FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENT RULES, 2003
COMPLETE SPECIFICATION
(See Section 10 and Rule 13)
A PROSTHESIS ASSEMBLY FOR KNEE JOINT BIORAD MEDISYS PRIVATE LIMITED
AN INDIAN COMPANY REGISTERED UNDER THE COMPANIES ACT
WITH ADDRESS
SURVEY NO. 48, 3 & 48 7, PASHAN – SUS ROAD, SUS, PUNE, MAHARASHTRA 411021
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE AND INVENTION THE MANNER IN WHICH IT IS TO BE PERFORMED.
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FIELD OF THE INVENTION
[0001] This invention is generally in the field of medical devices and relates to implantable knee joint prosthesis. More particularly, the invention relates to a prosthesis with locking feature for a tibial bearing component for total knee replacement for allowing essentially free translation, rotation and angulation through the range of articulation of the knee.
BACKGROUND
[0002] The natural human knee joint involves the distal end of the femur, the proximal end of the tibia and a meniscus bearing there between. The femur and tibia are connected by means of ligaments such as, the posterior cruciate ligament, the lateral collateral ligament, the medial collateral ligament, and the anterior cruciate ligament. These ligaments provide stability to the joint formed by the femur and tibia (i.e., the knee). The knee joint is a major weight bearing joint and degenerates more quickly than some other joints in case of abnormality. Also, the knee joint plays a critical role in ambulation and quality of life, resulting in great demand for surgical correction of abnormalities. Damage or disease can affect the ability of the natural knee to function properly. The damage or disease can deteriorate the bones, the articular cartilage, the ligaments or some combination thereof. Disease and trauma affecting the articular surfaces of the knee joint are commonly effectively treated by surgically replacing the articulating ends of the femur and tibia with prosthetic femoral and tibial implants, referred to as total knee replacements (TKR).
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[0003] A typical knee prosthesis includes a tibial tray, a femoral component, and a polymer insert or bearing positioned between the tibial tray and the femoral component. An incision is made into the knee joint to expose the bones comprising the joint. Cut guides are used to guide the removal of the articular surfaces that are to be replaced. Prostheses are used to replicate the articular surfaces. A femoral prosthesis is implanted on the distal end of the femur, which articulates with a tibial bearing component and a tibial component is implanted on the proximal end of a tibia to replicate the function of a healthy natural knee.
SUMMARY
[0004] This summary is provided to introduce concepts related to a knee prosthesis locking assembly. This summary is neither intended to identify essential features of the present invention nor intended to determine or limit the scope of the present invention.
[0005] In an embodiment of the present invention, the invention discloses a prosthesis assembly for knee joint. The invention discloses a prosthesis assembly for knee joint comprises a tibial prosthesis and a femoral prosthesis. The tibial prosthesis is disposed on tibia. The tibial prosthesis comprises a tibial plate, a tibial bearing component, an extension rod and a screw. The tibial plate comprises a proximal side and a distal side. The distal side comprises a cylindrical hollow projection. The tibial bearing component is disposed on the tibial plate. The tibial bearing component comprises a lateral medial articulating surface, a proximal medial articulating surface and a post. The post comprises a recess on an anterior portion. The extension rod is a
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cylindrical structure. The extension rod comprises an opening at a proximal end. The opening comprises an internal threading. The screw comprises a head and a shank. The shank comprises threads on an outer surface.
[0006] The femoral prosthesis is disposed on a femur. The femoral prosthesis comprises a medial condyle and a lateral condyle. An intercondylar space is formed in between the medial condyle and the lateral condyle. A cam is disposed in the intercondylar space in between medial condyle and lateral condyle.
[0007] During operation, in a first stage the tibial bearing component is disposed on the proximal surface of the tibial base plate. In a second stage, the tibial bearing component is secured to the tibial base plate by introducing the screw through the recess extended through anterior portion of the post. The screw is further extended to secure the extension rod thereby securing the tibial bearing component to the tibial base plate and the extension rod. In third stage, the femoral prosthesis is disposed on top of the tibial prosthesis and articulated with respect to the tibial prosthesis.
[0008] It will be appreciated that features of the present disclosure are susceptible to being combined in various combinations without departing from the scope of the present disclosure as defined by the below mentioned detailed description and drawings.

BRIEF DESCRIPTION OF THE FIGURES
[0009] The summary above, as well as the following detailed description of illustrative embodiment, is better understood when read in conjunction with the appended drawings. For the purpose of illustrating the present disclosure, example constructions of the disclosure are shown in the drawings. However, the present disclosure is not limited to specific methods and instrumentalities disclosed herein. Moreover, those in the art will understand that the drawings are not to scale. Wherever possible, like elements have been indicated by identical numbers.
[0010] The foregoing detailed description of embodiments is better understood when read in conjunction with the appended drawings. For the purpose of illustrating the disclosure, there is shown in the present document example constructions of the disclosure; however, the disclosure is not limited to the specific apparatus or method disclosed in the document and the drawings.
[0011] The present disclosure is described in detail with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the drawings to refer various features of the present subject matter.
[0012] Embodiment of the present disclosure will now be described, by way of example only, with reference to the following diagrams.

[0013] Fig 1. Illustrates a perspective view of a prosthesis assembly including a femoral component, a tibial bearing component, and a tibial base plate in accordance with an exemplary embodiment of the present disclosure;
[0014] Fig 2. Illustrates an exploded view of a prosthesis assembly including a femoral component, a tibial bearing component, and a tibial base plate in accordance with an exemplary embodiment of the present disclosure.
[0015] Fig 3 illustrates a side sectional view of one embodiment of a knee prosthesis in accordance with an exemplary embodiment of the present disclosure.
[0016] In the above accompanying drawings, a number relates to an item identified by a line linking the number to the item. When a number is accompanied by an associated arrow, the number is used to identify a general item at which the arrow is pointing.
[0017] Further the figures depict various embodiment of the present subject matter for purposes of illustration only. One skilled in the art will readily recognize from the following discussion that alternative embodiment of the structures and methods illustrated herein may be employed without departing from the principles of the present subject matter described herein.

DETAILED DESCRIPTION OF ACCOMPANYING DRAWINGS
[0018] The following detailed description illustrates embodiment of the present disclosure and manners by which they can be implemented. The words "comprising," "having," "containing," and "including," and other forms thereof, are intended to be equivalent in meaning and be open ended in that an item or items following any one of these words is not meant to be an exhaustive listing of such item or items, or meant to be limited to only the listed item or items. It must also be noted that as used herein and in the appended claims, the singular forms "a," "an," and "the" include plural references unless the context clearly dictates otherwise.
[0019] As used herein, the terms "proximal" and "distal" should be given their generally understood anatomical interpretation. The term "proximal" refers to a direction generally towards the torso of a patient and "distal" refers to the opposite direction of proximal, that is, against the torso of a patient. It should be understood that the use of the terms "proximal" and "distal" should be interpreted as if the patient were standing with the knee joint in extension even though the appliances described herein are generally used with the joint knee in flexion. The intention is to differentiate the terms "proximal" and "distal" from the terms "anterior" and "posterior". As used herein, the terms "anterior" and "posterior" should be given their generally understood anatomical interpretation. Thus, "posterior" refers to a rear portion of the patient, e.g. a rear portion of the knee. Similarly, "anterior" refers to a front part of the patient, e.g., a front part of the knee. Thus, "posterior" refers to the opposite direction of "anterior." Similarly, the term "lateral" refers to the opposite direction of "medial."

[0020] The present disclosure provides technical solutions to the technical problems identified in the prior art. In the prior art, prosthetic members have not been wholly satisfactory for knee implantation because they do not provide for the complexity involved when flexing the tibia relative to the femur. In a natural knee, internal rotation of the tibia occurs when the knee is flexed from full extension (i.e., zero degrees’ flexion) to about 20 degrees’ flexion, and, conversely, external rotation of the tibia occurs when the knee is extended from about 20 degrees to full extension. The prior art prosthetic joints do not provide for replacement of wear surfaces without completely removing the implanted unit. Some prior art prosthetic joints tend to become inoperative because of wear. This may reduce their ability to perform the complicated movements inherent in natural knee joints. While suitable prosthetic members have been devised utilizing simple ball joint construction, it has been found that a surface-to surface contact of the external parts of the joint provide better movement. This surface-to surface external contact of the spaced-apart prosthetic members cause wear of the surfaces and in time replacement is required. Some prior art discloses using of two metal structures, one as reinforcement structure for poly insert post and another structure as screw to hold Extension rod with tibial base plate and improve insert locking mechanism strength.
[0021] Accordingly, there is a need for a better reinforcement component which will overcome the prior art problems. This invention is therefore directed towards providing an improved reinforcement method and component, which is relatively simple in design and structure, and is highly effective for its intended purpose.

[0022] The prior art is thus characterized by several disadvantages that are addressed by the present disclosure. The present disclosure is therefore directed towards minimizing, and in some aspects eliminating the above-mentioned failures, and other problems, by utilizing the methods and structural features described herein.
[0023] Embodiment of the present disclosure present technological improvements as solutions to one or more of the above-mentioned technical problems recognized by the inventor(s) in conventional systems.
[0024] The person skilled in the art will recognize many variations, alternatives, and modifications of the embodiment of the present disclosure. It should be understood that this invention is not limited to the particular methodology, protocols, and the like, described herein and as such may vary. The terminology used herein is for the purpose of describing particular embodiment only and is not intended to limit the scope of the present invention, which is defined solely by the claims.
[0025] In an embodiment of the present invention, the invention discloses a prosthesis assembly for knee joint. The invention discloses a prosthesis assembly for knee joint comprises a tibial prosthesis and a femoral prosthesis. The tibial prosthesis is disposed on tibia. The tibial prosthesis comprises a tibial plate, a tibial bearing component, an extension rod and a screw. The tibial plate comprises a proximal side and a distal side. The distal side comprises a cylindrical hollow projection. The tibial bearing component is disposed on the tibial plate. The tibial bearing component comprises a lateral medial articulating surface, a proximal medial articulating surface and a post.
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The post comprises a recess on an anterior portion. The extension rod is a cylindrical structure. The extension rod comprises an opening at a proximal end. The opening comprises an internal threading. The screw comprises a head and a shank. The shank comprises threads on an outer surface.
[0026] The femoral prosthesis is disposed on a femur. The femoral prosthesis comprises a medial condyle and a lateral condyle. An intercondylar space is formed in between the medial condyle and the lateral condyle. A cam is disposed in the intercondylar space in between medial condyle and lateral condyle.
[0028] The femoral prosthesis includes a cam and the tibial prosthesis includes a post having a recess on an anterior portion that is adapted to be designed to cooperate with each other to stabilize femoral prosthesis relative to tibial prosthesis. A peg/screw is introduced in the recess on the tibial bearing and is extended upto an extension rod in such a way that will secure the tibial bearing with tibial base plate along with the extension rod. Such coupling provides a great stability.
[0029] During operation, in a first stage the tibial bearing component is disposed on the proximal surface of the tibial base plate. In a second stage, the tibial bearing component is secured to the tibial base plate by introducing the screw through the recess extended through anterior portion of the post. The screw is further extended to secure the extension rod thereby securing the tibial bearing component to the tibial base plate and the extension rod. In third stage, the femoral prosthesis is disposed on top of the tibial prosthesis and articulated with respect to the tibial prosthesis.
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[0030] The medial condyle and lateral condyle are configured to articulate with the medial proximal articular surface and the lateral proximal articular surface respectively. The intercondylar space between the medial condyle and lateral respectively is fully open and uninterrupted by cam. The post of the tibial bearing component is centrally located between the medial proximal articular surface and the lateral proximal articular surface. The post is configured to engage cam during flexion. The femoral prosthesis comprises a cam and the tibial prosthesis comprises a post configured to cooperate with each other to stabilize femoral prosthesis relative to tibial prosthesis at a site of a posterior cruciate ligament (PCL). The medial proximal articular surface and the lateral proximal articular surface comprises curved surface to facilitate articulation during flexion of the knee joint. The femoral prosthesis articulated relative to tibial prosthesis at 130° of flexion. The prosthesis assembly comprises a posterior stabilized prosthesis. The screw acts as reinforcement for post. The screw is configured to provide strength to the post (106).
[0031] Accordingly, there is a need for a better reinforcement component which will overcome the prior art problems. This invention is therefore directed towards providing an improved reinforcement method and component, which is relatively simple in design and structure, and is highly effective for its intended purpose.
[0032] Embodiment of the present disclosure present technological improvements as solutions to one or more of the above-mentioned technical problems recognized by the inventor(s) in conventional extension rods.

[0033] The present invention discloses a single screw as a reinforcement member to lock extension rod with tibial base plate along with tibial bearing.
[0034] The present invention reduces the number of parts and joints in implant interface eventually reducing cost.
[0035] The present invention discloses a new and improved joint prosthesis for total knee replacement which enables replacement of worn parts efficiently.
[0036] These and other features and advantages of the present invention will become apparent from the following description of the invention that is provided in connection with the accompanying drawings and illustrated embodiments of the invention.
[0037] Additional aspects, advantages, features and objects of the present disclosure would be made apparent from the drawings and the detailed description of the illustrative embodiment.
[0038] It will be appreciated that features of the present disclosure are susceptible to being combined in various combinations without departing from the scope of the present disclosure as defined by the below mentioned detailed description and drawings.
[0039] It should be noted that the above advantages and other advantages will be better evident in the subsequent description. Further, in the subsequent section, the present subject is better explained with reference to the figures. In
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order to maintain consistency and brevity of reading, the all the figures from 1, 2, and 3 are explained jointly. Further, the following table lists of nomenclature and numberings are used in the figure to illustrate the invention and the nomenclature is further used to describe in the invention the subsequent paragraph.

Nomenclature Number Nomenclature Number
femoural prosthesis 102 medial condyle 208
tibial prosthesis 104 lateral condyle 210
post 106 medial proximal articular surface 212
tibial bearing component 108 lateral proximal articular surface 214
tibial plate 110 screw 216
extension rod 112 proximal surface 218
recess 202 distal side 220
anterior portion 204 cylindrical hollow projection 222
intercondylar space 206 cam 302
[0040] Referring now to the drawings, Fig. 1 illustrates, a prosthesis assembly (100) is shown in perspective view with femoral prosthesis (102) articulated relative to tibial prosthesis (104) at 130° of flexion. Prosthesis assembly (100)
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may comprise a posterior stabilized prosthesis (PS). The tibial prosthesis includes a post (106), a tibial bearing component (108), a tibial base plate (110) and an extension rod (112).
[0041] Referring to Fig.2, exploded view (200) of a prosthesis assembly is disclosed. The tibial prosthesis includes a post (106) having a recess (202) on an anterior portion (204). The femoral prosthesis (102) defines an intercondylar space (206) between the medial and lateral condyles (208) and (210) respectively. The tibial bearing component may include a proximal medial articular surface (212) and a lateral proximal articular surface (214). Further, a screw/peg (216) is disclosed to be inserted into the recess (202). The tibial base plate has a proximal side (218) and a distal side (220).
[0042] Referring Fig.3 now, prosthesis assembly (100) in cross-sectional view (300) along a sagittal plane is disclosed. The sagittal plane extends along the anterior-posterior and proximal-distal directions of the prosthesis assembly (100). The femoral prosthesis (102) includes a cam (302) and the tibial prosthesis including a post (106) can be designed to cooperate with each other to stabilize femoral prosthesis (102) relative to tibial prosthesis (104) at the site of a posterior cruciate ligament (PCL). The femoral prosthesis (102) defining an intercondylar space (108) between the medial and lateral condyles (110) and (112) respectively is fully open and uninterrupted by cam (302).
[0043] As shown in Figures 1-3, The prosthesis assembly for knee joint comprises a tibial prosthesis (104) and a femoral prosthesis (102). The tibial prosthesis (104) is disposed on tibia. The tibial prosthesis (104) comprises a tibial plate (110), a tibial bearing component (108), an extension rod (112) and
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a screw (216). The tibial plate (110) comprises a proximal side (218) and a distal side (220). The distal side (220) comprises a cylindrical hollow projection (222). The tibial bearing component (108) is disposed on the tibial plate (110). The tibial bearing component (108) comprises a lateral medial articulating surface (214), a proximal medial articulating surface (212) and a post (106). The post (106) comprises a recess (202) on an anterior portion (204). The post (106) of the tibial bearing component (108) is centrally located between the medial proximal articular surface (212) and the lateral proximal articular surface (214). The post (106) is configured to engage cam (302) during flexion. The extension rod (112) is a cylindrical structure. The extension rod comprises an opening at a proximal end. The opening comprises an internal threading. The screw (216) comprises a head and a shank. The shank comprises threads on an outer surface. The screw (216) acts as reinforcement for post 106. The screw is configured to provide strength to the post (106).
[0044] The femoral prosthesis (102) is disposed on a femur. The femoral
prosthesis (102) comprises a medial condyle 208 and a lateral condyle (210).
The medial condyle (208) and lateral condyle (210) are configured to articulate
with the medial proximal articular surface (212) and the lateral proximal
articular surface (214) respectively. The medial proximal articular surface (212)
and the lateral proximal articular surface (214) comprises curved surface to
facilitate articulation during flexion of the knee joint. An intercondylar space
(206) is formed in between the medial condyle (208) and the lateral condyle
(210). A cam (302) is disposed in the intercondylar space (206) in between
medial condyle (208) and lateral condyle (210). The intercondylar space (206)
between the medial condyle (208) and lateral (210) respectively is fully open
and uninterrupted by cam (302). The femoral prosthesis (102) comprises a cam
(302) and the tibial prosthesis (104) comprises a post (106) configured to
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cooperate with each other to stabilize femoral prosthesis (102) relative to tibial prosthesis (104) at a site of a posterior cruciate ligament (PCL).
[0045] During operation, in a first stage the tibial bearing component (108) is disposed on the proximal surface (218) of the tibial base plate (110). In a second stage, the tibial bearing component (108) is secured to the tibial base plate (110) by introducing the screw (216) through the recess (202) extended through anterior portion (204) of the post (106). The screw (216) is further extended to secure the extension rod (112) thereby securing the tibial bearing component (108) to the tibial base plate (110) and the extension rod (112). In third stage, the femoral prosthesis (102) is disposed on top of the tibial prosthesis (104) and articulated with respect to the tibial prosthesis (104). The femoral prosthesis (102) articulated relative to tibial prosthesis (104) at 130° of flexion. The prosthesis assembly (100) comprises a posterior stabilized prosthesis.
[0046] The femoral prosthesis (102) can be disposed on top of and articulated with respect to the tibial prosthesis (104). The said articulation may be between the medial and lateral condyles (208) and (210) and the medial proximal articular surface (120) and the lateral proximal articular surface (122), respectively. The medial proximal articular surface (212) and the lateral proximal articular surface (214) may be shaped (e.g. curved) to facilitate such articulation during flexion of the knee joint. The post (106) of the tibial bearing component (108) may be centrally located between the medial proximal articular surface (212) and the lateral proximal articular surface (214) as shown in FIG. 1-2. Post (106) may be configured to engage cam (202) during flexion as shown in Figure 3. Tibial bearing component (108) is disposed on the proximal surface (218) of the tibial base plate (110) when assembled. The tibial

bearing component (108) is secured to the tibial base plate (110) as shown in Figures 1 and 3 by introducing the screw through the recess (202) which extends through anterior portion (204) of post (106). The screw (216) may be further extended to secure extension rod (112) eventually securing tibial bearing component (108) to tibial base plate (110) and extension rod (112). Such coupling provides a great stability. It is contemplated that the recess (202) may be arranged in a plurality of positions including passing through at least a portion of the post, anterior to the post or posterior to the post.
[0047] It is observed that use of multiple reinforcement components has been eliminated. Along with this advantage, a single screw for reinforcement has provided the much needed efficiency, reduction in components and cost as well as better stability and securement of tibial bearing with tibial base plate and extension rod as described in the present invention. The present invention has both technical as well as economic significance
[0048] While a particular embodiment of the invention has been illustrated and described, modifications thereof will readily occur to those skilled in the art. It is understood that the various embodiment, details and constructions and their features described above and illustrated in the attached figures may be interchanged among the various embodiment while remaining within the scope of the invention. Additionally, it is understood that various modifications could be made to any of the elements described herein above while remaining within the scope of the invention.

We Claim-1. A prosthesis assembly for a knee joint (100) comprises:
a tibial prosthesis (104), wherein the tibial prosthesis (104) is disposed on a tibia, wherein the tibial prosthesis (104) comprises:
a tibial plate (110), wherein the tibial plate (110) comprises a proximal side (218) and a distal side (220), wherein the distal side (220) comprises a cylindrical hollow projection (222);
a tibial bearing component (108), wherein the tibial bearing component (108) is disposed on the tibial plate (110), wherein the tibial bearing component (108) comprises a lateral medial articulating surface (214), a proximal medial articulating surface (212) and a post (106), wherein the post (106) comprises a recess (202) on an anterior portion (204);
an extension rod (112), wherein the extension rod (112) is a cylindrical structure, wherein the extension rod comprises an opening at a proximal end, wherein the opening comprises an internal threading;
a screw (216), wherein the screw (216) comprises a head and a shank, wherein the shank comprises threads on an outer surface.

a femoral prosthesis (102), wherein the femoral prosthesis (102) is disposed on a femur, wherein the femoral prosthesis (102) comprises a medial condyle (208) and a lateral condyle (210), wherein an intercondylar space (206) is formed in between the medial condyle (208) and the lateral condyle (210), wherein a cam (302) is disposed in the intercondylar space (206) in between the medial condyle (208) and the lateral condyle (210); and
wherein during operation, in a first stage, the tibial bearing component (108) is disposed on the proximal surface (218) of the tibial base plate (110), wherein in a second stage, the tibial bearing component (108) is secured to the tibial base plate (110) by introducing the screw (216) through the recess (202) extended through anterior portion (204) of the post (106), wherein the screw (216) is further extended to secure the extension rod (112) thereby securing the tibial bearing component (108) to the tibial base plate (110) and the extension rod (112), wherein in a third stage, the femoral prosthesis (102) is disposed on top of the tibial prosthesis (104) and articulated with respect to the tibial prosthesis (104).
2. The prosthesis assembly (100) as claimed in claim 1, wherein the medial condyle (208) and lateral condyle (210) are configured to articulate with the medial proximal articular surface (212) and the lateral proximal articular surface (214) respectively.
3. The prosthesis assembly (100) as claimed in claim 1, wherein the intercondylar space (206) between the medial condyle (208) and thelateral condyle (210) respectively is fully open and uninterrupted by cam (302).

4. The prosthesis assembly (100) as claimed in claim 1, wherein the post (106) of the tibial bearing component (108) is centrally located between the medial proximal articular surface (212) and the lateral proximal articular surface (214), wherein the post (106) is configured to engage cam (302) during flexion.
5. The prosthesis assembly (100) as claimed in claim 1, wherein the femoral prosthesis (102) comprises a cam (302) and the tibial prosthesis (104) comprises a post (106) configured to cooperate with each other to stabilize femoral prosthesis (102) relative to tibial prosthesis (104) at a site of a posterior cruciate ligament (PCL).
6. The prosthesis assembly (100) as claimed in claim 1, wherein the medial proximal articular surface (212) and the lateral proximal articular surface (214) comprises curved surface to facilitate articulation during flexion of the knee joint.
7. The prosthesis assembly (100) as claimed in claim 1, wherein the femoral prosthesis (102) articulated relative to tibial prosthesis (104) at 130° of flexion, wherein the prosthesis assembly (100) comprises a posterior stabilized prosthesis.
8. The prosthesis assembly (100) as claimed in claim 1, wherein the screw (216) acts as reinforcement for post 106, wherein the screw is configured to provide strength to the post (106).