CN111467090A

CN111467090A - Unicondylar femoral prosthesis system and unicondylar femoral prosthesis

Info

Publication number: CN111467090A
Application number: CN202010429962.4A
Authority: CN
Inventors: 鄢正清; 赵开宇; 孙延东; 史忠兵
Original assignee: Suzhou Microport Orthorecon Co Ltd
Current assignee: Suzhou Microport Orthorecon Co Ltd
Priority date: 2020-05-20
Filing date: 2020-05-20
Publication date: 2020-07-31
Also published as: WO2021233023A1

Abstract

The invention relates to a unicondylar femoral prosthesis system and a unicondylar femoral prosthesis, wherein the unicondylar femoral prosthesis system comprises N unicondylar femoral prostheses with gradually increasing sizes, wherein N is more than or equal to 2, and the ratio of the anteroposterior diameter of each unicondylar femoral prosthesis to the postcondylar height of each unicondylar femoral prosthesis is increased along with the increase of the sizes of the unicondylar femoral prostheses. Wherein the anterior-posterior diameter is a maximum length of the unicondylar femoral prosthesis in a horizontal direction, and the posterior condylar height is a maximum height of the unicondylar femoral prosthesis in a vertical direction. The unicondylar femoral prosthesis system better conforms to the anatomical structure of a human body, the problems of insufficient coverage and instability of the distal femur or the posterior femoral condyle are solved, the risk of postoperative pain of a patient is reduced, and postoperative feeling of the patient is better.

Description

Unicondylar femoral prosthesis system and unicondylar femoral prosthesis

Technical Field

The invention relates to the technical field of medical instruments, in particular to a unicondylar femoral prosthesis system and a unicondylar femoral prosthesis.

Background

The unicondylar replacement adopts a tiny incision, can keep anterior and posterior cruciate ligaments of the knee joint of a patient, and has the advantages of small wound, quick recovery, good physiological activity of the patient after operation and the like, so the unicondylar replacement is widely applied to the treatment of unicompartmental osteoarthritis. Unicondylar replacement requires replacement of the patient's diseased femoral articular surface with a femoral prosthesis and replacement of the patient's diseased tibial articular surface with a tibial insert to provide the patient with a new knee joint.

In the design of the traditional unicondylar femoral prosthesis, the parameters of the anterior-posterior diameter AP, the left-right diameter M L, the height H of the posterior condyle, the position of a fixed column, the curvature radius of a joint surface and the like of the unicondylar femoral prosthesis are combined from small to large according to a certain relation to form a group of the unicondylar femoral prostheses with gradually increasing sizes.

Disclosure of Invention

In view of the above, there is a need for a unicondylar femoral prosthesis system and a unicondylar femoral prosthesis, which better conform to the anatomy of the human body and avoid the situation of insufficient or unstable coverage of the distal femur or the posterior femoral condyle.

A unicondylar femoral prosthesis system comprises N unicondylar femoral prostheses with gradually increasing sizes, wherein N is more than or equal to 2, and the ratio of the anteroposterior diameter of each unicondylar femoral prosthesis to the postcondylar height of the unicondylar femoral prosthesis increases along with the increase of the sizes of the unicondylar femoral prostheses; wherein the anterior-posterior diameter is a maximum length of the unicondylar femoral prosthesis in a horizontal direction, and the posterior condylar height is a maximum height of the unicondylar femoral prosthesis in a vertical direction.

In one embodiment, the ratio of the anterior-posterior diameter to the posterior condylar height ranges from 1.2 to 1.6.

In one embodiment, the unicondylar femoral prosthesis further comprises an overhang that projects beyond the cortical bone of the human femoral posterior condyle, the anterior-posterior ratio of the difference between the height of the posterior condyle and the height of the overhang increasing with increasing size of the unicondylar femoral prosthesis.

In one embodiment, the anterior-posterior ratio is such that the ratio of the difference between the height of the posterior condyle and the height of the overhang ranges from 1.2 to 1.6.

In one embodiment, the ratio of the anterior-posterior diameter to the posterior condylar height, or the ratio of the anterior-posterior diameter to the difference between the posterior condylar height and the height of the overhang satisfies the following condition:

the value range of the unicondylar femoral prosthesis is 1.28-1.34 for the anteroposterior diameter of 40mm and less than or equal to AP and less than 50 mm; the value range of the unicondylar femoral prosthesis is 1.34-1.40 for the anteroposterior diameter of 50mm and less than or equal to AP and less than 55 mm; the value range of the unicondylar femoral prosthesis is 1.40-1.46 for the anteroposterior diameter of 55mm and not more than AP and not more than 65 mm.

In one embodiment, the unicondylar femoral prosthesis comprises an articular surface for mating with a tibial insert, the articular surface comprising, in series, a distal articular surface, a posterior condylar articular surface, and a posterior epicondylar articular surface, the distal articular surface having a radius of curvature in the sagittal plane that is a first radius of curvature, the posterior condylar articular surface having a radius of curvature in the sagittal plane that is a second radius of curvature, the posterior epicondylar articular surface having a radius of curvature in the sagittal plane that is a third radius of curvature, and the first radius of curvature being greater than the second radius of curvature and the second radius of curvature being greater than the third radius of curvature.

In one embodiment, the ratio of the first radius of curvature to the second radius of curvature of the unicondylar femoral prosthesis is constant.

In one embodiment, the ratio of the first radius of curvature to the second radius of curvature of the unicondylar femoral prosthesis ranges from 1.65 to 1.95.

In one embodiment, the radius of curvature of the articular surface on the coronal plane is a fourth radius of curvature, the fourth radius of curvature being equal to the second radius of curvature.

In one embodiment, the medial height of the anterior end of the unicondylar femoral prosthesis is less than the lateral height of the anterior end of the unicondylar femoral prosthesis in the coronal direction.

In one embodiment, the anterior end of the unicondylar femoral prosthesis comprises a first articular surface proximate to the medial side of the unicondylar femoral prosthesis and a second articular surface proximate to the lateral side of the unicondylar femoral prosthesis, the intersection of the first articular surface with the second articular surface on the coronal plane forms a nadir of the unicondylar femoral prosthesis on the coronal plane, the nadir is coincident with the centerline of the unicondylar femoral prosthesis, and the radius of curvature of the first articular surface on the coronal plane is less than the radius of curvature of the second articular surface on the coronal plane.

In one embodiment, the anterior end of the unicondylar femoral prosthesis includes a first articular surface proximate the medial side of the unicondylar femoral prosthesis and a second articular surface proximate the lateral side of the unicondylar femoral prosthesis, the intersection of the first articular surface with the second articular surface on the coronal plane forms a nadir of the unicondylar femoral prosthesis on the coronal plane that is offset a first distance from a centerline of the unicondylar femoral prosthesis in a direction proximate the lateral side of the unicondylar femoral prosthesis, and the radius of curvature of the first articular surface on the coronal plane is equal to the radius of curvature of the second articular surface on the coronal plane.

In one embodiment, the anterior end of the unicondylar femoral prosthesis includes a first articular surface proximate the medial side of the unicondylar femoral prosthesis and a second articular surface proximate the lateral side of the unicondylar femoral prosthesis, an intersection of the first articular surface with the second articular surface on the coronal plane forms a nadir of the unicondylar femoral prosthesis, the nadir is offset a second distance from a centerline of the unicondylar femoral prosthesis in a direction proximate the lateral side of the unicondylar femoral prosthesis, and a radius of curvature of the first articular surface on the coronal plane is less than a radius of curvature of the second articular surface on the coronal plane.

A unicondylar femoral prosthesis comprises an anteroposterior diameter and a posterior condylar height, wherein the anteroposterior diameter is the maximum length of the unicondylar femoral prosthesis in the horizontal direction, the posterior condylar height is the maximum height of the unicondylar femoral prosthesis in the vertical direction, and for the unicondylar femoral prosthesis with the anteroposterior diameter of 40mm and less than or equal to AP and less than 50mm, the ratio of the anteroposterior diameter to the posterior condylar height ranges from 1.28 to 1.34; for a unicondylar femoral prosthesis with the anteroposterior diameter of 50mm or more and AP less than 55mm, the ratio of the anteroposterior diameter to the postcondylar height ranges from 1.34 to 1.40; for a unicondylar femoral prosthesis with an anterior-posterior diameter of 55mm or more and an AP or less than 65mm, the ratio of the anterior-posterior diameter to the posterior condylar height ranges from 1.40 to 1.46.

The unicondylar femoral prosthesis system is based on the human knee joint anatomical structure, and the ratio of the anterior-posterior diameter to the posterior condylar height of the unicondylar femoral prosthesis is increased along with the increase of the size of the unicondylar femoral prosthesis, so that the unicondylar femoral prosthesis better conforms to the human anatomical structure, the problems of insufficient coverage and instability of the distal femur or the posterior femoral condyle are reduced, the risk of postoperative pain of a patient is reduced, and the postoperative feeling of the patient is better.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the invention and not to limit the invention.

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

FIG. 1 is a schematic view of a unicondylar femoral prosthesis in accordance with an embodiment in the sagittal plane;

FIG. 2 is a cross-sectional view of the unicondylar femoral prosthesis shown in FIG. 1;

FIG. 3 is an exemplary table of the anterior-posterior diameter, posterior condylar height, and aspect ratio of each of the unicondylar femoral prostheses of the unicondylar femoral prosthesis system in one embodiment;

FIG. 4 is a diagram of another embodiment of a unicondylar femoral prosthesis in mating relationship with a femur;

FIG. 5 is an exemplary table of the anterior-posterior diameter, posterior condylar height, and aspect ratio of each of the unicondylar femoral prostheses of the unicondylar femoral prosthesis system in another embodiment;

FIG. 6 is an exemplary table of radii of curvature of the articular surfaces of a unicondylar femoral prosthesis of an embodiment;

FIG. 7 is an exemplary table of radii of curvature of the articular surfaces of another embodiment of a unicondylar femoral prosthesis;

FIG. 8 is a cross-sectional view of the unicondylar femoral prosthesis shown in FIG. 1 at section A-A;

FIG. 9 is a cross-sectional view of another embodiment of a unicondylar femoral prosthesis at section A-A;

FIG. 10 is a cross-sectional view of a further embodiment of a unicondylar femoral prosthesis at section A-A.

Description of reference numerals:

10. a joint surface; 11. a distal articular surface; 12. the posterior condylar articular surface; 13. posterior epicondylar articular surface; 14. a hanging-out part; 15. a first articular surface; 16. a second articular surface; 20. cutting bone surface; 21. a distal osteotomy face; 22. a posterior condylar osteotomy face; 23. the posterior epicondyle osteotomy surface; p1, nadir; p2, highest point; p3, rear end point; p4, front end point.

Detailed Description

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

In order to better explain the technical scheme of the invention, firstly, the azimuth names involved in the embodiments are explained:

sagittal plane: the longitudinal section divides the human body or the prosthesis into a left part and a right part from the front and back directions, wherein, the sagittal plane passing through the middle of the human body or the prosthesis is the middle sagittal plane, and the plane divides the human body or the prosthesis into two parts which are equal to each other on the left and the right.

Coronal plane: this means a longitudinal section from the left to the right, which divides the body or prosthesis into two parts, anterior and posterior, and is perpendicular to the sagittal plane.

The cross section is as follows: also called horizontal plane, is a plane parallel to the horizontal plane that divides the body or prosthesis into upper and lower parts, which are perpendicular to the coronal and sagittal planes.

Inner side: relatively close to the midsagittal plane of the human body.

Outside: relatively far from the median sagittal plane of the human body.

Front side: on the sagittal plane, relatively near the side of the abdomen.

Rear side: on the sagittal plane, relatively near the side of the back.

Referring to fig. 1-3, fig. 1 shows a schematic view of a unicondylar femoral prosthesis according to an embodiment of the present invention in a sagittal plane, and fig. 2 shows a schematic view of a unicondylar femoral prosthesis according to an embodiment of the present invention in a transverse plane. FIG. 3 is a table comparing the anterior-posterior diameter AP, the posterior condylar height H, and the ratio thereof for each of the unicondylar femoral prostheses of the unicondylar femoral prosthesis system in an embodiment of the present invention. Specifically, as shown in FIG. 3, the unicondylar femoral prosthesis system of an embodiment of the present application includes a set of unicondylar femoral prostheses with gradually increasing sizes, and the number of the unicondylar femoral prostheses in the set of unicondylar femoral prostheses is N, wherein N is larger than or equal to 2. Here, the "size" of the unicondylar femoral prosthesis refers to the anteroposterior diameter AP of the unicondylar femoral prosthesis. As shown in FIG. 3, in the unicondylar femoral prosthesis system, the ratio AP/H of the anterior-posterior diameter AP of each unicondylar femoral prosthesis to the posterior condylar height H of the unicondylar femoral prosthesis increases as the size of the unicondylar femoral prosthesis increases.

Specifically, referring to fig. 1, the unicondylar femoral prosthesis includes an articular surface 10 for mating with a tibial insert, the articular surface 10 including a distal articular surface 11, a posterior condylar articular surface 12, and a posterior epicondylar articular surface 13 connected in series from anterior to posterior. The back of the joint surface 10 is a osteotomy surface 20 for contacting with a human femur, the osteotomy surface 20 comprises a distal osteotomy surface 21, a posterior condylar osteotomy surface 22 and a posterior epicondylar osteotomy surface 23 which are sequentially connected from the anterior side to the posterior side, wherein the distal osteotomy surface 21 is opposite to the distal joint surface 11, the posterior condylar osteotomy surface 22 is opposite to the posterior condylar joint surface 12, the posterior epicondylar osteotomy surface 23 is opposite to the posterior epicondylar joint surface 13, the osteotomy surfaces 20 are all planes, and the osteotomy surfaces 20 are all straight lines when viewed from the sagittal plane. The point on the distal articular surface 11 that is furthest from the perpendicular to the distal osteotomy surface 21 is the lowest point P1 of the prosthesis, and when implanted in a human, this lowest point P1 corresponds to the lowest point of the prosthesis when the human is upright. The posterior epicondylar articular surface 13 terminates at the highest point P2 of the prosthesis. The point on the posterior epicondylar articular surface 13 that is the farthest perpendicular distance from the posterior epicondylar osteotomy surface 23 is the posterior endpoint P3 of the prosthesis. The end point of the distal articular surface 11 is the anterior end point P4 of the prosthesis.

The circle center corresponding to the circular arc of the distal articular surface 11 is point C, the direction of the straight line connecting the lowest point P1 of the prosthesis and the point C of the circle center is the vertical direction of the prosthesis, and the direction perpendicular to the vertical direction is the horizontal direction. The posterior condylar height H of the prosthesis refers to the maximum height of the prosthesis in the vertical direction, i.e., the distance from the lowest point P1 to the highest point P2 of the prosthesis in the vertical direction. The anteroposterior diameter AP of the prosthesis refers to the maximum length of the prosthesis in the horizontal direction, i.e., the distance from the posterior point P3 to the anterior point P4 of the prosthesis in the horizontal direction.

The anatomical features of the ratio of the anteroposterior diameter to the posterior condylar height of a unicondylar femoral prosthesis are not fully considered in the design of a conventional unicondylar femoral prosthesis, and generally, the ratio of the anteroposterior diameter to the posterior condylar height of a unicondylar femoral prosthesis decreases with the size of the unicondylar femoral prosthesis or the ratio of the anteroposterior diameter to the posterior condylar height of a unicondylar femoral prosthesis hardly changes with the size of the unicondylar femoral prosthesis. Through extensive studies on anatomical data of human femurs, the applicant of the present application found that the ratio of the anterior-posterior diameter to the posterior condylar height of the femur actually after surgical osteotomy increases with increasing femur size. The utility model provides a unicondylar femoral prosthesis system uses human knee joint anatomical structure as the basis, and the ratio AP/H through the anterior-posterior footpath AP of designing unicondylar femoral prosthesis and the high H of back condyle increases along with the increase of size of unicondylar femoral prosthesis, and the unicondylar femoral prosthesis who makes accords with human anatomical structure more, reduces the not enough and instability problem of cover of distal femur or thighbone back condyle, reduces painful risk of patient postoperative, makes patient's postoperative impression better.

Further, referring to fig. 3, the anterior-posterior diameter AP and the posterior condylar height H of the unicondylar femoral prosthesis are in units of mm in the table of fig. 3. The unicondylar femoral prosthesis has a ratio AP/H (hereinafter referred to as the length to height ratio) of anterior-posterior diameter AP to posterior condylar height H in the range of 1.2-1.6, preferably 1.3-1.45. Furthermore, for the small-sized unicondylar femoral prosthesis (AP is more than or equal to 40mm and less than 50mm), the value range of the length-to-height ratio AP/H is 1.28-1.34; for the middle-sized unicondylar femoral prosthesis (AP is more than or equal to 50mm and less than 55mm), the value range of the length-to-height ratio AP/H is 1.34-1.40; for a large-size prosthesis (AP is more than or equal to 55mm and less than or equal to 65mm), the value range of the length-to-height ratio AP/H is 1.40-1.46. Further, for a unicondylar femoral prosthesis of a unicondylar femoral prosthesis system having a larger increase in size or size, the ratio of the aspect ratio AP/H of the unicondylar femoral prosthesis of adjacent sizes should be greater than or equal to the aspect ratio AP/H of the small-size unicondylar femoral prosthesis and less than or equal to the aspect ratio AP/H of the large-size unicondylar femoral prosthesis.

Further, referring to FIG. 4, in another embodiment, the unicondylar femoral prosthesis further includes an overhang 14, the overhang 14 projecting beyond the posterior cortical bone of the human femur, i.e., at a height that exceeds the contact point of the posterior cortical bone of the human femur with the unicondylar femoral prosthesis, such that the top of the unicondylar femoral prosthesis is free to contact the femur, hi particular, the overhang 14 of the unicondylar femoral prosthesis is the portion of the unicondylar femoral prosthesis that projects above the posterior condyles of the human femur upon installation into the human joint, further, referring to FIG. 5, the ratio of the anterior-posterior diameter AP to the difference between the posterior condylar-superior height H and the height L of the overhang 14 increases with increasing size of the unicondylar femoral prosthesis, wherein, as shown in FIG. 4, the height L of the overhang 14 is the height of the portion of the unicondylar femoral prosthesis above the posterior cortical bone of the human femur in the sagittal plane, and the ratio of the anterior-posterior height AP of the overhang 14 to the height L of the unicondylar femoral prosthesis increases with increasing size of the unicondylar femoral prosthesis, L, L, and L.

As shown in FIG. 5, in the present embodiment, the relationship AP/(H-L) between the anterior-posterior diameter AP and the posterior condylar height H ranges from 1.2 to 1.6, and the ratio increases with increasing size of the unicondylar femoral prosthesis, further, in the present embodiment, the height L of the overhang 14 of the unicondylar femoral prosthesis ranges from 1mm to 3mm, by properly overhanging the posterior condylar height of the unicondylar femoral prosthesis by 1mm to 3mm, and the overhang height L increases with increasing size of the unicondylar femoral prosthesis, better engagement of the posterior condylar of the unicondylar femoral prosthesis with soft tissue can be ensured, thereby improving stability of the unicondylar femoral prosthesis, preferably, the ratio AP/(H-L) ranges from 1.3 to 1.45, further, for small-sized unicondylar prostheses (40 mm. AP < 50mm, the height L mm of the overhang 14 is 1mm, the value of AP/(H-L) ranges from 1.28 to 1.34, for medium-sized prostheses (40mm, 3mm) and the height 5635 mm) for large-sized femoral prostheses (3514 mm, 26 mm) and the range of the overhang 34 mm, 26 mm, 3mm < 3mm, and 3565 for large-34 mm, 26 mm.

Further, referring to FIG. 1, the radius of curvature of the distal articular surface 11 in the sagittal plane is a first radius of curvature R1, the radius of curvature of the posterior condylar articular surface 12 in the sagittal plane is a second radius of curvature R2, the radius of curvature of the posterior condylar articular surface 13 in the sagittal plane is a third radius of curvature R3, and the first radius of curvature R1 is greater than the second radius of curvature R2 and the second radius of curvature R2 is greater than the third radius of curvature R3. By making the second radius of curvature R2 greater than the third radius of curvature R3 in the unicondylar femoral prosthesis, the posterior condyle of the unicondylar femoral prosthesis can be caused to converge inwardly, and the posterior condyle flexion angle of the unicondylar femoral prosthesis is made larger, which can improve the joint mobility. Additionally, adjusting the posterior condyle height H by adjusting the third radius of curvature R3 may make the unicondylar femoral prosthesis more compatible with the recommended aspect ratio AP/H.

Further, as shown in fig. 6-7, the ratio of the first radius of curvature R1 to the second radius of curvature R2 of the unicondylar femoral prosthesis is constant, i.e., the ratio of the first radius of curvature R1 to the second radius of curvature R2 of the unicondylar femoral prosthesis does not vary with the size of the unicondylar femoral prosthesis. Preferably, the ratio of the first radius of curvature R1 to the second radius of curvature R2 of the unicondylar femoral prosthesis is in the range of 1.65-1.95. The applicant has found that the anatomical features of the human femoral condyle are that the ratio of the distal radius of curvature of the femur in the sagittal plane to the posterior radius of curvature of the femur in the sagittal plane ranges from 1.45 to 2.1, and the ratio of the distal radius of curvature of the femur in the sagittal plane to the posterior radius of curvature of the femur in the sagittal plane has poor correlation with the size of the femoral condyle. Therefore, the ratio of the first radius of curvature R1 to the second radius of curvature R2 of the unicondylar femoral prosthesis is fixed, so that the unicondylar femoral prosthesis is more suitable for most patients, and compared with a floating ratio, the unicondylar femoral prosthesis with the fixed ratio is less prone to the situation that the matching difference is too large after the unicondylar femoral prosthesis is implanted into a patient.

Further, referring to fig. 2, the radius of curvature of the articular surface 10 in the coronal plane is a fourth radius of curvature R4, and the fourth radius of curvature R4 is equal to the second radius of curvature R2, i.e., the posterior condylar articular surface 12 of the unicondylar femoral prosthesis is a spherical structure. As the femoral posterior condyles of the natural knee joint are approximately spherical, the posterior condylar joint surface 12 condyles of the unicondylar femoral prosthesis are designed to have the same curvature radius on the sagittal plane and the coronal plane, namely R2 is R4, the anatomical reconstruction of the natural knee joint is realized, and the stability of the joint surface is improved.

Referring to fig. 8-10, the medial height h1 of the anterior end of the unicondylar femoral prosthesis is less than the lateral height h2 of the anterior end of the unicondylar femoral prosthesis in the coronal direction. By reducing the medial height h1 of the anterior end of the condylar femoral prosthesis. Therefore, the front end of the condyle femoral prosthesis is lower than the soft tissue of the joint surface, so that the impact of the unicondylar femoral prosthesis with the patella after being implanted into a human body is avoided, and the postoperative feeling of a patient is improved. Preferably, the medial height h1 of the anterior end of the unicondylar femoral prosthesis is less than 2mm, preferably 1.5mm to 1.6 mm.

Specifically, referring to FIGS. 8-10, an arbitrary A-A section (i.e., a section of an arbitrary coronal plane) of the anterior end of the unicondylar femoral prosthesis is illustrated. In one embodiment, the anterior end of the unicondylar femoral prosthesis includes a first articular surface 15 adjacent the medial side of the unicondylar femoral prosthesis and a second articular surface 16 adjacent the lateral side of the unicondylar femoral prosthesis, and the intersection of the first articular surface 15 and the second articular surface 16 on the coronal plane forms the lowest point O of the unicondylar femoral prosthesis on the a-a cross-section. Further, the medial height h1 of the anterior end of the condylar femoral prosthesis is reduced in many ways, such as shown in fig. 6 and 8, and in one embodiment, the lowest point O coincides with the centerline m of the unicondylar femoral prosthesis, i.e., the lowest point O is offset 0 from the centerline m of the unicondylar femoral prosthesis in a direction approaching the lateral side of the unicondylar femoral prosthesis. And the radius of curvature R5 of the first articular surface 15 in the coronal plane is smaller than the radius of curvature R4 of the second articular surface 16 in the coronal plane, i.e., the medial height h1 of the anterior end of the unicondylar femoral prosthesis is reduced by reducing the radius of curvature of the first articular surface 15 in the coronal plane.

Referring to fig. 7 and 9, in another embodiment, the radius of curvature R5 of the first articular surface 15 in the coronal plane is equal to the radius of curvature R4 of the second articular surface 16 in the coronal plane, and the nadir O is offset from the centerline m of the unicondylar femoral prosthesis by a first distance n1 toward a direction proximal to the lateral side of the unicondylar femoral prosthesis, preferably the first distance n1 decreases as the size of the unicondylar femoral prosthesis increases. Preferably, the first distance n1 ranges from 1mm to 1.4 mm. Reducing the medial height of the anterior end of the unicondylar femoral prosthesis is achieved by offsetting the nadir O a first distance n1 relative to the centerline m of the unicondylar femoral prosthesis in a direction proximal to the lateral side of the unicondylar femoral prosthesis.

It is noted that in other embodiments, the above two embodiments may be combined such that the medial height h1 of the anterior end of the condylar femoral prosthesis is reduced. Specifically, as shown in fig. 10, in one embodiment, the nadir is offset a second distance n2 from the centerline of the unicondylar femoral prosthesis in a direction proximal to the lateral side of the unicondylar femoral prosthesis, and the radius of curvature R5 of the first articular surface 15 in the coronal plane is less than the radius of curvature R4 of the second articular surface 16 in the coronal plane, thereby achieving a reduction in the medial height h1 of the anterior end of the unicondylar femoral prosthesis.

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.

In the description of the present invention, it is to be understood that the terms "central," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," and the like are used in the orientations and positional relationships indicated in the drawings for convenience in describing the invention and to simplify the description, and are not intended to indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and are not to be considered limiting of the invention.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.

In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

In the present invention, unless otherwise expressly stated or limited, the first feature "on" or "under" the second feature may be directly contacting the first and second features or indirectly contacting the first and second features through an intermediate. Also, a first feature "on," "over," and "above" a second feature may be directly or diagonally above the second feature, or may simply indicate that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature may be directly under or obliquely under the first feature, or may simply mean that the first feature is at a lesser elevation than the second feature.

It will be understood that when an element is referred to as being "secured to" or "disposed on" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and the like as used herein are for illustrative purposes only and do not denote a unique embodiment.

Claims

1. A unicondylar femoral prosthesis system comprising N unicondylar femoral prostheses of progressively increasing size, wherein N is greater than or equal to 2, and the ratio of the anteroposterior diameter of each said unicondylar femoral prosthesis to the posterior condylar height of said unicondylar femoral prosthesis increases as the size of said unicondylar femoral prosthesis increases; wherein the anterior-posterior diameter is a maximum length of the unicondylar femoral prosthesis in a horizontal direction, and the posterior condylar height is a maximum height of the unicondylar femoral prosthesis in a vertical direction.

2. The unicondylar femoral prosthesis system of claim 1, wherein the ratio of the anterior-posterior diameter to the posterior condyle height ranges from 1.2-1.6.

3. The unicondylar femoral prosthesis system of claim 1, further comprising an overhang that projects beyond the cortical bone of the human femoral posterior condyle, the anterior-posterior ratio increasing in ratio to the difference in height of the posterior condyle and the overhang as the size of the unicondylar femoral prosthesis increases.

4. The unicondylar femoral prosthesis system of claim 3, wherein said anterior-posterior ratio is characterized by a ratio of said difference between said posterior condyle height and said overhang height in the range of 1.2-1.6.

5. The unicondylar femoral prosthesis system of claim 2 or 4, wherein the ratio of the anterior-posterior diameter to the posterior condyle height, or the ratio of the anterior-posterior diameter to the difference between the posterior condyle height and the height of the overhang, satisfies the following condition:

6. The unicondylar femoral prosthesis system of claim 1, wherein the unicondylar femoral prosthesis comprises an articular surface for mating with a tibial insert, the articular surface comprising, in series, a distal articular surface, a posterior condylar articular surface, and a posterior epicondylar articular surface, the distal articular surface having a radius of curvature in the sagittal plane that is a first radius of curvature, the posterior condylar articular surface having a radius of curvature in the sagittal plane that is a second radius of curvature, the posterior epicondylar articular surface having a radius of curvature in the sagittal plane that is a third radius of curvature, and the first radius of curvature is greater than the second radius of curvature and the second radius of curvature is greater than the third radius of curvature.

7. The unicondylar femoral prosthesis system of claim 6, wherein a ratio of the first radius of curvature to the second radius of curvature of the unicondylar femoral prosthesis is constant.

8. The unicondylar femoral prosthesis system of claim 6, wherein the ratio of the first radius of curvature to the second radius of curvature of the unicondylar femoral prosthesis ranges from 1.65-1.95.

9. The unicondylar femoral prosthesis system of claim 6, wherein the radius of curvature of the articular surface on the coronal plane is a fourth radius of curvature, the fourth radius of curvature being equal to the second radius of curvature.

10. The unicondylar femoral prosthesis system of claim 1, wherein a medial height of an anterior end of the unicondylar femoral prosthesis is less than a lateral height of an anterior end of the unicondylar femoral prosthesis in a coronal direction.

11. The unicondylar femoral prosthesis system of claim 10, wherein the anterior end of the unicondylar femoral prosthesis comprises a first articular surface proximate the medial side of the unicondylar femoral prosthesis and a second articular surface proximate the lateral side of the unicondylar femoral prosthesis, the intersection of the first and second articular surfaces on the coronal plane forming a nadir of the unicondylar femoral prosthesis on the coronal plane, the nadir coinciding with the centerline of the unicondylar femoral prosthesis, and the radius of curvature of the first articular surface on the coronal plane being less than the radius of curvature of the second articular surface on the coronal plane.

12. The unicondylar femoral prosthesis system of claim 10, wherein the anterior end of the unicondylar femoral prosthesis comprises a first articular surface proximate the medial side of the unicondylar femoral prosthesis and a second articular surface proximate the lateral side of the unicondylar femoral prosthesis, an intersection of the first articular surface with the second articular surface on the coronal surface forming a nadir of the unicondylar femoral prosthesis on the coronal surface, the nadir offset a first distance from a centerline of the unicondylar femoral prosthesis in a direction proximate the lateral side of the unicondylar femoral prosthesis, and a radius of curvature of the first articular surface on the coronal surface equal to a radius of curvature of the second articular surface on the coronal surface.

13. The unicondylar femoral prosthesis system of claim 10, wherein the anterior end of the unicondylar femoral prosthesis comprises a first articular surface proximate the medial side of the unicondylar femoral prosthesis and a second articular surface proximate the lateral side of the unicondylar femoral prosthesis, an intersection of the first articular surface with the second articular surface on the coronal surface forms a nadir of the unicondylar femoral prosthesis on the coronal surface that is offset a second distance from a centerline of the unicondylar femoral prosthesis in a direction proximate the lateral side of the unicondylar femoral prosthesis, and a radius of curvature of the first articular surface on the coronal surface is less than a radius of curvature of the second articular surface on the coronal surface.

14. The unicondylar femoral prosthesis is characterized by comprising an anteroposterior diameter and a posterior condylar height, wherein the anteroposterior diameter is the maximum length of the unicondylar femoral prosthesis in the horizontal direction, the posterior condylar height is the maximum height of the unicondylar femoral prosthesis in the vertical direction, and for the unicondylar femoral prosthesis with the anteroposterior diameter of 40mm and less than or equal to AP and less than 50mm, the ratio of the anteroposterior diameter to the posterior condylar height ranges from 1.28 to 1.34; for a unicondylar femoral prosthesis with the anteroposterior diameter of 50mm or more and AP less than 55mm, the ratio of the anteroposterior diameter to the postcondylar height ranges from 1.34 to 1.40; for a unicondylar femoral prosthesis with an anterior-posterior diameter of 55mm or more and an AP or less than 65mm, the ratio of the anterior-posterior diameter to the posterior condylar height ranges from 1.40 to 1.46.