur), or damage to other tissue that surround the components. The magnetic fields that are formed to create the repelling forces help, thus, to simulate the biological structures that are no longer present in the artificial joint. Besides the knee joint, other joints can be aided by the teaching herein, such as other weight-bearing joints like the hip joint, ankle joint, or vertebral joints, or even more intermittent weight-bearing joints such as the shoulder joint, elbow joint, wrist, or even spinal column. The improvements described herein address many general challenges caused by impact, acceleration, and deceleration. The magnetically-created adjunctive forces in the embodiments taught herein serve to bridge the gap between the non-biologic and the biologic portions of the leg having an artificial knee prosthesis.

[0022] FIGS. 1-4 illustrate a magnetic total knee prosthesis 100 configured to be implanted within a patent (not shown) during a total knee arthroplasty surgery. The magnetictotal knee prosthesis 100 comprises a femoral component 102 (purposely removed in FIG. 1 to better show the other components), a tibial coupler 104, and a tibial bearing 106. The tibial coupler 104 and the tibial bearing 106 together comprise a tibial component 105. The components / elements 102, 104, 106 can each comprise a metal or metal alloy, for example a cobalt chromium alloy, or, in some embodiments, a polymer, such as polyethylene. In some embodiments, the tibial bearing 106, for example, comprises ultra -high molecular weight polyethylene (UHMWPE). In some embodiments, the tibial bearing 106 comprises highly cross-linker polyethylene (HXLPE). In some embodiments, the tibial component, the femoral component, and the tibial bearing can all comprise polyethylene.

[0023] As shown in FIG. 1, the tibial bearing 106 includes a top portion 150 and a bottom portion 152. The top portion 150 of the tibial bearing 106 includes a concave lateral bearing surface 154 and a concave medial bearing surface (on the opposite side, not shown). Turning to FIG. 2, the femoral component 102 comprises a lateral condyle 140 and a medial condyle (on the opposite side, not shown). Each condyle, lateral and medial, is configured to articulate in a sliding manner along an arcuate path within the concave lateral bearing surface 154 and the concave medial bearing surface, respectively. FIGS. 2-4 show the magnetic total knee prosthesis 100 when the femur (not shown) and tibia (not shown) are being angulated / articulated with respect to each other in from a bent leg position (FIG. 2), to a partially bent leg position (FIG. 3), to a substantially straight leg position (FIG. 4). Note that anterior 97 and posterior 99 sides of the prosthesis 100 are shown. A curved lateral condyle surface 146 slides over the concave lateral bearing surface 154 and, likewise, a spaced curved medial condyle surface slides over the concave medial bearing surface, while the femoral component 102 changes its relative rotational orientation in relation to the tibial bearing 106 (and thus in relation to the tibial component 105). When the legs are in a loaded, weightbearing condition, this occurs with equal and opposite normal forces between the femoral component 102 and the tibial bearing 106, applied at the interface between the lateral condyle 140 and the concave lateral bearing surface 154 (and between the medial condyle and the concave medial bearing surface). The change in rotational orientation is in relation to the transverse axis 144 (e.g., extending perpendicularly from the page). Thus, the rotational axis and the transverse axis 144 are colinear. In other embodiments, the rotational axis can be different from the transverse axis 144 (e.g., spaced from the transverse axis 144) but parallel to the transverse axis 144. In some embodiments the rotational axis and transverse axis 144 are non-parallel to each other. The magnetic total knee prosthesis 100 depicted in FIGS. 1-4 is intended for the left knee. A right knee model would typically be a mirror image of theprosthesis 100 depicted in FIGS. 1-4, and thus a reversed copy of all of the teachings presented herein should also be assumed to exist. However, in some embodiments, the right knee and left knee models can be designed to be the same, such that only a single model is needed. This may, for example, be applicable in locations with a minimal healthcare budget. In some embodiments, the single model, can be adaptable or easily modifiable in order to configure it for the left knee or right knee.

[0024] The femoral component 102 comprises a top portion 108 and a bottom portion 110. The top portion 108 and / or bottom portion 110 include a femoral coupler (not shown) configured to be coupled to a lower portion of a femur 316 (FIGS. 5-8). The tibial coupler 104 comprises a bottom portion 118 and a top portion 120. The bottom portion 118 includes a stem 122 configured to be coupled to an upper portion of a tibia. Like the tibial coupler 104, the femoral coupler can also comprise a stem. Both stems are configured for compatibility and adherence to bone.

[0025] All of the embodiments of the magnetic total knee prosthesis 100 disclosed herein, including alternative embodiments, can have a “cruciate retaining” configuration. Alternatively, all of the embodiments, can instead have an alternative “posterior stabilized” configuration, featuring a box on the femoral component 102 and a post on the tibial bearing 106. Alternatively, all of the embodiments can instead be configured with an alternative “anterior stabilized” configuration or with a “bicruciate retaining” (PCL and ACL) configuration.

[0026] Turning to FIG. 1, the tibial bearing 106 comprises an outer extremity 200, and also comprises a reduced outer diameter portion 202, located at the bottom portion 152. The reduced outer diameter portion 202 (or reduced transverse dimension portion) is configured to bi-directionally translate (+Z / -Z) or slide within an inner cavity 204 of the top portion 120 of the tibial coupler 104, at an inner diameter 206 (or inner transverse dimension). The inner diameter 206 is configured to be slightly larger than the reduced outer diameter portion 202, to allow smooth, but not overly loose translation / sliding. Ins some embodiment lubricant such as silicone grease may be used between the two portions. A first magnet 208 is bonded into, molded into, or otherwise secured to the inner cavity 204 of the tibial coupler 104. A second magnet 210 is bonded into, molded into, or otherwise secured to an inner cavity 212 of the tibial bearing 106. The first magnet 208 and the second magnet 210 are each poled along the +Z / -Z axis, as shown, the poles indicated by + and - signs. Positive (+) and negative (-) signs are being used herein to denote what are commonly referred to as the north pole (N) and south pole (S) of magnets. However, it is not intended to make positive (+) asynonym of a north pole (N) or a synonym of a south pole (S). It is merely done to indicate “one or the other” pole. Throughout, Throughout, the important constant is that in repulsive configurations, a particular pole of one magnet faces a like pole of another magnet. Thus, north vs. north can be denoted as + vs. + or as - vs. -. South vs. South can also be denoted as + vs. + or as - vs. -. Also, as shown, the positive pole (+) of magnet 208 faces the positive pole (+) of magnet 210, thus making the two magnets 208, 210 repel each other, defining them as a repelling pair 214. In other embodiments, each of the magnets 208, 210 can be flipped over, such that the negative poles (-) face each other. In this alternative embodiment, the magnets 208, 210 would still be a repelling pair 214. In other embodiments, one or both of the magnets 208, 210 can instead each be replaced with two or more magnets, e.g., in some embodiments an array of magnets.

[0027] Because the first magnet 208 is statically connected to the tibial coupler and the second magnet 210 is statically connected to the tibial bearing 216, the combination of the pistoning motion of the tibial bearing 106 in relation to the tibial coupler 104, with the repulsion between the magnets 208, 210 of the repelling pair 214, creates a magnetic shock absorber, which may also be referred to as a mag-lev element (magnetic levitation). In use in a patient, when a force is placed on a patient’s leg having the prosthesis 100 implanted therein, via walking, running, standing, jumping, or other motion, the force causes a gap G to decrease as the tibial bearing 106 moves (e.g., downwardly) within the tibial coupler 104 and their average distance from each other decreases. This motion causes the positive pole of magnet 210 to become closer to the positive pole of magnet 208, thus increasing the repulsive force between the two magnets 208, 210 non-linearly. As the face 216 of magnet 208 approaches the face 218 of magnet 210 (see FIG. 4), the repulsive force begins to increase significantly, and is capable of supporting a large amount of weight, without the magnets 208, 210 bottoming out (e.g., touching each other). In some embodiments, the tibial bearing 106 can include an internal detent 220 that stops it from being removed from the inner cavity 204 of the tibial coupler 104. For example, internal detents 220 on both sides of the tibial bearing 106 can snap within the inner cavity 204 of the tibial coupler 104. Likewise, the tibial coupler 104 can in some embodiments include a stop 222 (FIG. 3) to keep the face 216 of magnet 208 from actually being able to touch the face 218 of magnet 210. However, the stop 222 is not always necessary. The force when the faces 216, 218 are very close to each other, but not touching, can be so high that even a very heavy person can be at least a bit “magnetically levitated” by the prosthesis 100. In some embodiments, when a force of 136 kg is placed on the tibial bearing 106 by the femoral component 102 (e.g., a patient standing onone leg having the prosthesis 100 implanted), there is at least some space maintained between the first pole and the second pole, via magnetic repulsion. In some embodiments, this space comprises at least 0.001 millimeter in axial (e.g., Z-axis) distance In some embodiments, this space comprises at least 0.01 millimeter in axial (e.g., Z-axis) distance. In some embodiments, this space comprises at least 0.1 millimeter in axial (e.g., Z-axis) distance. In some embodiments, this space comprises at least 1 millimeter in axial (e g., Z-axis) distance. When the prosthesis has no load from the patient (e.g., FIG. 1), the gap G can be configured to have a nominal distance (face 216 to face 218) of between 1 millimeter and 10 millimeters, or between 1 millimeter and 5 millimeters, or between 1 millimeter and 3 millimeters. The gap G2 shown in FIG. 3 is smaller than the gap Gi shown in FIG. 2, and represents a higher load applied to the tibial bearing 106 by the patient. The gap G3. shown in FIG. 4 is smaller than the gap G2 shown in FIG. 3, and represents a higher load applied to the tibial bearing 106 by the patient. Thus, the repulsive force between the magnets 208, 210 in FIG. 3 is higher than the repulsive force between the magnets 208, 210 in FIG. 2. Furthermore, the repulsive force between the magnets 208, 210 in FIG. 4 is higher than the repulsive force between the magnets 208, 210 in FIG. 3. As there is typically an exponential-type increase between repulsive force as same poles of magnets approach each other, the increase in repulsive force (e g., shock absorber support) increases more than a linear increase, for example, at a substantially second power increase or more.

[0028] The magnetically-created adjunctive forces in the embodiments taught herein serve to bridge the gap between the non-biologic and the biologic portions of the leg having an artificial knee prosthesis. The variable characteristic of a repulsive magnetic field based on orientation, distance, and varied by motion along the arcuate path, adds some “float” into the “feel” of the knee of the patient having an implanted magnetic total knee prosthesis 100.

[0029] In the prosthesis 100 of FIGS. 1-4, any standard femoral component 102 can be utilized, as long as it is compatible with the material and shape of the tibial bearing 106 chosen. This can simplify the procedure, and maintain a relatively low cost. Thus, the magnetic portion of the prosthesis is the tibial component 105 only. It can be offered for sale on its own, if desired, or can be paired with a particular femoral component 102.

[0030] FIG. 5 illustrates a magnetic total knee prosthesis 300 configured to be implanted within a patent 1 during a total knee arthroplasty surgery. The magnetic total knee prosthesis 300 comprises a femoral component 302, a tibial coupler 304, and a tibial bearing 306. The femoral component 302 and the tibial coupler 304 can each comprise a metal or metal alloy, for example a cobalt chromium alloy. The tibial bearing 306 can comprise a polymer, such aspolyethylene. In some embodiments, the tibial bearing 306 comprises ultra-high molecular weight polyethylene (UHMWPE). In some embodiments, the tibial bearing 306 comprises highly cross-linker polyethylene (HXLPE). In some embodiments, the tibial component, the femoral component, and the tibial bearing can all comprise polyethylene. In some embodiments the tibial bearing 306 is configured to be screwed into the tibial coupler 304. For example, the tibial bearing 306 and the tibial coupler 304 can each have cooperative threading configured to allow their screwable attachment to each other. In other embodiments, the tibial bearing 306 is configured to snap into the tibial coupler 304. In some embodiments, the tibial bearing 306 is configured to unsnap form the tibial coupler 304. Having the snappable portions also be unsnappable allows for more adaptability during surgery preparation and even during the surgery itself, as multiple combinations of components can be trialed.

[0031] The femoral component 302 comprises a top portion 308 and a bottom portion 310. The top portion 308 and / or bottom portion 310 include a femoral coupler 312 configured to be coupled to a lower portion 314 of a femur 316. The tibial coupler 304 comprises a bottom portion 318 and a top portion 320. The bottom portion 318 includes a stem 322 configured to be coupled to an upper portion 324 of a tibia 326, and is configured for compatibility and adherence to bone. The femoral coupler 312 comprises a first peg 328 and a second peg 330 configured for compatibility and adherence to bone. The femoral coupler 312 further comprises pairs of first 332, second 334, third 336 faces, a fourth face 338, and a fifth face 339, each pair (medial and lateral) 332, 334, 336 non-parallel to the other pairs. The faces 332, 334, 336, 338, 339 are configured to extend around the lower portion 314 of the femur 316. The femur 316 can be cut by a surgeon to improve the fit with the femoral component 302. The bottom portion 310 of the femoral component 302 includes a lateral condyle 340 and a medial condyle 342 which each curve around a transverse axis 344. The lateral condyle 340 includes a curved lateral condyle surface 346 and the medial condyle 342 includes a curved medial condyle surface 348. The tibial bearing 306 includes a top portion 350 and a bottom portion 352. The top portion 350 of the tibial bearing 306 includes a concave lateral bearing surface 354 and a concave medial bearing surface 356. The lateral condyle 340 and the medial condyle 342 are each configured to articulate in a sliding manner along an arcuate path within the concave lateral bearing surface 354 and the concave medial bearing surface 356, respectively. Specifically, the curved lateral condyle surface 346 slides over the concave lateral bearing surface 354 and the curved medial condyle surface 348 slides over the concave medial bearing surface 356, while the femoral component 302 changes itsrelative rotational orientation in relation to the tibial bearing 306 (and thus in relation to the tibial coupler 304). The change in rotational orientation is in relation to the transverse axis 344. Thus, the rotational axis and the transverse axis 344 are colinear. In other embodiments, the rotational axis can be different from the transverse axis 344 but parallel to the transverse axis 344. In some embodiments the rotational axis and transverse axis 344 are non-parallel to each other. The magnetic total knee prosthesis 300 is intended for the left knee. A right knee model would typically be a mirror image, and thus a reversed copy of all of the teachings presented herein should also be assumed to exist. However, in some embodiments, the right knee and left knee models can be designed to be the same, such that only a single model is needed. This may, for example, be applicable in locations with a minimal healthcare budget. In some embodiments, the single model, can be adaptable or easily modifiable in order to configure it for the left knee or right knee.

[0032] FIG. 5 illustrates one position of the articulation with the magnetic total knee prosthesis 300 implanted within a leg 2 of a patient 1. “Articulation” does not require attachment, though it can include attachment. However, “articulation” may also include simply having the condyles 340, 342 movably seated within the tibial bearing 306. The femoral coupler 312 is shown coupled to the femur 316, and the tibial coupler 304 is shown coupled to the tibia 326. Most of the soft tissue of the leg 2 is not shown, for clarity purposes. In the generally 45° semi -flexed position shown in FIG. 5, the faces 332 are adjacent the concave lateral bearing surface 354 and the concave medial bearing surface 356. The magnetic total knee prosthesis 300 shown in FIG. 5 is a cruciate retaining knee prosthesis, thus comprising a horizontally-extending space 358 or groove in the tibial coupler 304 and the tibial bearing 306 configured for the posterior cruciate ligament (PCL) 360 of the patient 1 to extend therethrough. Any alternative embodiment of the magnetic total knee prosthesis 300 can have this “cruciate retaining” configuration. Alternatively, all of the embodiments, can instead have an alternative “posterior stabilized” configuration, featuring a box on the femoral component 302 and a post on the tibial coupler 304. Alternatively, all of the embodiments can instead be configured with an alternative “anterior stabilized” configuration or with a “bicruciate retaining” (PCL and ACL) configuration.

[0033] The faces 332, 334 do not represent fully planar faces on the interior portion 335 of the femoral component 302, but instead, each portion comprises a cavity for the placement of a permanent magnet, and a perimeter surrounding the cavity, and approximating the face. A first magnet 362 is held within a first rectangular cavity 364, in the lateral condyle 340. A second magnet 366 is held within a second rectangular cavity 368, in the medial condyle 342.A third magnet 370 is held within a third cavity 372, in the lateral condyle 340. And, a fourth magnet 374 is held within a fourth cavity 376, in the medial condyle 342. The cavities 364, 368, 372, 376 each extend from the interior portion 335 of the femoral component 302. In relation to the repulsive, magnetic shock-absorber, first magnet 351 is similar in structure, attachment, and function to first magnet 208 of FIGS. 1-4. A second magnet 353 is similar in structure, attachment and function to second magnet 210 of FIGS. 1-4. Thus, first magnet 351 and second magnet 353 provide the same repelling “levitation” and shock-absorber-like function as do first magnet 208 and second magnet 210.

[0034] However, in addition, the second magnet 353 has an upper face 355 at the negative pole (-) that faces to bottom faces (also negative poles -) of magnets 362, 366, 370, 374, as the rotation of the femur 2 places each particular magnet 362, 366, 370, 374 opposite the second magnet 353, via rotation about the transverse axis 344. Thus, the negative poles of each of the magnets 362, 366, 370, 374 of the femoral component 302 are configured to cause one or more magnetically-formed repelling forces (FR) with the negative pole of the upper face 355 of the second magnet 353, that is statically held by the tibial bearing 306. This / these repelling forces are configured to counteract some of the normal forces (FN) between the condyles 340, 342 and the concave bearing surfaces 354, 356, thus decreasing the frictional force (FF) along the arcuate path (PA) of the condyles 340, 342 with respect to the concave bearing surfaces 354, 356. As previously mentioned, the magnetically-created adjunctive forces in the embodiments taught herein serve to bridge the gap between the nonbiologic and the biologic portions of the leg having an artificial knee prosthesis. The variable characteristic of a repulsive magnetic field based on orientation, distance, and varied by motion along the arcuate path (PA), adds some “float” into the “feel” of the knee of the patient having an implanted magnetic total knee prosthesis 300. This float is combined with the effect of the magnetic levitation between the first magnet 351 and the second magnet 353. Thus, the second magnet 353 serves the combined function of (A) levitating the tibial bearing 306 in relation to the tibial coupler 304, and (B) decreasing normal forces between the lateral condyle 340 and the curved lateral condyle surface 346 and between the medial condyle 342 includes a curved medial condyle surface 348. The “A” element of the combined function is caused by the repulsion between the positive (+) pole of the second magnet 353 and the positive pole (+) of the first magnet 351. The “B” element of the combined function is caused by the repulsion between the upward-facing negative (-) pole of the of the second magnet 353 and the downward-facing negative (-) poles of each of the magnets 362, 366, 370, 374 of the femoral component 302 (when rotated into facing or close to facing positions).

[0035] FIGS. 6-8 illustrate a magnetic total knee prosthesis 400 configured to be implanted within a patent 1 during a total knee arthroplasty surgery. The magnetic total knee prosthesis 400 comprises a femoral component 402, a tibial coupler 404, and a tibial bearing 406. The femoral component 402 and the tibial coupler 404 can each comprise a metal or metal alloy, for example a cobalt chromium alloy. The tibial bearing 406 can comprise a polymer, such as polyethylene In some embodiments, the tibial bearing 406 comprises ultra- high molecular weight polyethylene (UHMWPE). In some embodiments, the tibial bearing 406 comprises highly cross-linker polyethylene (HXLPE). In some embodiments, the tibial component, the femoral component, and the tibial bearing can all comprise polyethylene. In some embodiments the tibial bearing 406 is configured to be screwed into the tibial coupler 404. For example, the tibial bearing 406 and the tibial coupler 404 can each have cooperative threading configured to allow their screwable attachment to each other. In other embodiments, the tibial bearing 406 is configured to snap into the tibial coupler 404. In other embodiments, the tibial bearing 406 is configured to unsnap from the tibial coupler 404. Having the snappable portions also be unsnappable allows for more adaptability during surgery preparation and even during the surgery itself, as multiple combinations of components can be trialed.

[0036] The femoral component 402 comprises a top portion 408 and a bottom portion 410. The top portion 408 and / or bottom portion 410 include a femoral coupler 412 configured to be coupled to a lower portion 314 of a femur 316. The femoral coupler 412 can be configured similarly to the femoral coupler 312 of FIG. 5. The tibial coupler 404 comprises a bottom portion 418 and a top portion 420. The bottom portion 418 includes a stem 422 configured to be coupled to an upper portion of a tibia (not shown), configured for compatibility and adherence to bone. The femoral coupler 412 is adjacent a single curved magnetic plate (magnet) 466. The curved magnet 466 can be carried within a cavity 467 in the femoral component 402 and to be secured therein by adhesive, epoxy, hot melt, and / or mechanical securement. A first magnet 451 carried by the tibial coupler 404 has positive and negative poles (+, -) as shown. A second magnet 453 is carried by the tibial bearing 406 and has positive and negative poles (+, -) as shown. In this embodiment, the poles are all configured to be oriented in an opposite manner to those of the embodiment of the prosthesis 300 of FIG. 5, though still in a repulsive orientation (in this case negative against negative, instead of positive against positive). Thus, first magnet 451 and second magnet 453 are similar to the first magnet 351 and the second magnet 353, and provide the same repelling “levitation” and shock-absorber-like function as do first magnet 208 and second magnet 210.

[0037] In addition, the curved magnet 466 of the femoral component 402 is configured to cause one or more magnetically-formed repelling forces (FR) with the positive pole of the second magnet 453, that is held by the tibial bearing 406 This / these repelling force / s is / are configured to counteract some of the normal forces (FN) between the condyles 440, 442 and the concave bearing surfaces 454, 456 (see FIG, 5), thus decreasing the frictional force along the arcuate path of the condyles 440, 442 with respect to the concave bearing surfaces 454, 456. As previously mentioned, the magnetically-created adjunctive forces in the embodiments taught herein serve to bridge the gap between the non-biologic and the biologic portions of the leg having an artificial knee prosthesis. The variable characteristic of a repulsive magnetic field based on orientation, distance, and varied by motion along the arcuate path, adds some “float” into the “feel” of the knee of the patient having an implanted magnetic total knee prosthesis 400. This float is combined with the effect of the magnetic levitation between the first magnet 451 and the second magnet 453.

[0038] FIGS. 6-8 illustrate three positions of the articulation with the magnetic total knee prosthesis 400 implanted within a leg 2 of a patient 1. “Articulation” does not require attachment, though it can include attachment. However, “articulation” may also include simply the condyles 440, 442 movably seated within the tibial bearing 406. The femoral coupler 412 is shown coupled to the femur 416, but the tibia is not shown. The soft tissue of the leg 2 is not shown, for clarity purposes. As shown in FIGS. 6-8, regardless of the extent of rotation of the knee joint, the positive pole (+) of the curved magnet 466 opposes the positive pole (+) of the second magnet 453. Thus, the second magnet 453 serves the combined function of (A) levitating the tibial bearing 406 in relation to the tibial coupler 404, and (B) decreasing normal forces between the condyles 440, 442 and the concave bearing surfaces 454, 456. The magnetic total knee prosthesis 400 is a cruciate retaining knee prosthesis configured for the posterior cruciate ligament (PCL) (not shown) to extend therethrough. Any alternative embodiment of the magnetic total knee prosthesis 400 can have this “cruciate retaining” configuration. Alternatively, all of the embodiments, can instead have an alternative “posterior stabilized” configuration, featuring a box on the femoral component 402 and a post on the tibial coupler 404. Alternatively, all of the embodiments can instead be configured with an alternative “anterior stabilized” configuration or with a “bicruciate retaining” (PCL and ACL) configuration.

[0039] The magnets 208, 210, 362, 366, 370, 374, 351, 353, 466, 451, 453 in the embodiments described herein comprise permanent magnets, however, in alternative embodiments, one of more of the magnets 208, 210, 362, 366, 370, 374, 351, 353, 466, 451,453 can comprise electromagnets. Each of the magnets has a north pole N, a south pole S, and a thickness t. These repelling set-ups (south opposing south, and / or north opposing north) is what forms one or more magnetically -formed repelling forces (FR), as shown in FIG. 5. In some embodiments, the mass, volume, thickness t, and / or overall magnetic field strength of one magnet (e.g., first magnet 208) can be the same as the mass, volume, thickness t, and / or overall magnetic field strength of a paired repelling magnet (e g., second magnet 210). However, in alternative embodiments, the mass, volume, thickness t, and / or overall magnetic field strength of the first magnet 208 can be greater or less than the mass, volume, thickness t, and / or overall magnetic field strength of the second magnet 210. Alternatively, one or more of the paired magnets 362, 366, 370, 374 can be the same as its pair (e.g., medial to lateral) or may be different. If different, this can thus allow the potential of a complex magnetic field that provides an uneven distribution of magnetically-formed repelling forces (FR) between medial and lateral aspects of the artificial knee. This uneven strength between the medial and lateral aspects may be useful in patients having a particular non-standard condition, such as genu varum (bow legs), genu valgum (knock -knees), pronation, supination, in-toeing (pigeon toes), out-toeing (duck footed), or improperly healed bone (e.g., complex or spiral fracture). The permanent magnets may also be considered magnetic shims, and can be available to the user in a number of different thicknesses. Choosing a certain thickness of magnetic shim can allow the magnet to be flush with the remainder of the implant (e.g., flush with one or more of the faces). Alternatively, the user can choose a thickness of the magnetic shim such that the magnets are configured to be sub-flush.

[0040] FIG. 9 illustrates a tibial bearing 500 that has been insert molded. A magnet 502 has been insert molded within an outer shell 504 comprising polyethylene. The magnet 502 is fully embedded within the outer shell 504, and thus protected by the polyethylene material from any contact with the body of the patient, including any fluids, proteins, or other biological materials.

[0041] FIG. 10 illustrates a tibial coupler 506 that has been insert molded. A magnet 508 has been insert molded within an outer shell 510 comprising polyethylene. The magnet 508 is fully embedded within the outer shell 510. The outer shell 510 includes an upper portion 512 and a lower portion 514 comprising a stem 516.

[0042] FIG. 11 illustrates a tibial coupler 518 that has been insert molded. A magnet 520 has been insert molded within an outer shell 522 comprising polyethylene. The magnet 520 is fully embedded within the outer shell 522. The outer shell 522 includes an upper portion 524 and a lower portion 526 comprising a stem 528. The magnet 520 includes a bottom extension530 that extends into the stem 528. The bottom extension 530 includes an undercut portion 532 configured to further physically lock the magnet 520 in place as the outer shell 522 is insert molded around the magnet 520. The undercut portion 532 includes a continuous curved portion 534 intended to allow smooth or laminar flow of the molten polymer during molding.

[0043] The combination of a tibial bearing 500 and a tibial coupler 506 (or tibia coupler 518) that have all been insert molded from a polymer, such as polyethylene, provides an allpolymer shell lower portion. Thus, there is increased manufacturability and decreased cost. In other embodiments, the femoral component can also be insert molded.

[0044] While the foregoing is directed to embodiments of the present disclosure, other and further embodiments may be devised without departing from the basic scope thereof.

[0045] The ranges disclosed herein also encompass any and all overlap, sub-ranges, and combinations thereof. Language such as “up to,” “at least,” “greater than,” “less than,” “between,” and the like includes the number recited. Numbers preceded by a term such as “approximately”, “about”, and “substantially” as used herein include the recited numbers (e.g., about 10%=10%), and also represent an amount close to the stated amount that still performs a desired function or achieves a desired result. For example, the terms “approximately”, “about”, and “substantially” may refer to an amount that is within less than 10% of, within less than 5% of, within less than 1% of, within less than 0.1% of, and within less than 0.01% of the stated amount.

[0046] For purposes of the present disclosure and appended claims, the conjunction “or” is to be construed inclusively (e.g., “an apple or an orange” would be interpreted as “an apple, or an orange, or both”; e.g., “an apple, an orange, or an avocado” would be interpreted as “an apple, or an orange, or an avocado, or any two, or all three”), unless: (i) it is explicitly stated otherwise, e.g., by use of “either... or,” “only one of,” or similar language; or (ii) two or more of the listed alternatives are mutually exclusive within the particular context, in which case “or” would encompass only those combinations involving non-mutually-exclusive alternatives. For purposes of the present disclosure and appended claims, the words “comprising,” “including,” “having,” and variants thereof, wherever they appear, shall be construed as open-ended terminology, with the same meaning as if the phrase “at least” were appended after each instance thereof.

Claims

WHAT IS CLAIMED IS:

1. An orthopedic knee prosthesis comprising: a femoral component comprising a top potion comprising a femoral coupler configured to couple to a lower portion of a femur, and a bottom portion comprising a curved medial condyle surface and a curved lateral condyle surface; a tibial bearing comprising a top portion comprising a concave medial bearing surface configured to articulate with the curved medial condyle surface and a concave lateral bearing surface configured to articulate with the curved lateral condyle surface; a tibial coupler configured to couple to an upper portion of a tibia, the tibial coupler associated with the tibial bearing; a first magnetic portion associated with the tibial bearing and / or the tibial coupler and comprising a first pole having a first pole polarity; and a second magnetic portion associated with the tibial bearing and / or the tibial coupler and comprising a second pole having a second pole polarity, the second pole polarity the same as the first pole polarity, wherein the first pole and the second pole face each other, and wherein at least one of the first magnetic portion and the second magnetic portion is configured to bidirectionally translate with respect to the tibial bearing and / or the tibial coupler.

2. The prosthesis of claim 1, wherein the tibial bearing and the tibial coupler together comprise a tibial component.

3. The prosthesis of claim 2, wherein the tibial bearing and the tibial coupler are integral within the tibial component.

4. The prosthesis of any one of claims 1-3, wherein the at least one of the first magnetic portion and the second magnetic portion is configured to bidirectionally translate with respect to the tibial bearing.

5. The prosthesis of any one of claims 1-4, wherein the at least one of the first magnetic portion and the second magnetic portion is configured to bidirectionally translate with respect to the tibial coupler.

6. The prosthesis of any one of claims 1-5, wherein the first magnetic portion is located closer to the femoral component than is the second magnetic portion.

7. The prosthesis of any one of claims 1-7, wherein the at least one of the first magnetic portion and the second magnetic portion configured to bidirectionally translate with respect to the tibial bearing and / or the tibial coupler is configured to translate along atranslation axis configured to be substantially colinear with a central axis of an intramedullary canal of the upper portion of the tibia.

8. The prosthesis of any one of claims 1-7, wherein the at least one of the first magnetic portion and the second magnetic portion configured to bidirectionally translate with respect to the tibial bearing and / or the tibial coupler is configured to translate along a translation axis configured to be substantially colinear with a hole drilled in the upper portion of the tibia.

9. The prosthesis of either one of claims 1 or 2, wherein the first magnetic portion is statically secured to the tibial coupler.

10. The prosthesis of claim 9, wherein the second magnetic portion is statically secured to the tibial bearing.

11. The prosthesis of claim 10, wherein the tibial bearing is configured to bidirectionally translate with respect to the tibial coupler.

12. The prosthesis of claim 11, wherein at least a portion of the tibial bearing is configured to bidirectionally translate within a cavity of the tibial coupler.

13. The prosthesis of claim 12, wherein the tibial bearing comprises one or more detent, configured to limit at least a first direction of the bidirectional translation.

14. The prosthesis of claim 12, wherein the tibial coupler comprises one or more stop, configured to limit at least a second direction of the bidirectional motion.

15. The prosthesis of any one of claims 9-14, wherein the second magnetic portion comprises a third pole having a third pole polarity, the third pole polarity opposite of the second pole polarity and facing away from the tibial coupler, and wherein the femoral component further comprises a third magnetic portion comprising a fourth pole configured to face the third pole in at least one orientation of the tibial bearing with the tibial coupler, the fourth pole polarity the same as the third pole polarity.

16. The prosthesis of any one of claims 1-15, wherein when a force of 136 kg is placed on the tibial bearing by the femoral component, there is at least some space maintained between the first pole and the second pole, via magnetic repulsion.

17. The prosthesis of claim 16, wherein the at least some space comprises at least 0.001 millimeter axial separation between the first pole and the second pole.

18. The prosthesis of claim 16, wherein the at least some space comprises at least 0.01 millimeter axial separation between the first pole and the second pole.

19. The prosthesis of claim 16, wherein the at least some space comprises at least 0.1 millimeter axial separation between the first pole and the second pole.

20. The prosthesis of claim 16, wherein the at least some space comprises at least 1 millimeter axial separation between the first pole and the second pole.

21. The prosthesis of claim 15, wherein the third magnetic portion comprises an arc-shape.

22. The prosthesis of claim 21, wherein the third magnetic portion comprises a curved plate.

23. The prosthesis of any one of claims 1-3, wherein the at least one of the first magnetic portion and the second magnetic portion is configured to bidirectionally translate with respect to the tibial coupler.

24. The prosthesis of any one of claims 1-3, wherein the first magnetic portion is located closer to the femoral component than is the second magnetic portion.

25. The prosthesis of any one of claims 1-3, wherein the at least one of the first magnetic portion and the second magnetic portion configured to bidirectionally translate with respect to the tibial bearing and / or the tibial coupler is configured to translate along a translation axis configured to be substantially colinear with a central axis of an intramedullary canal of the upper portion of the tibia.

26. The prosthesis of any one of claims 1-3, wherein the at least one of the first magnetic portion and the second magnetic portion configured to bidirectionally translate with respect to the tibial bearing and / or the tibial coupler is configured to translate along a translation axis configured to be substantially colinear with a hole drilled in the upper portion of the tibia.

27. The prosthesis of any one of claims 1-3, wherein when a force of 136 kg is placed on the tibial bearing by the femoral component, there is at least some space maintained between the first pole and the second pole, via magnetic repulsion.

28. The prosthesis of claim 27, wherein the at least some space comprises at least 0.001 millimeter axial separation between the first pole and the second pole.

29. The prosthesis of claim 27, wherein the at least some space comprises at least 0.01 millimeter axial separation between the first pole and the second pole.

30. The prosthesis of claim 27, wherein the at least some space comprises at least 0.1 millimeter axial separation between the first pole and the second pole.

31. The prosthesis of claim 27, wherein the at least some space comprises at least 1 millimeter axial separation between the first pole and the second pole.

32. The prosthesis of claim 1, wherein the first magnetic portion is statically secured to the tibial coupler , and wherein the second magnetic portion comprises a third polehaving a third pole polarity, the third pole polarity opposite of the second pole polarity and facing away from the tibial coupler, and wherein the femoral component further comprises a third magnetic portion comprising a fourth pole configured to face the third pole in at least one orientation of the tibial bearing with the tibial coupler, the fourth pole polarity the same as the third pole polarity.

33. The prosthesis of claim 32, wherein the third magnetic portion comprises an arc-shape.

34. The prosthesis of claim 33, wherein the third magnetic portion comprises a curved plate.

35. An orthopedic knee prosthesis comprising: a femoral component comprising a top potion comprising a femoral coupler configured to couple to a lower portion of a femur, and a bottom portion comprising a curved medial condyle surface and a curved lateral condyle surface; a tibial bearing comprising a top portion comprising a concave medial bearing surface configured to articulate with the curved medial condyle surface and a concave lateral bearing surface configured to articulate with the curved lateral condyle surface; a tibial coupler configured to moveably couple to the tibial bearing and configured to couple to an upper portion of a tibia; a first magnetic portion statically coupled to the femoral component and comprising a first pole having a first pole polarity; a second magnetic portion statically coupled to the tibial bearing and comprising a second pole having a second pole polarity, the second pole polarity the same as the first pole polarity, wherein, when the curved medial condyle surface is articulatably coupled to the concave medial bearing surface and the curved lateral condyle surface is articulatably coupled to the concave lateral bearing surface, the first pole and the second pole are in sufficient proximity to each other such that a first magnetic repulsive force is present, the first repulsive force configured to subtract from compressive forces that are applied between the femoral component and the tibial bearing, the second magnetic portion further comprising a third pole opposite the second pole and having a third pole polarity that is opposite the first pole polarity and the second pole polarity, the third pole configured to generally face the tibial coupler; and a third magnetic portion statically coupled to the tibial coupler and comprising a fourth pole configured to generally face the third pole and having a polarity that is the same as the polarity of the third pole, wherein movement of the tibial bearing in relation to thetibial coupler that causes the third pole and the fourth pole to decrease their relative distance from each other causes an increase in a second magnetic repulsive force between the third pole and the fourth pole.

36. The prosthesis of claim 35, wherein the second magnetic repulsive force increases non-linearly in relation to an inverse of the relative distance.

37. The prosthesis of claim 35, wherein second magnetic repulsive force is proportional to l / dxin relation to relative distance d, wherein x is 2 or greater.

38. A method for performing a total knee arthroplasty, comprising: providing an orthopedic knee prosthesis comprising: a femoral component comprising a top potion comprising a femoral coupler configured to couple to a lower portion of a femur, and a bottom portion comprising a curved medial condyle surface and a curved lateral condyle surface; a tibial bearing comprising a top portion comprising a concave medial bearing surface configured to articulate with the curved medial condyle surface and a concave lateral bearing surface configured to articulate with the curved lateral condyle surface; a tibial coupler configured to moveably couple to the tibial bearing and configured to couple to an upper portion of a tibia; a first magnetic portion statically coupled to the femoral component and comprising a first pole having a first pole polarity; a second magnetic portion statically coupled to the tibial bearing and comprising a second pole having a second pole polarity, the second pole polarity the same as the first pole polarity, wherein, when the curved medial condyle surface is articulatably coupled to the concave medial bearing surface and the curved lateral condyle surface is articulatably coupled to the concave lateral bearing surface, the first pole and the second pole are in sufficient proximity to each other such that a first magnetic repulsive force is present, the first repulsive force configured to subtract from compressive forces that are applied between the femoral component and the tibial bearing, the second magnetic portion further comprising a third pole opposite the second pole and having a third pole polarity that is opposite the first pole polarity and the second pole polarity, the third pole configured to generally face the tibial coupler; and a third magnetic portion statically coupled to the tibial coupler and comprising a fourth pole configured to generally face the third pole and having a polarity that is the same as the polarity of the third pole, wherein movement of the tibial bearing in relation to the tibial coupler that causes the third pole and the fourth pole to decrease their relative distancefrom each other causes in increase in a second magnetic repulsive force between the third pole and the fourth pole; coupling the femoral coupler to a portion of a femur bone of a patient; coupling the tibial coupler to a portion of a tibia bone of a patient; coupling the tibial coupler to the tibial bearing such that the tibial bearing can move in relation to the tibial coupler; and coupling the femoral component in articulation with the tibial bearing.

39. An orthopedic knee prosthesis comprising: a femoral component comprising a top potion comprising a femoral coupler configured to couple to a lower portion of a femur, and a bottom portion comprising one or more curved condyle surfaces; a tibial bearing comprising a top portion comprising one or more concave bearing surfaces configured to articulate with the one or more curved condyle surfaces; a tibial coupler configured to be dynamically coupled to the tibial bearing and configured to couple to an upper portion of a tibia; a first magnetic portion statically coupled to the tibial coupler and comprising a first pole having a first pole polarity; and a second magnetic portion statically coupled to the tibial bearing and comprising a second pole configured to generally face the first pole and having a polarity that is the same as the polarity of the first pole, wherein movement of the tibial bearing in relation to the tibial coupler that causes the first pole and the second pole to decrease their relative distance from each other causes an increase in a magnetic repulsive force between the first magnetic portion and the second magnetic portion.

40. The prosthesis of claim 39, wherein the magnetic repulsive force increases non-linearly in relation to an inverse of the relative distance.

41. The prosthesis of claim 39, wherein magnetic repulsive force is proportional to l / dxin relation to relative distance d, wherein x is 2 or greater.

42. The prosthesis of any one of claims 35-38, wherein the first magnetic portion comprises a permanent magnet.

43. The prosthesis of any one of claims 35-38, wherein the second magnetic portion comprises a permanent magnet.

44. The prosthesis of any one of claims 35-38, wherein the third magnetic portion comprises a permanent magnet.

45. The prosthesis of any one of claims 39-41, wherein the first magnetic portion comprises a permanent magnet.

46. The prosthesis of any one of claims 39-41, wherein the second magnetic portion comprises a permanent magnet.

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