Patellar prostheses and total knee joint prostheses

Abstract

Embodiments of the present invention provide a patellar prosthesis and a total knee joint prosthesis. In this embodiment of the invention, the patellar prosthesis is used to cooperate with a femoral prosthesis. The femoral prosthesis includes a medial condyle, a lateral condyle, and an intercondylar fossa for corresponding cooperation with the tibia. The medial and lateral condyles have a recessed groove in the middle to form a trochlear groove for receiving the patellar prosthesis. The width of the intercondylar fossa is L7. The patellar prosthesis includes a patellar articular surface that cooperates with the femoral articular surface. When the human body is flexed greater than 90°, the patellar prosthesis cooperates with the intercondylar fossa. The width of the overlap between the patellar prosthesis and the lateral condyle is L6, and the width of the overlap between the patellar prosthesis and the medial condyle is L5. When the human body is flexed between 90° and 135°, L5 / L7 is 0.11 to 1.30, and L6 / L7 is 0.11 to 1.42. Therefore, the patellar prosthesis according to embodiments of the present invention has the advantage of improving the stability of the patellar joint.

Description

Technical Field

[0001] This invention relates to the field of prosthetics, specifically to a patellar prosthesis and a total knee joint prosthesis having the patellar prosthesis. Background Technology

[0002] The patella protects the knee joint. Patellar prostheses are used to replace necrotic patellae in the knee joint. The patella is a common source of pain and disability after total knee replacement surgery. Patellar complications include fractures, dislocations, subluxations, loosening and wear of the patellar implant, osteonecrosis, and erosion. As the knee flexion angle increases, the restraining effect of the fixation structure and the prosthesis gradually increases, becoming a major factor in preventing subluxation. In related techniques, the patellar prosthesis used is prone to getting stuck in the intercondylar fossa under high knee flexion, causing dislocation, pain, and poor stability. Summary of the Invention

[0003] This invention aims to at least partially address one of the technical problems in related art. To this end, embodiments of the invention provide a patellar prosthesis. This patellar prosthesis has the advantage of improving the stability of the patellofemoral joint.

[0004] Embodiments of the present invention also propose a total knee joint prosthesis.

[0005] A patellar prosthesis is used to cooperate with a femoral prosthesis. The femoral prosthesis includes a medial condyle, a lateral condyle, and an intercondylar fossa for corresponding cooperation with the tibia. A trochlear groove is formed between the medial and lateral condyles to accommodate the patellar prosthesis. The connecting surface formed by the medial condyle, the lateral condyle, the intercondylar fossa, and the trochlear groove constitutes a femoral articular surface for cooperation with the patellar prosthesis. The width of the intercondylar fossa is L7. The bone prosthesis includes a patellar articular surface that mates with the femoral articular surface. When the human body is flexed to a degree greater than 90°, the patellar prosthesis mates with the intercondylar fossa. The width of the overlap between the patellar prosthesis and the lateral condyle is L6, and the width of the overlap between the patellar prosthesis and the medial condyle is L5. When the human body is flexed between 90° and 135°, the ratio of L5 to L7 is 0.11 to 1.30, and the ratio of L6 to L7 is 0.11 to 1.42.

[0006] The patellar prosthesis of this invention includes a patellar articular surface that mates with the femoral articular surface. The width of the intercondylar fossa of the femoral prosthesis is L7. When the human body is flexed to a position greater than 90°, the patellar prosthesis mates with the intercondylar fossa. The width of the overlap between the patellar prosthesis and the lateral condyle is L6, and the width of the overlap between the patellar prosthesis and the medial condyle is L5. When the human body is flexed between 90° and 135°, L5 / L7 is 0.11 to 1.30, and L6 / L7 is 0.11 to 1.42. The patellar prosthesis and the femoral prosthesis overlap in the medial and lateral directions of the human body.

[0007] The width of the intercondylar fossa is positively correlated with the width between the medial and lateral condyles. A larger intercondylar fossa will result in larger medial and lateral condyles, which in turn will increase the required length of the medial and lateral condyles to fit with the patellar prosthesis when used together.

[0008] The patellar prosthesis of this invention, by defining the relationship between the width L7 of the intercondylar fossa and the width L5 of the overlap between the patellar prosthesis and the medial condyle, and by defining the relationship between the width L7 of the intercondylar fossa and the width L6 of the overlap between the patellar prosthesis and the lateral condyle, can avoid the problem of the patellar joint surface of the patellar prosthesis getting stuck in the intercondylar fossa of the femur due to the small contact area during high knee flexion, thus preventing injury and pain. By increasing the contact area between the patellar prosthesis and the femoral prosthesis, the pressure distribution on the femur is improved, enhancing patellofemoral joint stability and preventing subluxation or the patellar prosthesis getting stuck in the intercondylar fossa. This method is used to evaluate the safety of the femoral condyle and patellar prosthesis during movement, preventing patellar displacement, dislocation, and getting stuck in the intercondylar fossa.

[0009] Therefore, the patellar prosthesis of the present invention has the advantage of improving the stability of the patellar joint.

[0010] In some embodiments, when the human body is flexed at 135°, L5 is 3.5mm to 15.5mm and L6 is 3.5mm to 15.5mm.

[0011] In some embodiments, when the human body is flexed at 120°, L5 is 3.5mm to 15.5mm and L6 is 3.5mm to 15.5mm.

[0012] In some embodiments, when the human body is flexed at 90°, L5 is 4.0mm to 15.5mm and L6 is 5.0mm to 17mm.

[0013] In some embodiments, the patellar articular surface projects an ellipse onto the coronal plane, the ellipse comprising a major axis ML and a minor axis AP; the length of the major axis ML is 20 mm to 50 mm.

[0014] In some embodiments, the length of the short axis AP is 14mm to 40mm.

[0015] In some embodiments, L7 is 12mm to 30mm.

[0016] In some embodiments, the radius of curvature of the arc corresponding to the major axis ML is 8mm to 30mm.

[0017] In some embodiments, the radius of curvature of the arc corresponding to the short axis AP is 12mm to 50mm.

[0018] In some embodiments, the outer periphery of the patellar joint surface is a chamfered portion.

[0019] In some embodiments, the radius of curvature of the chamfer is 1 to 5 mm.

[0020] In some embodiments, the patellar articular surface has a most prominent patellar peak, and the side of the lateral condyle that mates with the tibia is a convex surface that protrudes towards the tibia. The peak of the convex surface forms the lateral condyle peak curve. The distance between the lateral condyle peak curve and the patellar peak in the anterior-posterior direction of the human body is the dislocation height H. The flexion angle α and H of the human body between 0° and 120° satisfy the following relationship: H = k1α + b1, where k1 is a constant, k1 = 0.029 to 0.16, and b1 is a constant, b1 = 0.9 to 2.5.

[0021] In other embodiments, the distance between the central axis of the intercondylar fossa and the medial condylar peak curve in the medial-lateral direction is the dislocation displacement LL. The angle of human flexion α and LL between 0° and 120° satisfy the following relationship: LL = k2α + b2, where k2 is a constant, k2 = 0.02 to 0.26, and b2 is a constant, b2 = 6.98 to 11.85.

[0022] In some embodiments, when the human body is flexed at 135°, H is 6.06mm to 6.46mm and LL is 20.26mm to 23.20mm.

[0023] In some embodiments, when the human body is flexed at 120°, H is 6.06mm to 6.46mm and LL is 20.26mm to 23.20mm.

[0024] In some embodiments, when the human body is flexed at 90°, H is 5.96mm to 6.40mm and LL is 20.00mm to 22.97mm.

[0025] In some embodiments, when the human body is flexed at 60°, H is 5.28mm to 5.90mm and LL is 17.34mm to 22.37mm.

[0026] In some embodiments, when the human body is flexed at 30°, H is 3.59mm to 5.56mm and LL is 12.53mm to 17.85mm.

[0027] In some embodiments, when the human body is flexed at 0°, H is 0.93mm to 2.49mm and LL is 6.98mm to 11.85mm.

[0028] In some embodiments, when the human body is flexed at 135°, the contact area between the patellar prosthesis and the medial condyle is 3.8 mm. 2~11.36mm 2 .

[0029] In some embodiments, when the human body is flexed at 120°, the contact area between the patella and the medial condyle is 3.8 mm. 2 ~11.36mm 2 .

[0030] In some embodiments, when the human body is flexed at 90°, the contact area between the patellar prosthesis and the medial condyle is 3.86 mm. 2 ~11.91mm 2 .

[0031] The total knee joint prosthesis of this invention includes a femoral prosthesis and a patellar prosthesis according to any one of the above-described embodiments. Attached Figure Description

[0032] Figure 1 This is a front view of the patellar prosthesis according to an embodiment of the present invention.

[0033] Figure 2 This is a top view of the patellar prosthesis according to an embodiment of the present invention.

[0034] Figure 3 This is a top view of the total knee joint prosthesis according to an embodiment of the present invention, with the human body flexed at 0°.

[0035] Figure 4 This is a top view of the total knee joint prosthesis according to an embodiment of the present invention, with the human body flexed at 30°.

[0036] Figure 5 This is a top view of the total knee joint prosthesis according to an embodiment of the present invention, with the human body flexed at 60°.

[0037] Figure 6 This is a top view of the total knee joint prosthesis according to an embodiment of the present invention, with the human body flexed at 90°.

[0038] Figure 7 This is a top view of the total knee joint prosthesis according to an embodiment of the present invention, with the human body flexed at 120°.

[0039] Figure 8 This is a top view of the total knee joint prosthesis according to an embodiment of the present invention, with the human body flexed at 135°.

[0040] Figure label:

[0041] Patellar prosthesis 10; Patellar articular surface 101; Patellar peak 102; Patellar connecting column 103;

[0042] Femoral prosthesis 20; medial condyle 201; lateral condyle 202; lateral condyle peak 203; intercondylar fossa 204. Detailed Implementation

[0043] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0044] Based on basic anatomical positioning, the human body can be defined by three typical mutually perpendicular axes: the sagittal axis, a horizontal line running anteroposteriorly; the coronal (frontal) axis, a horizontal line running laterally; and the vertical axis, a perpendicular line running vertically. The human body or organs can be cut into different sections according to these axes. The sagittal plane is a vertical section along the sagittal axis, dividing the body into left and right parts; the coronal plane is a vertical section along the coronal axis, dividing the body into anterior and posterior parts; and the horizontal or transverse plane is a horizontal section along a horizontal line, dividing the body into superior and inferior parts, and is perpendicular to the two aforementioned longitudinal sections.

[0045] The following is for reference. Figures 1-8 The patellar prosthesis 10 and the total knee joint prosthesis according to embodiments of the present invention are described.

[0046] The patellar prosthesis 10 is used to mate with the femoral prosthesis 20. The femoral prosthesis 20 includes a medial condyle 201, a lateral condyle 202, and an intercondylar fossa 204 for corresponding mating with the tibia. A trochlear groove is formed between the medial condyle 201 and the lateral condyle 202 to accommodate the patellar prosthesis 10. The connecting surface formed by the medial condyle 201, the lateral condyle 202, the intercondylar fossa 204, and the trochlear groove constitutes the femoral articular surface for mating with the patellar prosthesis 10. The width of the intercondylar fossa 204 is... The degree of flexion is L7; the patellar prosthesis 10 includes a patellar articular surface that matches the femoral articular surface. When the human body is flexed greater than 90°, the patellar prosthesis 10 matches the intercondylar fossa 204. The overlap width between the patellar prosthesis 10 and the lateral condyle 202 is L6, and the overlap width between the patellar prosthesis 10 and the medial condyle 201 is L5. When the human body is flexed between 90° and 135°, L5 / L7 is 0.11 to 1.30, and L6 / L7 is 0.11 to 1.42. It can be understood that when the human body is flexed between 90° and 135°, the patellar prosthesis 10 and the femoral prosthesis 20 overlap in the medial and lateral directions of the human body. The width of the intercondylar fossa 204 is positively correlated with the width between the medial condyle 201 and the lateral condyle 202. The larger the width of the intercondylar fossa 204, the larger the size of the medial condyle 201 and the lateral condyle 202 will be. Consequently, when the intercondylar fossa 204 is fitted with the patellar prosthesis 10, the overlap length between the medial condyle 201 and the lateral condyle 202 and the patellar prosthesis 10 will also increase.

[0047] The patellar prosthesis 10 of this invention, by defining the relationship between the width L7 of the intercondylar fossa 204 and the width L5 of the overlap between the patellar prosthesis 10 and the medial condyle 201, and by defining the relationship between the width L7 of the intercondylar fossa 204 and the width L6 of the overlap between the patellar prosthesis 10 and the lateral condyle 202, can avoid the problem of the patellar articular surface 101 of the patellar prosthesis 10 getting stuck in the intercondylar fossa 204 of the femoral bone due to its small contact area when the knee is highly flexed, thus preventing injury and pain to the human body. By increasing the contact area between the patellar prosthesis 10 and the femoral prosthesis 20, the pressure distribution on the femur is improved, the stability of the patellofemoral joint is enhanced, and subluxation or the patellar prosthesis 10 getting stuck in the intercondylar fossa 204 of the femoral bone is prevented. To prevent patellar displacement, dislocation, and jamming within the intercondylar fossa 204, and to assess the safety of the femoral condyle and patellar prosthesis 10 during movement.

[0048] Therefore, the patellar prosthesis 10 of the present invention has the advantage of improving the stability of the patellar joint.

[0049] Optionally, the patellar prosthesis 10 further includes patellar connecting posts 103, which are disposed opposite to the patellar articular surface 101. Specifically, three patellar connecting posts 103 may be provided in a triangular arrangement to increase the stability of the connection, and a bone cement groove may be provided on one side of the patellar connecting posts 103.

[0050] When the knee is flexed at 135°, the overlap width between the patellar prosthesis 10 and the medial condyle 201 is 3.5mm–15.5mm for L5 and 3.5mm–15.5mm for L6. This ensures that when the knee is flexed at 135°, interference with the medial condyle 201 and lateral condyle 202 is avoided due to excessively large L5 and L6 values, while also avoiding poor patellofemoral joint stability due to excessively small L5 and L6 values. Therefore, it achieves both high joint stability and avoids interference with the femoral prosthesis 20.

[0051] Optionally, when the human body is flexed at 135°, the overlap width L5 between the patellar prosthesis 10 and the medial condyle 201 is 3.5mm, 4.0mm, 4.5mm, 5.0mm, 5.5mm, 6.0mm, 6.5mm, 7.0mm, 7.5mm, 8.0mm, 8.5mm, 9.0mm, 9.5mm, 9.0mm, 10.5mm, 11.0mm, 11.5mm, 12.0mm, 12.5mm, 13.0mm, 13.5mm, 14.0mm, or 15.5mm.

[0052] Optionally, when the human body is flexed at 135°, the overlap width L6 between the patellar prosthesis 10 and the lateral condyle 202 is 3.5mm, 4.0mm, 4.5mm, 5.0mm, 5.5mm, 6.0mm, 6.5mm, 7.0mm, 7.5mm, 8.0mm, 8.5mm, 9.0mm, 9.5mm, 9.0mm, 10.5mm, 11.0mm, 11.5mm, 12.0mm, 12.5mm, 13.0mm, 13.5mm, 14.0mm, or 15.5mm.

[0053] When the knee is flexed to 120°, L5 is 3.5mm–15.5mm and L6 is 3.5mm–15.5mm. This ensures that at 120° knee flexion, interference with the medial condyle 201 and lateral condyle 202 caused by excessively large L5 and L6 values ​​is avoided, as well as poor patellofemoral joint stability caused by excessively small L5 and L6 values. Therefore, it achieves both high joint stability and avoids interference with the femoral prosthesis 20.

[0054] Optionally, when the human body is flexed at 120°, the overlap width L5 between the patellar prosthesis 10 and the medial condyle 201 is 3.5mm, 4.0mm, 4.5mm, 5.0mm, 5.5mm, 6.0mm, 6.5mm, 7.0mm, 7.5mm, 8.0mm, 8.5mm, 9.0mm, 9.5mm, 9.0mm, 10.5mm, 11.0mm, 11.5mm, 12.0mm, 12.5mm, 13.0mm, 13.5mm, 14.0mm, or 15.5mm.

[0055] Optionally, when the human body is flexed at 120°, the overlap width L6 between the patellar prosthesis 10 and the lateral condyle 202 is 3.5mm, 4.0mm, 4.5mm, 5.0mm, 5.5mm, 6.0mm, 6.5mm, 7.0mm, 7.5mm, 8.0mm, 8.5mm, 9.0mm, 9.5mm, 9.0mm, 10.5mm, 11.0mm, 11.5mm, 12.0mm, 12.5mm, 13.0mm, 13.5mm, 14.0mm, or 15.5mm.

[0056] When the knee is flexed at 90°, L5 ranges from 4.0mm to 15.5mm, and L6 ranges from 5.0mm to 17mm. This ensures that when the knee is flexed at 90°, the L5 and L6 values ​​avoid interference with the medial condyle 201 and lateral condyle 202, which could be caused by excessively large values, and also avoids poor patellofemoral joint stability caused by excessively small values. Therefore, this improves joint stability at 90° knee flexion while preventing interference with the femoral prosthesis 20.

[0057] Optionally, when the human knee is flexed at 90°, the overlap width L5 between the patellar prosthesis 10 and the medial condyle 201 is 4.0mm, 4.5mm, 5.0mm, 5.5mm, 6.0mm, 6.5mm, 7.0mm, 7.5mm, 8.0mm, 8.5mm, 9.0mm, 9.5mm, 9.0mm, 10.5mm, 11.0mm, 11.5mm, 12.0mm, 12.5mm, 13.0mm, 13.5mm, 14.0mm, or 15.5mm.

[0058] Optionally, the overlap width L6 between the patellar prosthesis 10 and the lateral condyle 202 is 5.0mm, 5.5mm, 6.0mm, 6.5mm, 7.0mm, 7.5mm, 8.0mm, 8.5mm, 9.0mm, 9.5mm, 9.0mm, 10.5mm, 11.0mm, 11.5mm, 12.0mm, 12.5mm, 13.0mm, 13.5mm, 14.0mm, 15.5mm, 16.0mm, 16.5mm, or 17.0mm.

[0059] like Figures 1 to 2 As shown, the patellar projection on the coronal plane of the patellar articular surface 101 is elliptical, comprising a major axis ML and a minor axis AP. Specifically, the patellar projection forms the major axis ML of the patellar articular surface 101 on a straight line parallel to the coronal axis, and the patellar projection forms the minor axis AP on a straight line parallel to the sagittal axis. L7 is 12mm–30mm, the length of the major axis ML is 20mm–50mm, and the length of the minor axis AP is 14mm–40mm. This avoids interference with the medial condyle 201 and lateral condyle 202 caused by excessively large values ​​of the major axis ML and minor axis AP, and also avoids poor patellar joint stability caused by excessively small values ​​of L5 and L6. Therefore, it achieves both high joint stability and avoids interference with the femoral prosthesis 20.

[0060] The radius of the arc corresponding to the major axis ML is 8mm to 30mm. This avoids interference with the medial condyle 201 and lateral condyle 202 caused by an excessively large radius of the arc corresponding to the major axis ML, and also avoids poor patellofemoral joint stability caused by an excessively small radius of the arc corresponding to the major axis ML. Therefore, it improves knee joint stability while avoiding interference with the femoral prosthesis 20.

[0061] The radius of the arc corresponding to the short axis AP is 12mm to 50mm. This avoids interference with the medial condyle 201 and lateral condyle 202 caused by an excessively large radius of the arc corresponding to the short axis AP, and also avoids poor patellofemoral joint stability caused by an excessively small radius of the arc corresponding to the short axis AP. Therefore, it improves knee joint stability while avoiding interference with the femoral prosthesis 20.

[0062] like Figure 2 As shown, the outer periphery of the patellar articular surface 101 is chamfered. The function of this arc is to reduce direct cutting with the femoral condyle during the internal and external rotation of the patella, thereby reducing patellar wear and debris, osteolysis, and secondary trauma.

[0063] Furthermore, the radius of curvature of the chamfered portion is 1–5 mm. This helps to reduce the problems of patellar wear, debris production, and osteolysis.

[0064] like Figures 3 to 8 As shown, the patellar joint surface 101 has the most prominent patellar peak 102. The side of the lateral condyle 202 that mates with the tibia is a convex surface that protrudes towards the tibia. The peak of the convex surface forms the lateral condyle peak curve. The distance between the lateral condyle peak curve and the patellar peak in the anterior-posterior direction of the human body is the dislocation height H. The flexion angle α and H of the human body between 0° and 120° satisfy the following relationship: H = k1α + b1, where k1 is a constant, k1 = 0.029 to 0.16, and b1 is a constant, b1 = 0.9 to 2.5.

[0065] The patellar prosthesis 10 of this invention defines the dislocation height H as the distance between the posterior edge of the lateral condyle projection and the patellar peak 102 in the anterior-posterior direction of the human body. The flexion angle α and H of the human body between 0° and 120° satisfy the following relationship, which has important guiding, evaluation, and tracking significance for the correct selection of the patellar prosthesis 10. This improves the safety during use after prosthesis implantation.

[0066] In the medial and lateral directions, the distance between the central axis of the intercondylar fossa and the curve of the medial condyle peak is the dislocation displacement LL. The angle of human flexion α and LL between 0° and 120° satisfy the following relationship: LL=k2α+b2, where k2 is a constant, k2=0.02~0.26, and b2 is a constant, b2=6.98~11.85.

[0067] The patellar prosthesis 10 of this invention uses the following formulas to evaluate the movement of the femoral condyle and patellar prosthesis 10: the dislocation height H is defined as the distance between the posterior edge of the lateral condyle projection and the patellar peak 102 in the anterior-posterior direction of the human body, and the dislocation displacement LL is defined as the distance between the central axis and the medial condyle peak. This provides guidance for the selection and size of the patellar prosthesis 10. It has important guiding, evaluation, and tracking significance for the correct selection of the patellar prosthesis 10, and improves the safety during use after prosthesis implantation. Simultaneously, by limiting the dislocation height H and dislocation displacement LL through the above two formulas, it ensures that when the patellar prosthesis 10 moves to the intercondylar fossa, the overlap size between it and the medial condyle 201 and the lateral condyle 202 is just right, neither too small nor too large, thus avoiding dislocation of the patellar prosthesis 10 and also preventing the patellar prosthesis 10 from being too large.

[0068] When the human body is flexed at 135°, H is 6.06mm~6.46mm and LL is 20.26mm~23.2mm.

[0069] When the human body is flexed at 120°, H is 6.06mm~6.46mm and LL is 20.26mm~23.20mm.

[0070] When the human body is flexed at 90°, H is 5.96mm~6.40mm and LL is 20.00mm~22.97mm.

[0071] When the human body is flexed at 60°, H is 5.28mm to 5.90mm and LL is 17.34mm to 22.37mm.

[0072] When the human body is flexed at 30°, H is 3.59mm~5.56mm and LL is 12.53mm~17.85mm.

[0073] When the human body is flexed at 0°, H is 0.93mm to 2.49mm and LL is 6.98mm to 11.85mm.

[0074] When the human body is flexed at 135°, the contact area between the patellar prosthesis 10 and the medial condyle 201 is 3.8 mm. 2 ~11.36mm 2 .

[0075] The patellar prosthesis 10 of this invention improves the pressure distribution on the femur by increasing the contact surface between the patellar prosthesis 10 and the medial condyle 201 when the human body is flexed at 90°, thereby enhancing the stability of the patellar joint and preventing subluxation or the patellar prosthesis 10 from getting stuck in the intercondylar fossa 204 of the femur.

[0076] When the human body is flexed at 120°, the contact area between the patella and the medial condyle 201 is 3.8 mm. 2 ~11.36mm2 .

[0077] The patellar prosthesis 10 of this invention improves the pressure distribution on the femur by increasing the contact surface between the patellar prosthesis 10 and the medial condyle 201 when the human body is flexed at 120°, thereby enhancing the stability of the patellar joint and preventing subluxation or the patellar prosthesis 10 from getting stuck in the intercondylar fossa 204 of the femur.

[0078] When the human body is flexed at 90°, the contact area between the patellar prosthesis 10 and the medial condyle 201 is 3.86 mm. 2 ~11.91mm 2 .

[0079] The patellar prosthesis 10 of this invention improves the pressure distribution on the femur by increasing the contact surface between the patellar prosthesis 10 and the medial condyle 201 when the human body is flexed at 90°, thereby enhancing the stability of the patellar joint and preventing subluxation or the patellar prosthesis 10 from getting stuck in the intercondylar fossa 204 of the femur.

[0080] It is known that when the human body is flexed to less than 90°, the patellar prosthesis 10 and the trochlear groove are in contact and have not yet moved to the intercondylar fossa. Therefore, it is not in contact with the medial condyle 201, so there is no need to consider the contact area.

[0081] The total knee joint prosthesis of this invention includes a femoral prosthesis 20 and a patellar prosthesis 10 according to any one of the above. The femoral prosthesis 20 includes a medial condyle 201 and a lateral condyle 202, and an intercondylar fossa 204 for correspondingly engaging with the patellar prosthesis 10. The medial condyle 201 and the lateral condyle 202 are recessed to form a trochlear groove for receiving the patellar prosthesis 10. The connecting surface formed by the medial condyle 201, the lateral condyle 202, the intercondylar fossa 204 and the trochlear groove constitutes a femoral articular surface for engaging with the patellar prosthesis 10.

[0082] Therefore, the total knee joint prosthesis of the present invention has the advantage of improving the stability of the patellar joint.

[0083] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0084] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0085] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0086] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0087] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0088] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A patellar prosthesis, characterized in that, For use with a femoral prosthesis, the femoral prosthesis includes a medial condyle, a lateral condyle, and an intercondylar fossa for corresponding engagement with the tibia. A trochlear groove is formed between the medial and lateral condyles to accommodate the patellar prosthesis. The connecting surface formed by the medial condyle, the lateral condyle, the intercondylar fossa, and the trochlear groove constitutes a femoral articular surface for engagement with the patellar prosthesis. The width of the intercondylar fossa is L7. The body includes a patellar articular surface that mates with the femoral articular surface. When the human body is flexed to a degree greater than 90°, the patellar prosthesis mates with the intercondylar fossa. The width of the overlap between the patellar prosthesis and the lateral condyle is L6, and the width of the overlap between the patellar prosthesis and the medial condyle is L5. When the human body is flexed between 90° and 135°, L5 / L7 is 0.11 to 1.30, and L6 / L7 is 0.11 to 1.

42. The patellar articular surface has the most prominent patellar peak. The side of the lateral condyle that mates with the tibia is a convex surface that protrudes towards the tibia. The peak of the convex surface forms the lateral condyle peak curve. The distance between the lateral condyle peak curve and the patellar peak in the anterior-posterior direction of the human body is the dislocation height H. The flexion angle α and H of the human body between 0° and 120° satisfy the following relationship: H = k1α + b1, where k1 is a constant, k1 = 0.029 to 0.16, and b1 is a constant, b1 = 0.9 to 2.

5. And / or, in the medial and lateral directions, the distance between the central axis of the intercondylar fossa and the medial condylar peak curve is the dislocation displacement LL. The angle of human flexion α and LL between 0° and 120° satisfy the following relationship: LL=k2α+b2, where k2 is a constant, k2=0.02~0.26, and b2 is a constant, b2=6.98~11.

85.

2. The patellar prosthesis according to claim 1, characterized in that, When the human body is flexed at 135°, L5 is 3.5mm to 15.5mm, and L6 is 3.5mm to 15.5mm. And / or, when the human body is flexed at 120°, L5 is 3.5mm to 15.5mm, and L6 is 3.5mm to 15.5mm; And / or, when the human body is flexed at 90°, L5 is 4.0mm to 15.5mm and L6 is 5.0mm to 17mm.

3. The patellar prosthesis according to claim 1, characterized in that, The patellar articular surface is projected as an ellipse in the coronal plane, and the ellipse includes a major axis ML and a minor axis AP. The length of the major axis ML is 20mm to 50mm; And / or, the length of the short axis AP is 14mm to 40mm; And / or, L7 is 12mm to 30mm.

4. The patellar prosthesis according to claim 3, characterized in that, The radius of curvature of the arc corresponding to the major axis ML is 8mm to 30mm; And / or, the radius of curvature of the arc corresponding to the short axis AP is 12mm to 50mm.

5. The patellar prosthesis according to claim 1, characterized in that, The outer periphery of the patellar joint surface is chamfered.

6. The patellar prosthesis according to claim 5, characterized in that, The radius of curvature of the chamfer is 1 to 5 mm.

7. The patellar prosthesis according to claim 1, characterized in that, When the human body is flexed at 135°, H is 6.06mm~6.46mm and LL is 20.26mm~23.20mm; And / or, when the human body is flexed at 120°, H is 6.06mm to 6.46mm and LL is 20.26mm to 23.20mm; And / or, when the human body is flexed at 90°, H is 5.96mm to 6.40mm and LL is 20.00mm to 22.97mm; And / or, when the human body is flexed at 60°, H is 5.28mm to 5.90mm and LL is 17.34mm to 22.37mm; And / or, when the human body is flexed at 30°, H is 3.59mm to 5.56mm and LL is 12.53mm to 17.85mm; And / or, when the human body is flexed at 0°, H is 0.93mm to 2.49mm and LL is 6.98mm to 11.85mm.

8. The patellar prosthesis according to claim 1, characterized in that, When the human body is flexed at 135°, the contact area between the patellar prosthesis and the medial condyle is 3.8 mm. 2 ~11.36mm 2 ; And / or, when the human body is flexed at 120°, the contact area between the patellar prosthesis and the medial condyle is 3.8 mm. 2 ~11.36mm 2 ; And / or, when the human body is flexed at 90°, the contact area between the patellar prosthesis and the medial condyle is 3.86 mm. 2 ~11.91mm 2 .

9. A total knee joint prosthesis, characterized in that, Including femoral prostheses and patellar prostheses according to any one of claims 1-8.

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