DESC:FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(Section 10 and Rule 13)

1. TITLE OF THE INVENTION:
KNEE IMPLANT
2. APPLICANT:
Meril Healthcare Pvt. Ltd., an Indian company of the Survey No. 135/139, Bilakhia House, Muktanand Marg, Chala, Vapi- 396191, Gujarat, India.

The following specification particularly describes the invention and the manner in which it is to be performed:

FIELD OF INVENTION
[1] The present disclosure relates to an implant. More particularly, the present disclosure relates to a knee replacement implant.
BACKGROUND OF INVENTION
[2] The knee joint is one of the biggest joints in a human body that connects the femur bone to the tibia. The knee joint provides flexibility, stability and balance, thereby helping a human in movement. The knee in a human body may be affected by various conditions such as osteoarthritis, rheumatoid arthritis, avascular neurosis, etc. caused by factors such as infections, trauma, heavy exercise, aging, etc.
[3] Such conditions of the knee may be treated using a knee replacement surgery. Conventionally, a total knee joint replacement surgery, also known as total knee arthroplasty, is used where a damaged or worn-out knee joint is replaced with artificial components. This is due to the fact that since the procedure requires replacement of the entire joint, most of the knee’s natural structures, such as ligaments and cartilage, are removed and replaced by artificial components.
[4] Although the conventionally available implants may provide temporary relief to the patient, in some cases these implants may cause various complications in the patients leading to pain, infections, skin/muscle irritation, etc.
[5] Further, the conventionally available implants in certain circumstances may become loose with time, which may lead to dislocation of at least one component of the implant. This may in turn cause uneven mechanical load distribution between the joints leading to rise of several complications and diseases and may require another surgery to fix a new implant.
[6] Hence, there arises a need of an implant which overcomes the problem associated with conventional implants.
SUMMARY OF INVENTION
[7] Particular embodiments of the present disclosure are described herein below with reference to the accompanying drawings; however, it is to be understood that the disclosed embodiments are mere examples of the disclosure, which may be embodied in various forms. Well-known functions or constructions are not described in detail to avoid obscuring the present disclosure in unnecessary detail. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present disclosure in virtually any appropriately detailed structure.
[8] The present disclosure relates to an implant. In an embodiment, the implant includes a liner and a tibial component. The liner includes a top portion and a bottom portion. The top portion includes a bearing surface. The bottom portion includes at least one of: a first dovetail structure and a chamfer cut. The tibial component includes a base plate. The base plate includes a wall and a cavity. The cavity is configured to receive the bottom portion of the liner. An inner side of the wall includes at least one of: a second dovetail structure and one or more fins. The second dovetail structure is configured to mate with the first dovetail structure of the liner, forming a dovetail joint. The one or more fins are configured to form an interference lock with the chamfer cut of the liner.
BRIEF DESCRIPTION OF DRAWINGS
[9] The summary above, as well as the following detailed description of illustrative embodiments, is better understood when read in conjunction with the apportioned drawings. For the purpose of illustrating the present disclosure, exemplary constructions of the disclosure are shown in the drawings. However, the disclosure is not limited to specific methods and instrumentality disclosed herein. Moreover, those in the art will understand that the drawings are not to scale.
[10] Fig. 1 depicts an assembled view of an implant 100, according to one or more exemplary embodiments of the present disclosure.
[11] Fig. 2a depicts a side view of a femoral component 110, according to one or more exemplary embodiments of the present disclosure.
[12] Fig. 2b depicts a posterior view of the femoral component 110, according to one or more exemplary embodiments of the present disclosure.
[13] Fig. 2c depicts a side perspective view of the femoral component 110 disposed on a condyle of a femoral bone, according to an embodiment of the present disclosure.
[14] Fig. 3a depicts a perspective view of a liner 130, according to one or more exemplary embodiments of the present disclosure.
[15] Fig. 3b depicts a side view of the liner 130, according to one or more exemplary embodiments of the present disclosure.
[16] Fig. 3c depicts a bottom perspective view of the liner 130, according to an embodiment of the present disclosure.
[17] Fig. 4a depicts a perspective view of a tibial component 150, according to one or more exemplary embodiments of the present disclosure.
[18] Figs. 4a1 and 4a2 depict fins 151a2 of the tibial component 150, according to one or more exemplary embodiments of the present disclosure.
[19] Fig. 4b depicts a side perspective view of the tibial component 150, according to an embodiment of the present disclosure.
[20] Fig. 4c depicts a side view of the tibial component 150, according to one or more exemplary embodiments of the present disclosure.
[21] Fig. 4d depicts a bottom view of the tibial component 150, according to one or more exemplary embodiments of the present disclosure.
[22] Fig. 4e depicts a side perspective view of the tibial component 150 disposed on a condyle of a tibial bone, according to an embodiment of the present disclosure.
[23] Fig. 5 depicts a cross-sectional side view of the implant 100, according to one or more exemplary embodiment of the present disclosure.
[24] Fig. 5a depicts an interference locking between the liner 130 and the tibial component 150 of the implant 100, according to one or more exemplary embodiment of the present disclosure.
[25] Fig. 5b depicts a dovetail joint between the liner 130 and the tibial component 150 of the implant 100, according to one or more exemplary embodiment of the present disclosure.
[26] Fig. 6 depicts a posterior view of the implant 100 implanted at a knee joint, according to an embodiment of the present disclosure.
DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS
[27] Prior to describing the invention in detail, definitions of certain words or phrases used throughout this patent document will be defined: the terms "include" and "comprise", as well as derivatives thereof, mean inclusion without limitation; the term "or" is inclusive, meaning and/or; the phrases "coupled with" and "associated therewith", as well as derivatives thereof, may mean to include, be included within, interconnect with, contain, be contained within, connect to or with, couple to or with, be communicable with, cooperate with, interleave, juxtapose, be proximate to, be bound to or with, have a property of, or the like. Definitions of certain words and phrases are provided throughout this patent document, and those of ordinary skill in the art will understand that such definitions apply in many, if not most, instances to prior as well as future uses of such defined words and phrases.
[28] Reference throughout this specification to “one embodiment,” “an embodiment,” or similar language means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, appearances of the phrases “in one embodiment,” “in an embodiment,” and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment, but mean “one or more but not all embodiments” unless expressly specified otherwise. The terms “including,” “comprising,” “having,” and variations thereof mean “including but not limited to” unless expressly specified otherwise. An enumerated listing of items does not imply that any or all of the items are mutually exclusive and/or mutually inclusive, unless expressly specified otherwise. The terms “a,” “an,” and “the” also refer to “one or more” unless expressly specified otherwise.
[29] Although the operations of exemplary embodiments of the disclosed method may be described in a particular, sequential order for convenient presentation, it should be understood that the disclosed embodiments can encompass an order of operations other than the particular, sequential order disclosed. For example, operations described sequentially may in some cases be rearranged or performed concurrently. Further, descriptions and disclosures provided in association with one particular embodiment are not limited to that embodiment, and may be applied to any embodiment disclosed herein. Moreover, for the sake of simplicity, the attached figures may not show the various ways in which the disclosed system, method, and apparatus can be used in combination with other systems, methods, and apparatuses.
[30] Furthermore, the described features, advantages, and characteristics of the embodiments may be combined in any suitable manner. One skilled in the relevant art will recognize that the embodiments may be practiced without one or more of the specific features or advantages of a particular embodiment. In other instances, additional features and advantages may be recognized in certain embodiments that may not be present in all embodiments. These features and advantages of the embodiments will become more fully apparent from the following description and apportioned claims, or may be learned by the practice of embodiments as set forth hereinafter.
[31] The present invention discloses a knee replacement implant (or implant) which replaces at least one compartment of the knee (usually the medial or lateral) due to one or more conditions like, but not limited to, infections, trauma, osteoarthritis, rheumatoid arthritis, avascular neurosis, etc. In an embodiment, the implant includes a femoral component, a liner and a tibial component.
[32] Unlike the conventional implants which require resection of the natural knee joint, the implant of the present disclosure may be used to replace an affected portion of at least one of the compartments of the knee joint. The implant of the present disclosure helps to preserve the natural bone as surgery is performed on only the affected portion of the natural knee (also known as uni-compartmental) and not the entire knee. For example, the implant may be placed in the medial compartment of the knee joint in case where the medial condyle of the distal femur bone and/or the medial condyle of the superior tibial bone is affected. Similarly, the implant may be placed in the lateral compartment of the knee joint where the lateral condyle of the distal femur bone and/or the lateral condyle of the superior tibial bone is affected.
[33] Further, the present disclosure provides a secure locking mechanism that locks the liner and the tibial component of the implant. The secure locking mechanism ensures that the liner and the tibial component of the implant remain firmly in place. This reduces the risk of dislocation, enhancing the implant’s function and longevity. The secure locking mechanism further helps to distribute mechanical load evenly thus, minimizing stress concentration in the knee joint. Further, the secure locking mechanism between the liner and tibial component, eliminates the need for external adhesives or chemicals to achieve the lock between the two, thereby eliminating any exposure of foreign substances to human anatomy and possibilities of infections, etc.
[34] The implant of the present disclosure has been explained in the context of replacing the medial condyle part of the knee joint (including medial condyle of distal femur bone and the medial condyle of the superior tibial bone). However, the description is not intended to limit the implant’ application solely to the medial condyle of the knee joint. The implant may be extended to replace the lateral condyle of the knee joint (including lateral condyle of distal femur bone and the lateral condyle of the superior tibial bone).
[35] Now referring to the figures, Fig. 1 depicts an assembled view of an exemplary implant 100, according to an embodiment of the present invention. The implant 100 includes a femoral component 110, a liner 130 and a tibial component 150. In an exemplary embodiment, the femoral component 110 is implanted to a femur bone (not shown) and the tibial component 150 is implanted to a tibia bone (not shown). The liner 130 is coupled to the tibial component 150 such that the liner 130 provides a bearing surface for gliding movement of the femoral component 110 when there is relative movement between the femur and the tibia bone.
[36] Figs. 2a and 2b depict the femoral component 110, according to an embodiment of the present disclosure. The femoral component 110 may have a shape and dimensions complementing distal and posterior face of the condyle of the distal femur bone. In an exemplary embodiment, as shown in Fig. 2a, the femoral component 110 has a curvature that may be J-like shape or C-like shape. The femoral component 110 may be made of one or more biocompatible materials including, but not limited to, titanium, cobalt chromium, stainless steel 316, etc. In an exemplary embodiment, the femoral component 110 is made of cobalt chromium.
[37] As shown in Fig. 2a, the femoral component 110 includes an anterior face 111 and a posterior face 113. The anterior face 111 is configured to articulate with the liner 130 (described later). In an exemplary embodiment, as shown in Fig. 2a, the anterior face 111 includes a convex-shaped surface that contours the natural curved anatomy of the condyle. In an exemplary embodiment, the anterior face 111 is polished to provide a smooth surface for the gliding movement.
[38] The posterior face 113 of the femoral component 110 includes a stepped configuration defined by at least three portions, namely, a first portion 113a, a second portion 113b and a third portion 113c, as shown in Fig. 2b. The second portion 113b connects the first portion 113a to the third portion 113c. The first portion 113a is angled relative to the second portion 113b at a first predefined angle ‘a’. The third portion 113c is angled relative to the second portion 113b at a second predefined angle ‘b’. The first predefined angle ‘a’ and the second predefined angle ‘b’ may vary depending upon the anatomy of the condyle.
[39] As shown in Fig. 2c, in an exemplary embodiment, the first portion 113a, after implantation, is disposed on a distal face of a condyle of the distal femur bone. In an exemplary embodiment, the third portion 113c, after implantation, is disposed on a posterior face of the condyle of the distal femur bone.
[40] The stepped configuration of the posterior face 113 of the femoral component 110 helps in bone preservation and easy preparation of the femur bone for implantation of the femoral component 110.
[41] The posterior face 113 may be provided with one or more protrusions. The one or more protrusions extend posteriorly from the posterior face 113 of the femoral component 110. The one or more protrusion may extend from the posterior face 113 at a predefined angle. The predefined angle corresponds to an anatomy of the femur bone. The one or more protrusion may have a shape including, but not limited to, cylindrical, rectangle, pyramid, cone, etc.
[42] In an exemplary embodiment, the one or more protrusion on the posterior face 113 of the femoral component 110 includes a first protrusion 115a and a second protrusion 115b. In an exemplary embodiment, as shown in Figs. 2a and 2b, the first portion 113a of the posterior face 113 includes one first protrusion 115a. It should be understood though that the first portion 113a may include more than one first protrusion 115a. The second protrusion 115b is disposed over a partial portion of the first portion 113a and a partial portion of the second portion 113b. In other words, the second protrusion 115b is disposed at a point where the first portion 113a and the second portion 113b are connected. The first and second protrusions 115a, 115b provide good primary and rotational stability to the femoral component 110. Structurally, the first protrusion 115a and the second protrusion 115b may be the same or different. In an exemplary embodiment, as shown in Figs. 2a and 2b, the first protrusion 115a and the second protrusion 115b are cylindrically shaped, though they may have different shapes.
[43] The first protrusion 115a and the second protrusion 115b may have a pre-defined dimension including, length, thickness etc., corresponding to the anatomical structure of the condyle of the distal femur. The first protrusion 115a and the second protrusion 115b extend posteriorly from the respective positions at a respective pre-defined angle. The pre-defined angle defined by the first protrusion 115a with the first portion 113a and the predefined angle defined by the second protrusion 115b with the first portion 113a correspond to the anatomical structure of the femur bone. The angles defined by the first and second protrusions 115a, 115b with the first portion 113a help in automatic pressing of the stepped configuration of the posterior face 113 of the femoral component 110 into the distal face of the condyle of the distal femur at the time of implantation. The pre-defined angle defined by the first protrusion 115a with the first portion 113a and the predefined angle defined by the second protrusion 115b with the first portion 113a may be the same or different. The predefined angle defined by the first protrusion 115a and the second protrusion 115b with respect to the first portion 113a may range between 0° to 45°. In an exemplary embodiment, the pre-defined angle defined by the first protrusion 115a with the first portion 113a and the predefined angle defined by the second protrusion 115b with the first portion 113a is 10°.
[44] Additionally, at least a portion of the first protrusion 115a and at least a portion of the second protrusion 115b may have one or more indentations. The first protrusion 115a and the second protrusion 115b may have the same or different number of indentations. In the depicted embodiment, both the first protrusion 115a and the second protrusion 115b include four indentations each. It should be understood though that the first protrusion 115a and the second protrusion 115b may have more/less than four indentations. The one or more indentations may be carved in any suitable pattern. The one or more indentations may be formed using techniques, such as, without limitation, laser cut, machining, etc. In the depicted embodiment, the one or more indentations of the first protrusion 115a and the one or more indentations of the second protrusion 115b have the same pattern, though they may have different pattern. The one or more indentations help in attaching the femoral component 110 to the distal femoral bone. Further, they provide stability and prevent the shifting or loosening of the femoral component 110 over time.
[45] As shown in Fig. 2b, the posterior face 113 of the femoral component 110 having the first portion 113a, the second portion 113b and the third portion 113c are respectively provided with a first section 113a1, a second section 113b1 and a third section 113c1. The first, second and third section 113a1, 113b1, 113c1 provide better fixation of the femoral component 110 with the femur bone.
[46] In an exemplary embodiment, for cemented implantation, the first section 113a1, the second section 113b1 and the third section 113c1 are in the form of pockets and are filled with cement before implantation of the tibial component 150 for stability.
[47] In an alternate embodiment, for cementless implantation, the first section 113a1, the second section 113b1 and the third section 113c1 are made of 3D lattice structures for bone in-growth.
[48] The femoral component 110 may be provided with one or more slots 117 (as shown in Fig. 2b). In an exemplary embodiment, as shown in Fig. 2b, the femoral component 110 is provided with two slots 117 adjacent to the first portion 113a. The slots 117 enable the user to better hold the femoral component 110 during insertion and extraction procedures of the implant 100.
[49] Fig. 3a depicts the liner 130, according to an embodiment of the present disclosure. The liner 130 may have a shape corresponding to the tibial component 150. In an embodiment, the liner 130 has a D-shape. The liner 130 has dimensions corresponding to the tibial component 150 (described later). The liner 130 may be made of a biocompatible material including, but not limited to, ultra-high molecular weight polyethylene (UHMWPE), polymethyl methacrylate (PMMA), highly cross-linked polyethylene including vitamin E (HXLPE), etc. In an exemplary embodiment, the liner 130 is made up of UHMWPE.
[50] As shown in Figs. 3a and 3b, the liner 130 includes a top portion 131 and a bottom portion 133. The top portion 131 provides structural support to the femoral component 110 of the implant 100.
[51] As shown in Fig. 3a, the top portion 131 defines a bearing surface 131a and an edge 131b surrounding the bearing surface 131a. In an exemplary embodiment, as shown in Fig. 3b, the bearing surface 131a has a concave structure corresponding to the convex-shaped anterior face 111 of the femoral component 110. The anterior face 111 is configured to articulate with the bearing surface 131a. The bearing surface 131a allows the anterior face 111 to articulate. In an embodiment, the edge 131b tapers downwards gradually. In an exemplary embodiment, both the bearing surface 131a and the edge 131b have smooth surfaces, giving the object a polished finish. The bearing surface 131a facilitates the gliding movement of the femoral component 110 on the liner 130 via an interaction between the anterior face 111 of the femoral component 110 and the bearing surface 131a of the liner 130. The refined finish of the edge 131b reduces friction with surrounding tissues, thereby reducing the trauma to the surrounding tissues.
[52] The bottom portion 133 of the liner 130 is coupled with the tibial component 150 (described later).
[53] As shown in Fig. 3b, the liner 130 includes a posterior end 130a and an anterior end 130b. In an embodiment, the bottom portion 133 extends away from a bottom surface of the top portion 131 of the liner 130. The bottom portion 133 is configured to be seated over a base plate 151 of the tibial component 150 for effective locking of the liner 130 with the tibial component 150, as described below. The bottom portion 133 has a predefined dimensions and a predefined shape. The predefined dimensions and predefined shape of the bottom portion 133 may vary depending on the shape and dimensions of the base plate 151 of the tibial component 150. In an embodiment, the bottom portion 133 includes an asymmetric shape, e.g., a nearly D-like shape, though the bottom portion 133 may have a symmetrical shape including, but not limited to, circular, oval, square, rectangle, etc.
[54] In an exemplary embodiment, the bottom portion 133 includes a first liner side 133a, a second liner side 133b, a third liner side 133c, a fourth liner side 133d, a fifth liner side 133e and a sixth liner side 133f, as shown in Fig. 3c. In an embodiment, the first liner side 133a and the second liner side 133b are provided towards the posterior end 130a of the liner 130. The fourth liner side 133d and the fifth liner side 133e are provided towards the anterior end 130b of the liner 130. In an embodiment, the structural geometries of the first liner side 133a, the second liner side 133b, the third liner side 133c, the fourth liner side 133d, the fifth liner side 133e and the sixth liner side 133f are asymmetric with respect to each other, thus forming the asymmetric shape of the bottom portion 133. The asymmetric shape of the bottom portion 133 provides an effective locking between liner 130 and the tibial component 150 and prevents movement of the liner 130 with respect to the tibial component 150, thereby enhancing the longevity of the implant 100.
[55] The bottom portion 133 includes at least one of: a first dovetail structures and chamfer cut. In an embodiment, the bottom portion 133 includes the first dovetail structure at the posterior end 130a and the chamfer cut at the anterior end 130b of the liner 130. The bottom portion 133 may include at least one additional first dovetail structure and at least one additional chamfer cut.
[56] For example, in an embodiment, the first liner side 133a includes a slant portion followed by a curved portion. The curved portion of the first liner side 133a is followed by the second liner side 133b. The second liner side 133b includes a vertical portion followed by a curved portion. The first liner side 133a and the second liner side 133b, towards the posterior end 130a, are angled relative to the bottom portion 133 at a predefined angle, thereby forming the first dovetail structure. The predefined angle may vary depending upon the height of the bottom portion 133. The first dovetail structure helps the liner 130 to be securely coupled with the tibial component 150, described later.
[57] The curved portion of the second liner side 133b is followed by the third liner side 133c. The third liner side 133c includes a vertical portion followed by a curved portion. The third liner side 133c is configured to mate with a corresponding portion provided within a base plate 151 of the tibial component 150, as described later.
[58] The curved portion of the third liner side 133c is followed by the fourth liner side 133d. The fourth liner side 133d includes a horizontal portion followed by a curved portion. The curved portion of the fourth liner side 133d is followed by the fifth liner side 133e. In an embodiment, the fifth liner side 133e includes a slant portion followed by a curved portion. The fourth liner side 133d and the fifth liner side 133e, at the anterior end 130b, includes a chamfered portion each, forming the chamfered cut. The chamfer cut formed by the fourth liner side 133d and the fifth liner side 133e enables in easy coupling of the liner 130 with the tibial component 150, described later.
[59] The curved portion of the fifth liner side 133e is followed by the sixth liner side 133f. In an embodiment, the sixth liner side 133f includes a horizontal portion and a curved portion. The curved portion of the sixth liner side 133f is followed by the slant portion of the first liner side 133a. The sixth liner side 133f is configured to mate with a corresponding portion provided within a base plate 151 of the tibial component 150, as described later.
[60] Figs. 4a and 4b depict the tibial component 150, according to an embodiment of the present disclosure. The tibial component 150 may have a shape and dimensions complementing a superior face of the condyle of the tibia bone. In an exemplary embodiment, as shown in Fig. 4a, the tibial component 150 has a D-like shape having a straight side 150d and a semi-circular side. The tibial component 150 may be made of a biocompatible material including but not limited to titanium, cobalt chromium, Stainless Steel 316, etc. In an exemplary embodiment, the tibial component 150 is made up of titanium. The tibial component 150 has an anterior end 150a and a posterior end 150b. In an exemplary embodiment, as shown in Figs. 4a and 4d, a curved periphery 150c of the tibial component 150 is asymmetric anatomically shaped for optimum bone coverage.
[61] The tibial component 150 includes a base plate 151, as shown in Fig. 4a. The base plate 151 may include a wall 151a defining a periphery of the base plate 151. Towards the anterior end 150a, the wall 151a may include one or more chamfered corners 151a0 to reduce risk of patella impingement. Alternatively, or in addition, the one or more chamfered corner 151a0 may be provided towards the anterior end 150a of the tibial component 150.
[62] The wall 151a of the base plate 151 defines a cavity 151b configured to receive the bottom portion 133 of the liner 130. The cavity 151b may have a predefined dimensions corresponding to the dimensions of the bottom portion 133.
[63] An inner side 151a1 of the wall 151a of the base plate 151 is carved in such a way that the bottom portion 133 of the liner 130 snugly fits into the cavity 151b of the tibial component 150. In an embodiment, the inner side 151a1 of the wall 151a includes at least one of: a second dovetail structure and one or more fins 151a2 complementary to the first dovetail structure and the chamfer cut of the bottom portion 133 on the liner 130, respectively, that snugly fits upon assembly. In an embodiment, the second dovetail structure and the one or more fins 151a2 are provided at the posterior end 150b and the anterior end 150a of the tibial component 150.
[64] For example, in an embodiment, the inner side 151a1 of the wall 151a includes a first wall side 152a, a second wall side 152b, a third wall side 152c, a fourth wall side 152d, a fifth wall side 152e and a sixth wall side 152f, as shown in Figs. 4a and 4b. The first wall side 152a and the second wall side 152b are provided towards the posterior end 150b of the tibial component 150. The fourth wall side 152d and the fifth wall side 152e are provided towards the anterior end 150a of the tibial component 150. In an embodiment, each side of the wall 151a is configured to receive a corresponding side of the bottom portion 133. For example, the first wall side 152a and the second wall side 152b of the wall 151a are configured to receive the first liner side 133a and the second liner side 133b, respectively, as shown in Figs. 4a and 4b. In an embodiment, the first wall side 152a and the second wall side 152b are carved to form the second dovetail structure. The second dovetail structure of the tibial component 150 corresponds to the first dovetail structure formed by the first liner side 133a and the second liner side 133b of the bottom portion 133 in the liner 130. The second dovetail structure of the tibial component 150 is configured to mate with the first dovetail structure of the liner 130, thereby forming a dovetail joint (described later) between the liner 130 and the tibial component 150. This helps in securely coupling the liner 130 and the tibial component 150. Although the coupling between the liner 130 and the tibial component 150 is described with the help of a single dovetail joint, more than one dovetail joint may be used. For example, the inner side 151a1 of the wall 151a may include at least one additional second dovetail structure configured to mate with the corresponding at least one first additional dovetail structure of the bottom portion 133, forming respective dovetail joints. Additionally, the use of one or more dovetail joints in combination with other functionally equivalent locking mechanism are in the scope of the teachings of the present disclosure.
[65] The one or more fins 151a2 provided in the inner side 151a1 of the wall 151a are configured to form an interference lock with the chamfer cut of the liner 130. As shown in Figs. 4a1 and 4a2, in an embodiment, the wall 151a is provided with two fins 151a2 projecting towards the cavity 151b of the base plate 151 of the tibial component 150. In the depicted embodiment, one fin 151a2 is provided on the fourth wall side 152d and another fin 151a2 is provided on the fifth wall side 152e. The anterior end 130b of the liner 130 is coupled within the cavity 151b of the base plate 151 of the tibial component 150 via the fins 151a2, thus forming the interference lock between the one or more fins 151a2 and the chamfer cut of the liner 130. In other words, the geometry of the fin 151a2 on the fourth wall side 152d corresponds to the chamfered portion of the fourth liner side 133d of the bottom portion 133, and the geometry of the fin 151a2 on the fifth wall side 152e corresponds to the chamfered portion of the fourth liner side 133d and the fifth liner side 133e of the bottom portion 133. In an exemplary embodiment, the fins 151a2 are used for interference locking (described later) the liner 130 with the tibial component 150.
[66] It is to be noted that using more/less than two fins 151a2 or other functionally equivalent structure to secure the anterior end 130b of the liner 130 to the base plate 151 of the tibial component 150 are within the scope of the teachings of the present disclosure.
[67] The inner side 151a1 of the wall 151a may include at least one or more additional fins configured to form an interference lock with the at least with the at least one additional chamfer cut of the bottom portion 133.
[68] The third wall side 152c and the sixth wall side 152f are carved such a way that their dimensions correspond to the third liner side 133c and the sixth liner side 133f, respectively, of the bottom portion 133 of the liner 130, respectively. The third wall side 152c and the sixth wall side 152f are configured to mate with the third liner side 133c and the sixth liner side 133f of the bottom portion 133, upon assembling the liner 130 with the tibial component 150.
[69] As shown in Figs. 4c and 4d, a bottom surface of the base plate 151 may include at least one of: at least one keel 153, and one or more pegs. In the depicted embodiment, the base plate 151 includes one keel 153. In an embodiment, the keel 153 extends away from the bottom surface of the base plate 151. For example, the keel 153 may be situated such that the keel 153 is aligned with the straight side 150d of the base plate 151. In an exemplary embodiment, as shown in Fig. 4a, the keel 153 has a shark fin-like shape, though the keel 153 may have any other shape. The keel 153 interacts with the tibia bone to provide rotational stability to the tibial component 150. In an exemplary embodiment, not shown, the keel 153 has a curved surface for better fixation with the tibia bone.
[70] The one or more pegs extend away from the bottom surface of the base plate 151. In an exemplary embodiment, as shown in Fig. 4d, the bottom surface of the base plate 151 is provided with a first peg 155a and a second peg 155b, though, the tibial component 150 may include more/less than two pegs. The first peg 155a may be disposed anterior to the second peg 155b.
[71] The first and second pegs 155a, 155b may have a pre-defined shape including, but not limited to cylindrical, hourglass, rectangle, square, cone, pyramid, etc. In an exemplary embodiment, the first and second pegs 155a, 155b are hourglass shaped for improved cement interlock. The first and second pegs 155a, 155b provides good primary and rotational stability.
[72] The bottom surface of the tibial component 150 includes a plurality of sections 157. The sections 157 are spread across at least a portion of the bottom surface of the tibial component 150. In an exemplary embodiment, the tibial component 150 is provided with five sections 157 spread across the entire bottom surface of the base plate 151. The sections 157 help in better fixation of the tibial component 150 with the bone.
[73] In an exemplary embodiment, for cemented implantation, the sections 157 are in the form of pockets and are filled with cement before implantation of the tibial component 150 for stability. In an alternate embodiment, for cementless implantation, the sections 157 are made of 3D lattice structures for bone in growth.
[74] As shown in Fig. 4e, in an exemplary embodiment, the tibial component 150, after implantation, is disposed on a medial of a condyle of the superior tibial bone.
[75] Fig. 5 depicts a cross-sectional assembled view of the implant 100 illustrating the coupling between the liner 130 and the tibial component 150. In an exemplary embodiment, the posterior end 130a of the liner 130 is first coupled to the posterior end 150b of the tibial component 150 via the dovetail joint and then the liner 130 is hammered within the cavity 151b of the tibial component 150 to provide the interference locking at the anterior ends 130b, 150a.
[76] In an exemplary embodiment, as shown in Fig. 5a, after interference locking, the one or more fins 151a2 are lodged inside the bottom portion 133 of the liner 130.
[77] In an exemplary embodiment, as shown in Fig. 5b, after forming the dovetail joint, the first dovetail structure formed by the first liner side 133a and the second liner side 133b of the liner 130 interlocks with the second dovetail structure formed by the first wall side 152a and the second wall side 152b of the wall 151a of the tibial component 150.
[78] During the implantation procedure (or during a pre-operative assessment phase), a surgeon may accurately assess the patient’s distal femur bone’s anatomy, identify optimal place/places in the condyle (medial or lateral) where the one or more protrusions of the femoral component 110 (e.g., the first protrusion 115a and the second protrusion 115b) could be placed for fixing the femoral component 110 in the distal femoral bone. Based on the assessment, the surgeon prepares the patient’s condyle of the distal femur bone surface during the implantation procedure by removing damaged or diseased tissue, ensuring a clean and stable surface for implantation. Similarly, the surgeon may accurately assess the patient’s superior tibial bone’s anatomy, identify optimal place/places in the condyle (medial/lateral) where the one or more pegs of the tibial component 150 (e.g., the first peg 155a and the second peg 155b) could be placed for fixing the assembly of the liner 130 and the tibial component 150 in the superior tibial bone. Subsequently, the surgeon prepares bone cement and applies it onto the prepared surface of the distal femur bone and the superior tibial bone. In the orthopedic surgical procedure, cemented fixation is commonly used, particularly in the joint replacement surgeries such as uni-compartmental arthroplasty or partial knee replacement. Once the bone cement is applied, the one or more projections of the femoral component 110 are pressed into the prepared surface of the condyle (medial/lateral) in the distal femur bone, and the one or more pegs of the tibial component 150 are pressed into the prepared surface of the condyle (medial/lateral) in the superior tibial bone, as shown in Fig. 6. The cement acts as an intermediary layer between the bone and the implant 100, providing stability and fixation. The one or more indentations on the one or more projection of the femoral component 110 and the one or more and the hourglass shape of the one or more pegs of the tibial component 150 enhance fixation and ensure firm stability of the implant 100 within the respective prepared positions. The bone cement is allowed to cure and harden. During this time, the surgeon may maintain pressure on the implant 100 to ensure optimal fixation and adherence to the bone.
[79] After the tibial component 150 is implanted, the liner 130 is inserted in between the femoral component 110 and the tibial component 150. The dovetail features of both the liner 130 and the tibial component 150 mates with each other to form the dovetail joint. After which, the liner 130 is hammered on the anterior end 130b to form interference locking between the liner 130 and the tibial component 150, as the fins 151a2 of the tibial component 150 gets lodged in the bottom portion 133 of the liner 130.
[80] Due to the firm locking of the liner 130 with the tibial component 150, the risk of inadequate displacement or loosening of the implant 100 is reduced. Consequently, the stability and functionality of the implant 100 improves and increases the longevity of the implant 100. And, the overall patient outcome is improved.
[81] The scope of the invention is only limited by the appended patent claims. More generally, those skilled in the art will readily appreciate that all parameters, dimensions, materials, and configurations described herein are meant to be exemplary and that the actual parameters, dimensions, materials, and/or configurations will depend upon the specific application or applications for which the teachings of the present invention is/are used. ,CLAIMS:
WE CLAIM
1. An implant (100) comprising:
a. a liner (130) comprising a top portion (131) having a bearing surface (131a) and a bottom portion (133) comprising at least one of: a first dovetail structure and a chamfer cut; and
b. a tibial component (150) comprising a base plate (151) having a wall (151a) and a cavity (151b) configured to receive the bottom portion (133) of the liner (130), the wall (151a) having an inner side (151a1) comprising at least one of: a second dovetail structure configured to mate with the first dovetail structure, forming a dovetail joint, and one or more fins (151a2) configured to form an interference lock with the chamfer cut.
2. The implant (100) as claimed in claim 1, wherein the first dovetail structure is provided towards a posterior end (130a) of the liner (130) and the chamfer cut is provided towards an anterior end (130b) of the liner (130), and wherein the second dovetail structure is provided towards a posterior end (150b) of the tibial component (150) and the one or more fins (151a2) are provided towards an anterior end (150a) of the tibial component (150).
3. The implant (100) as claimed in claim 1, wherein:
a. the bottom portion (133) comprises a first liner side (133a) and a second liner side (133b) disposed towards a posterior end (130a) of the liner (130), the first liner side (133a) and the second liner side (133b) are angled relative to a bottom surface of the top portion (131), thereby forming the first dovetail structure; and
b. the inner side (151a1) of the wall (151a) comprises a first wall side (152a) and a second wall side (152b) disposed towards a posterior end (150b) of the tibial component (150) and configured to receive the first liner side (133a) and the second liner side (133b), respectively, wherein the first wall side (152a) and the second wall side (152b) are carved to form the second dovetail structure.
4. The implant (100) as claimed in claim 1, wherein
a. the bottom portion (133) comprises a fourth liner side (133d) and a fifth liner side (133e) disposed towards an anterior end (130b) of the liner (130), wherein each of the fourth liner side (133d) and the fifth liner side (133e) is provided with a chamfered portion, forming the chamfered cut; and
b. the inner side (151a1) of the wall (151a) comprises a fourth wall side (152d) and a fifth wall side (152e) disposed towards an anterior end (150a) of the tibial component (150), wherein each of the fourth wall side (152d) and the fifth wall side (152e) is provided with a fin (151a2) of the one or more fins (151a2) corresponding to the chamfered portion of the fourth liner side (133d) and the fifth liner side (133e), respectively;
c. wherein when the liner (130) and the tibial component (150) are assembled, the one or more fins (151a2) are lodged inside the bottom portion (133).
5. The implant (100) as claimed in claim 1, wherein the bottom portion (133) comprises at least one additional first dovetail structure and the inner side (151a1) of the wall (151a) comprises at least one second additional dovetail structure configured to mate with the corresponding at least one first additional dovetail structure of the bottom portion (133).
6. The implant (100) as claimed in claim 1, wherein the bottom portion (133) comprises at least one additional chamfer cut and the inner side (151a1) of the wall (151a) comprises one or more additional fins configured to form an interference lock with the at least one additional chamfer cut of the bottom portion (133).
7. The implant (100) as claimed in claim 1, wherein:
a. the bottom portion (133) comprise a third liner side (133c) and a sixth liner side (133f); and
b. the inner side (151a1) of the wall (151a) comprise a third wall side (152c) and a sixth wall side (152f) configured to mate with the third liner side (133c) and the sixth liner side (133f), respectively.
8. The implant (100) as claimed in claim 1, wherein the wall (151a) comprises one or more chamfered corners (151a0) provided towards an anterior end (150a) of the tibial component (150) or a posterior end (150b) of the tibial component (150).
9. The implant (100) as claimed in claim 1, wherein the implant (100) comprises a femoral component (110) comprising:
a. an anterior face (111) configured to articulate with the bearing surface (131a) of the liner (130);
b. a posterior face (113) having a first portion (113a), a second portion (113b) and a third portion (113c), wherein the second portion (113b) connects the first portion (113a) and the third portion (113c), wherein the first portion (113a) is angled relative to the second portion (113b) at a first pre-defined angle ‘a’ and the third portion (113c) is angled relative to the second portion (113b) at a second pre-defined angle ‘b’; and
c. one or more protrusions extending posteriorly from the posterior face (113).
10. The implant (100) as claimed in claim 9, wherein the one or more protrusions comprises:
a. a first protrusion (115a) disposed on the first portion (113a); and
b. a second protrusion (115b) disposed over a partial portion of the first portion (113a) and a partial portion of the second portion (113b),
c. wherein the first protrusion (115a) and the second protrusion (115b) define a respective pre-defined angle with the first portion (113a) .
11. The implant (100) as claimed in claim 9, wherein the first portion (113a), the second portion (113b) and the third portion (113c) are provided with a first section (113a1), a second section (113b1) and a third section (113c1), respectively, facilitating fixation of the femoral component (110) with the femur.
12. The implant (100) as claimed in claim 1, wherein the tibial component (150) comprises at least one of:
a. at least one keel (153) extending away from the bottom surface of the base plate (151); and
b. one or more pegs extending away from the bottom surface of the base plate (151).
13. The implant (100) as claimed in claim 1, wherein a plurality of sections (157) is provided on a bottom surface of the tibial component (150).