Prosthetic knee joint with increased freedom of patellar movement

Abstract

A knee implant and its components are disclosed. The femoral component (500) of the knee implant may include a reduced constraint area (505) positioned over a portion of the patellar pathway (560). The reduced constraint area may be configured to provide increased freedom of movement for the patella to move over the reduced constraint area. The increased freedom of movement may be for medial-lateral movement and / or internal-external rotation of the patella. The patellar pathway may include a constraint area (e.g., a trochlear groove 506) positioned below the reduced constraint area. The patella may move within the reduced constraint area during extension (or partial flexion) and within the trochlear groove during flexion. A prosthetic patella (800) having a raised portion (804) is also disclosed. The raised portion may be configured to facilitate engagement of the prosthetic patella with the trochlear groove of the femoral component as the patella transitions from the reduced constraint area to the trochlear groove.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application is a nonprovisional application of pending U.S. Provisional Patent Application No. 63 / 082,316, entitled "Knee Prosthesis with Increased Patella Freedom of Movement," filed September 23, 2020, and claims the benefit of the filing date thereof, which is incorporated herein by reference in its entirety.

[0002] The present disclosure relates generally to a knee prosthesis, and more particularly to a femoral component and / or patellar implant of a knee prosthesis configured to facilitate increased freedom of movement of the patella or patellar implant during articulation of the femoral component. [Background technology]

[0003] Severe disease or injury affecting the knee joint can be treated by total knee arthroplasty (TKA), in which the ends of a patient's femur and tibia are surgically replaced with a prosthetic knee device, which may include a prosthetic femoral implant or component, a tibial implant or component, and, in some cases, a patellar implant or component (without any intended distinction or limitation, the terms prosthesis, implant, component, and device are used interchangeably herein). The femoral component may be placed on the patient's distal femur after appropriate resection of the patient's femur. The tibial component may include a tibial tray that generally fits over the patient's resected proximal tibia. The tibial component may also include a stem extending from the tray to extend into a surgically created opening in the intramedullary canal of the patient's tibia. A plastic or polymer insert or bearing may be positioned between the tray of the tibial component and the femoral component to provide a surface against which the femoral component can articulate as the patient's knee moves between extension and flexion positions. A TKA procedure may also include replacement of the patient's patella with a prosthetic patella, for example, to enhance the function and cooperation of the patellofemoral joint of the prosthetic knee device.

[0004] A common complaint among TKA patients is that their replaced knee joint doesn't function or feel like a normal knee joint. In more severe cases, patients report pain or discomfort during articulation of the prosthetic knee device. Pain and instability in the anterior knee joint are common causes of patient dissatisfaction with TKA procedures. Conventional prosthetic knee devices generate motions that differ from those of a normal knee joint during walking due to the complex nature of the knee joint and the relative movement of the femur, tibia, and patella during flexion and extension. For example, patient pain and discomfort in the patellofemoral joint can result from constraints on the movement of components, such as the patella, which can cause impingement between the native anatomy and the implanted components.

[0005] Therefore, it would be beneficial to provide a prosthetic knee device that supports the natural motion of the knee components, including facilitating the range of motion of the components, to reduce the pain and instability associated with conventional prosthetic knee devices. Summary of the Invention

[0006] This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended as an aid in determining the scope of the claimed subject matter.

[0007] The present disclosure provides a femoral component of a prosthetic knee implant that includes a reduced constraint region disposed over a portion of the patellar pathway. The reduced constraint region can be configured to provide increased freedom of movement for the patella to move over the reduced constraint region. In some embodiments, the increased freedom of movement can be for medial-lateral movement and / or internal-external rotation of the patella. The patellar pathway can include a constraint region in the form of a trochlear groove below the reduced constraint region. In some embodiments, the patella can move within the reduced constraint region during extension (or partial flexion) and within the trochlear groove during flexion.

[0008] In some embodiments, the reduced constraint region can include a flattened proximal anterior flange region of the femoral component. In various embodiments, the reduced constraint region can have a length of about 1 percent to about 20 percent of the distal anterior flange region. In various embodiments, the reduced constraint region can have a length of about 1 mm to about 20 mm.

[0009] In various embodiments, the reduced constraint region can be located in a region of the patellar pathway where the patella moves during extension and / or partial flexion below the constrained degree of flexion. In some embodiments, the reduced constraint region can be located in a region of the patellar pathway where the patella moves during approximately 0 degrees of flexion (i.e., extension or full extension). In some embodiments, the constrained degree of flexion can be less than approximately 10 degrees of flexion. In some embodiments, the constrained degree of flexion can be less than approximately 30 degrees of flexion.

[0010] In some embodiments, the length of the reduced constraint region can be provided or determined such that the patella is within the reduced constraint region during a threshold percentage of flexion, which in some embodiments can be between about 0 degrees and about 45 degrees of flexion.

[0011] In various embodiments, the patella can have increased medial-lateral movement within the patellar pathway in a reduced restriction region compared to within the trochlear groove of the patellar pathway. In some embodiments, the percentage increase in medial-lateral movement can be from about 105 percent to about 150 percent. In some embodiments, the percentage increase in medial-lateral movement can be from about 1 mm to about 20 mm. In various embodiments, the increase in medial-lateral movement can be achieved in extension (or substantially near extension, such as less than about 5% flexion).

[0012] In various embodiments, the patella can have increased internal-external rotation within the patellar pathway in a reduced restriction region compared to within the trochlear groove of the patellar pathway. In some embodiments, the percentage increase in internal-external rotation can be from about 105 percent to about 150 percent. In various embodiments, the increase in internal-external rotation can be achieved in extension (or substantially near extension, such as less than about 5% flexion).

[0013] In some embodiments, the reduced constraint region may be characterized by a maximum groove angle of about 150 degrees to about 180 degrees. In various embodiments, the reduced constraint region may be characterized by an average groove angle of about 150 degrees to about 180 degrees. In exemplary embodiments, the reduced constraint region may be characterized by a maximum groove depth of about 1 mm to about 2 mm. In exemplary embodiments, the reduced constraint region may be characterized by an average groove depth of about 1 mm to about 2 mm.

[0014] The present disclosure provides a prosthetic patella of a prosthetic knee implant having a raised portion. In some embodiments, the raised portion is positioned on a distal region of the posterior surface of the prosthetic patella. In various embodiments, the raised portion can be configured to facilitate engagement of the prosthetic patella with the trochlear groove of the femoral component as the prosthetic patella transitions from the reduced constraint region of the femoral component to the trochlear groove.

[0015] In some embodiments, the raised portion can be shaped to flare out and move from the lateral edge to the center of the posterior surface. In various embodiments, the raised portion can have a height of about 1 mm to about 5 mm. In some embodiments, the location of the raised portion can be determined based on various factors, such as whether the patella tracks medially, laterally, or centrally in extension.

[0016] Some embodiments may provide a knee implant system having a femoral component and a prosthetic patella. The femoral component may include a reduced constraint region disposed over a portion of the patellar pathway. The reduced constraint region may be configured to provide increased freedom of movement for the patella to move over the reduced constraint region. In some implementations, the increased freedom of movement may be for medial-lateral movement and / or internal-external rotation of the patella. The patellar pathway may include a constraint region in the form of a trochlear groove below the reduced constraint region. In some implementations, the patella may move within the reduced constraint region during extension (or partial flexion) and within the trochlear groove during flexion.

[0017] In various embodiments, the patella can have a raised portion. In some embodiments, the raised portion is located on a distal region of the posterior surface of the prosthetic patella. In various embodiments, the raised portion can be configured to facilitate engagement of the prosthetic patella with the trochlear groove of the femoral component as the prosthetic patella transitions from the reduced constraint region of the femoral component to the trochlear groove.

[0018] Some embodiments may provide a surgical method for implanting a prosthetic knee system having a femoral component, a tibial component, and a patella in a patient, The method may include securing the prosthetic knee system to the patient's bony anatomy.

[0019] In various embodiments, the femoral component may include a reduced constraint region disposed over a portion of the patellar pathway. The reduced constraint region may be configured to provide increased freedom of movement for the patella to move over the reduced constraint region. In some implementations, the increased freedom of movement may be for medial-lateral movement and / or internal-external rotation of the patella. The patellar pathway may include a constraint region in the form of a trochlear groove below the reduced constraint region. In some implementations, the patella may move within the reduced constraint region during extension (or partial flexion) and within the trochlear groove during flexion.

[0020] In various embodiments, the prosthetic patella can include a raised portion. In some embodiments, the raised portion is located on a distal region of the posterior surface of the prosthetic patella. In various embodiments, the raised portion can be configured to facilitate engagement of the prosthetic patella with the trochlear groove of the femoral component as the prosthetic patella transitions from the reduced constraint region of the femoral component to the trochlear groove.

[0021] Embodiments of the present disclosure provide numerous advantages. In one non-limiting exemplary advantage, a knee implant system may include a femoral component with a reduced constraint area configured to provide increased freedom of movement to the patella, for example, when there is more variability in the natural patellar position while transitioning the patella to a trochlea that accommodates load transfer between the patella and the femur as the knee joint extends and the patella flexes. Thus, knee implants according to some embodiments may provide more natural patellar kinematics compared to conventional systems. Additionally, knee implants according to some embodiments may operate to reduce (or even eliminate) residual pain or discomfort in the anterior knee due to femoro-patellar joint motion after TKA.

[0022] At least some further features and advantages of the embodiments of the present disclosure, as well as the structure and operation of various embodiments of the present disclosure, are described in detail below with reference to the accompanying drawings. [Brief explanation of the drawings]

[0023] By way of example, particular embodiments of devices of the present disclosure will now be described with reference to the accompanying drawings, in which: [Figure 1] 1 shows a perspective view of an embodiment of a conventional left knee prosthesis. [Figure 2] 1A-1C illustrate various side views of a prosthetic knee joint (e.g., femoral component and patella) showing the movement of the prosthetic knee joint during extension and varying degrees of flexion. [Figure 3] 3 shows a side view of an embodiment of a femoral component according to the present disclosure, which may be used in conjunction with the knee prosthesis shown in FIGS. 1 and 2. FIG. [Figure 4A] 3 shows a front view of an embodiment of a femoral component according to the present disclosure, which may be used in conjunction with the knee prosthesis shown in FIGS. 1 and 2. FIG. [Figure 4B] 3 shows a side view of an alternative embodiment of a femoral component according to the present disclosure, which may be used in conjunction with the knee prosthesis shown in FIGS. 1 and 2. FIG. [Figure 4C] 3 shows a front view of an alternative embodiment of a femoral component according to the present disclosure, which may be used in conjunction with the knee prosthesis shown in FIGS. 1 and 2. FIG. [Figure 5A] 3A and 3B show a side view and corresponding cross-sectional view of an embodiment of a femoral component according to the present disclosure, which may be used in conjunction with the knee prosthesis shown in FIGS. 1 and 2. [Figure 5B] 5B illustrates patella trajectory information for the example cross-sectional view of FIG. 5A in accordance with the present disclosure. [Figure 5C] 5B illustrates patella trajectory information for the example cross-sectional view of FIG. 5A in accordance with the present disclosure. [Figure 6] 3A and 3B show a side view and corresponding cross-sectional view of an embodiment of a femoral component according to the present disclosure, which may be used in conjunction with the knee prosthesis shown in FIGS. 1 and 2. [Figure 7] 1 shows a perspective view of an embodiment of a patella implant according to the present disclosure. [Figure 8] 10 shows a graph of patella medial-lateral tracking during degrees of knee flexion for a simulated prosthetic knee joint according to the present disclosure.

[0024] The drawings are not necessarily to scale. The drawings are not intended to portray specific parameters of the present disclosure but are merely representations. The drawings are intended to illustrate exemplary embodiments of the present disclosure and therefore should not be considered limiting in scope. In the drawings, like numbers represent like elements.

[0025] Additionally, certain elements in some of the figures may be omitted or illustrated not to scale for clarity of illustration. Cross-sectional views may be in the form of a "slice," or a "close-up" cross-section, which omits certain background lines that would otherwise be visible in a "true" cross-sectional view for clarity of illustration. Additionally, some reference numbers may be omitted in certain figures for clarity. DETAILED DESCRIPTION OF THE INVENTION

[0026] Embodiments of the improved knee joint will now be more fully described herein with reference to the accompanying drawings, in which preferred embodiments of the present disclosure are presented. As described and illustrated, in some embodiments, the improved knee joint prosthesis can include a femoral component for use in the knee prosthesis, the femoral component having an articulating surface configured to provide a patellar pathway for engaging and guiding a patella or patellar implant during extension and flexion of the knee joint. In some embodiments, the patellar pathway can include a reduced patellar constraint (or reduced constraint) portion, region, segment, or area (terms used interchangeably herein without any intention of distinction) configured to allow increased freedom of movement of the patella or patellar implant as it moves across this portion of the patellar pathway compared to the range of motion provided by the patellar pathway of a conventional femoral component. For example, the reduced constraint area may facilitate greater freedom of movement of the patella or patella implant compared to movement of the patella or patella implant during movement within the trochlear groove or patellar track of a conventional prosthetic femoral component. The increased freedom of movement may be for one or more movements of the patella or patella implant, including, without limitation, medial-lateral translation, internal-external rotation (e.g., patellar tilt), and / or the like.

[0027] As described in more detail herein, in some embodiments, the reduced constraint region can be configured as a flattened region on the proximal anterior flange of the femoral component. In various embodiments, the reduced constraint region can be located in a region of the patellar pathway where the patella moves during extension and / or partial flexion.

[0028] In various embodiments, the patellar pathway can include a reduced constraint region and a patella constraint (or constraint) region. In various embodiments, the constraint region can be or include the trochlear groove or patellar track. In some embodiments, the femoral component can include a constraint region (i.e., trochlear groove) that extends inferiorly rather than superiorly from the distal femoral condyle, allowing more freedom of movement of the patella or patella implant in extension and / or partial flexion, compared to the trochlear groove of a conventional femoral component.

[0029] Referring to FIG. 1 , existing femoral components include an anterior flange sized and shaped to cover as much of the resected anterior bone as possible, and the trochlear groove for the patella or patellar implant extends to the superior edge of the anterior flange. Multiple designs exist for creating the trochlear groove (e.g., straight, angled, offset, S-curve, funnel, and / or the like) and prosthetic patella (e.g., circular dome / sombrero, centered ellipse, offset ellipse, anatomical, mobile-bearing, and / or the like). Different methods have been used to position the femur (e.g., aligning internal-external rotation based on the anterior-posterior axis / Whiteside's line, epicondyle, posterior condyle, and / or the like) and patella (medialized, high-coverage, lateral facetectomy to remove uncovered bone with a medialized implant, non-resurfaced).

[0030] The most common complications after total knee arthroplasty (TKA) are related to femoropatellar problems, with residual anterior knee pain evident in a significant patient population. Malformed patellar kinematics have been cited as a major contributing factor to the development of patellar complications after TKA. For example, in conventional femoral implants, the trochlear groove or patellar track extends further superiorly than the native trochlear groove. Therefore, patellar or patellar implant motion with conventional femoral implants may be constrained in portions of the patellar pathway that are not constrained by the native anatomy, particularly in extension. A femoral component of a knee implant with a reduced constrained region of the patellar pathway may allow freedom of movement of the patella or patellar implant that corresponds or more closely corresponds to the patellar motion in the native anatomy.

[0031] Thus, some embodiments may provide multiple technical advantages over existing knee implants. One non-limiting example of a technical advantage may include providing a femoral component, and in various embodiments, a patellar implant, configured to provide a femoral-patellar joint that allows increased freedom of movement of the patella or patellar implant, particularly in extension and / or partial flexion. Another non-limiting example of a technical advantage may include allowing increased freedom of movement that corresponds to, or more closely corresponds to, the movement of the patella or patellar implant in extension and / or partial flexion within the native anatomy. A further non-limiting example of a technical advantage may include providing a knee implant with reduced (or even eliminated) femoral-patellar problems, particularly residual pain or discomfort in the anterior knee due to femoral-patellar joint movement.

[0032] Figure 1 shows a perspective view of an embodiment of a left knee prosthesis. As shown in Figure 1, the knee prosthesis 100 can be designed to replace at least a portion of a left knee joint between the distal end of a patient's femur and the proximal end of the patient's tibia. A mirror image (not shown) of the knee prosthesis 100 can be configured to replace at least a portion of a right knee joint between the distal end of a patient's femur and the proximal end of the patient's tibia.

[0033] The knee prosthesis 100 may include a femoral component 200 for attachment to the distal end of a patient's femur, a tibial component 300 for attachment to the proximal end of the patient's tibia, and an insert 400 positioned between the femoral component 200 and the tibial component 300. The femoral component 200 may include a medial condylar section 202, a lateral condylar section 204, and a trochlear groove 206 joining anterior portions 214, 216 of the medial and lateral condylar sections 202, 204 together.

[0034] The medial and lateral condylar sections 202, 204 may be spaced apart to form an intercondylar recess or notch 208. Each condylar section 202, 204 may have an outer surface 210, 212, such as for contacting and engaging the tibial component 300 or insert 400. The outer surface 210, 212 of each condylar section 202, 204 may have a distal portion (not shown), such as for contacting and engaging a portion of the tibial component 300 or insert 400 when the knee joint is in extension and partial flexion, and a posterior portion 222, 224, such as for contacting and engaging a portion of the tibial component 300 or insert 400 when the knee joint is flexed substantially 90 degrees or greater.

[0035] An anterior flange 250 extends proximally from the medial and lateral condylar sections 202, 204 and the intercondylar notch 208 and may articulate with the patella or patella implant (not shown, see, for example, FIG. 2).

[0036] In some embodiments, the femoral component 200 can have a thickness that generally matches the bone resection required for TKA. In various embodiments, the femoral component 200 can have a lateral condyle section 204 that has a different geometry than the geometry of the medial condyle section 202. For example, the anterior size of the lateral condyle section 204 can be larger than the anterior size of the medial condyle section 202. In some embodiments, the femoral component 200 can include a rounded medial contour. The embodiments are not limited in this context.

[0037] In a native human knee joint, the knee glides over the femoral condyles from full extension to full flexion. At approximately 20 degrees to 30 degrees of flexion, the patella first begins to articulate within the trochlear groove 206. At extreme flexion, the patella sits in the intercondylar recess 208. Initially, patellar contact occurs distally, and with increased flexion, the contact area eventually shifts proximally on the patella. Patella-femoral contact forces are substantially body weight during walking and increase to substantially five times body weight during stair climbing. These contact forces therefore impose substantial loads on the knee joint that certain embodiments of the prosthesis address to provide a knee implant with reduced (or even eliminated) femoro-patellar pain and / or discomfort following a TKA procedure.

[0038] Figure 2 shows a side view of a prosthetic knee joint, illustrating the movement of the prosthetic knee joint (e.g., the femoral component and patella) during extension and varying degrees of flexion. As shown in Figure 2, the patella 265 can move along the anterior flange 250 along a patellar pathway 260 during (full) extension 270 and flexion 271-275 (approximately 30 degrees, approximately 60 degrees, approximately 90 degrees, approximately 120 degrees, and approximately 150 degrees of flexion, respectively). The dotted line in the patellar pathway 260 indicates the path of movement of the patella 265 in contact with the anterior surface of the femoral component 200 during extension 270 and various degrees of flexion 271-275.

[0039] In some embodiments, the patella 265 may be an autologous human patella. In various embodiments, the patella 265 may be a prosthetic patella. Accordingly, references herein to a patella are intended to include both an autologous human patella and a patella implant, unless expressly stated otherwise. In some embodiments, the prosthetic patella may have a variety of shapes known to those skilled in the art, including, without limitation, a round dome / sombrero, a centered ellipse, an offset ellipse, an anatomical structure, and a mobile bearing. In some embodiments, as described in more detail herein, the patella 265 may include one or more raised portions, such as a raised distal portion (see, e.g., FIG. 6 ).

[0040] FIG. 3 illustrates a side view of an embodiment of a femoral component 500 that may be used in a knee prosthesis, such as knee prosthesis 100, according to the present disclosure. As shown in FIG. 3, the femoral component 500 includes a patellar pathway 560. In one embodiment, the patellar pathway 560 extends along the anterior flange 550 from a pathway start region 510 (in extension) to a pathway end region 512 at the intercondylar notch 508 (in flexion). A portion of the patellar pathway 560 may include a reduced constraint region 505, for example, extending from the transition region 511 to the start region 510 (or, in some embodiments, to the apex 513 of the anterior flange 550). Another portion of the patellar pathway 560 may include a constraint region, for example, in the form of a trochlear groove 506, extending from the end region 512 (i.e., the intercondylar notch 508) to the transition region 511. Generally, the transition region 511 may be a starting point, line, region, or other element associated with the lower beginning of the reduced constraint region 505 (ie, the end closest to the trochlear groove 506).

[0041] In some embodiments, the transition region 511 may provide a gradual transition between the trochlear groove 506 and the reduced restriction region 505. For example, trochlear conformance may begin below the transition region 511 and develop gradually distal to the reduced restriction region 505.

[0042] In various embodiments, the patella (e.g., patella 265 in FIG. 2 ) may be positioned (e.g., may move or move) within the reduced constraint region 505 when the femoral component 500 is in extension (i.e., 0 degrees of flexion) or partial flexion below the constrained degree of flexion. In some embodiments, the constrained degree of flexion may be less than about 1° of flexion, about 1° of flexion, about 2° of flexion, about 3° of flexion, about 4° of flexion, about 5° of flexion, about 10° of flexion, about 15° of flexion, about 20° of flexion, about 30° of flexion, about 60° of flexion, and any value or range (including the endpoints) between any two of these values. Thus, in some embodiments, the patella may move through the reduced constraint region 505 and the trochlear groove 506 during extension and flexion of the femoral component 500.

[0043] 4A illustrates a front view of an embodiment of a femoral component 500 that may be used in a knee prosthesis, such as knee prosthesis 100, according to the present disclosure. As shown in FIG. 4A, the femoral component 500 may include a reduced constraint region 505 formed on a portion of the femoral component 500. In some embodiments, location, size, and / or other characteristics may be based with respect to various portions of the femoral component 500, such as the anterior flange 550, the medial anterior portion 514, the lateral anterior portion 516, the articular surface and / or portions thereof, the medial condylar section 502, the lateral condylar section 504, the (distal) knee resection area or border, and / or the like.

[0044] In some embodiments, the reduced constraint region 505 can be formed in an upper portion of the anterior flange 550. In some embodiments, the reduced constraint region 505 can have a length 540 that extends, for example, from the top or upper region 513 of the anterior flange 550 (or start region 510) to the transition region 511. Generally, the length 540 of the reduced constraint region 505 can be determined to provide the femoral component 500 with a trochlear groove 506 that extends inferiorly rather than superiorly from the distal femoral condyles 502, 504 to allow more freedom of movement of the patella within the reduced constraint region 505 compared to conventional knee implants.

[0045] In various embodiments, the length 540 of the reduced constraint region 505 can be determined based on the percentage of the anterior-posterior length of the femoral component 500 or anterior flange 550 at the opposite end of the intercondylar notch 508 (i.e., the percentage of the length of the distal portion of the femoral component 500 or anterior flange 550 that is covered by the reduced constraint region 505, for example, at the distal portion of the femoral component 500 or anterior flange 550). For example, the length 540 of the reduced constraint region 505 can be a percentage of the length of the femoral component 500 of less than about 1 percent, less than about 5%, less than about 10%, less than about 15%, less than about 20%, less than about 30%, less than about 40%, less than about 50%, less than about 60%, less than about 70%, less than about 80%, less than about 90%, less than about 100%, about 1 percent, about 5%, about 10%, about 15%, about 20%, about 30%, about 40%, about 50%, about 60%, about 70%, about 80%, about 90%, about 95%, and any value or range between any two of these values ​​(including the endpoints). For example, the length 540 of the reduced restriction region 505 can be a percentage of the length of the forward flange 550 that is less than about 1 percent, less than about 5%, less than about 10%, less than about 15%, less than about 20%, less than about 30%, less than about 40%, less than about 50%, less than about 60%, less than about 70%, less than about 80%, less than about 90%, less than about 100%, about 1 percent, about 5%, about 10%, about 15%, about 20%, about 30%, about 40%, about 50%, about 60%, about 70%, about 80%, about 90%, about 95%, and any value or range between any two of these values ​​(including the endpoints).

[0046] In some embodiments, the length 540 of the reduced restriction region 505 may be a discrete value. For example, the length 540 of the reduced restriction region 505 may be less than about 0.25 mm, less than about 0.5 mm, less than about 1 mm, less than about 2 mm, less than about 3 mm, less than about 4 mm, less than about 5 mm, less than about 6 mm, less than about 7 mm, less than about 8 mm, less than about 9 mm, less than about 10 mm, less than about 11 mm, less than about 12 mm, less than about 13 mm, less than about 14 mm, less than about 15 mm, less than about 16 mm, less than about 17 mm, less than about 18 mm, less than about 19 mm, less than about 20 mm, less than about 21 mm, less than about 22 mm, less than about 23 mm, or the like. The thickness may be less than about 24 mm, less than about 25 mm, about 0.25 mm, about 0.5 mm, about 1 mm, about 2 mm, about 3 mm, about 4 mm, about 5 mm, about 6 mm, about 7 mm, about 8 mm, about 9 mm, about 10 mm, about 11 mm, about 12 mm, about 13 mm, about 14 mm, about 15 mm, about 16 mm, about 17 mm, about 18 mm, about 19 mm, about 20 mm, about 21 mm, about 22 mm, about 23 mm, about 24 mm, about 25 mm, and any value or range between any two of these values ​​(endpoints included).

[0047] In some embodiments, the length 540 of the reduced constraint region 505 may ensure or be determined to ensure that the patella remains within the reduced constraint region 505 during a threshold percentage of flexion (extension approximately 0 degrees of flexion). For example, the threshold percentage of bend can be about a 0 degree bend, less than about a 1 degree bend, less than about a 5 degree bend, less than about a 10 degree bend, less than about a 15 degree bend, less than about a 20 degree bend, less than about a 25 degree bend, less than about a 30 degree bend, less than about a 35 degree bend, less than about a 40 degree bend, less than about a 45 degree bend, less than about a 50 degree bend, less than about a 55 degree bend, less than about a 60 degree bend, about a 1 degree bend, about a 5 degree bend, about a 10 degree bend, about a 15 degree bend, about a 20 degree bend, about a 25 degree bend, about a 30 degree bend, about a 35 degree bend, about a 40 degree bend, about a 45 degree bend, about a 50 degree bend, about a 55 degree bend, about a 60 degree bend, and any value or range between any two of these values ​​(including the endpoints).

[0048] In various embodiments, the width 541 of the reduced constraint region 505 can be determined based on the percentage of the anterior-posterior width of the femoral component 500 (i.e., the percentage of the width of the femoral component 500 or anterior flange 550 that is covered by the reduced constraint region 505). For example, the width 541 of the reduced constraint region 505 can be a percentage of the width of the femoral component 500 of less than about 1 percent, less than about 5%, less than about 10%, less than about 15%, less than about 20%, less than about 30%, less than about 40%, less than about 50%, less than about 60%, less than about 70%, less than about 80%, less than about 90%, less than about 100%, about 1 percent, about 5%, about 10%, about 15%, about 20%, about 30%, about 40%, about 50%, about 60%, about 70%, about 80%, about 90%, about 95%, about 100%, and any value or range between any two of these values ​​(including the endpoints).

[0049] In some embodiments, the width 541 of the reduced constraint region 505 may be a discrete value (e.g., evenly spanning the midline of the femoral component 500). For example, the width 541 of the reduced constraint region 505 may be less than about 0.25 mm, less than about 0.5 mm, less than about 1 mm, less than about 2 mm, less than about 3 mm, less than about 4 mm, less than about 5 mm, less than about 6 mm, less than about 7 mm, less than about 8 mm, less than about 9 mm, less than about 10 mm, less than about 11 mm, less than about 12 mm, less than about 13 mm, less than about 14 mm, less than about 15 mm, less than about 16 mm, less than about 17 mm, less than about 18 mm, less than about 19 mm, less than about 20 mm, less than about 21 mm, less than about 22 mm, or less than about 23 mm. The thickness may be less than about 24 mm, less than about 25 mm, about 0.25 mm, about 0.5 mm, about 1 mm, about 2 mm, about 3 mm, about 4 mm, about 5 mm, about 6 mm, about 7 mm, about 8 mm, about 9 mm, about 10 mm, about 11 mm, about 12 mm, about 13 mm, about 14 mm, about 15 mm, about 16 mm, about 17 mm, about 18 mm, about 19 mm, about 20 mm, about 21 mm, about 22 mm, about 23 mm, about 24 mm, about 25 mm, and any value or range between any two of these values ​​(endpoints included).

[0050] 4A, some embodiments may provide a knee implant including a femoral component 500 having a reduced constraint (i.e., flattened) region 505 in the region of the proximal anterior flange 550 where the conforming trochlear groove typically resides. In various embodiments, the trochlear conformance of the trochlear groove 506 may be gradually developed distal to the reduced constraint region 505 below a transition region 511.

[0051] 4B shows a side view of an alternative embodiment of a femoral component 500 that may be used in a knee prosthesis, such as knee prosthesis 100, according to the present disclosure. As illustrated, in some embodiments, the transition region 511 (i.e., the beginning of the reduced constraint region 505) may be based on the distal medial articular surface 502 or the distal lateral articular surface 504. For example, the transition region 511 may be a distance (i.e., distance D) from an edge 514 of the medial articular surface 502 or an edge 515 of the distal lateral articular surface 504. In various embodiments, the transition region 511 may be based on a knee resection region 516. For example, in some embodiments, transition region 511 can be a discrete distance above end 514, end 515, and / or region 516, including, without limitation, about 5 mm, about 10 mm, 15 mm, about 20 mm, about 25 mm, about 30 mm, about 35 mm, about 40 mm, about 45 mm, about 50 mm, about 60 mm, about 70 mm, about 80 mm, and any value or range between any two of these values ​​(end points included).

[0052] 4C shows a front view of an alternative embodiment of a femoral component 500 that may be used in a knee prosthesis, such as knee prosthesis 100, according to the present disclosure. In some embodiments, femoral component 500 includes an anterior tip 570 that is truncated, for example, at or just above transition region 511. In such embodiments, reduced constraint region 505 may extend from transition region 511 to end region 517. In some embodiments, length 540 of reduced constraint region 505 in the embodiment of FIG. 4C may be about 1 mm, about 5 mm, about 10 mm, about 20 mm, and / or any value or range between any two of these values ​​(endpoints included).

[0053] 4A and 4C, the trochlear groove 506 and reduced constraint region 505 can operate to provide patellar pathway segments 560a, 560b with different degrees of freedom of movement for the patella. For example, the patella can have increased medial-lateral movement in pathway segment 560b located in the reduced constraint region 505 compared to pathway segment 560a located in the trochlear groove 506. In some embodiments, the reduced constraint region 505 can be configured to provide an increased percentage of medial-lateral movement within the reduced constraint region 505 compared to the trochlear groove 506. For example, the patella may have a constrained medial-lateral motion value or range (e.g., 1 mm) within the trochlear groove 506 and an increased medial-lateral motion value or range within the reduced constraint region 505 (e.g., the increased medial-lateral motion value or range within the reduced constraint region 505 may be a percentage increase over the constrained medial-lateral motion value or range within the trochlear groove 506). In some embodiments, the percentage increase in medial-lateral motion within the reduced constraint region 505 may be about 105 percent, about 110 percent, about 125 percent, about 150 percent, about 300 percent, about 300 percent, about 400 percent, about 500 percent, about 1000 percent, greater than about 1000 percent, and any value or range between any two of these values ​​(including the endpoints). In some embodiments, the reduced constraint region 505 can be configured to provide a discrete value of medial-lateral motion within the reduced constraint region 505 relative to the trochlear groove 506 (or an increase in motion compared to conventional devices), for example, about 0.25 mm, about 0.5 mm, about 1 mm, about 5 mm, about 10 mm, about 20 mm, greater than about 20 mm, and any value or range between any two of these values ​​(including the endpoints).

[0054] In another example, the patella may have increased internal-external rotation within path portion 560b of reduced constraint region 505 compared to the internal-external rotation provided in path portion 560a of trochlear groove 506. For example, the patella may have a constrained internal-external rotation value or range within trochlear groove 506 and an increased internal-external rotation value or range within reduced constraint region 505 (e.g., the increased internal-external rotation value or range within reduced constraint region 505 may be a percentage increase over the constrained internal-external rotation value or range within trochlear groove 506). In some embodiments, the percentage increase in internal-external rotation within the reduced constraint region 505 can be about 105 percent, about 110 percent, about 125 percent, about 150 percent, about 300 percent, about 300 percent, about 400 percent, about 500 percent, about 1000 percent, greater than about 1000 percent, and any value or range between any two of these values ​​(inclusive). In some embodiments, the reduced constraint region 505 can be configured to provide discrete values ​​of internal-external rotation within the reduced constraint region 505 compared to the trochlear groove 506, for example, about 1 degree, about 5 degrees, about 10 degrees, about 20 degrees, about 30 degrees, and any value or range between any two of these values ​​(inclusive).

[0055] In various embodiments, one or more stops 575 (FIG. 4A) may be positioned within the reduced constraint region 505. Generally, the stops 575 may be positioned to provide a limit or boundary to the degree of freedom of movement of the patella, such as medial-lateral movement. In some embodiments, the stops 575 may be or include, without limitation, protrusions, bumps, ridges, and / or the like.

[0056] In alternative embodiments, the anterior flange 570 of the femoral component 500 may be cut, for example, at an upper starting location of the reduced constraint region 505 and / or may reduce the conformance (e.g., groove depth, groove angle) of the reduced constraint region 505 instead of "flattening" the reduced constraint region 505.

[0057] FIG. 5A illustrates a side view and corresponding cross-sectional view of an embodiment of a femoral component 500 according to the present disclosure that may be used in a knee prosthesis, such as knee prosthesis 100. As shown in FIG. 5A, cross-sections 610-616 through the reduced constraint region 505 illustrate the contrast between an exemplary embodiment of a femoral component according to features of the present disclosure and an exemplary conventional device having, for example, a trochlear groove or other constraint region that extends to the top of the anterior flange. As illustrated, the femoral component 500 including the reduced constraint region according to one or more features of the present disclosure is shown shaded. An exemplary conventional implant is shown without shading. As shown in FIG. 5A, the reduced constraint region 505 may be flatter than the same region of an exemplary conventional device.

[0058] FIG. 5B illustrates patella trajectory information for the exemplary cross-section of FIG. 5A in accordance with the present disclosure. The reduced constraint or “flatness” of the reduced constraint region 505 may correspond to various constraint factors, such as groove angle, groove depth, and / or the like. FIG. 650 illustrates groove angle measurements for an exemplary conventional device of cross-section 611 of FIG. 5A. Generally, groove angle SA-01 may be measured using groove angle lines SAL-01 and SAL-02 that intersect through the eminences of both condyles. FIG. 651 illustrates groove angle SA-02 for a femoral component 500 in accordance with one or more features of the present disclosure of cross-section 611 of FIG. 5A. As shown in FIG. 5B, for the same region of the femoral component, SA-02 > SA-01. Generally, the groove angle for the trochlear groove of an exemplary conventional device may be less than about 160 degrees, less than about 150 degrees, or more typically less than about 145 degrees. In comparison, the reduced constrained region 505 may have an area having an angle greater than about 145 degrees, greater than about 150 degrees, greater than about 160 degrees, greater than about 170 degrees, greater than about 180 degrees, or any value or range between any two of these values ​​(including the endpoints). In some embodiments, the groove angle within the reduced constrained region 505 may be greater than about 150 degrees. In various embodiments, the groove angle within the reduced constrained region 505 may be greater than about 160 degrees. The groove angle within the reduced constrained region 505 may be a maximum value or an average value.

[0059] FIG. 652 illustrates a groove depth measurement for an exemplary conventional device of cross-section 611 of FIG. 5A. Generally, the groove depth can be measured as the distance between a line drawn tangent to the inner and lateral femoral condyles at their anterior edges and the deepest part of the groove. Groove depth D-01 can be measured based on tangent depth line DL-01 for an exemplary conventional device. FIG. 652 illustrates groove depth D-02 based on tangent line DL-02 for the same region of a device configured in accordance with one or more features of the present disclosure. As shown in FIG. 5B, D-02 < D-01. In some embodiments, the groove depth of the area of reduced constraint region 505 can be less than about 4 mm, less than about 3 mm, less than about 2 mm, less than about 1 mm, less than about 0.5 mm, less than about 0.25 mm, less than about 0 mm, or any value or range between any two of these values (including the endpoints).

[0060] FIG. 5C shows patellar track information for an exemplary cross-section of FIG. 5A according to the present disclosure. FIG. 654 illustrates a groove angle measurement for an exemplary conventional device of cross-section 611 of FIG. 5A. As shown in FIG. 5C, a plurality of groove angles can be determined based on various anatomical reference points. For example, lateral groove angle LSA-01 or medial groove angle MSA-01 can be determined with respect to the medial-lateral axis 670. In some embodiments, the medial-lateral axis 670 can be defined with respect to Whiteside’s line, the anterior-posterior axis, the superior condylar axis, the posterior condylar axis, and / or the like. Lateral groove angle LSA-01 can be the angle between SAL-03 (or other groove angle reference line) and the medial-lateral axis 670, and / or medial groove angle MSA-01 can be the angle between SAL-04 (or other groove angle reference line) and the medial-lateral axis 670.

[0061] FIG. 6 shows a side view and corresponding cross-section of an embodiment of a femoral component 700 that can be used in an artificial knee joint, such as artificial knee joint 100, according to the present disclosure. According to one or more features of the femoral component 700, the femoral component 700 includes a patellar path having a reduced constraint region 705. According to a feature of the femoral component 700, the reduced constraint region 705 can be provided as a completely flat surface on the anterior flange.

[0062] As shown in FIG. 6 , cross-sections 710-716 through reduced constraint region 705 illustrate the contrast between an exemplary embodiment of a femoral component having a completely flat surface on the anterior flange in accordance with features of the present disclosure and an exemplary prior art device having, for example, a trochlear groove or other constraint region that extends to the top of the anterior flange. As illustrated, femoral component 700 including a reduced constraint region in accordance with one or more features of the present disclosure is shown shaded. An exemplary prior art implant is shown without shading. As shown in FIG. 6 , reduced constraint region 705 is completely flat and, therefore, flatter than the same region of an exemplary prior art device.

[0063] 7 shows a perspective view of an embodiment of a patella implant 800 according to the present disclosure. In extension (and certain states of partial flexion), the patella implant 800 can be positioned in a reduced constraint region with a variety of potential medial-lateral positions. As the knee begins to flex, the trochlear groove of the femoral component and patella implant 800 must guide the patella implant 800 into the trochlear groove from a wide range of potential medial-lateral positions. Thus, in some embodiments, the distal portion of the posterior surface of the patella implant 800, which is more likely to be a functional contact area in extension than in flexion, can be shaped to assist the patella implant 800 in transitioning into the trochlear groove (or other constraint region) during initial flexion.

[0064] As shown in Figure 7, a patella implant 800 according to some embodiments can have a ridge or transition portion 804 located on a distal region of the posterior surface 802 of the patella implant 800. During flexion, as the patella implant 800 moves from the reduced constraint area into the trochlear groove (or other constraint area), the ridge portion 804 of the patella implant 800 can act to guide the patella implant 800 into the trochlear groove. As shown in Figure 7, the ridge portion 804 can be formed to flare out and move from the outer edge to the center of the posterior surface 802.

[0065] The patella implant 800 may be formed from a variety of materials known to those skilled in the art, including metals, ceramics, composites, fiber-reinforced composites, polymers, ultra-high cross-linked polyethylene (UHXLPE), ultra-high molecular weight polyethylene (UHMWPE), combinations thereof, and / or the like.

[0066] In some embodiments, raised portion 804 can have a height (e.g., based on the difference between the lowest point of posterior surface 802 and the highest point of raised portion 804) of about 0.1 mm or more, about 0.2 mm or more, about 0.3 mm or more, about 0.4 mm or more, about 0.5 mm or more, about 1 mm or more, about 2 mm or more, about 3 mm or more, about 4 mm or more, about 5 mm or more, and any value or range between any two of these values ​​(inclusive). In some embodiments, raised portion 804 can have a length of about 0.1 mm or more, about 0.2 mm or more, about 0.3 mm or more, about 0.4 mm or more, about 0.5 mm or more, about 1 mm or more, about 2 mm or more, about 3 mm or more, about 4 mm or more, about 5 mm or more, and any value or range between any two of these values ​​(inclusive). In some embodiments, the location of the raised portion 804 may be determined based on various factors, such as whether the patella implant 800 tracks medially, laterally, or centrally in extension. In various embodiments, the groove angle and / or groove depth of the reduced constraint region may be determined based on the height of the raised portion.

[0067] 8 shows a graph of patella medial-lateral tracking during knee flexion for a simulated prosthetic knee joint according to the present disclosure. Graph 905 illustrates knee implant simulation data generated via LifeMOD™ / KneeSIM, produced by LifeModeler of San Clemente, California, United States. More specifically, graph 905 illustrates knee implant simulation data of patella medial-lateral tracking relative to the tibia for a condition in which the initial patella position is more lateral and superior than in a typical patient, comparing an existing implant positioned at a typical 3° external rotation (910). The typical 3° external rotation (910) is compared to 8° external rotation (911) and 13° external rotation (912). The increased external rotation smooths the lateral translation of the patella as the knee extends. Graph 913 illustrates an implant modified in accordance with one or more features of the present disclosure, where the modified implant includes a reduced constraint region (i.e., a flattened trochlea). As illustrated, the reduced constraint region smooths lateral translation of the patella during knee extension, without the drawback of affecting the flexion balance of the knee joint. Graph 914 illustrates an implant modified to include a reduced constraint region, where the reduced constraint region includes a fully flattened surface that provides increased patellar degrees of freedom.

[0068] While the present disclosure refers to particular embodiments, numerous modifications, changes, and variations to the described embodiments are possible without departing from the scope and scope of the present disclosure, as defined by the appended claims. Accordingly, the present disclosure is not intended to be limited to the described embodiments, but to have full scope defined by the language of the following claims and their equivalents. The discussion of any embodiments is for illustrative purposes only and is not intended to suggest that the scope of the present disclosure, including the claims, is limited to those embodiments. In other words, while exemplary embodiments of the present disclosure have been described in detail herein, it should be understood that the concepts of the present invention may be embodied and employed in various other ways.

[0069] The foregoing discussion has been presented for purposes of illustration and description and is not intended to limit the disclosure to the form disclosed herein. For example, various features of the present disclosure have been grouped together in one or more embodiments or configurations for purposes of streamlining the disclosure. However, it will be understood that various features of specific embodiments or configurations of the present disclosure may be combined in alternative embodiments or configurations.

[0070] As used herein, elements or steps listed in the singular and preceded by the terms "a" or "an" should be understood as not excluding a plurality of elements or steps, unless the exclusion of a plurality of elements or steps is explicitly recited. Furthermore, references to "one embodiment" of the present disclosure are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features.

[0071] As used herein, the terms "at least one," "one or more," and / or "and / or" are open-ended expressions, having both connective and disjunctive properties in implementation. The terms "a" (or "an"), "one or more," and "at least one" may be used interchangeably herein. All directional references (e.g., proximal, distal, superior, inferior, upward, downward, left, right, lateral, longitudinal, front, rear, top, bottom, upper, lower, vertical, horizontal, radial, axial, clockwise, and counterclockwise) are used for identification purposes only to aid the reader in understanding this disclosure and do not create limitations, particularly with respect to location, orientation, or use of the disclosure.

[0072] Connection references (e.g., engage, attach, couple, connect, fasten, mount, join, and / or the like) should be construed broadly and, unless otherwise indicated, may include intermediate members between groups of elements and for movement between elements. As such, connection references do not necessarily infer that two elements are directly connected and in fixed relationship to each other. All rotational references describe relative movement between various elements. Identification references (e.g., primary, secondary, first, second, third, fourth, etc.) are not intended to indicate importance or priority, but are used to distinguish one feature from another. The drawings are for illustrative purposes only, and the dimensions, positions, order, and relative sizes reflected in the drawings attached hereto may be changed.

Claims

1. 1. A knee joint implant, comprising: a femoral component positioned and configured to engage the patient's femur, the femoral component including an articular surface positioned and configured to articulate relative to a tibial component or insert; the articular surface includes a patellar pathway along which a patella moves, the patellar pathway including a constrained region and a reduced constrained region, the reduced constrained region positioned and configured to provide an increased degree of freedom of movement of the patella as the patella moves over the reduced constrained region compared to a degree of freedom of movement of the patella as the patella moves over the constrained region; a patella implant positioned and configured to move along the patellar pathway formed in the articular surface of the femoral component, the patella implant including a raised portion positioned and configured on a distal region of a posterior surface of the patella implant.

2. The knee implant of claim 1, wherein the increased freedom of movement of the patella provided by the reduced restriction area allows increased medial-lateral movement of the patella.

3. 3. The knee joint implant of claim 2, wherein the increased medial-lateral movement of the patella within the reduced constraint area of ​​the patellar pathway is about 105 percent to about 150 percent greater than the medial-lateral movement of the patella within the constraint area of ​​the patellar pathway.

4. 4. The knee joint implant according to claim 1, wherein the increased medial-lateral movement of the patella within the reduced constraint area of ​​the patellar pathway is greater by about 1 mm to about 20 mm compared to the medial-lateral movement of the patella within the constraint area of ​​the patellar pathway.

5. 5. The knee joint implant of claim 1, wherein the increased freedom of movement of the patella provided by the reduced restriction area allows for increased internal-external rotation of the patella.

6. 6. The knee joint implant of claim 5, wherein the increased internal-external rotation of the patella within the reduced constraint area of ​​the patellar pathway is about 105 percent to about 150 percent greater than the internal-external rotation of the patella within the constraint area of ​​the patellar pathway.

7. The knee implant of any one of claims 1 to 6, wherein the restricted area of ​​the patellar pathway includes a trochlear groove positioned inferiorly relative to the reduced restricted area.

8. The knee implant of claim 7 , wherein the patella moves within the reduced constraint area during extension and within the trochlear groove during flexion.

9. 9. The knee joint implant of claim 8, wherein the femoral component is positioned and configured such that the patella is within the reduced constraint region when the patella moves through less than about 10 degrees of flexion.

10. The knee joint implant of any one of claims 1 to 9, wherein the reduced constraint area comprises a flattened area formed adjacent a proximal anterior flange of the femoral component.

11. The knee implant of any one of claims 1 to 10, wherein the reduced constraint region has a length that is between about 1 percent and about 20 percent of the length of the distal anterior flange region.

12. The knee implant of any one of claims 1 to 11, wherein the reduced restriction area has a length of from 1 mm to about 20 mm.

13. The knee implant of claim 12 , wherein the raised portion is positioned and configured to facilitate engagement of the patella implant within the restricted region of the patellar pathway.

14. The knee implant of claim 13 , wherein the raised portion is positioned and configured to flare out and move from the outer edge to the center of the posterior surface.

15. A knee joint implant as described in claim 1, wherein one or more stops are positioned within the reduced constraint area, the stops being positioned to provide a limit or boundary to the freedom of movement of the patella.

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