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:
TIBIAL PROSTHESIS

2. APPLICANT:
Meril Corporation (I) Private Limited, an Indian company of the address Survey No. 135/139, Muktanand Marg, Bilakhia House, Pardi, Vapi, Valsad-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 a medical prosthesis. More particularly, the present disclosure relates to a tibial prosthesis.
BACKGROUND
[2] Knee replacement surgery, also known as knee arthroplasty, is a medical procedure aimed at relieving pain and restoring function in severely damaged knee joints. This procedure is typically considered when conservative treatments like medication and physiotherapy no longer provide adequate relief from pain and immobility caused by conditions, such as, osteoarthritis, rheumatoid arthritis, or traumatic injury.
[3] Knee arthroplasty encompasses two types of surgery, namely, total knee replacement and unicompartmental knee replacement. Total knee replacement involves replacing the entire knee joint with prosthetic components such as, for example, a femoral component, a tibial component, a patellar component and a liner. On the other hand, unicompartmental knee replacement, also known as partial knee replacement, targets replacing only affected portion of knee joint. For example, if one side of the tibial joint is affected, the affected part is replaced with prosthetic components such as, for example, a tibial prosthesis having a tibial component and a tibial liner.
[4] In unicompartmental knee arthroplasty, upon implementation, the tibial component acts as a natural tibial joint and the tibial liner act as a cushion between the tibial component and other natural joints and/or prosthesis joints. The tibial liner is coupled with the tibial component. It is critical that the tibial liner remains in place and provides a smooth articulating surface for other natural joints and/or prosthesis joint.
[5] Various tibial liners and tibial components are currently available; however, conventional tibial liners heavily suffer from problems, such as, dislocation, wear and premature failure, etc. due to improper or loose coupling and/or locking with the tibial components. This may lead to a revision surgery, which not only increases the patient’s trauma but also their medical costs.
[6] Additionally, conventional tibial liners are impacted over the tibial component to create a proper fit between the two. However, impacting involves several risks, such as, damage to tibial liners, improper alignment, tissue damage, implant fracture, loosening, etc.
[7] Thus, there arises a need for a tibial prosthesis that overcomes the problems associated with the conventional prosthesis.
SUMMARY OF THE INVENTION
[8] 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.
[9] The present disclosure relates to a tibial prosthesis. In an embodiment, the tibial prosthesis includes a tibial component, a tibial liner and a locking member. The tibial component includes a base and a wall. The wall is provided along a periphery of the base and defines a cavity. A cut-out is provided in the wall extending from an inner surface of the wall to an outer face of the wall. The tibial liner includes a protrusion provided on a bottom surface of the tibial liner. The protrusion is configured to fit within the cavity. The protrusion includes a first slot. The locking member is configured to lock the tibial liner with the tibial component. The locking member includes a first coupling portion configured to seat within the cut-out of the tibial component and a second coupling portion configured to fit within the first slot of the tibial liner.
BRIEF DESCRIPTION OF DRAWINGS
[10] 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.
[11] Fig. 1a depicts an assembled view of a tibial prosthesis 100, in accordance with an embodiment of the present disclosure.
[12] Fig. 1b depicts an exploded view of the tibial prosthesis 100, in accordance with an embodiment of the present disclosure.
[13] Fig. 1c depicts a top cross-sectional view of the tibial prosthesis 100, in accordance with an embodiment of the present disclosure.
[14] Fig. 2a depicts a top perspective view of a tibial component 110 of the tibial prosthesis 100, in accordance with an embodiment of the present disclosure.
[15] Fig. 2b depicts an enlarged view of a cut-out 113 of the tibial component 110, according to the embodiment of the present disclosure.
[16] Figs. 2c – 2d depicts various perspective views of the tibial component 110 showing different sides of an inner surface 115, according to the embodiment of the present disclosure.
[17] Fig. 2e depicts a bottom perspective view of the tibial component 110, according to the embodiment of the present disclosure.
[18] Figs. 3a - 3b depict various views of a locking member 120 of the tibial prosthesis 100, in accordance with an embodiment of the present disclosure.
[19] Fig. 4a depicts a perspective view of a tibial liner 130, according to the embodiment of the present disclosure.
[20] Fig. 4b depicts a bottom perspective view of the tibial liner 130, according to an embodiment of the present disclosure.
[21] Fig. 4c depicts another bottom perspective view of the tibial liner 130, according to an embodiment of the present disclosure.
DETAILED DESCRIPTION OF THE DRAWINGS
[22] 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.
[23] 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.
[24] 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.
[25] 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.
[26] The present disclosure discloses a tibial prosthesis assembly. The tibial prosthesis assembly of present disclosure includes a tibial component, a locking member and a tibial liner. The tibial component is securely coupled with the tibial liner using the locking member. This prevents loosening of the coupling between the tibial component and the tibial liner. Consequently, the proposed tibial prosthesis avoids dislocation of the tibial liner from the tibial component. Also, the proposed tibial liner need not to be impacted like conventional tibial prosthesis which coupling with the tibial component. The proposed tibial liner can be placed within the tibial component and can be locked using the locking member. This minimizes the failure chances of the tibial prosthesis due to the impacting and improves patient outcome.
[27] Referring to figures, Fig. 1a depicts an assembled view of a tibial prosthesis 100, Fig. 1b depicts an exploded view of the tibial prosthesis 100 and Fig. 1c depicts a top cross-sectional view of the tibial prosthesis 100, according to an embodiment of the present disclosure. The tibial prosthesis 100 is used to replace a damaged or diseased tibial joint during a partial knee replacement surgery. In an embodiment, the tibial prosthesis 100 is used to replace/repair injuries in one half of the tibial joint. The tibial prosthesis 100 mimics the structure and function of the natural tibial joint, allowing or improved mobility and reduced pain. Though the present disclosure has been explained in the context of the partial knee replacement surgery, the teachings of the present disclosure can be applied to a tibial prosthesis in a total knee replacement surgery and the same is within the scope of the present disclosure. The tibial prosthesis 100 includes a tibial component 110, a locking member 120 and a tibial liner 130. The tibial component 110 is coupled to the tibial liner 130 with the help of the locking member 120. The tibial prosthesis 100 includes an anterior end 100a and a posterior end 100b. The anterior end 100a and the posterior end 100b of the tibial prosthesis 100 are designed to align towards the anterior and posterior sides of the tibia, respectively.
[28] It should be understood that the tibial component 110 and the tibial liner 130 illustrated herein are merely exemplary and teachings of the present disclosure can be extended to any suitable tibial components and tibial liners and the same is within the scope of the present disclosure.
[29] Fig. 2a depicts the tibial component 110, according to an embodiment of the present disclosure. The tibial component 110 replaces the damaged or diseased portion of the tibia (shinbone) in patients suffering from severe knee arthritis or injury. In an embodiment, the tibial component 110 is used to replace one half of the natural tibial joint.
[30] The tibial component 110 includes a predefined shape and predefined dimensions. In an embodiment, the tibial component 110 has a D-shape, though it may have any other suitable shape. The predefined dimensions of the tibial component 110 may vary depending upon the patient’s anatomy. The tibial component 110 may be made of a biocompatible material including, but not limited to, cobalt-chromium (Co-Cr), titanium, stainless steel, etc. In an embodiment, the tibial component 110 is made of cobalt-chromium (Co-Cr).
[31] The tibial component 110 includes a base 111a and a wall 110a provided along a periphery of the base 111a of the tibial component 110. The wall 110a defines a cavity 111 in the tibial component 110. The cavity 111 is configured to receive a portion of the tibial liner 130 (explained later). The cavity 111 may have a predefined shape and predefined dimensions. In an embodiment, the cavity 111 is D-shaped, though it may have any other suitable shape (e.g., elliptical, square, rectangular, hexagonal, etc.). The predefined dimensions of the cavity 111 may vary depending upon the portion of the tibial liner 130 to be received by the cavity 111.
[32] The wall 110a includes an inner surface 115. The inner surface 115 of the wall 110a may be sculpted uniformly or non-uniformly. In an embodiment, the inner surface 115 of the wall 110a is sculpted non-uniformly (or asymmetrically). This facilitates easier insertion of the tibial liner 130 into the tibial component 110 and provides a better fixation therebetween. In an exemplary embodiment, the inner surface 115 includes six sides, namely, a first side 115a, a second side 115b, a third side 115c, a fourth side 115d, a fifth side 115e, and a sixth side 115f.
[33] In an embodiment, the third side 115c and the fourth side 115d are provided towards the posterior end 100b of the tibial prosthesis 100. The first side 115a and the sixth side 115f are provided towards the anterior end 100a of the tibial prosthesis 100. In an embodiment, the structural geometries of the first side 115a, the second side 115b, the third side 115c, the fourth side 115d, the fifth side 115e, and the sixth side 115f are asymmetric with respect to each other, forming the non-uniform structure. The asymmetric geometry of the inner surface 115 provides an effective locking between the tibial component 110 and the tibial liner 130 (explained later).
[34] In an embodiment, the first side 115a includes a straight portion followed by a curved portion. The curved portion of the first side 115a is followed by the second side 115b. The second side 115b (as shown in Fig. 2c) includes a straight portion followed by a curved portion. The curved portion of the second side 115b is followed by the third side 115c. The third side 115c includes a straight portion followed by a curved portion. The curved portion of the third side 115c is followed by the fourth side 115d. The fourth side 115d (as shown in Fig. 2d) includes a slanted portion followed by a curved portion. The curved portion of the fourth side 115d is followed by a fifth side 115e. The fifth side 115e includes a straight portion followed by a curved portion. The curved portion of the fifth side 115e is followed by the sixth side 115f. The sixth side 115f includes a slanted portion and a curved portion. The curved portion of the sixth side 115f smoothly transits into the straight portion of the first side 115a. The curved portion of sixth side 115f is followed by the straight portion of the first side 115a, thereby forming a D-shape.
[35] Optionally, the inner surface 115 may include one or more first dovetail structures. In an embodiment, the inner surface 115 includes one first dovetail structure provided towards the posterior end 100b of the tibial prosthesis 100. At least a portion of one or more of: the second side 115b, the third side 115c and the fourth side 115d are angled relative to the base 111a, forming the first dovetail structure. For example, the curved portion of the second side 115b, the straight portion and the curved portion of the third side 115c, the slanted portion and the curved portion of the fourth side 115d, towards the posterior end 100b, are carved angularly relative to the base 111a of the tibial component 110 at a predefined angle, thus forming the first dovetail structure. The predefined angle may vary depending upon the portion of the tibial liner 130 that is received by the cavity 111 (explained later). The first dovetail structure provides a secure coupling between the tibial component 110 and the tibial liner 130.
[36] The first side 115a, the second side 115b, the third side 115c, the fourth side 115d, the fifth side 115e, and the sixth side 115f are configured to mate with a corresponding portion provided on the tibial liner 130, which has been explained later.
[37] In an embodiment, the tibial component 110 includes a cut-out 113 towards the anterior end 100a of the tibial prosthesis 100. The cut-out 113 is provided in the wall 110a and extends from an inner surface 115 to the outer face of the wall 110a. In the depicted embodiment, the cut-out 113 is provided on the straight portion of the first side 115a of the inner surface 115. The cut-out 113 is configured to receive a portion of the locking member 120 (explained later). In an embodiment, the cut-out 113 includes a first face 113a and a second face 113b, as shown in Fig. 2b. The second face 113b is located opposite to the first face 113a. In an exemplary embodiment, the first face 113a and the second face 113b are symmetrical and are mirror images of each other. In an embodiment, the cut-out 113 includes one or more of: a first ledge 113a1 and a second ledge 113b1. The first ledge 113a1 projects inwards from the first face 113a into the cut-out 113, forming a first recess (not shown). Similarly, the second ledge 113b1 projects inwards from the second face 113b into the cut-out 113, forming a second recess (not shown). The first ledge 113a1 and the second ledge 113b1 may be contiguous with the wall 110a. In the depicted embodiment, the first ledge 113a1 and the second ledge 113b1 are symmetrical and identical. It should be understood though that the first ledge 113a1 and the second ledge 113b1 may be asymmetrical.
[38] The cut-out 113 includes one or more of: a first groove 113a2 or a second groove 113b2 provided on the first ledge 113a1 and the second ledge 113b1, respectively. The first groove 113a2 and the second groove 113b2 extend vertically. The first groove 113a2 and the second groove 113b2 may have a pre-defined shape including, but not limited to, semi-circle, rectangle, square, triangle, frustum, etc. In an exemplary embodiment, the first groove 113a2 and the second groove 113b2 have semi-circular shape. The first groove 113a2 and the second groove 113b2 are configured to receive a corresponding portion of the locking member 120 (explained later).
[39] The tibial component 110 may include one or more pegs 117 and/or at least one keel 119 provided on a bottom surface 110b of the tibial component 110. In an embodiment, the tibial component 110 includes two pegs 117 and a keel 119 integrally extending from the bottom surface 110b of the tibial component 110 as shown in Fig. 2e. The one or more of pegs 117 and the keel 119 ensure a secured coupling of the tibial component 110 with the tibia, which prevents dislocation/de-attachments of the tibial component 110 from the tibia. The pegs 117 and the keel 119 may have any suitable shape based upon the requirements. In an embodiment, the pegs 117 are hour-glass shaped protrusions provided at the bottom surface 110b of tibial component 110 for improved cement interlock. The pegs 117 provide rotational stability to the tibial component 110. In an embodiment, the keel 119 at the bottom surface 110b of tibial component 110 has a fish fin-like shape with a smooth surface. The smooth surface of the keel 119 prevents damages to the surrounding tissues post-implantation.
[40] The bottom surface 110b of the tibial component 110 may include a plurality of the pockets 110c. The pockets 110c are spread across at least a portion of the bottom surface 110b of the tibial component 110. In an exemplary embodiment, the tibial component 110 is provided with five pockets 110c spread across the entire bottom surface 110b of tibial component 110. The pockets 110c help in enhancing the coupling between the tibial component 110 and the tibia bone, thereby improving fixation and stability during implantation.
[41] Figs. 3a and 3b depict various perspective views of the locking member 120, according to an embodiment of the present disclosure. The locking member 120 is configured to securely lock the tibial component 110 with the tibial liner 130. The locking member 120 ensures the stability and longevity of the coupling of the tibial component 110 and the tibial liner 130, and prevents loosening of the tibial liner 130. The locking member 120 is configured to be disposed within the cut-out 113 and the tibial liner 130. The locking member 120 may have a pre-defined shape including, without limitation, U-shape, V-shape, Y-shape, semi-circle, horseshoe, etc. In the depicted embodiment, the locking member 120 generally has a U-shape. In an embodiment, the locking member 120 includes a first coupling portion 121 and a second coupling portion 123.
[42] The first coupling portion 121 is coupled to the tibial component 110. The first coupling portion 121 is configured to seat within the cut-out 113 of the tibial component 110. In an embodiment, the first coupling portion 121 includes a first arm 121a and a second arm 121b spaced apart from the first arm 121a, defining a space 125 therebetween. The first arm 121a and the second arm 121b may be mirror images of each other. The first arm 121a and the second arm 121b include a first face 121d1 and a second face 121d2, respectively. In an embodiment, the first face 121d1 and the second face 121d2 are oblique and slope away from the respective arms (the first arm 121a and the second arm 121b). In another embodiment, the first face 121d1 and the second face 121d2 may be straight.
[43] In an embodiment, the first arm 121a includes a first base 121a4 and a first plate 121c1, and the second arm 121b includes a second base 121b4 and a second plate 121c2. The first base 121a4 and the second base121b4 may have a pre-defined shape, such as, without limitation, rectangle, square, parallelogram, etc. In the depicted embodiment, the first base 121a4 and the second base 121b4 have an inverted L-shape. The first plate 121c1 and the second plate 121c2 are seated on the first base 121a4 and the second base 121b4, respectively. In an embodiment, inner faces of the first base 121a4 and the first plate 121c1 align with each other. Similarly, the inner faces of the second base 121b4 and the second plate 121c2 align with each other. The width of the first plate 121c1 is smaller than the width of the first base 121a4, and the width of the second plate 121c2 is smaller than the width of the second base 121b4, forming a respective step-profile as shown in Fig. 3. The first plate 121c1 and the second plate 121c2 form an integrated structure with the first base 121a4 and the second base 121b4, respectively, though they may be separate components coupled together using a suitable technique. The first base 121a4 and the second base 121b4 are configured to seat within the cut-out 113.
[44] The locking member 120 includes one or more of: a first projection 121b1 or a second projection 121b2 provided on the first plate 121c1 and the second plate 121c2, respectively. The first projection 121b1 extends vertically between a top surface of the first plate 121c1 and a top surface of the first base 121a4. Similarly, the second projection 121b2 extends vertically between a top surface of the second plate 121c2 and a top surface of the second base 121b4. The first projection 121b1 and the second projection 121b2 are configured to fit within the first groove 113a2 and the second groove 113b2 provided on the first ledge 113a1 and the second ledge 113b1, respectively, of the cut-out 113 in the tibial component 110. The shape and dimensions of the first projection 121b1 and the first ledge 113a1, and of the second projection 121b2 and the second ledge 113b1 are complementary to each other. In an embodiment, the first projection 121b1 and the second projection 121b2 have a semi-circular shape. The mating of the first projection 121b1 and the second projection 121b2 with the first groove 113a2 and the second groove 113b2 provides an efficient locking of the tibial component 110 with the locking member 120 and prevents slippage of the locking member 120 from the cut-out 113.
[45] The second coupling portion 123 may have a pre-defined shape, e.g., rectangular, oval, square, frustum, triangular, etc. In an embodiment, the second coupling portion 123 of the locking member 120 has D-shaped structure. In an embodiment, the second coupling portion 123 is disposed within the tibial liner 130 (explained later). According to an embodiment, the second coupling portion 123 extends integrally from the first plate 121c1 and the second plate 121c2, thus giving an overall U-shaped structure to the locking member 120. It is possible though that the second coupling portion 123 is a separate component coupled to the first arm 121a and the second arm 121b using any suitable coupling mechanism.
[46] The space 125 between the first arm 121a and the second arm 121b facilitates insertion and extraction of the locking member 120 as explained later. In an embodiment, the first face 121d1 and a second face 121d2 include a respective hole (namely, a first hole 121e1 and a second hole 121e2). The holes 121e1 and 121e2 are used to hold the locking member 120 using, for example, a plier during insertion and/or extraction of the locking member 120.
[47] The locking member 120 may be made of a biocompatible material including, but not limited to, cobalt-chromium (Co-Cr), titanium, stainless steel, etc. In an embodiment, the locking member 120 is made of cobalt-chromium (Co-Cr).
[48] Figs. 4a – 4c depict the tibial liner 130, according to an embodiment of the present disclosure. The tibial liner 130 replaces the natural cartilage tissues and provides an articulating surface to a femoral component of the knee prosthesis. The tibial liner 130 facilitates smooth movement within the joint, mimicking the natural gliding motion of a healthy knee cartilage. In an embodiment, the tibial liner 130 is used to replace one half of the natural tibial joint.
[49] In an embodiment, the tibial liner 130 has a D-shape, though it may have any other suitable shape. The tibial liner 130 includes a bottom surface 130a and a top surface 130b. The top surface 130b of the tibial liner 130 is configured to articulate with the femoral condyles and/or the femoral component of the knee prosthesis.
[50] The tibial liner 130 includes a protrusion 131 provided on the bottom surface 130a. The protrusion 131 forms an integral structure with the tibial liner 130, for example, the protrusion 131 may be extruded from the bottom surface 130a. The protrusion 131 is configured to fit within the cavity 111 of the tibial component 110 for effective locking of the tibial liner 130 with the tibial component 110, as described below. The shape and dimensions of the protrusion 131 correspond to the shape and dimensions of the cavity 111 so that the protrusion 131 can snugly fit within the cavity 111.
[51] The protrusion 131 includes a plurality of edges (hereinafter, edges). The edges of the protrusion 131 are carved in such a way that the protrusion 131 snugly fits into the cavity 111 of the tibial component 110. In an exemplary embodiment, the protrusion 131 includes six edges, namely, a first edge 131a, a second edge 131b, a third edge 131c, a fourth edge 131d, a fifth edge 131e, and a sixth edge 131f (as shown in Figs. 4b-4c). Each edge (131a-131f) is configured to align and mate with a corresponding side (115a-115f) of the inner surface 115 of the wall 110a. In an embodiment, the protrusion 131 has a non-uniform structure to align with the non-uniform structure of the inner surface 115 of the wall 110a, ensuring an effective and secure locking mechanism between the tibial liner 130 and the tibial component 110. It should be understood though the protrusion 131 may have a uniform structure complementary to the uniform structure of the inner surface 115 of the wall 110a of the tibial component 110.
[52] In an embodiment, the first edge 131a and the sixth edge 131f are provided towards the anterior end 100a of the tibial prosthesis 100. Further, the third edge 131c and the fourth edge 131d are provided towards the posterior end 100b of the tibial prosthesis 100. In an embodiment, the first edge 131a, the second edge 131b, the third edge 131c, the fourth edge 131d, the fifth edge 131e and the sixth edge 131f are configured to engage or mate with the first side 115a, the second side 115b, the third side 115c, the fourth side 115d, the fifth side 115e and the sixth side 115f, respectively.
[53] In an embodiment, the first edge 131a of the protrusion 131 includes a straight portion followed by a curved portion. The curved portion of the first edge 131a transitions smoothly into the second edge 131b. The second edge 131b includes a straight portion followed by a curved portion. The curved portion of the second edge 131b is followed by the third edge 131c. The third edge 131c includes a straight portion followed a curved portion. The curved portion of the third edge 131c is followed by the fourth edge 131d. The fourth edge 131d includes a slant portion followed by a curved portion. The curved portion of the fourth edge 131d is followed by the fifth edge 131e. The fifth edge 131e includes a straight portion followed by a curved portion. The curved portion of the fifth edge 131e is followed by the sixth edge 131f. The sixth edge 131f includes a slant portion followed by a curved portion. The curved portion of the sixth edge 131f connects to the straight portion of the first edge 131a, completing the structure of the protrusion 131.
[54] The protrusion 131 may include one or more second dovetail structures 135. Each of the one or more second dovetail structures 135 is configured to engage with, and is complementary to, a corresponding one of the first dovetail structures of the wall 110a, forming a dovetail joint. In an embodiment, the protrusion 131 includes one second dovetail structure 135 provided on an outer periphery of the protrusion 131 towards the posterior end 100b of the tibial prosthesis 100. The second dovetail structure 135 is configured to engage with the first dovetail structure of the wall 110a, forming a dovetail joint. This provides additional mechanical stability and prevents relative motion, loosening between the tibial liner 130 and the tibial component 110 under operational loads. In an embodiment, at least a portion of one or more of: the second edge 131b, the third edge 131c and the fourth edge 131d are carved to form the second dovetail structure 135. For example, the curved portion of the second edge 131b, the straight portion and the curved portion of the third edge 131c, the slant portion and the curved portion of the fourth edge 131d of the protrusion 131 are carved angularly at a predefined angel, thus forming the second dovetail structure 135. The angular carving of the protrusion 131 matches the predefined angle of the inner surface 115 of the wall 110a, ensuring precise engagement with the first dovetail structure of the tibial component 110.
[55] The protrusion 131 includes a first slot 133 towards the anterior end 100a of the tibial prosthesis 100. In an embodiment, the first slot 133 is provided on the first edge 131a of the protrusion 131. The first slot 133 is configured to receive the second coupling portion 123 of the locking member 120. In other words, the second coupling portion 123 is configured to fit within the first slot 133 of the tibial liner 130. The first slot 133 has the shape and dimensions matching that of the second coupling portion 123 so that the second coupling portion 123 snugly fits within the first slot 133 and provides an interference lock. In an embodiment, the first slot 133 has a D shape.
[56] The dimensions of the tibial liner 130 may vary according to or based upon the anatomy of the patient and/or of patient population in consideration. The tibial liner 130 may be made of a biocompatible material including, but not limited to, Ultra-High Molecular Weight Polyethylene (UHMWPE) including vitamin E, high cross-linked polyethylene (HXLPE), ceramic, etc. In an embodiment, the tibial liner 130 is made of high cross-linked polyethylene (HXLPE).
[57] Optionally, the tibial component 110 may include at least one protrusion (not shown) and the tibial liner 130 may include at least one slot provided towards the posterior end 100b of the tibial prosthesis 100, alternately or in addition, to respective dovetail structures. Each of the protrusion of the at least one protrusion is configured to engage with a corresponding slot of the at least one slot. This provides additional stability to the coupling between the tibial component 110 and the tibial liner 130. The at least one protrusion and the at least one slot have a complementary shape including, without limitation, tapered rectangular, trapezoidal, T-shape, circular or semi-circular grooves combined with flat or angled surfaces, cylindrical, planar with tight clearances, etc.
[58] An embodiment of coupling the tibial liner 130 with the tibial component 110 is now explained. The tibial liner 130 is aligned with and disposed over the tibial component 110. For example, the protrusion 131 aligns with the cavity 111. The top surface 130b of the tibial liner 130 is pushed gently. As a result, the protrusion 131 moves into the cavity 111. Further, a bottom face 130c of the protrusion 131 mates with a base 111a of the cavity 111. In addition, a top face 110d of the wall 110a of the tibial component 110 mates with the bottom surface 130a of the tibial liner 130. Further, the first dovetail structure of the tibial component 110 mates with the second dovetail structure 135 of the tibial liner 130. Thus, the tibial liner 130 is assembled with the tibial component 110. To couple the locking member 120 with the tibial component 110 and the tibial liner 130, the first arm 121a and the second arm 121b are gripped using a plier and pushed towards each other. Consequently, the first arm 121a and the second arm 121b flex towards each other (reducing the space 125) so that the locking member 120 can be easily inserted through the cut-out 113. The second coupling portion 123 is inserted into the first slot 133. The first arm 121a and the second arm 121b are aligned with the first face 113a and the second face 113b of the cut-out 113, respectively. Once the second coupling portion 123 fits into the first slot 133 of the tibial liner 130, and the first arm 121a and the second arm 121b fit within the cut-out 113, the first arm 121a and the second arm 121b are released. The first arm 121a and the second arm 121b flex away from each other, and the first coupling portion 121 of the locking member 120 snugly fits into the cut-out 113. At this stage, the first projection 121b1 and the second projection 121b2 of the locking member 120 mate with first groove 113a2 and the second groove 113b2 provided on the first ledge 113a1 and the second ledge 113b1 of the cut-out 113, respectively. Also, lateral faces 122a, 122b of the first base 121a4 and the second base 121b4 mate with the first face 113a and the second face 113b, respectively, of the cut-out 113. Thus, the tibial component 110 and the tibial liner 130 are securely locked with each other via the locking member 120 and any chances of dislocation or loosening are eliminated. An assembled view of the tibial liner 130 and the tibial component 110 is depicted in Fig. 1a and a cross sectional view of an assembled tibial prosthesis 100 is depicted in Fig. 1c.
[59] The present disclosure provides several advantages. For example, unlike the conventional prosthesis which are more prone to dislocation and loosening of the conventional tibial liner from the conventional tibial component, the tibial liner in the present disclosure is securely coupled to the tibial component using the locking member. The locking member ensures a firm locking of the tibial liner with the tibial components. This prevents dislocation and loosening. This reduces the chances of failure and increases the life of the proposed tibial prosthesis. Further, the proposed tibial liner does not need to be impacted over the proposed tibial component, which in turns reduces the risk of damage to tibial liners, improper alignment, tissue damage, implant fracture, loosening, etc. Thus, the proposed tibial prosthesis improves the overall patient outcome.
[60] 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. A tibial prosthesis (100) comprising:
a. a tibial component (110) comprising:
i. a base (111a);
ii. a wall (110a) provided along a periphery of the base (111a) and defining a cavity (111); and
iii. a cut-out (113) provided in the wall (110a) and extending from an inner surface (115) of the wall (110a) to an outer face of the wall (110a);
b. a tibial liner (130) comprising: a protrusion (131) provided on a bottom surface (130a) of the tibial liner (130) and configured to fit within the cavity (111), the protrusion (131) comprising a first slot (133); and
c. a locking member (120) configured to lock the tibial component (110) with the tibial liner (130), the locking member (120) comprising:
i. a first coupling portion (121) configured to seat within the cut-out (113) of the tibial component (110); and
ii. a second coupling portion (123) configured to fit within the first slot (133) of the tibial liner (130).
2. The tibial prosthesis (100) as claimed in claim 1, wherein the first coupling portion (121) comprises:
a. a first arm (121a) comprising:
i. a first base (121a4); and
ii. a first plate (121c1) seated on the first base (121a4); and
b. a second arm (121b) spaced apart from the first arm (121a), the second arm (121b) comprising:
i. a second base (121b4); and
ii. a second plate (121c2) seated on the second base (121b4).
3. The tibial prosthesis (100) as claimed in claim 2, wherein:
a. the cut-out (113) comprises one or more of:
i. a first groove (113a2) provided on a first ledge (113a1) projecting inward from a first face (113a) of the cut-out (113); or
ii. a second groove (113b2) provided on a second ledge (113b1) projecting inward from a second face (113b) of the cut-out (113); and
b. the locking member (120) comprises one or more of:
i. a first projection (121b1) on the first arm (121a) configured to fit in the first groove (113a2) of the cut-out (113); or
ii. a second projection (121b2) provided on the second arm (121b) configured to fit in the second groove (113b2) of the cut-out (113).
4. The tibial prosthesis (100) as claimed in claim 2, wherein the width of the first plate (121c1) is smaller than the width of the first base (121a4) and the width of the second plate (121c2) is smaller than the width of the second base (121b4).
5. The tibial prosthesis (100) as claimed in claim 2, wherein the first arm (121a) comprises a first face (121d1) comprising a first hole (121e1) and the second arm (121b) comprises a second face (121d2) comprising a second hole (121e2).
6. The tibial prosthesis (100) as claimed in claim 5, wherein, the first face (121d1) and the second face (121d2) are oblique.
7. The tibial prosthesis (100) as claimed in claim 2, wherein the second coupling portion (123) integrally extends from the first plate (121c1) and the second plate (121c2).
8. The tibial prosthesis (100) as claimed in claim 1, wherein the cut-out (113) is provided on a first side (115a) of the inner surface (115) of the wall (110a) and the first slot (133) is provided on a first edge (131a) of the protrusion (131).
9. The tibial prosthesis (100) as claimed in claim 1, wherein:
a. the wall (110a) of the tibial component (110) comprises one or more first dovetail structures provided on the inner surface (115) of the wall (110a); and
b. the protrusion (131) of the tibial liner (130) comprises one or more second dovetail structures (135) provided on an outer periphery of the protrusion (131), each of the one or more second dovetail structures (135) is configured to mate with a corresponding first dovetail structure of the one or more first dovetail structures of the wall (110a), forming a dovetail joint.
10. The tibial prosthesis (100) as claimed in claim 9, wherein the wall (110a) comprises one first dovetail structure and the protrusion (131) comprises one second dovetail structure (135), wherein:
a. the inner surface (115) of the wall (110a) comprises a second side (115b), a third side (115c) and a fourth side (115d), at least a portion of one or more of: the second side (115b), the third side (115c) and the fourth side (115d) are angled relative to a base (111a) of the tibial component (110), thereby forming the first dovetail structure; and
b. the protrusion (131) of the tibial liner (130) comprises a second edge (131b), a third edge (131c) and a fourth edge (131d), at least a portion of one or more of: the second edge (131b), the third edge (131c) and the fourth edge (131d) are carved to form the second dovetail structure (135).
11. The tibial prosthesis (100) as claimed in claim 1, wherein the tibial component (110) includes at least one keel (119) provided on a bottom surface (110b) of the tibial component (110).
12. The tibial prosthesis (100) as claimed in claim 1, wherein the tibial component (110) includes one or more pegs (117) on a bottom surface (110b) of the tibial component (110).
13. The tibial prosthesis (100) as claimed in claim 1, wherein the tibial component (110) includes one or more pockets (110c) on a bottom surface (110b) of the tibial component (110).