CN117224288A

CN117224288A - Femoral lateral medial and lateral unicondylar prosthesis and femoral trochlear prosthesis

Info

Publication number: CN117224288A
Application number: CN202311160924.3A
Authority: CN
Inventors: 温晓玉
Original assignee: Individual
Current assignee: Individual
Priority date: 2016-03-31
Filing date: 2016-03-31
Publication date: 2023-12-15
Also published as: CN107280817A

Abstract

A medial femoral unicondylar prosthesis (201) and lateral femoral unicondylar prosthesis (301) and trochlear femoral prosthesis (401) are disclosed. The medial femoral unicondylar prosthesis comprises: a articular surface, which is the surface that contacts the medial patella and the medial tibial plateau during knee joint movement, that appears as an arc (203) on a first ellipse (38) in the sagittal position and as an arc (95) on a first circle (94) in the coronal position; and an inner surface, which is a portion adjacent to the bone-cutting surface and bone cement of the femoral condyle after the prosthesis is inserted, and which is a portion of the inner surface that is a portion of the posterior condyle in a straight-line section (202), and a distal portion of the inner surface (209) that is coincident with the articular surface arc section (203). The prosthesis utilizing the embodiment of the disclosure can be closer to the geometrical form of the femoral condyle of a normal human body, and design parameter values of various types of femoral prostheses are simplified.

Description

Femoral lateral medial and lateral unicondylar prosthesis and femoral trochlear prosthesis

The application relates to a split application of a femoral medial side, lateral side unicondylar prosthesis and a femoral trochlear prosthesis of Chinese application patent application No. 201610196679.5, which is applied for the date of 2016, 3 and 31.

Technical Field

The present disclosure relates to artificial knee prostheses, and in particular to single compartment replacement prostheses for use in early knee medial compartment, lateral compartment and patellofemoral osteoarthritis.

Background

The knee joint is divided into three compartments, namely a medial compartment, a lateral compartment and a patellofemoral compartment. Early knee Osteoarthritis (OA) may involve either compartment, but is particularly predominant in the medial compartment of the knee. At this time, the force lines of the knee joint are deflected inwards (varus deformity), resulting in excessive wear of the medial compartment, causing thinning and spalling of the medial femoral condyle and corresponding medial tibial plateau cartilage surface. Typical symptoms of medial compartment OA are varus deformity, pain with joint chordae, osteophyte formation and collateral ligament laxity. The conservative treatment or non-operative treatment measures (such as non-steroidal anti-inflammatory analgesics, articular cartilage nutrition protection drugs, intra-articular injection of hyaluronic acid, knee joint braces and the like) have certain curative effects only on patients with mild OA. Whereas medial compartment unicondylar replacement of the knee (Unicompartmental Knee Arthroplasty, UKA) is the ultimate treatment modality when conservative treatment is ineffective. The knee joint medial compartment UKA refers to the medial tibiofemoral joint surface of the knee joint, i.e. the part of the articular cartilage surface of the distal end of the medial femur which is in direct contact with the medial tibial plateau during flexion and extension activities, and the corresponding tibial plateau articular cartilage surface. The aim of the operation is to keep the normal joint structure as much as possible with the least operation wound, finally achieve better function recovery, and simultaneously keep enough residual bone mass and operation margin for the total knee joint replacement operation which can be carried out later. And with the improvement of the endophyte materials and processing technology, the more suitable selection of case indications and the improvement of the surgical skills, the curative effect of the medial compartment UKA is becoming more and more accepted. The incidence of lateral and patellofemoral compartments OA is significantly less than that of medial compartment OA, but treatment is based on the same principle as medial compartment OA, with the need for UKA prosthesis replacement if necessary.

Medial-lateral compartment UKA prostheses can be further divided into tibial side UKA prostheses (tibial plateau medial-lateral UKA prostheses) and femoral side UKA prostheses (femoral medial-lateral condyle UKA prostheses); the patellofemoral compartment UKA prosthesis is divided into trochlear (part) UKA prosthesis and patella prosthesis. The design of the femoral side UKA prosthesis is more important than the tibial side UKA prosthesis because it directly affects the function of the knee joint after surgery. At present, the national and international agreement is as follows: the femoral side UKA prosthesis closest to the design of the internal and external femoral condyle geometry of a normal human body can provide the sensation of motion closest to the normal knee joint. However, the geometrical morphology of the medial and lateral femoral condyles is extremely complex and is not uniformly acknowledged. The medial and lateral femoral condyles were initially considered to be circular and rotated 1 about a fixed axis. The learner then considers that the medial and lateral femoral condyles are spiral and that the axis of rotation is not fixed, but there is an instantaneous center of rotation 2. In the 90 s of the last century, students have again supported the idea that the medial and lateral femoral condyles are circular and the rotation axis is fixed 3-5. In particular, the application of nuclear magnetic sagittal scan has led these researchers to trust that the medial and lateral femoral condyles are formed 6-9 from two circles in the sagittal position. These different theories lead to different biomechanical and kinematic experimental results and directly influence the design of the femoral medial and lateral condyle UKA prosthesis. For example, according to the theory that the femoral condyle is round with single curvature, the oxford unicondylar prosthesis is designed; the Miler-Galante prosthesis was designed based on the theory that the femoral condyle had two or more rounded components, and so on. However, the current medial and lateral femoral condyle UKA prosthesis has more or less disadvantages. Such as Oxford unicondylar prosthesis (Oxford UKA): although the long-term follow-up result is good, the shape of the prosthesis is not matched with that of the femoral condyle, so that the prosthesis and the femoral condyle have a deeper worn-out groove; and due to the single curvature circular design characteristic, the oxford unicondylar prosthesis cannot recover the lower limb force line of the patient with varus deformity. Other types of UKA prostheses are often preoperatively mismatched to the medial and lateral femoral condyles, which results in impingement of the patella with the prosthesis during flexion of the knee, which is highly susceptible to pain and surgical failure. The geometry of the femoral trochlear is fundamental to the manufacture of the femoral trochlear UKA prosthesis, but the geometric features of the femoral trochlear are more complex and difficult to release, so one has simplified the trochlear UKA prosthesis to have valgus grooves and accordingly convexly replace the patella surface.

The femoral medial and lateral condyle UKA prosthesis produced by the prior art is not well matched with the form of the femoral medial and lateral condyle and the femoral trochlear. The mismatching of the shape causes the impact between the patella and the prosthesis in the knee joint buckling process, thereby causing pain in the knee bending, loosening of the prosthesis and failure of the final operation. Even though the probability of collision is slightly less like the oxford unicondylar prosthesis, the oxford unicondylar prosthesis is designed according to the fact that the inner condyle of the femur is in a circular shape with a single curvature. This results in a deeper recess between the anterior of the UKA prosthesis and the remaining bone of the medial femoral condyle. While this recess has no clinical evidence of an impact on knee kinematics or prosthesis life, in fact it is the distal-most femur where the height cannot be restored resulting in a non-corrected knee varus deformity. If the prosthesis must be placed higher to correct the varus deformity, this will result in the patella striking the prosthesis during flexion, and the approach of the oxford unicondylar technique without loosening the medial collateral ligament, itself to prevent dislocation of the sliding pad.

Disclosure of Invention

In view of one or more problems in the prior art, a knee unicondylar prosthesis and a trochlear prosthesis are presented.

According to one aspect of the present disclosure, there is provided a femoral lateral medial unicondylar prosthesis comprising: a articular surface, which is the surface that contacts the medial patella and the medial tibial plateau during knee joint movement, that appears as an arc on a first ellipse in the sagittal view and as an arc on a first circle in the coronal view; and an inner side surface, which is a part adjacent to the bone cutting surface and bone cement of the femoral condyle after the prosthesis is put in, and is represented by an inner side surface posterior condyle position with a straight-line section and an inner side surface distal end part consistent with the arc section of the joint surface.

According to some embodiments, the femoral lateral medial unicondylar prosthesis further comprises: the first upright post is arranged on the inner side surface, corresponds to the circle center of the first ellipse, and is arranged on the inner side surface, corresponds to the focus of the first ellipse.

According to some embodiments, the anterior end of the femoral medial unicondylar prosthesis is formed with a locking screw hole formed such that the direction of a locking screw inserted therein is different from the direction of the first and second posts.

According to some embodiments, the major axis of the first ellipse is perpendicular to the mechanical axis of the femur and its center corresponds to the medial collateral ligament attachment point of the medial femoral condyle.

According to some embodiments, the respective first ellipses, which appear on the sagittal level as respective layers, are assembled in three-dimensional space, which constitute the complete medial femoral unicondylar prosthesis shape, with their centers coincident on the sagittal level and with their long and short axes coincident, and with the line of all centers coincident with the condyle line (TEA) and perpendicular to the Whiteside line.

According to some embodiments, the prosthesis is placed in a direction parallel to the Whiteside line and perpendicular to the through-the-condyle line (TEA) and has a straight edge on the outer side of the prosthesis, parallel to the Whiteside line and perpendicular to the TEA, and a rounded medial arc edge to accommodate the distal contour of the medial condyle of the femur, the curvature of the anterior arc edge corresponding to the parameters of the mill circle, the bottom being the curvature of the first circle of the coronal position.

According to some embodiments, the angle of the arc segment on the first ellipse ranges from 150 degrees to 200 degrees and the angle of the arc segment on the first circle ranges from 50 degrees to 90 degrees.

According to another aspect of the present disclosure, there is provided a femoral lateral unicondylar prosthesis comprising: a articular surface, which is the surface that contacts the outside of the patella and the outside of the tibial plateau during knee joint movement, which appears as an arc on a second ellipse in the sagittal position and as an arc on a third ellipse in the coronal position; and an inner side surface, which is a part adjacent to the bone cutting surface and the bone cement of the femoral condyle after the prosthesis is put in, and is represented by an inner side surface posterior condyle position with a straight-line section and an inner side surface distal end part consistent with the arc section of the joint surface.

According to some embodiments, the femoral lateral unicondylar prosthesis further comprises: and the third upright post is arranged on the inner side surface and corresponds to the focus of the second ellipse.

According to some embodiments, the distal end of the femoral lateral unicondylar prosthesis is formed with a locking screw hole formed such that the direction of a locking screw inserted therein is different from the direction of the third post.

According to some embodiments, the respective second ellipses (78) representing the respective levels in the sagittal view are assembled in three dimensions, which form a complete femoral lateral unicondylar prosthesis shape with their centers sagittal view coincident and with the long and short axes coincident, and with the line of all centers coincident with the condyle line (TEA) and perpendicular to the Whiteside line.

According to some embodiments, the prosthesis is placed in a direction parallel to the Whiteside line and perpendicular to the through-the-condyle line (TEA) and has a straight edge on the inner side of the prosthesis parallel to the Whiteside line and perpendicular to the TEA, and the outer arcuate edge is rounded to accommodate the distal contour of the lateral femoral condyle, the curvature of the anterior arcuate edge corresponds to the rounded curvature parameter, and the bottom is the curvature of the arcuate segment of the third ellipse of the coronal site.

According to some embodiments, the angle of the arc segment on the second ellipse is in the range of 120 degrees to 160 degrees, and the angle of the arc segment on the third ellipse is in the range of 50 degrees to 90 degrees.

According to yet another aspect of the present disclosure, there is provided a femoral trochlear prosthesis comprising: a articular surface, which is the surface that contacts the patellar articular surface during knee joint movement, and which appears as a set of arc spaces on the fourth ellipse or circle and the fifth ellipse or circle in the sagittal position; and an inner surface, wherein the inner surface is a part adjacent to the bone cutting surface and bone cement of the femoral block part after the prosthesis is put in, and is consistent with the shape of the joint surface of the femoral block.

According to some embodiments, the fourth ellipse or circle and the fifth ellipse or circle are arranged in a concentric arrangement, with the concentric axis spatially parallel to TEA and perpendicular to the Whiteside line.

According to some embodiments, the femoral trochlear prosthesis has a post at the center and four locking screw holes around to receive locking screws.

The prosthesis utilizing the embodiment of the disclosure can be closer to the geometrical form of the femoral condyle of a normal human body, and design parameter values of various types of femoral prostheses are simplified.

Drawings

For a clearer description of the embodiments of the present disclosure or of the solutions of the prior art, the drawings that are necessary for the description of the embodiments or of the prior art will be briefly described, it being obvious to a person skilled in the art that, without inventive effort, further drawings can be obtained from these drawings, in which:

FIG. 1A is a sagittal sectional view of a knee intra-condyle depicting a prosthesis according to an embodiment of the present disclosure, illustrating the principles and features of a femoral intra-condyle ellipse;

FIG. 1B is a sagittal sectional view of a knee joint illustrating the principles and features of a medial femoral trochlear ellipse and relationship to a medial femoral condyle ellipse depicting a prosthesis in accordance with an embodiment of the present disclosure;

FIG. 2 is a sagittal sectional view depicting the most concave portion of a knee femoral sled of a prosthesis illustrating rounded features herein according to an embodiment of the present disclosure;

FIG. 3 is a schematic representation of the femoral external condyle ellipse principle and features and relationship to the femoral trochlear circle herein depicting a knee femoral external condyle and a femoral trochlear sagittal sectional view of a prosthesis in accordance with an embodiment of the present disclosure;

FIG. 4 is an overlapping schematic view depicting the elliptical and circular configuration of a knee sagittal femoral condyle of a prosthesis, showing the femoral condyle being composed of an ellipse and a circle and features thereof, in accordance with an embodiment of the present disclosure;

FIG. 5 is a coronal view of a knee joint depicting a prosthesis showing the medial and lateral femoral condyles being composed of circles and ovals and features in accordance with an embodiment of the present disclosure;

FIG. 6 illustrates a sagittal view of a medial femoral condyle UKA prosthesis, in accordance with an embodiment of the present disclosure;

FIG. 7 illustrates a coronal view of a medial femoral condyle UKA prosthesis, in accordance with an embodiment of the present disclosure;

FIG. 8 illustrates an axial view of a medial femoral condyle UKA prosthesis, in accordance with an embodiment of the present disclosure;

FIG. 9 is a perspective view of a medial femoral condyle UKA prosthesis depicting an embodiment of the present disclosure;

FIG. 10A is a schematic diagram depicting the operation of the femoral medial condyle UKA prosthesis placement and corresponding instrument use, in accordance with an embodiment of the present disclosure;

FIG. 10B is a schematic diagram depicting the operation of the femoral medial condyle UKA prosthesis placement and corresponding instrument use, in accordance with an embodiment of the present disclosure;

FIG. 11 is a sagittal view depicting a femoral external condyle UKA prosthesis, in accordance with an embodiment of the present disclosure;

FIG. 12 is a coronal view depicting a femoral external condyle UKA prosthesis in accordance with an embodiment of the present disclosure;

FIG. 13 is a perspective view depicting a femoral external condyle UKA prosthesis, in accordance with an embodiment of the present disclosure;

FIG. 14 is a construction principle and perspective view depicting a femoral sled UKA prosthesis according to an embodiment of the present disclosure.

Detailed Description

Specific embodiments of the present disclosure will be described in detail below, it should be noted that the embodiments described herein are for illustration only and are not intended to limit the present disclosure. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present disclosure. However, it will be apparent to one of ordinary skill in the art that: no such specific details need be employed to practice the present disclosure. In other instances, well-known materials or methods have not been described in detail in order to avoid obscuring the present disclosure.

UKA prostheses (including medial femoral condyles, lateral femoral condyles, and trochlear femoral articular surfaces) according to embodiments of the present disclosure have a contour that is closest to the geometry of the normal human femoral condyles and trochlear portions. One or more embodiments described below detail this ellipse principle and the design method applied to the UKA. One or more embodiments will be presented in a pictorial representation. But these illustrations and descriptions are not limiting of the innovations that the present disclosure intends to protect. Each illustration and description will be associated with other illustrations.

In accordance with one or more embodiments, the present disclosure provides a UKA prosthetic element comprising: medial femoral condyle, lateral femoral condyle, and femoral trochlear replacement component. They can be used alone in the case of specific single compartment osteoarthritis, or in combination with two or three compartments osteoarthritis. In particular, the medial femoral condyle UKA prosthetic element refers to the portion of the knee joint that articulates with the medial tibial compartment; the femoral lateral condyle UKA prosthetic element refers to a joint part between the knee joint and the tibial lateral compartment during the movement of the knee joint; the femoral trochlear UKA prosthetic element refers to the portion of the knee that corresponds to the patella when the knee joint is in motion. Wherein any UKA prosthetic element comprises a prosthetic articular surface and a prosthetic medial surface. "anterior" as used herein refers to toward the ventral side of the human body; "rear" refers to the back side toward the human body; "inner" means toward the central axis of the torso of a person; "external" refers to the center axis away from the torso of a person; "proximal" refers to toward the head side of the human body; "distal" refers to toward the caudal side of the human body, and so on. Likewise, the descriptions of "sagittal," "coronal," and "axial" are defined with respect to an anatomical plane. The horizontal axis points in the front and back directions and is parallel to the ground; the "vertical axis" points in the "far" and "near" directions and is perpendicular to the ground. In general, the "distal-most point" of a UKA prosthetic element refers to the furthest point of contact established with the corresponding tibial bearing when the knee is fully straightened; the "last point" of a UKA prosthetic element refers to the point of maximum posterior eccentricity of the UKA prosthesis that is perpendicular to the "furthest point". The "forward most point" of a UKA prosthetic element refers to the point of maximum forward eccentricity of the UKA prosthesis opposite the "rearward most point".

The embodiments described in this disclosure are shown as left femur UKA prosthetic elements. The right femur UKA prosthetic element and the left femur UKA prosthetic element are sagittal images. Thus, we state that the characteristic principles of the femoral UKA prosthesis described herein apply equally to either left or right knee configurations. It should be noted that the femoral trochlear UKA prosthesis designs of the present disclosure include prostheses that "replace the patellar articular surface" and "do not replace the patellar articular surface". Wherein, the femur pulley UKA prosthesis for replacing the patella joint surface is compared with the prosthesis for not replacing the patella joint surface, and the corresponding pulley groove and angle of the patella are designed.

In accordance with one or more embodiments of the present disclosure, in the sagittal position, the medial and lateral femoral condyle articular surface topography is formed from an ellipse, the medial and lateral trochlear articular surface topography is formed from an ellipse and/or a circle, and in the coronal position, the medial and lateral femoral condyle articular surface topography is formed from an ellipse and a circle.

For example, the medial femoral condyle UKA prosthesis is designed and constructed on the principles of sagittal ellipses and coronal circles. In the sagittal view, the layers of the medial femoral condyle articular surface are oval collections that form the complete medial femoral condyle shape in three dimensions. Wherein the direction of the articular cartilage surface of the inner femoral condyle is a concentric ellipse structure perpendicular to the through-condyle line (TEA) and parallel to the Whiteside line. In the coronal position, the medial femoral condyle articular surface presents a circular arc.

For another example, the femoral external condyle UKA prosthesis is designed and constructed based on the principles of sagittal ellipses and coronal ellipses. In the sagittal view, the layers of the articular surface of the lateral femoral condyle are oval-shaped collections that form the complete lateral femoral condyle shape in three dimensions. The outer femoral condyle ellipse is slightly smaller than the inner femoral condyle ellipse, and the long axis direction of the outer femoral condyle ellipse rotates clockwise by a certain angle with reference to the inner femoral condyle ellipse. The outer femoral condyle articular cartilage surface is oriented in a concentric oval perpendicular to the condyle line (TEA) and parallel to the Whiteside line. In the coronal position, the articular surface of the lateral femoral condyle presents an arc of an ellipse.

According to embodiments of the present disclosure, the femoral prosthesis sled UKA prosthesis is designed and configured in an elliptical and circular principle. In the sagittal position, all levels of the femoral head may be represented in an oval or circular shape. They form a complete femoral sled structure in three dimensions. The sagittal layers of the articular cartilage surface of the medial trochlear of the femur are elliptic sets, the directions of the long and short axes of the ellipses are the same, and the centers of the ellipses are concentrically arranged. But the eccentricity of each ellipse is not the same. The size of these ellipses is, for example, in a fibonacci sequence. All the femur outside pulley layers are in circular shapes, and the circle center projections of all the outside pulleys are overlapped although the radius of each outside pulley is different. The straight line connecting the center of the femur trochanter ellipse and circle is perpendicular to the condyle line (TEA) and parallel to the Whiteside line. The parameters of the femoral internal condyle ellipse and the most concave layer circle of the femoral trochlear determine the shape and the length and diameter parameters of the whole prosthesis.

For example, the best or most correct way to scan the knee joint for the nuclear Magnetic Resonance (MRI) sagittal view: when the scanned knee joint is in a straightening 0-degree position, the knee joint axial positioning phase is set along the connecting line direction of the highest point of the medial condyle and the lateral condyle of the femur, and the knee joint coronal positioning phase is set along the tangential tibial plateau joint surface direction. The medial femoral condyle geometry may be represented by an ellipse, which is an arc on the ellipse. In one embodiment, we choose the sagittal level at which the maximum value of the medial femoral condyle final eccentricity (offset) is located, i.e., the medial femoral condyle level, and the medial femoral condyle and oval relationship is shown in FIG. 1A. Starting from anterior notch 34 formed in articular cartilage surface 36 of medial femoral condyle 42 when medial anterior meniscus angle 33 is straightened, and ending with posterior notch 35 formed in medial femoral condyle 42 when medial posterior meniscus angle 43 is highly flexed, articular cartilage surface 36 of medial femoral condyle 42 of this segment fully coincides with an ellipse 38. The major axis of this ellipse 38 is perpendicular to the mechanical axis of the femur with its center 39 corresponding to the medial collateral ligament attachment point 123 of the medial femoral condyle on an MRI axial scan. In one embodiment, the ellipse 38 has a semi-major axis of 31mm, a semi-minor axis of 25mm, and an eccentricity of 0.591. In another embodiment, the ellipse here has a semi-major axis of 27mm, a semi-minor axis of 22mm, and an eccentricity of 0.58. In various embodiments, the semi-major axis is between 20mm and 35mm, the semi-minor axis is between 16mm and 30mm, and the eccentricity is between 0.5 and 0.7. Meanwhile, by measuring the included angle alpha between the circle center 39 of the ellipse and the connecting lines of the front and rear notches 34, 35; the included angle beta between the connecting line of the circle center 39 of the ellipse and the rear notch 35 and the long axis of the ellipse 38 can accurately describe the shape and length of the articular cartilage surface 36 of the section. In one example, the angle α is 180 degrees and the angle β is 35 degrees. In another embodiment, the angle α is 190 degrees and the angle β is 40 degrees. In various embodiments, included angle α is between 170 degrees and 195 degrees and included angle β is between 20 degrees and 45 degrees. In most cases, there is no medial femoral trochlear articular surface in front of the medial femoral condyle intermediate layer, i.e., the ellipse 38 of the medial femoral condyle intermediate layer does not correspond to the most anterior point eccentricity (offset) maximum layer of the medial femoral condyle, and the ellipses of the two layers are not coincident. Thus, we project this medial femoral condyle ellipse 38 in the MRI sagittal scan direction to the level of the maximum anterior most point eccentricity (offset) of the medial femoral trochlear, as shown in FIG. 1B. Starting from the anterior notch 46 formed in the medial femoral condyle 42 articular cartilage surface 36 when the medial meniscus anterior angle 45 of this level straightens, and ending anteriorly and anteriorly to the medial femoral trochlear articular cartilage surface 37 of this level, this trochlear articular cartilage surface 37 may be represented by an arc of an ellipse 40. While a portion of the subjects exhibited a circular shape for this articular surface, most subjects exhibited an elliptical shape. The major axis of this medial trochlear articular cartilage surface ellipse 40 of the femur is perpendicular to the major axis of the medial condylar level ellipse 38 of the femur. The ellipse 40 is made with reference to the circle 70 on the most concave level of the femoral trochlear (fig. 2), so the center 41 of the ellipse 40 coincides completely with the center 41 of the circle 70 on the most concave level of the femoral trochlear (fig. 2) in the projection of the sagittal scan. In one embodiment, the ellipse 40 has a semi-major axis of 29mm, a semi-minor axis of 27mm, and an eccentricity of 0.365. In various embodiments, the ellipse 40 has a semi-major axis between 20mm and 35mm and a semi-minor axis between 20mm and 30 mm. In general, the difference between the semi-major axis and the semi-minor axis of the ellipse 40 is not large, such as 1mm,2mm, or 3mm. Meanwhile, by measuring the included angle gamma between the circle center 41 and the front notch 46 and between the line from the circle center 41 to the end point of the cartilage surface of the pulley and the included angle gamma' between the line from the circle center 41 to the end point of the cartilage surface of the pulley and the semi-minor axis of the ellipse 40, the arc 37 of the articular cartilage surface of the pulley can be accurately described. In various embodiments, the included angle γ is between 40 degrees and 80 degrees and the included angle γ' is between-5 degrees and 40 degrees.

According to some embodiments, the positional relationship of the center 39 of the medial femoral condyle ellipse 38 and the center 41 of the medial femoral trochlear ellipse 40 determines the spatial positional relationship of the entire femoral condyle portion and the femoral trochlear portion, and determines the value of the parameter of the outer diameter and inner diameter of the femoral prosthesis. The relationship between the medial femoral condyle ellipse 38 and the medial femoral trochlear ellipse 40 may be described by a rectangle 50 defined by the intersection of their long and short axes. In one embodiment, rectangle 50 has a length 107 of 13mm and a width 109 of 9mm. In another embodiment, rectangle 50 has a length 107 of 12mm and a width 109 of 7mm. In various embodiments, rectangle 50 is between 8mm and 16mm long 107 and between 4mm and 12mm wide 109. The angle between the line connecting the centers 39, 41 of the two ellipses 38, 40 and the long axis of the femoral internal condyle ellipse 38 is theta. In one embodiment, θ is 32 degrees. In another embodiment, θ is 35 degrees. In various embodiments, the angle θ ranges between 25 degrees and 35 degrees.

The most concave level 62 of the femoral head is the level on which the Whiteside line is located clinically, as shown in fig. 2. This layer 62 is an important basis for determining the geometry of the articular surfaces of the medial and lateral pulleys of the femur. The round shape of the articular cartilage surface 64 of the pulley level 62 and the round shape of the subchondral bone surface 65 of the level 62 can be optimally overlapped, and only one 70 can be arranged. The center 41 of the circle 70 is completely coincident with the center of the medial trochlear ellipse 40 and the center of the lateral trochlear circle 80 of the femur in the MRI sagittal scan projection, and is denoted by the center 41. Clinical Blumensaat line 63 is encompassed by this circle 70. Similar to the previous description, the sled articular cartilage surface 64 of this layer 62 is an arc of the circle 70 and may be represented by the radius and angle of the circle 70. The included angle between the connecting line of the circle center 41 and the front and rear boundaries of the pulley joint cartilage surface 64 is phi; the angle epsilon between the line connecting the center 41 of the circle and the front boundary of the articular cartilage surface 64 and the horizontal axis. In one embodiment, the radius of this circle 70 is 24mm, ψ is 100 degrees, ε is 0 degrees. In another embodiment, the radius of this circle 70 is 25mm, ψ is 105 degrees, ε is 5 degrees. In various embodiments, the circle 70 has a radius size of 16mm to 30mm, and ψ ranges from 90 degrees to 125 degrees, ε ranges from-20 degrees to 10 degrees. And the radius of this circle 70 is in a specific ratio, such as 2/5,3/5 or 3/4, to the length of the semi-major axis of the medial femoral condyle ellipse 38.

According to embodiments of the present disclosure, the femoral external condyle geometry may be represented by an ellipse, which is an arc of such an ellipse. In one embodiment, we choose the sagittal plane where the maximum value of the femoral lateral condyle final eccentricity (offset) is located, i.e., the medial plane of the femoral lateral condyle, which is also the maximum value of the femoral lateral trochlear anterior-most eccentricity (offset) in the sagittal plane, and the relationships are shown in fig. 3. Starting from anterior notch 74 formed in articular cartilage surface 76 of lateral femoral condyle 82 when lateral anterior meniscus angle 73 is straightened, and ending with posterior notch 75 formed in lateral femoral condyle 82 when lateral posterior meniscus angle 83 is highly flexed, articular cartilage surface 76 of this segment of lateral femoral condyle 82 fully coincides with an ellipse 78. The major axis of this ellipse 78 is rotated clockwise by an angle Ω, for example 12 degrees in one embodiment, 18 degrees in another embodiment, and between 5 and 25 degrees on average in many embodiments, relative to the major axis of the medial femoral condyle ellipse 38. The center 79 of the circle is projected in the sagittal position to completely coincide with the center 39 of the femoral medial condyle ellipse 38; corresponds to the femoral external condyle lateral collateral ligament attachment point 122 on the MRI axis. In one embodiment, the ellipse 78 has a semi-major axis of 30mm and a semi-minor axis of 26mm; in another embodiment, the ellipse 78 has a semi-major axis of 26mm and a semi-minor axis of 23mm. In various embodiments, the ellipse 78 has a semi-major axis between 21mm and 33mm, a semi-minor axis between 16mm and 30mm, and an eccentricity between 0.5 and 0.7. Meanwhile, by measuring the angle phi between the center 79 and the connection between the anterior and posterior cuts 74, 75, the angle zeta between the center 79 and the connection between the posterior cut 75 and the major axis of the lateral condyle ellipse 78, the arc of this segment of articular surface 76 can be accurately described. In one embodiment, φ is 130 degrees and ζ is 40 degrees. In various embodiments, the included angle φ is between 120 degrees and 160 degrees and the included angle ζ is between 30 degrees and 70 degrees.

At this level, starting from anterior notch 74 and ending at the articular cartilage surface 77 of the lateral trochlear of the femur, this segment 77 may be represented by a circle 80. Although a portion of the subjects exhibited an oval shape, most of the subjects exhibited a circular shape. The center 41 of the circle 80 of the lateral trochlear surface 72 of the femur is completely coincident with the center of the medial trochlear ellipse 40 of the femur and the center of the concave femoral surface 62 of the femur in the sagittal MRI view. The radius of this circle 80 is between 25mm and 35mm, for example 28mm, or 26mm. The connecting line of the intersection point of the circle center 41 of the circle 80 and the lower part of the ellipse 78 of the circle 80, the connecting line of the circle center 41 of the circle 80 and the end point of the articular surface of the pulley cartilage on the outer side of the femur, and the included angle between the connecting lines is ρ; the included angle between the line between the circle center 41 of the circle 80 and the end point of the cartilage surface of the outer pulley of the femur and the horizontal axis is ρ'. The included angle ρ is between 80 degrees and 120 degrees, such as 90 degrees, 100 degrees or 110 degrees; the included angle ρ' is between-30 degrees and 20 degrees, such as-10 degrees, 0 degrees, or 10 degrees.

According to an embodiment of the present disclosure, the femoral condyle is in the MRI sagittal scan direction: the articular cartilage surfaces of the medial and lateral condyles of the femur can be almost represented by ellipses, the articular cartilage surfaces of the medial and lateral trochlear of the femur can be almost represented by ellipses and/or circles, and the most concave part of the trochlear of the femur (i.e., the center of the trochlear groove) is represented by a circle, as shown in fig. 4.

The sagittal planes of the medial femoral condyle articular cartilage surfaces are a collection 92 of concentric ellipses, each of which is of a different size, consistent and coincident in the longitudinal axis, each of which has an approximate eccentricity, as shown in fig. 4. This represents the femoral external condyle prosthesis running direction with the sagittal direction. So the real direction of the articular cartilage surface of the inner femoral condyle is parallel to the Whiteside line and perpendicular to the condyle penetrating line TEA. The sagittal planes of the articular cartilage surfaces of the lateral femoral condyles are oval shaped collections 93, as shown in fig. 4. The ellipses are different in size, the directions of the long and short axes are consistent and approximately coincide, namely the circle centers of the ellipses approximately coincide and are arranged in concentric circles. This represents the femoral external condyle prosthesis running direction with the sagittal direction. The femoral external condyle articular cartilage surface is truly oriented parallel to the Whiteside line and perpendicular to the through-the-condyle line (TEA). The sagittal layers of the articular cartilage surface of the medial trochlear of femur are elliptical sets (figure 4), the directions of the long and short axes of the ellipses are the same, and the centers of the ellipses are concentrically arranged. But the eccentricity of each ellipse is not the same. The size of these ellipses is ordered in fibonacci series. The MRI sagittal scan of the femoral condyle shows a circular appearance for all lateral trochlear layers of the femur, with the projection of the center 41 coinciding, although the radius of each lateral trochlear circle varies.

On the coronal plane passing through the center 39 of the medial femoral condyle ellipse and the center 79 of the lateral femoral condyle ellipse, the medial femoral condyle coronal articular surfaces 95, 97 may be represented by circles and ovals, as shown in fig. 5. A circle 94 is centered on the medial femoral condyle ellipse center 39 and well coincides with the medial femoral condyle coronal articular surface 95 with a radius equal to the semi-minor axis of the medial femoral condyle ellipse 38. The arc of the articular surface of this segment may be represented by an angle lambda. The perpendicular line lambda is divided into lambda 1 and lambda 2, wherein lambda 1 and lambda 2 can be equal or unequal. In one embodiment, the λ angle is 65 degrees; in another embodiment, the λ angle is 70 degrees. An ellipse 96 is rotated clockwise by δ1 degrees about the femoral outside condyle ellipse center 79 and is exactly tangential to the medial circle 94 and coincident with the femoral outside condyle coronal articular surface 97. The eccentricity of this ellipse 96 is equal to 0.618, which is a perfect ellipse. The arc of the articular surface of this segment may be represented by an angle delta. The perpendicular line is divided into δ1 and δ2, where δ1 and δ2 are not equal. In one embodiment, the delta angle is 70 degrees; in another embodiment, the delta angle is 75 degrees.

The medial femoral condyle UKA prosthesis according to embodiments of the present disclosure has a sagittal oval geometry and a coronal circular geometry. From the above examples, it is known that the medial femoral condyles are a collection of concentric ellipses, and that these elliptical planes are spatially parallel to the Whiteside line of the trochlear. The centers of these ellipses correspond to the points of attachment of the medial collateral ligaments of the medial femoral condyle. The geometry of the medial femoral condyle UKA prosthesis is therefore: the sagittal position is composed of concentric ellipses as in fig. 6; the coronal portion is formed with a circular shape as shown in fig. 7. The femoral medial condyle UKA prosthesis 201 of the present disclosure is divided into articular surface portions, i.e., the outer prosthesis peripheral surface that contacts the medial patella and medial tibial plateau during knee joint movement; and medial portions, i.e., portions of the femoral medial condyle UKA prosthesis 201 that abut the bone-cutting surface and bone cement of the femoral condyle after placement, represent the medial posterior condyle of a straight-line cross-section, and the medial distal portion that coincides with the articular surface arc segment.

In the sagittal position, the medial femoral condyle UKA prosthesis 201 has an arc 203 of an ellipse 38, as shown in FIG. 6. The anterior-posterior point of the arc 203 corresponds to the meniscus notch, forming an arc range, e.g., 150 degrees to 200 degrees, where the arc range is 175 degrees in one embodiment, 185 degrees in another embodiment, and 180 degrees in yet another embodiment. Which may be specifically represented as the angle β of the line passing through the center 39 of the ellipse and the major axis of the ellipse connecting the anterior and posterior meniscal cuts 207, 208. This angle β is 30 degrees in one embodiment, 35 degrees in another embodiment, and 40 degrees in another embodiment. The medial posterior condyle 202 of the femoral medial condyle UKA prosthesis is the perpendicular to the long axis of the ellipse of the meniscus posterior notch 208, i.e. the posterior condyle osteotomy position. This position varies with the parameters of the prosthesis. The distal end 203 of the medial femoral condyle UKA prosthesis 201 is in an elliptical arc configuration. The inner side surface of the device is provided with two upright posts, center posts 204 corresponding to the centers 39 of the ellipses, respectively; and a rear post 205 corresponding to the focus of the ellipse. At the end of the distal part 203 of the UKA prosthesis there is also a locking screw hole 206 for a locking screw 206'. This position contacts the meniscus during normal human body and does not contact the tibial plateau articular surface; and also does not contact the patella at the same time, so in this position the screw fixation does not affect the contact of the articular surface. And the locking set screw 206' is oriented differently than the center post and the rear post, the stability of the prosthesis may be enhanced. It will be appreciated that a greater number of posts may be provided as desired by those skilled in the art.

In the coronal aspect, it is known from FIG. 5 that the coronal articular surface profile of the medial femoral condyle can be represented by an arc 95 of a circle 94 having an arc λ, e.g., in the range of 50 degrees to 90 degrees, so that the coronal aspect of the medial UKA prosthesis 201 is shown in FIG. 7. The sagittal upper arc 203 may be considered to approximately coincide with a circle 221, the radius of the circle 221 being greater than the radius of the coronal circle 94 of the UKA prosthesis 201. The curvature and parameters of this circle 221 are used as grinding tool parameters to prepare the bone bed surface.

The joint surface of the medial femoral condyle UKA prosthesis 201 is asymmetric in axial view, as shown in FIG. 8. The direction of prosthesis placement is parallel to the Whiteside line and perpendicular to the condyle line TEA. The inner and outer sides of the prosthesis each have a straight edge 243, 245, parallel to the Whiteside line and perpendicular to TEA. While the medial arc edge 241 is arc-shaped to accommodate the distal contour of the medial femoral condyle; the curvature of the front arc 242 corresponds to the parameters of the mill circle 221; the base 244 is the curvature of the coronal circle 94. Therefore, a perspective view of the medial femoral condyle UKA prosthesis 201 is shown in FIG. 9. In addition to the above-mentioned positions, the inner side of the prosthesis has corresponding concave grooves to accommodate bone cement.

With the previously described femoral condyle MRI scan orientation, the optimal prosthesis size and position can be planned on the pre-operative MRI image. Specific surgical procedures: after exposure, the Whiteside lines of the trochlear groove were first identified, and the medial condylar surface was marked with an electric knife with a prosthetic orientation line parallel to the Whiteside lines. The articulating surface is well conformed by an ellipsometry jig 251 that best fits the internal femoral condyle ellipse, as shown in fig. 10A. The front end of the measuring tool 251 has a catch 254 structure that can hold the medial and posterior condyles well. At the end of the measuring mill 251 there are two nail holes 255, which are fixed with short nails for greater stability. It must be ensured that the hollow arm 257 of the measuring mill is aligned with the direction of the attachment point of the medial collateral ligament, i.e. the direction of the center 39 of the ellipse. The hollow arm 257 can be placed into a drill bit to drill a hole 258 in the medial femoral condyle to facilitate the next placement of the center post for milling. At the lower end of the measuring mill 251 is an osteotomy groove 256 which is in direct opposition to the posterior osteotomy line 202 of the medial femoral condyle. The measuring mill 251 is then removed, and a fixing peg 259 is placed on the central bore 258, with a hollow drill 271 having a radius equal to the aforementioned circle 221. The depth of the rasp is limited by the stakes 259 during which the depth is continually compared with the prosthetic trial.

The femoral external condyle UKA prosthesis according to embodiments of the present disclosure has an elliptical geometry in both sagittal and coronal positions. From the above examples, it is known that the lateral femoral condyles are a collection of concentric ellipses, and that these elliptical planes are spatially parallel to the Whiteside line of the trochlear. The centers of these ellipses correspond to the points of attachment of the lateral collateral ligaments of the lateral femoral condyle. The geometry of the femoral external condyle UKA prosthesis is therefore: the sagittal position is formed by concentric ellipses; the coronal portion is formed by an oval shape as shown in fig. 6. The femoral medial condyle UKA prosthesis 201 of the present disclosure is divided into articular surface portions, i.e., the outer prosthesis peripheral surface that contacts the medial patella and medial tibial plateau during knee joint movement; and medial portions, i.e., portions of the femoral medial condyle UKA prosthesis 201 that abut the resected surface of the femoral condyle and the bone cement after placement, represent the medial posterior condyle of a straight-line cross-section, and the medial distal portion that coincides with the articular surface arc.

In the sagittal position, the femoral external condyle UKA prosthesis 301 is an arc of an ellipse 78, FIG. 11. The anterior and posterior points of the arc correspond to meniscal cuts 307, 308 which form a range of angles, for example, the arc ranges from 120 degrees to 160 degrees, in one embodiment 145 degrees, and in another embodiment 150 degrees. Which may be specifically represented as the angle α enclosed by the anterior-posterior meniscal notch 307, 308 and the center 79 of the ellipse. Wherein the center 79 posterior meniscal notch 308 is connected at an angle β to the horizontal axis, which is 35 degrees in one embodiment, 40 degrees in another embodiment, and an average of 35 degrees in many embodiments. The medial posterior condyle osteotomy direction 302 of the femoral lateral condyle UKA prosthesis 301 is perpendicular to the horizontal axis. This position varies with the elliptical parameters. The distal end 303 of the femoral external condyle UKA prosthesis 301 is in an elliptical arc configuration. The inner side of which has a post, the rear post 305, corresponding to the focal point of the ellipse. At the end of the distal part 303 of the UKA prosthesis there is also a locking screw hole 306 for a locking screw 306'. This position contacts the meniscus during normal human body and does not contact the tibial plateau articular surface; at the same time, the screw hole is not in contact with the patella outside, so that the contact of the joint surface is not affected by the fixation of the screw at the position. And the locking set screw 306' is oriented differently than the posterior post, the stability of the prosthesis may be enhanced.

In coronal position, we know from fig. 5 that the contour of the femoral lateral condyle articular surface passing through the center 79 conforms to an arc 97 of an ellipse 96 with an arc δ, for example, in the range of 50 degrees to 90 degrees, so that the contour of the lateral condyle UKA prosthesis 301 is as shown in fig. 12 with the corresponding tibial side prosthetic articular surface crown shaped to conform to the concavity 325 of the ellipse. The segment of arc 97 may approximately coincide with a circle 321 that does not pass through center 79, where the center is 322, and the radius of the circle may be considered the semi-minor axis length of ellipse 96. The direction axis 323 is not only the direction of the rear pillar 305, but also the direction of the rasp drill and the fixing post, the angle with the vertical axis is 15 degrees, and the curvature and the parameters of the circle 321 are used as grinding tool parameters to prepare the bone bed surface. In the coronal position, the locking pin hole and locking screw 306 are oriented at an angle of 15 degrees to the vertical axis. The locking screw 306 is angled 30 degrees to the rear post 305 to achieve maximum stability of the prosthesis.

In the axial view, the joint surface of the femoral external condyle UKA prosthesis 301 is asymmetric, as shown in FIG. 8. The direction of prosthesis placement is parallel to the Whiteside line and perpendicular to the condyle line TEA. The medial and lateral condyles of the prosthesis each have a straight edge 343, 345, parallel to the Whiteside line and perpendicular to TEA. While the outer arc edge 341 is arc-shaped to adapt to the distal contour of the outer femoral condyle; the curvature of the front arc 342 corresponds to the curvature parameter of the circle 321; the base 344 is the curvature of the coronal ellipse 96. Accordingly, a perspective view of the medial femoral condyle UKA prosthesis 201 is shown in FIG. 13. In addition to the various positions described above, the inner side of the prosthesis has corresponding concave grooves to accommodate bone cement.

The operation steps of placing the femoral external condyle UKA prosthesis are the same as the operation steps of placing the medial condyle UKA prosthesis, and the femoral external condyle UKA prosthesis has a corresponding special outline grinding tool and is not repeated.

The femoral trochlear UKA prosthesis according to embodiments of the present disclosure has sagittal medial trochlear oval or circular and lateral trochlear circular or oval geometries, as well as designs suitable for non-patellar replacement and patellar replacement. For example, the femoral trochlear prosthesis 401 includes: a articular surface, which is the surface that contacts the patellar articular surface during knee joint motion, that appears in the sagittal plane as a spatial collection of arc segments 37 on ellipse or circle 40 and segment arcs 77 on ellipse or circle 80; and an inner surface 409 which is a portion adjacent to the bone-cutting surface of the femoral block portion and bone cement after the prosthesis is inserted and which is formed to conform to the shape of the femoral block joint surface. According to the above embodiment, the femoral head inner and outer pulleys are formed by an elliptical and circular arc, respectively, arranged concentrically, as shown in fig. 4. The femoral trochlear UKA prosthesis 401 of the present disclosure is designed to be constructed with the oval shape of the medial trochlear and the circular geometry of the lateral trochlear of the femur in a concentric arrangement. Concentric axis 41' is spatially parallel to TEA and perpendicular to Whiteside line. As shown in fig. 14 a, the concentric oval and circular configuration of the inboard and outboard scooter parts is shown, with the center circle 70 being the most concave circle of the scooter passing through the Whiteside line. At the center of the femoral block UKA prosthesis 401 is a post 402 with four locking screw holes 403, 404, 405, 406 around to receive locking screws, as shown in fig. 14B.

In the above embodiments, the femoral external condyle UKA prosthesis design is based on the formation of a femoral external condyle ellipse designed according to the shape of the articular cartilage surface of the external femoral posterior condyle of a normal human knee. The ellipse of the lateral femoral condyle is slightly smaller than the ellipse of the medial femoral condyle. The long axis direction of the femoral internal condyle ellipse rotates clockwise by a certain angle. Meanwhile, the circle centers of the internal and external femoral condyle ellipses are coincided on the sagittal position of the femoral prosthesis. The alternative scheme can simplify the outer femoral condyle ellipse into a step of enabling the long-short axis direction to be consistent with the inner femoral condyle ellipse and canceling the clockwise rotation, so that the designing and manufacturing process of the femoral prosthesis can be simplified. Although the changed shape is not consistent with the shape of the cartilage surface of the external condyle of the femur of the normal human shoulder joint, the shape of the cartilage surface of the external condyle of the femur of the human shoulder joint is not necessary. The matched tibial plateau side prosthesis pad is used as an auxiliary, so that a good joint kinematics effect can be achieved.

Furthermore, in the trochlear UKA prosthesis design, the medial and lateral trochlear of the femur is described as being composed of an oval or circular shape. This protocol was derived by final statistical analysis. While most embodiments exhibit an oval shape, a small portion of the embodiments exhibit a rounded shape; while most embodiments exhibit a rounded shape, a small portion of the embodiments exhibit an oval shape. And our specific embodiment is based on analyzing the normal knee joint structure of Chinese. If the medial femoral condyle is described as circular and the lateral femoral condyle is described as elliptical; the medial and lateral femoral condyles are described as circles or ellipses, and good joint kinematics can be achieved by matching the patella replacement prosthesis.

It should be noted that the prosthesis proposed by the present disclosure will also be protected by this patent in non-mass production, such as in custom-made personalized three-dimensional (3D) printed knee prostheses.

Thus, the elliptical and circular primary prosthesis provided in the embodiments of the present disclosure is more consistent with the morphological structure of a normal human knee joint. The ellipse and circle principle simplifies the complex, non-interpretable knee joint structure into a simple, effectively repeatable, ellipse and circle space configuration.

In addition, the parameters of each component of the femur prosthesis manufactured by the ellipse and circle principles provided by the embodiment of the disclosure can be embodied by ellipse, circle and important angle parameters, and the parameters change correspondingly along with the change of each parameter, so that the accurate manufacturing of prostheses of different models is realized. Also, each individual UKA prosthesis can be used alone or in combination. The correction of the joint force line can be realized.

While the present disclosure has been described with reference to several exemplary embodiments, it is understood that the terminology used is intended to be in the nature of words of description and illustration rather than of limitation. As the present disclosure may be embodied in several forms without departing from the spirit or essential characteristics thereof, it should also be understood that the above-described embodiments are not limited by any of the details of the foregoing description, but rather should be construed broadly within its spirit and scope as defined in the appended claims, and therefore all changes and modifications that fall within the meets and bounds of the claims, or equivalences of such meets and bounds are therefore intended to be embraced by the appended claims.

Claims

1. A femoral trochlear prosthesis (401) comprising:

a articular surface, which is the surface that contacts the patellar articular surface during knee joint motion, that appears in the sagittal plane as a spatial collection of arcs (37) on a fourth ellipse or circle (40) and segment arcs (77) on a fifth ellipse or circle (80); and

an inner surface (409) which is a portion adjacent to the bone-cutting surface of the femoral head block portion and bone cement after the prosthesis is inserted and which is in conformity with the form of the articular surface of the femoral head block.

2. The femoral trochlear prosthesis (401) of claim 1, wherein said fourth ellipse or circle and fifth ellipse or circle are arranged concentrically, the concentric axis (41') being spatially parallel to TEA and perpendicular to the Whiteside line.

3. The femoral block prosthesis (401) of claim 1, wherein said femoral block prosthesis (401) has a post (402) at the center and four locking screw holes (403, 404, 405, 406) around to receive locking screws.