Abstract: An artificial knee joint includes: a femoral component including a medial condyle and a lateral condyle; and a tibial component including an inner sliding surface that receives the medial condyle and an outer sliding surface that receives the lateral condyle. A curvature radius of each of the inner sliding surface and the outer sliding surface in a medial-lateral direction increases from an anterior side toward a posterior side within a predetermined range in an anterior-posterior direction. In the medial-lateral direction, the inner sliding surface and the outer sliding surface are positioned inward such that a middle point between a lowest point of the medial condyle and a lowest point of the lateral condyle in a knee extended position is shifted inward relative to a center of the tibial component by 2 to 10% of a width of the tibial component.

Abstract: The present disclosure provides knee prostheses that replicate at least a portion of the function of an individual patient's anterior cruciate ligament (ACL). An exemplary knee prosthesis includes a femoral component configured to be implanted on the distal end of the patient's femur and a tibial component configured to be implanted on the proximal end of the patient's tibia. In extension, the femoral component and the tibial component may cooperate to limit anterior movement of the tibial component relative to the femoral component. In flexion, the femoral component may be free to rotate relative to the tibial component.

Abstract: A femoral prosthesis includes a femur body and a cam portion. A joint surface of the femur body has a first joint surface portion for abutting a tibial prosthesis within a first knee flexion angle range from a first knee flexion angle to a second knee flexion angle, and a second joint surface portion for abutting the tibial prosthesis within a second knee flexion angle range from the second knee flexion angle to a third knee flexion angle. At the second knee flexion angle, the first joint surface portion has a first radius of curvature, and the second joint surface portion has a second radius of curvature. A center of a circle of an anterior joint surface of the cam portion is located in a first quadrant of a circle with the second radius of curvature in a sagittal section when the femoral prosthesis is in an extended state.

Abstract: A knee joint prosthesis is capable of moving between an extended position and a flexion position. The knee joint prosthesis includes a femoral component that is configured to be mounted to a femur, and a tibial component that is configured to be mounted to a tibia. The femoral component and the tibial component are at least partially connected together by a geared arrangement.

Abstract: According to one example, a posterior-stabilized femoral prosthesis for a knee arthroplasty. The femoral prosthesis can include medial and lateral condyles, a femoral cam and a recess. The medial and lateral condyles can be shaped to articulate with a tibial articular surface of a tibial bearing component through a range of motion, in which full extension corresponds to zero degrees flexion of a knee joint and positive flexion corresponds to greater than zero degrees flexion of the knee joint. In a sagittal plane, the medial and lateral condyles can define medial and lateral multi-radius curves, respectively. The medial multi-radius curve can have a single common radius swept through a first angular extent to define a single arc length that extends from between substantially ?20 degrees flexion to substantially 90 degrees flexion, inclusive.

Abstract: A modular spacer device for a knee joint includes a tibial element adapted to be constrained to an end of the tibial bone and a femoral element adapted to be constrained to an end of the femoral bone and to be articulated on the tibial element. The tibial element has first and second surfaces opposite to each other, and the femoral element has first surface and second surfaces opposite to each other. The first surface of the femoral element is convex and laterally has a curved, ammonite-shaped contour with a curvature radius that increases starting from a rear section with a curvature radius R1, a first central section having a curvature radius R2, a second central section having a curvature radius R3, and a front section having a curvature radius R4, with R1?R2?R3?R4.

Abstract: An orthopaedic surgical system for a total knee implant includes a plurality of commonly-sized femoral trial components. Each commonly-sized femoral trial component includes a first femoral condyle having a first articulation surface configured to engage a tibial component, and a second femoral condyle may be spaced apart from the first femoral condyle. The second femoral condyle has a second articulation surface configured to engage the tibial component. An anterior cam is positioned between the first femoral condyle and the second femoral condyle. A method of using such a system is also disclosed.

Abstract: Systems, devices and methods for providing orthopedic augments having recessed pockets that receive a fixation material. The orthopedic augments include an outer surface that interfaces with a patient's tissue or bone, an inner surface that interfaces with an implant and having a recessed pocket configured to receive a fixation material, a rim around at least a portion of the recessed pocket, and a port in the rim, wherein the recessed pocket extends along the inner surface in at least a lateral direction from the port.

Abstract: A human knee prosthetic implant having a tibia component forming first and second medial concave surfaces and first and second lateral concave surfaces, and a femur component forming first and second medial convex surfaces and first and second lateral convex surfaces. The tibia and femur surfaces are formed to provide contact interaction in full extension, a mid flexion range and in a state of full flexion of the knee prosthetic implant.

Abstract: Implant assemblies, systems, and methods for replacing a knee joint may include a method of revising a knee joint prosthesis implanted in a knee of a patient to provide increased stability to the knee joint prosthesis by replacing a first tibial insert with a second tibial insert that provides more constraint that the first tibial insert. A knee joint prosthesis system and kit are also provided that may include a tibial baseplate component, a femoral component, and a tibial insert that is selectively interchangeable with other tibial inserts to provide varying levels of constraint and stability to the knee joint prosthesis.

Abstract: An orthopedic implant comprising: (a) a distal femoral component comprising a first condyle bearing surface having a first profile comprising at least three consecutive arcs of curvature; and (b) a proximal tibial component comprising a first condyle bearing surface having a second profile comprising at least three parallel arcs of curvature.

Abstract: A knee joint implant that prevents hyperextension includes a femoral component having an anterior surface with reference to the lowermost point of a convex condyle, the anterior surface being configured to have different curvature radii in respective sections thereof, and a bearing component having an anterior surface with reference to the lowermost point of a concave articular surface, the anterior surface being configured to have different curvature radii in respective sections, so that when an extended knee is about to be hyperextended, the convex condyle of the femoral component slides toward the anterior side and is brought into contact with a plurality of points of the concave articular surface of the bearing component, thereby producing resistance so as to suppress hyperextension exceeding a design range due to behavioral habits, a decrease in muscle mass, and the like of the patient.

Abstract: A system and process for performing orthopedic surgery is provided that uses a tibial trial system in total knee arthroplasty for assessing optimal internal-external rotation and posterior tibial slope, and for measuring the rotation of a tibial trial throughout flexion-extension to determine and mark the best position for the final tibial component. The tibial trial system determines the internal-external location on a patient specific basis with improved component placement well within the present manual methods. One particular advantage to the tibial trial system is to assess the natural internal-external rotation that the tibial component will experience relative to the femoral component during flexion-extension as opposed to simply recording and balancing forces on a static tibial trial. The invention disclosed herein may also be adapted to be used with a computer assisted surgical device. Such surgical devices include active, semi-active, and haptic devices as well as articulating drill and saw systems.

Abstract: A tibial insert includes a base and a post extending from the base along a longitudinal axis. The post has a medial surface, a lateral surface, a height along the longitudinal axis, and a rotational offset in a superior-inferior aspect of the post. The medial surface has a medial section, and the lateral surface has a lateral section oriented substantially parallel to the medial section. The medial section and the lateral section each have a width in a substantially anterior-posterior direction that is sufficient to enable varus/valgus constraint over a flexion/extension range from extension to about 90 to 120 degrees of flexion when the tibial insert is mated with a femoral component.

Abstract: An orthopaedic tibial prosthesis includes a tibial baseplate sized and shaped to cover substantially all of a resected proximal tibial surface, and a tibial bearing component sized to leave a posteromedial portion of the tibial baseplate exposed when the tibial bearing component is mounted to the baseplate. The exposed posteromedial portion of the tibial baseplate includes a chamfered profile which cooperates with a correspondingly chamfered profile at a posteromedial edge of the tibial bearing component to create a substantially continuous chamfer extending from the resected tibial surface to the medial articular surface of the tibial bearing component. Advantageously, this chamfer leaves an absence of material (i.e., a relief or void) at the posteromedial edge of the tibial prosthesis, thereby enabling deep flexion of the prosthesis without impingement between the tibial prosthesis and adjacent anatomic tissues or prosthetic structures.

Abstract: A knee prosthesis includes a femoral component, a tibial component, and a coupling component interconnecting the femoral component and the tibial component. The tibial component includes ball. The femoral component is configured to move relative to the tibial component. The coupling component defines an internal cavity including a first spherical end portion and a second spherical end portion. The internal cavity is dimensioned to receive the ball of the tibial component. The ball is repositioned between the first spherical end portion and the second spherical end portion of the internal cavity upon movement of the femoral component relative to the tibial component.

Abstract: An orthopedic surgical system includes a sensor module for determining the joint force of a patient's knee joint and an adaptor for coupling various tibial trialing components to the sensor module. The sensor module includes a tibial paddle to which the adaptor is configured to couple. The adaptor and tibial paddle include structures that control the orientation at which the adaptor is attachable to the tibial paddle. Some tibial trialing components may be positioned over the adaptor in a mobile orientation that facilities rotation of the tibial trialing component relative to the tibial paddle or a fixed orientation that restricts the rotation of the tibial trialing component.

Abstract: A total knee replacement prosthesis is presented whose bearing surfaces are derived from an anatomically representative femur and a modified baseline tibial surface. The contacting femoral and tibial bearing surfaces include the inter-condylar as well as condylar regions. The modified baseline tibial surface is generated by modifying a baseline tibial surface. For example, the baseline tibial surface can be flattened mathematically to generate the modified baseline tibial surface.

Abstract: The present disclosure provides knee prostheses that replicate at least a portion of the function of an individual patient's anterior cruciate ligament (ACL). An exemplary knee prosthesis includes a femoral component configured to be implanted on the distal end of the patient's femur and a tibial component configured to be implanted on the proximal end of the patient's tibia. In extension, the femoral component and the tibial component may cooperate to limit anterior movement of the tibial component relative to the femoral component. In flexion, the femoral component may be free to rotate relative to the tibial component.

Abstract: An orthopaedic knee prosthesis includes a tibial bearing component with articular features which operate to protect adjacent soft tissues of the natural knee, promote and/or accommodate desired articulation with an abutting femoral component, and facilitate expedient and effective implantation by a surgeon.

Abstract: An orthopedic tibial prosthesis includes a tibial baseplate sized and shaped to cover substantially all of a resected proximal tibial surface, and a tibial bearing component sized to leave a posteromedial portion of the tibial baseplate exposed when the tibial bearing component is mounted to the baseplate. The exposed posteromedial portion of the tibial baseplate includes a chamfered profile which cooperates with a correspondingly chamfered profile at a posteromedial edge of the tibial bearing component to create a substantially continuous chamfer extending from the resected tibial surface to the medial articular surface of the tibial bearing component. Advantageously, this chamfer leaves an absence of material (i.e., a relief or void) at the posteromedial edge of the tibial prosthesis, thereby enabling deep flexion of the prosthesis without impingement between the tibial prosthesis and adjacent anatomic tissues or prosthetic structures.

Abstract: A hinged knee prosthesis comprises a tibial component and a femoral component. The tibial component is configured to attach to a tibia. The tibial component has a bearing surface. The femoral component is configured to hingedly attach to the tibial component and rotate relative to the tibial component. The femoral component comprises a medial condyle and a lateral condyle. The medial and lateral condyles have an eccentric sagittal curvature surface configured to rotate and translate on the bearing surface of the tibial component. A method of rotating a hinged knee through a range of flexion is provided. The method fixedly attaches a femoral component to a tibial component. Axial rotation of the femoral component is induced relative to the tibial component when the hinged knee is flexed.

Abstract: In an orthopaedic knee joint prosthesis, an intercondylar fossa of a femoral component cooperates with a spine formed in a tibial component to reproduce the screw home mechanism of a natural knee. When the femoral component and tibial component are positioned to correspond with slight flexion of the knee, the components are mutually rotationally locked against internal or external rotation. At higher degrees of flexion, such as greater than about 10-20 degrees of flexion, internal/external rotation of the tibia is permitted. The tibia is in an externally rotated position when locked, thereby reproducing the screw home mechanism and providing high stability.

Abstract: A tibial insert includes a base and a post extending from the base along a longitudinal axis. The post has a medial surface, a lateral surface, and a height along the longitudinal axis. The medial surface has a medial section, and the lateral surface has a lateral section oriented substantially parallel to the medial section. The medial section and the lateral section each have a width in a substantially anterior-posterior direction that is sufficient to enable varus/valgus constraint over a flexion/extension range from extension to about 90 to 120 degrees of flexion when the tibial insert is mated with a femoral component.

Abstract: An implant system for knee prosthesis includes a superiorly located femoral bearing block having a femoral component bearing surface and an inferiorly located stem selectively attachable to the bearing block. A strengthening rod is disposed within at least a portion of the femoral bearing block and the stem.

Abstract: A total knee replacement system includes a tibial component having a tibial post with a posterior portion, and a femoral component with medial and lateral condylar protrusions forming separated bearing surfaces configured to articulate with the tibial component. In one disclosed embodiment the posterior portion of the tibial post has a concave surface in the sagittal plane and a convex surface in the transverse plane, and the femoral component includes an intercondylar femoral cam mechanism configured to articulate with the posterior surface of the tibial post. The femoral cam mechanism may include an intercondylar bridging structure with distinct bars or interconnected structural elements providing convex and concave distal surfaces in the sagittal plane, and a concave surface in the transverse plane to facilitate rotation of the femoral component relative to the tibial component in the transverse plane.

Abstract: A knee prosthesis includes a femoral component, a tibial component, and a coupling component interconnecting the femoral component and the tibial component. The tibial component includes ball. The femoral component is configured to move relative to the tibial component. The coupling component defines an internal cavity including a first spherical end portion and a second spherical end portion. The internal cavity is dimensioned to receive the ball of the tibial component. The ball is repositioned between the first spherical end portion and the second spherical end portion of the internal cavity upon movement of the femoral component relative to the tibial component.

Abstract: An orthopaedic knee prosthesis includes a tibial bearing component with surface features which operate to protect adjacent soft tissues of the natural knee throughout a wide range of flexion. More particularly, the tibial bearing component provides an anterior relief space disposed between the dished lateral and medial articular compartments, in which the relief space is convex as viewed from a sagittal perspective across the medial/lateral extent of the relief space.

Abstract: The present invention relates to a spacer implant (I) for the temporary replacement of a knee prosthesis, said implant (I) having a femoral condyle (1) and a tibial plateau (2), the lower surface (7) of the femoral condyle (1) resting on the upper surface (8) of the tibial plateau (2), the lower surface (7) of the femoral condyle (1) having a convex shape while the upper surface (8) of the tibial plateau (2) has a concave shape, a stud (9) being supported by the tibial plateau (2) and penetrating into a receiving means (17) provided on the femoral condyle (1), the femoral condyle (1) comprising two flanges (12, 13) having different sizes and being joined together via a base (7) traversed by a notch (17) forming the receiving means, the shorter flange (13) consisting of two elements (15) referred to as condyles, which are spaced apart from one another by the extension of the notch (17), and a stabilizing bar (16) joining the two condyles (15) together at the free end of said flange (13).

Abstract: A posterior cruciate ligament retaining knee implant prosthesis comprising a femoral component including a medial condyle and a lateral condyle separated from one another by an intercondylar channel adapted to accommodate throughput of a native cruciate ligament, both the medial condyle and the lateral condyle posteriorly terminate individually, the medial condyle including a medial condyle bearing surface and the lateral condyle including a lateral condyle bearing surface, the femoral component including an anterior cam, and a tibial component including a medial condyle receiver having a medial condyle receiver bearing surface, the tibial component also including a lateral condyle receiver having a lateral condyle receiver bearing surface, the tibial component also including an anterior post.

Abstract: A total knee replacement prosthesis comprising condylar and intercondylar bearing surfaces configured to manage anterior/posterior displacement between the articulating femoral and tibial components.

Abstract: A prosthetic joint assembly supports articulation of a joint. The joint assembly includes a first component configured to be fixed to an anatomical feature. The first component includes a first impact surface and a second component that engages the first component. The second component includes a second impact surface that impacts the first impact surface as the first component moves relative to the second component. Furthermore, at least one of the first impact surface and the second impact surface includes a dampening member that dampens energy resulting from impact of the first and second impact surfaces.

Abstract: A knee prosthesis including a femoral implant, a tibial implant, a tibial insert and a cam post. The femoral implant is secured to a femur and has a gap for receiving a natural PCL. The tibial implant is secured to a tibia. The tibial insert comprises a medial cavity with a rotational axis. The tibial insert has articulating surfaces that match the contours of the condyles of the femoral implant and a notch for retaining the natural PCL. The tibial insert has a medial boss that aligns with the medial cavity allowing it to rotate about the rotational axis. A post is secured to the tibial implant and enters a hole of the tibial insert providing anterior and posterior stops for the rotation of the tibial insert about the rotational axis.

Abstract: A femoral component for a knee joint prosthesis is formed of a body having an anterior side, a posterior side, and pair of laterally spaced condylar portions. The femoral component includes an intercondylar portion that joins the condylar portions and includes a recess. The intercondylar portion has an arcuate shaped roof that extends between a pair of opposing side walls. The arcuate shaped roof is formed so as to be defined by a single radius.

Abstract: An orthopaedic knee joint prosthesis (10) provides guided motion in a wide range of motion, and in both extension and flexion. In flexion, a tibial bearing component (16) shifts to a first position in which a posterior cam (36) formed in a femoral component (12) engages a tibial spine (18) coupled to a tibial component (14). Contact between the posterior cam and the spine guides the motion profile of the knee joint prosthesis throughout a wide range of flexion movement. In extension, the bearing component shifts to a second position in which an anterior cam (34) formed in the femoral component engages the spine. Contact between the anterior cam and spine guides the motion profile of the knee joint prosthesis throughout a wide range of extension. The anterior and posterior cams, mobile bearing component, and tibial component-mounted spine cooperate to facilitate guided flexion and extension of the knee joint prosthesis throughout a wide range of motion.

Abstract: A method of implanting a prosthetic knee joint assembly. The method includes: coupling a femoral component to a femur, and coupling a tibial component to a tibia; coupling a ligament link to one of the femur or the tibia; coupling the ligament link to a coupling component of one of the femoral component or the tibial component; arranging the ligament link in a first position relative to the tibial component when the prosthetic knee joint assembly is implanted in a left knee; and arranging the ligament link in a second position relative to the tibial component when the prosthetic knee joint assembly is implanted in a right knee, the second position is different from the first position.

Abstract: A prosthesis for replacing a knee joint between a femur and a tibia can include a femoral component, a tibial component, a bearing and a yoke assembly. The yoke assembly can have a yoke disposed between the bearing and the femoral component and an axle having an axle axis. The axle can hingedly couple the yoke with the femoral component. Rotation of the femoral component about a rotation axis that is perpendicular to the axle axis causes concurrent rotation of the yoke about the rotation axis.

Abstract: An artificial knee joint (1) is described and comprises a femoral component (10) and a tibial component (30), for attachment to the femur (2) and tibia (3) of a patient (4) respectively. The femoral component (10) comprises a lateral condyle (11) and a medial condyle (12) which extend from the posterior (13) to the anterior (14) of the femoral component (10). A femoral gap (15) is provided between the lateral (11) and medial (12) condyles extending from the posterior (13) toward the anterior (14) of the femoral component (10). The lateral (11) and medial (12) condyles are joined at the anterior (13) of the femoral component (10) to form a patella tracking path or bearing surface (16) which is located at and forms the anterior end of the gap (17). A femoral cam (18) is provided bridging the posterior ends of both the lateral (11) and medial (12) condyles, and forms a posterior end of the gap (19), wherein the femoral cam (18) is structured to have the shape of a section of a ring (20).

Abstract: An orthopaedic knee prosthesis includes a femoral component which exhibits enhanced articular features, minimizes removal of healthy bone stock from the distal femur, and minimizes the impact of the prosthesis on adjacent soft tissues of the knee.

Abstract: An orthopaedic knee prosthesis includes a tibial bearing and a femoral component configured to articulate with the tibial bearing. The femoral component includes a posterior cam configured to contact a spine of the tibial bearing and a condyle surface curved in the sagittal plane. The radius of curvature of the condyle surface decreases gradually between early-flexion and mid-flexion. Additionally, in some embodiments, the radius of curvature of the condyle surface may be increased during mid-flexion.

Abstract: A knee prosthesis including a femoral implant, a tibial implant, a tibial insert and a cam post. The femoral implant is secured to a femur and has a cam feature and condyles. The tibial implant is secured to a tibia. The tibial insert comprises a medial cavity with a rotational axis. The tibial insert has articulating surfaces that match the contours of the condyles of the femoral implant. The tibial insert has a medial boss that aligns with the medial cavity allowing it to rotate about the rotational axis. A cam post is secured to the tibial implant and passes through a channel of the tibial insert providing anterior and posterior stops for the rotation of the tibial insert about the rotational axis. The cam post interacts with the femoral implant cam feature and, with the tibial insert, allows more anatomically correct rollback and femoral external rotation during knee flexion.

Abstract: A tibial insert includes a base and a post extending from the base along a longitudinal axis. The post has a medial surface, a lateral surface, and a height along the longitudinal axis. The medial surface has a medial section, and the lateral surface has a lateral section oriented substantially parallel to the medial section. The medial section and the lateral section each have a width in a substantially anterior-posterior direction that is sufficient to enable varus/valgus constraint over a flexion/extension range from extension to about 90 to 120 degrees of flexion when the tibial insert is mated with a femoral component.

Abstract: A prosthetic joint according to the present invention includes a first implant component for attachment to a first bone and a second implant component for attachment to a second bone. The first implant component has a condylar portion that includes first and second condylar bearing surfaces and similarly, the second implant component has bearing surfaces that receive and are complementary to the first and second condylar bearing surfaces. Each of the first and second condylar bearing surfaces and each of the bearing surfaces of the second implant component has a cross-section in a coronal plane that exhibits two different radii and a contact point is established between the first and second condylar bearing surfaces and the bearing surfaces of the second implant component. The bearing surfaces of the respective implant components are configured such that varus and valgus rotation of the first implant component relative to the second implant component causes the contact point to move outwardly.

Abstract: There is provided an orthopaedic bearing comprising at least one capacitive sensing element arranged within the bearing material, and operable to measure a change in capacitance resultant from any compression or tension of the bearing during use. There is also provided a method of assessing an orthopaedic implant including an instrumented orthopaedic bearing.

Abstract: A knee joint prosthesis is disclosed. The knee joint prosthesis can include a tibial baseplate, a tibial insert, and a spine. The tibial baseplate can include a tibial plateau, having a proximal surface and an opposing distal surface, and a tibial stem extending from the distal surface of the tibial plateau. The tibial insert can be located on the proximal surface of the tibial plateau and can include an aperture. The spine can extend through the aperture of the tibial insert and into a cavity of the tibial stem, from the proximal surface of the tibial plateau. The spine can be rotatable with respect to the tibial baseplate and the tibial insert. The knee joint prosthesis can further include a femoral component including a posteriorly-located femoral cam. The posteriorly-located femoral cam can engage the spine during movement of the knee joint prosthesis.

Abstract: An orthopaedic knee prosthesis includes a tibial bearing and a femoral component configured to articulate with the tibial bearing. The femoral component includes a posterior cam configured to contact a spine of the tibial bearing and a condyle surface curved in the sagittal plane. The radius of curvature of the condyle surface decreases gradually between early-flexion and mid-flexion. Additionally, in some embodiments, the radius of curvature of the condyle surface may be increased during mid-flexion.

Abstract: A knee prosthesis that includes a tibial component and femoral component. The tibial component includes an articular surface, a posterior portion and an anterior portion. The posterior portion includes a recess for receipt of a posterior cruciate ligament. The anterior portion includes a post extending therefrom. The post includes a posterior surface. The femoral component includes a condylar portion and an intercondylar portion. The intercondylar portion includes a posterior recess for receipt of the posterior cruciate ligament, a cam, and an engagement recess for receipt of the post. The cam includes a sliding surface and is disposed between the engagement recess and posterior recess. The sliding surface of the cam slides along the posterior surface of the post for restricting anterior subluxation of a femur bone when the articular surface and the condylar portion articulates through flexion of a knee joint.

Abstract: A distal femoral knee-replacement component provides additional points of cam action by either distinct bars or interconnected structural elements such as cam extensions to prevent early translation of the knee or dislocation of the femoral component over the tibial post which can occur in cruciate-substituting designs.

Abstract: The present invention provides a PS-type artificial knee joint implant, with which the gap balance can be adjusted in order to realize a stable deep flexion movement, the burden on a surgeon and a patient can be reduced, and the patient can perform a natural flexion movement. An artificial knee joint implant 1 includes femoral components, one of which is selected and attached to a distal portion of a femur of the patient, and tibial inserts, one of which is selected and attached to a proximal portion of a tibia of the patient. The femoral components have a cam portion that is disposed between posterior portions of two femoral joint faces, respectively. The tibial inserts have posts that can be brought into contact with the cam portion. The posts have different antero-posterior positions.

Abstract: Tibial inserts and tibial femoral systems are provided for improved knee reconstruction systems. External rotation of a knee joint implant is enhanced by modifications to the post, providing a recess that allows clearance of the post against the corners of a box wall within the femoral component. The rotation provides for a more natural knee joint motion of the implant. The depth, size, and location of the post relief may be modified for certain applications to provide both improved rotational motion and constraint against undesirable motion of the knee.