FORM 2
THE PATENTS ACT, 1970 (39 OF1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[SEE SECTION 10, RULE 13]
A KNEE IMPLANT WITH
INTERLOCKING MECHANISM
BIORAD MEDISYS PRIVATE LIMITED
AN INDIAN COMPANY HAVING OFFICE ADDRESS AT
Survey No. 48, 3 & 48 7, Pashan - Sus Rd, Sus, Pune,
Maharashtra 411021

THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE
INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED
2
FIELD OF THE INVENTION
[0001] This invention is generally in the field of medical devices and relates
to components of knee joint prostheses that have a tibial bearing insert which can rotate
5 and translate with respect to the tibial tray upon which it is mounted.
BACKGROUND
[0002] Knee replacement surgeries have become a common and essential procedure for
individuals suffering from severe knee joint conditions, such as osteoarthritis,
rheumatoid arthritis, and traumatic injuries. These surgeries aim to restore mobility and
10 alleviate pain by replacing the damaged knee joint with an artificial implant. Despite the
advancements in knee implant technology, existing knee replacement systems still face
significant challenges that can affect the long-term success and patient satisfaction.
[0003] The natural human knee joint involves the distal end of the femur, the proximal
end of the tibia and a meniscus bearing therebetween. The femur and tibia are connected
15 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
20 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
25 of the femur and tibia with prosthetic femoral and tibial implants, referred to as total
knee replacements (TKR).

[0004] Accordingly, there is thus, a need to provide alternative mechanisms and devices
for reinforcing the securement of a tibia/bearing insert to a tibial tray in a knee prosthesis.
Despite the benefits of existing designs for knee joint prostheses having a rotatable tibial
component, there remains a need for prostheses that still reduce stress, provide optimal
5 roll back and maintain optimal contact of the tibial and femoral components to
accommodate the stresses placed upon the knee. This invention is therefore directed
towards providing the same, which is relatively simple in design and structure, and is
highly effective for its intended purpose.
SUMMARY
10 [0005] 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 prosthesis.
[0006] The present invention is related to a knee implant which can rotate and translate
with respect to the tibial tray upon which it is mounted. The knee implant comprises a
15 tibial implant and a femoral implant. The tibial implant comprises a tibial insert. The
tibial insert comprises a first structure and a second structure. The first structure is a
hollow cylindrical structure. The first structure comprises a projection disposed at one
end on the outer surface. The second structure is a flat structure disposed at a proximity
to the projection, thereby forming a slot. The tibial implant further comprises a bearing
20 component. The bearing component is disposed on the second structure. The bearing
component comprises a lip and an insert rod. The lip is configured to engage with the
projection to prevent liftoff and dislocation of the bearing component. The insert rod is
inserted in the first structure through an opening. The insert rod and the lip allow rotation
and translation of the bearing component with respect to tibial insert.
25 [0007] The present invention discloses a novel interlock mechanism for the tibial and
femoral implant, aiming to overcome the aforementioned limitations and provide
4
improved stability, increased contact area, load-bearing efficiency, higher liftoff
distance, and superior proximal-distal dislocation force resistance. The design
incorporates a rotating platform weight-bearing insert with a strong interlocking feature
that ensures enhanced alignment and movement synchronization between the prosthetic
5 tibial implant and the femoral implant. The bearing component is mounted on the tibial
insert and articulates with the femoral implant.
BRIEF DESCRIPTION OF THE FIGURES
[0008] The summary above, as well as the following detailed description of illustrative
embodiment, is better understood when read in conjunction with the appended drawings.
10 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.
15 [0009] Embodiment of the present disclosure will now be described, by way of example
only, with reference to the following diagrams wherein:
[0010] Fig 1. Illustrates a perspective view of bearing component in accordance with an
exemplary embodiment of the present disclosure;
[0011] Fig 2(a) and 2(b) is a perspective view of contact area of femur and tibial plate
20 in extension and flexion in accordance with an exemplary embodiment of the present
disclosure.

[0012] Figure 2 (c) and Figure 2 (d) illustrates perspective sectional view of
interlocking mechanism for liftoff prevention in accordance with an exemplary
embodiment of the present disclosure.
[0013] In the above accompanying drawings, a number relates to an item identified by
5 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.
[0014] 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
10 illustrated herein may be employed without departing from the principles of the present
subject matter described herein.
DETAILED DESCRIPTION OF EMBODIMENTS
[0015] The following detailed description illustrates embodiment of the present
disclosure and manners by which they can be implemented. The words "comprising,"
15 "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
20 unless the context clearly dictates otherwise.
[0016] 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
6
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
5 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, eg, 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."
10 [0017] 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
15 present invention, which is defined solely by the claims.
[0018] The present disclosure provides technical solutions to the technical problems
identified in the prior art. In the prior art, the primary issues with current knee implant
designs is the stability of the bearing component, which is crucial for ensuring smooth
articulation and proper load distribution during movement. Many existing implants fail
20 to adequately prevent liftoff or dislocation of the bearing component under normal or
excessive loading conditions. This instability can lead to complications such as improper
alignment, wear and tear of the implant components, and, ultimately, implant failure.
Patients experiencing these issues may require revision surgeries, which are more
complex and pose additional risks compared to the initial procedure.
25 [0019] Furthermore, the design of the bearing component and its interaction with the
tibial and femoral components often leads to excessive wear and impingement. The
articulation surfaces, if not properly designed, can cause abnormal stress on the

surrounding tissues and the implant itself. This can result in discomfort, limited range
of motion, and accelerated deterioration of the implant, necessitating earlier replacement
than anticipated.
[0020] Another problem observed in the current state of knee implant technology is the
5 lack of an effective mechanism to replicate the natural kinematics of the knee joint.
Many implants offer limited rotation and translation capabilities, which can lead to
unnatural movement patterns and reduced functionality. This limitation often affects the
overall performance of the knee implant, leading to patient dissatisfaction due to
restricted mobility and discomfort during daily activities.
10 [0021] A typical knee prosthesis includes a femoral component securely mounted to the
distal end of a resected femur, a tibial component securely mounted to the proximal end
of a resected tibia and a bearing disposed between the femoral and tibial components.
Prosthetic knee joints can be considered either constrained or unconstrained.
Constrained prosthetic knees include femoral and tibial prosthetic components which
15 are mechanically linked or constrained to each other by a hinge structure. An
unconstrained prosthetic knee includes femoral and tibial components which are not
mechanically linked. An unconstrained knee utilizes the patient's existing ligaments to
provide joint stability. Typically, the tibial tray is mounted within the tibia of a patient.
The tibial bearing insert, which is usually made of ultra high molecular weight
20 polyethylene (UHMWPE) is mounted upon the superior surface of the tibial tray.
Flexion of the knee joint causes the tibia to rotate relative to the femur about an axis
extending generally in a medial-to-lateral direction. Flexion also generates rotation of
the tibia about its own axis.
[0022] Load and stress are placed upon the knee prosthesis, and particularly on the tibial
25 bearing insert, during normal daily use. To accommodate these forces, and to reduce the
chances for dislocation a range of types of orthopedic knee implants is available which
may take many different forms depending upon the preferences of the orthopedic
8
surgeon, the condition of the natural knee and the health, age and mobility of the patient.
Some prior art knee joint prostheses fixedly mount the inferior surface of the bearing to
the superior surface of the tibial component. some tibial components of knee prostheses
have been designed to allow rotation of the tibial bearing insert relative to the proximal
5 or superior surface of the tibial tray, about the longitudinal axis of the prosthesis.to
reduce stress on the tibial bearing insert as well as avoid dislocation in response to
normal walking movement without reliance upon a fixed hinged connection. Other knee
joint prostheses permit sliding movement between the bearing and the tibial component.
some of the knee joint prostheses that provide a floating bearing may not be reliable and
10 moreover may dislocate due to the shape of the bearing itself. Further in some designs,
movement of the tibial bearing insert in the anterior-posterior direction, or roll back, can
place undesirable levels of stress on the stabilizing post of the prosthesis.
[0023] The present invention is related a knee implant with interlocking mechanism.
The knee implant comprises a tibial implant and a femoral implant. The tibial implant
15 comprises a tibial insert. The tibial insert comprises a first structure and a second
structure. The first structure is a hollow cylindrical structure. The first structure
comprises a projection disposed at one end on the outer surface. The second structure is
a flat structure disposed at a proximity to the projection, thereby forming a slot.
[0024] The tibial implant further comprises a bearing component. The bearing
20 component is disposed on the second structure. The bearing component comprises a lip
and an insert rod. The lip is configured to engage with the projection to prevent liftoff
and dislocation of the bearing component. The insert rod is inserted in the first structure
through an opening. The insert rod and the lip allow rotation and translation of the
bearing component with respect to tibial insert. The bearing component comprises the
25 opening. The opening comprises predefined shape to allow translation and rotation of
the bearing component. The opening comprises an upper surface and a lower surface.
The lower surface comprises the lip.

[0025] The bearing component further comprises a concave superior surface configured
to minimize the possibility of impingement of the natural or prosthetic patella and the
patellar tendon. The bearing component further comprises a superior articulation surface
and inferior mating surface. The superior articulation surface comprises a lateral condyle
5 and a medial condyle.
[0026] The knee implant further comprises a femoral implant and a connecting part.
The connecting part is coupled with the femoral implant via hinged joint. The
connecting part is connected to the insert rod with threaded joint. The insert rod is
inserted inside a hollow part of the first structure. The first structure allows sliding
10 motion of the insert rod inside hollow part. The femoral implant comprises a lateral
articulation surface and a medial articulation surface. The medial articulation surface
and the lateral articulation surface are configured to articulate on the medial condyle and
the lateral condyle respectively.
[0027] The present invention provides a knee prosthesis in which some of the load
15 directed to the tibial bearing insert can be transferred to the tibial tray.
[0028] The present invention increases the contact area between the femoral condyles
and the tibial bearing insert throughout the range of knee motion, thus reducing stress
on the tibial bearing insert.
[0029] The invention provides an effective reinforcing pin that reduces the load exerted
20 on the tibial bearing insert by the femoral component.
[0030] The invention provides a reinforcement pin for increasing the strength of
attachment of the tibial bearing insert to the tibial tray.
10
[0031] The present invention provides a tibial knee component with a movable bearing,
which is easier to manufacture and have sufficient movement between the bearing and
the tibial plate with strong flexion of the knee joint.
[0032] It will be appreciated that features of the present disclosure are susceptible to
5 being combined in various combinations without departing from the scope of the present
disclosure as defined by the below mentioned detailed description and drawings.
[0033] 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 order to maintain consistency
10 and brevity of reading, the all the figures from 1, 2, 3, 4a, 4b, 5a and 5b 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
Bearing Component 101 Second Structure 208
Superior Articulation Surface 106 Femoral Implant 210
Inferior Mating Surface 108 Projection 212
Lateral Condyle 110 Upper surface 214
Medial Condyle 112 Lower Surface 216
Opening 114 Lip 218
Concave Superior Surface 116 Lateral Articulation Surface 220
Tibial Implant 202 Medial Articulation Surface 222
Tibial Insert 204 Connecting Part 224
First Structure 206 Insert Rod 226
15 [0034] Referring now to the drawings, Fig. 1 illustrates, a bearing component 101 is
shown in perspective view. The bearing component 101 has an anterior side 102 and a
posterior side 104, a superior articulation surface 106 and an inferior mating surface
108. The superior surface 102 may have one or more condylar elements that are adapted

to articulate with complementary condyle(s) of a femoral component. Specifically, the
condylar elements include lateral and medial condyles 110, 112 respectively. The tibial
bearing insert 100 further has an opening 114 extending therethrough from the superior
articulation surface 106 to the inferior mating surface 108. The opening 114 may be of
5 any suitable shape which allows for translation and rotation of the tibial bearing insert
100. Insert 100 also includes a generally anteriorly positioned generally
concave superior surface 116 configured to minimize the possibility of impingement of
the natural or prosthetic patella (not shown) and the patellar tendon.
[0035] Figure 2(a) and figure 2(b) illustrates a perspective view of contact area of femur
10 implant 210 and tibial implant 202 in extension and flexion. The design maximizes the
contact area between the prosthetic tibial insert and the femoral component, promoting
optimal load distribution and reducing wear and tear over time.
[0036] Referring to figure 2(c) and figure 2(d), the tibial insert 204 has an interlock
mechanism with the bearing component 101 that prevents liftoff and dislocation of the
15 bearing component from the tibial insert. The tibial implant 202 comprises a tibial insert
204. The tibial insert 204 comprises a first structure 206 and a second structure 208. The
first structure 206 is a hollow cylindrical structure. The first structure 206 comprises a
projection 212 disposed at one end on the outer surface. The second structure 208 is a
flat structure disposed at a proximity to the projection 212, thereby forming a slot.
20 [0037] The tibial implant 202 further comprises a bearing component 101. The bearing
component 101) is disposed on the second structure 208. The bearing component 101
comprises a lip 218 and an insert rod 226. The lip 218 is configured to engage with the
projection 212 to prevent liftoff and dislocation of the bearing component 101. The
insert rod 226 is inserted in the first structure 206 through an opening 114. The insert
25 rod 226 and the lip 218 allow rotation and translation of the bearing component 101 with
respect to tibial insert 204. The bearing component 101 comprises the opening 114. The
opening 114 comprises predefined shape to allow translation and rotation of the bearing
12
component 101. The opening 114 comprises an upper surface 214 and a lower surface
216. The lower surface 216 comprises the lip 218.
[0038] The knee implant further comprises a femoral implant 210 and a connecting part
224. The connecting part 224 is coupled with the femoral implant (210) via hinged joint.
5 The connecting part 224 is connected to the insert rod 226 with threaded joint. The insert
rod 226 is inserted inside a hollow part of the first structure 206. The first structure 206
allows sliding motion of the insert rod 226 inside hollow part.
[0039] The femoral implant 210 comprises a lateral articulation surface 220 and a
medial articulation surface 222. The medial articulation surface 222 and the lateral
10 articulation surface 220 are configured to articulate on the medial condyle 112 and the
lateral condyle 110 respectively.
[0040] . The inclusion of a lip 218 feature on the bearing component 101 prevents liftoff,
minimizing the risk of dislocation and enhancing patient safety. The interlock
mechanism enables efficient load transmission through the implant, enhancing its
15 weight-bearing capacity and overall durability.
[0041] The present invention introduces an innovative Knee Implant with Interlock
Mechanism that addresses the limitations of existing knee joint prostheses. Through its
unique design, the invention enhances stability, contact area, load-bearing capacity, and
liftoff prevention, ultimately improving patient mobility and quality of life. The present
20 invention has both technical as well as economic significance.
[0042] 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 knee implant, wherein knee implant comprises:
a tibial implant (202), wherein the tibial implant (202) comprises:
a tibial insert (204), wherein the tibial insert (204) comprises:
a first structure (206), wherein the first structure (206) is a hollow
cylindrical structure, wherein the first structure (206) comprises a
projection (212) disposed at one end on the outer surface; and
a second structure (208), wherein the second structure (208) is a
flat structure disposed at a proximity to the projection (212), thereby
forming a slot;
a bearing component (101), wherein the bearing component (101) is
disposed on the second structure (208), wherein the bearing component (101)
comprises:
a lip (218), wherein the lip (218) is configured to engage with the
projection (212) to prevent liftoff and dislocation of the bearing
component (101);
an insert rod (226), wherein the insert rod (226) is inserted in the
first structure (206) through an opening (114); and
wherein the insert rod (226) and the lip (218) allow rotation and
translation of the bearing component (101) with respect to tibial
insert (204).

2. The knee implant as claimed in claim 1, wherein the knee implant further comprises
a femoral implant (210) and a connecting part (224), wherein the connecting part (224)
is coupled with the femoral implant (210) via hinged joint.

3. The knee implant as claimed in claim 1, wherein the connecting part (224) is
connected to the insert rod (226) with threaded joint.

4. The knee implant as claimed in claim 1, wherein the insert rod (226) is inserted inside
a hollow part of the first structure (206), wherein the first structure (206) allows sliding
motion of the insert rod (226) inside hollow part.

5. The knee implant as claimed in claim 1, wherein the bearing component (101)
comprises the opening (114), wherein the opening (114) comprises an upper surface
(214) and a lower surface (216), wherein the lower surface (216) comprises the lip (218).

6. The knee implant as claimed in claim 1, wherein the opening (114) comprises
predefined shape to allow translation and rotation of the bearing component (101).

7. The knee implant as claimed in claim 1, wherein the bearing component (100) further
comprises a concave superior surface (116) configured to minimize the possibility of
impingement of the natural or prosthetic patella and the patellar tendon.

8. The knee implant as claimed in claim 1, wherein the bearing component (101) further
comprises a superior articulation surface (106) and inferior mating surface (108),
wherein the superior articulation surface (106) comprises a lateral condyle (110) and a
medial condyle (112).

9. The knee implant as claimed in claim 1, wherein the femoral implant (210) comprises
a lateral articulation surface (220) and a medial articulation surface (222), wherein the
medial articulation surface (222) and the lateral articulation surface (220) are configured
to articulate on the medial condyle (112) and the lateral condyle (110) respectively.

Dated this on,
16th Day of August, 2024