Description: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:
JOINT PROSTHESIS

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
[001] The present disclosure relates to a medical prosthesis. More specifically, the present disclosure relates to a joint of a medical prosthesis.
BACKGROUND OF INVENTION
[002] Human body has different types of joints namely ball and socket joints, hinge joints, pivot joints and ellipsoidal joints that support different types of body movements. For example, ball-and-socket joints such as the shoulder and hip joints, allow backward, forward, sideways, and rotating movements. While hinge joints such as in the fingers, knees, elbows, and toes, permit only bending and straightening movements. Pivot joints such as the neck joints, facilitate limited rotating movements. Ellipsoidal joints such as the wrist joint, allow all types of movement except pivotal movements.
[003] At any point in the lifetime of a human being, a disease or trauma may necessitate performing a joint replacement procedure to provide pain relief, restore function and/or improve quality of life. A joint replacement technique refers to a surgical procedure where a damaged joint is removed and replaced with a suitable biocompatible device called prosthesis or a prosthetic joint. The prosthesis may be implanted into one or more of a patient's bones.
[004] Prosthesis joints designed for cemented fixation typically involve coupling the components by using bone cement i.e., full cementation, proximal cementation etc. The conventional prosthesis also has reduced lifespan due to the sub-optimal fit of the joint coupling components. Further, most prosthesis fail due to wear, osteolysis, prosthetic joint infections and/or aseptic failure of the joint coupling components.
[005] Thus, a need exists for techniques for mounting the implants on a surface of a joint that overcome limitations of current techniques.
SUMMARY OF INVENTION
[006] 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.
[007] The present disclosure relates to a joint for coupling a first component and a second component of a prosthesis. The joint comprising: a first joint portion provided with the first component, the first joint portion including: a first leg having an anchored end and a free end; a first recess adjacent to the anchored end of the first leg; and a first tab provided at the free end of the first leg; and a second joint portion provided with the second component, the second joint portion including: a second leg having an anchored end and a free end; a second recess adjacent to an anchored end of the second leg ; and a second tab provided at a free end of the second leg; wherein, upon coupling, the first leg of the first joint portion overlaps with the second leg of the second joint portion; wherein, upon coupling, the first tab is seated in the second recess and the second tab is seated in the first recess.
[008] The foregoing features and other features as well as the advantages of the disclosure will become more apparent from the following detailed description, which proceeds with reference to the accompanying figures.
BRIEF DESCRIPTION OF DRAWINGS
[009] 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 instrumentalities disclosed herein. Moreover, those in the art will understand that the drawings are not to scale.
[0010] FIG. 1a illustrates a prosthesis 100 formed using the teachings of a joint of the present disclosure.
[0011] FIG. 1b depicts an exploded view 100b of the reciprocal L-shaped joint according to an embodiment of the present disclosure.
[0012] FIG. 1c depicts an enlarged view 100c of a first joint portion 107 according to an embodiment of the present disclosure.
[0013] FIG. 1d depicts a detailed view 100d of a second joint portion 119 provided in the keel 105 of the base plate 103 according to an embodiment of the present disclosure.
[0014] FIG. 1e depicts a flow chart of a method 150 for connecting the stem extension 101 and the base plate 103 via the joint of the present disclosure in accordance with the first embodiment.
[0015] FIG. 2a illustrates an exploded view 200 of a second prosthesis 200 formed using the teachings of the joint of the present disclosure.
[0016] FIG. 2b depicts an enlarged view 200b of a first joint portion 207 provided with the stem extension 201 of the second prosthesis 200 according to an embodiment of the present disclosure.
[0017] FIG. 2c represented by 200c depicts a second joint portion 219 provided with the femoral component 203 of the second prosthesis 200 according to an embodiment of the present disclosure.
[0018] FIG. 2d depicts a flow chart of a method 250 for connecting the stem extension 201 and the femoral component 203 via the joint of the present disclosure in accordance with an embodiment of the present disclosure.
DETAILED DESCRIPTION OF ACCOMPANYING DRAWINGS
[0019] Prior to describing the disclosure 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.
[0020] 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.
[0021] 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.
[0022] 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.
[0023] The terms “proximal” and “distal” are used herein to refer to the relative positions of the components of the present disclosure. When used herein, “proximal” refers to a position relatively closer to the exterior of the body or closer to the physician, or other user dealing with a medical prosthesis. In contrast, “distal” refers to a position relatively further away from the surgeon, or other user, dealing with the medical prosthesis or deeper inside the interior of the body.
[0024] The term “end” as used herein refers to an extreme position of the component/device while the term “portion” refers to a finite length of the component/device.
[0025] The present disclosure is directed to a joint to be employed in a prosthesis, which offers a greater degree of surgical flexibility. The joint of the present disclosure provides stronger connection between two components of a prosthesis and helps to avoid the dislocation and loosening of the connection between the two components of the prosthesis. For example, in a knee joint, a stem extension (first component) is engaged with a base plate has an upraised keel (second component). The keel and the stem extension are attached together with a reciprocal L-shaped joint of the present disclosure. The reciprocal L-shaped joint formed between the first component and second component , may be secured with the help of one or more screws which pass through an overlapped portion of the first component and second component . As another example, the reciprocal L-shaped joint may be used to secure a stem extension to a femoral component. The teachings of the joint of the present disclosure are explained in the context of the two exemplary embodiments. However, it is to be noted that the teachings of the present disclosure can be extended to any joints that require coupling of two components in a medical prosthesis.
[0026] Now referring to the figures, FIG. 1a illustrates a prosthesis 100 formed using the teachings of a joint of the present disclosure. In this embodiment, the prosthesis 100 includes a stem extension 101 joined to a base plate 103 including a keel 105, to be implanted in the tibial bone of a knee.
[0027] The stem extension 101 includes a body 101a (or stem body) having a distal end 101b and a proximal end (not shown, coupled to the keel) defining a length therebetween. The stem body 101a of the stem extension 101 may be tubular in shape and may include a rough or smooth outer surface. Further, the body 101a of the stem extension 101 may be hollow or solid. The stem extension 101 may be made of any medical grade metallic biocompatible material, including without limitation titanium, cobalt chromium, SS316 etc. In an exemplary embodiment, the stem extension 101 is made of titanium.
[0028] The proximal portion of the stem extension 101 is coupled to the distal portion of the keel 105 using the joint of the present disclosure as explained in the following paragraphs. The stem extension 101 reduces micromotions at the tibial bone implant interface and, as a result, reduces the risk of aseptic loosening, which is one of the main causes of implant failure.
[0029] The base plate 103 is a tray-like structure having an outer surface and an inner surface, with a predefined width. The two surfaces define the predefined width of the base plate 103. On the inner surface, the base plate 103 includes the upraised keel 105. In an embodiment, the base plate 103 and the keel 105 are a unitary structure. The stem extension 101 is coupled to the base plate 103 via the upraised keel 105. The base plate 103 ensures optimal knee kinematics and improved fixation of the implant. The base plate 103 may be made of any medical grade metallic biocompatible material, such as, without limitation titanium, cobalt chromium, SS316 etc. In an exemplary embodiment, the base plate 103 is made of cobalt chromium.
[0030] The keel 105 extends from the inner surface of the base plate 103 and has a predefined height. In an embodiment, the keel 105 extends from the central part of the base plate 103. The keel 105 may include without limitation, a body with a pair of triangular wings or an upraised conical structure. In the depicted embodiment, the keel 105 includes a body with a pair of triangulated wings (shown in Fig. 1c) such that the wings are placed on the lateral sides of the body. The body of the keel 105 (or ‘keel body’) includes a proximal end and a distal end defining a length therebetween. The distal portion of the keel body 105 is attached to the stem extension 101 via the reciprocal L-shaped joint as explained in the following diagrams.
[0031] FIG. 1b depicts an exploded view of the reciprocal L-shaped joint according to an embodiment of the present disclosure.
[0032] The proximal portion of the stem extension 101 includes a first joint portion 107 of the joint. In one embodiment, the first joint portion 107 may be formed in the stem body 101a by combining wire cutting and computer numerical control (CNC) machining techniques. Alternately, the first joint portion 107 may be formed in the stem body 101a by using laser cutting in combination with CNC machining. The details of the first joint portion 107 formed in the stem body 101a have been discussed in the succeeding paragraphs.
[0033] The enlarged view of the first joint portion 107 is provided in FIG. 1c. The first joint portion 107 includes a first leg 109 on the proximal portion of the stem extension 101, a first face 111 and a first recess 113 adjacent to an anchored end of the first leg 109. The first joint portion 107 may resemble an inverted L-shape. The first leg 109 has an anchored end and a free end.
[0034] The first leg 109 may include a D shaped cross-section, namely, an arc shape 109a on the outer surface of the stem body 101a and an inner wall 109b.The inner wall 109b may be straight or tapered to form a slant, in construction. The first leg 109 further includes one or more holes 115, for example, a first hole 115 and a second hole 115 carved therein. The holes 115 extend through the entire width of the first leg 109. The holes 115 may be threaded, semi-threaded or non-threaded. In the depicted embodiment, the holes 115 are threaded. Further, the holes 115 may be of the same or different shape and dimensions. For example, in case there are multiple holes 115, the first hole 115 may be circular while the second hole 115 may be oblong. Alternately, if there is a singe hole 115, it can be of any suitable shape such as circular or oblong etc. Further, the hole 115 may include but not be limited to a blind hole, a thorough hole, an interrupted hole, a counterbore hole, a spot face hole, a countersink hole, a tapered hole, a screw clearance hole, a tapped hole, a threaded hole and combinations thereof.
[0035] The first leg 109 further includes a first tab 117 provided at a free end of the first leg 109. The first tab 117 acts as a lock when the first joint portion 107 is coupled to the second joint portion 119. The first tab 117 may include a smooth or tapered edge to ensure minimal injury to the underlying tissue.
[0036] The first joint portion 107 includes the first recess 113 in the first face 111, and adjacent to the inner wall 109b of the first leg 109. The first recess 113 may be a cut-out of any shape at one end of the first face 111. The first recess 113 seats a second tab 129 provided with the second joint portion 119 and thus acts as a lock, avoiding any unwanted movements or dislocation of the two joint portions 107, 119 once coupled.
[0037] FIG. 1d depicts a detailed view of a second joint portion 119 provided in the keel 105 of the base plate 103 according to an embodiment of the present disclosure. The keel 105 includes a second joint portion 119 of the joint. The second joint portion 119 is provided towards the distal portion of the keel 105 or may extend from the central portion of the keel 105 till the distal end of the keel 105. The second joint portion 119 includes a second leg 121 having one or more slots 123, for example, a first slot 123 and a second slot 123. The second leg 121 has an anchored end and a free end. The number of slots 123 correspond to the number of holes 115 in the first leg 109. The slots 123 may be drilled at least up to a predefined width of the second leg 121. Further, the slots 123 may be threaded, semi-threaded or non-threaded. In the depicted embodiment, the slots 123 are threaded. Further, the slots 123 may be of the same or different shape corresponding to the holes 115. The slots 123 may have dimensions corresponding to the dimensions of the holes 115. The slots 123 may be of any suitable shape such as circular or oblong etc.
[0038] The second leg 121 may include a D shaped cross-section, namely, an arc shape on its outer surface 121a and an inner wall 121b. The inner wall 121b may be straight or tapered in construction as corresponding to the construction of the inner wall 109b. The length of the second leg 121 may be complementary to the length of the first leg 109. On top of the second leg 121, a second tab 129 is provided at its free end. The second tab 129 at the free end of the second leg 121 acts as a locking member.
[0039] The second joint portion 119 further includes a second recess 125 adjacent to an anchored end of the second leg 121 and a second face 127. The second recess 125 may be a cut-out of a shape in the second face 127 that corresponds to the shape of the first tab 117. The second recess 125 seats a first tab 117 provided with the first joint portion 107 and thus acts as a lock avoiding any unwanted movements or dislocation of the two joint portions 107, 119 once coupled.
[0040] In the depicted embodiment, the second joint portion 119 resembles an L-shape. The first joint portion 107 and the second joint portion 119 form a reciprocal L-shaped joint.
[0041] FIG. 1e depicts a flow chart of a method 150 for connecting the stem extension 101 and the base plate 103 via the joint of the present disclosure in accordance with one embodiment. The method 150 commences at step 160. At step 160, the stem extension 101 is positioned in front of the keel 105 of the base plate 103. In this step, the inner wall 109b of the first leg 109 of the stem extension 101 is placed in close proximity or overlapped with the inner wall 121b of the second leg 121 of the keel 105 of the base plate 103.
[0042] At step 162, the first tab 117 provided at the free end of the first leg 109 is placed inside the second recess 125 adjacent to the anchored end of the second leg 121 of the keel 105. Similarly, the second tab 129 at the free end of the second leg 121 of the keel 105 is placed inside the first recess 113 provided adjacent to an anchored end of the first leg 109 and is carved in the proximal portion of the stem extension 101. The mechanism of coupling acts as a lock and prevents any unwanted movements or dislocation of the two portions.
[0043] Once coupled or placed, the first hole 115 and the second hole 115 present in the first joint portion 107 overlap with the corresponding first slot 123 and the second slot 123 of the second joint portion 119 of the keel 105. At step 164, the screws 131 are passed through the respective holes 115 and are tightened in the respective slots 123. During tightening, the first screw 131 and the second screw 131 may be rotated for example, in a clockwise direction to fix the screws in the respective slots 123. Thus, the threads of the first screw 131 and the second screw 131 are coupled with the internal threads of the first slot 123 and second slot 123 (as shown in FIG. 1a). The length and diameter of the one or more screws 131 is designed in such a way that the screws 131 can easily fit into the respective holes 115 and slots 123.
[0044] The coupling of the first and second joint portions 109, 119 forms a reciprocal L-shaped joint between the base plate 103 and the stem extension 101 that provides functional stability by preventing dislocation or breakage between these components. It is to be noted that the reciprocal L-shaped joint acts as a double lock due to the engagement of two tabs in two recesses, namely, the first tab 117 in the second recess 125 and the second tab 129 in the first recess 113. Further, the complementary shapes of the tabs and recesses ensure greater coupling of the two and results in negligible chances of dislocation of the two components.
[0045] FIG. 2a illustrates an exploded view of a second prosthesis 200 formed using the teachings of the joint of the present disclosure. The second prosthesis 200 pertains to a femoral component 203 of a prosthesis wherein a stem extension 201 is attached to a femoral component 203 via the joint of the present disclosure. In this embodiment, the second prosthesis 200 includes a stem extension 201 joined to the femoral component 203 to be implanted in the femur bone. The stem extension 201 includes a body 201a (or stem body) having a distal end 201b and a proximal end (not shown) defining a length therebetween. The proximal portion of the stem extension 201 is provided with a first joint portion 207. The first joint portion 207 includes a first leg 209 and one or more screws 231. Fig. 2a also depicts a femoral component 203 including a boss 206. The femoral component 203 is a ball-shaped structure including an outer surface and an inner surface. From the inner surface of the femoral component 203, the boss 206 centrally extends thereon. The boss 206 includes a second joint portion 219. The details of the first joint portion 207 provided with the stem extension 201 can be referred from FIG’s. 1b and 1c and are not repeated for the sake of brevity. The details of the second joint portion 219 provided in the femoral component 203 can be referred from FIG.1d and is not repeated for the sake of brevity.
[0046] FIG. 2b depicts an enlarged view of a first joint portion 207 provided with the stem extension 201 of the second prosthesis 200 according to an embodiment of the present disclosure. The stem extension 201 includes a first joint portion 207 at the proximal end (not shown). The first joint portion 207 includes a first leg 209, a first recess 213 adjacent to an anchored end of the first leg 209 and a first tab 217 provided at a free end of the first leg 209. The first joint portion 207 may resemble an inverted L-shape.
[0047] The first leg 209 on the proximal end of the stem 201c further includes one or more holes 215, for example, a first hole 215 and a second hole 215 carved therein that extend through the entire width of the first leg 209. The first leg 209 includes one or more screws 231, for example a first screw 231 and a second screw 231. The first leg 209 on the proximal end of the stem 201c may include a D shaped cross-section, namely, an arc shape 209a on the outer surface of the stem body 201a and an inner wall 209b. Further details of the first joint portion 207 provided with the stem extension 201 can be referred from FIG.s 1b and 1c and are not repeated for the sake of brevity.
[0048] FIG. 2c depicts a second joint portion 219 provided with the femoral component 203 of the second prosthesis 200 according to an embodiment of the present disclosure. As can be seen, the second joint portion 219 is provided on a boss 206 of the femoral component 203. The second joint portion 219 includes a second leg 221, a second recess 225 adjacent to an anchored end of the second leg 221and a second tab 229 provided at a free end of the second leg 221 The second recess 225 may be a cut-out of any shape in the second face 227. The second leg 221includes one or more slots 223. The second joint portion 219 resembles an L-shape. The structural and functional details like components of the second joint portion 219 can be referred from FIG. 1d and is not repeated for the sake of brevity.
[0049] FIG. 2d depicts a flow chart of a method 250 for connecting the stem extension 201 and the femoral component 203 via the joint of the present disclosure in accordance with an embodiment of the present disclosure. The method 250 commences at step 260. At step 260, the stem extension 201 is positioned in front of femoral component 203. In this step, the inner surface of the first leg 209 of the stem extension 201 is placed in close proximity or overlapped with the inner surface of the second leg 221 of the boss 206 of the femoral component 203.
[0050] At step 262, the first tab 217 provided at the free end of the first leg 209 is placed inside the second recess 225 adjacent to the anchored end of the second leg 221 of the boss 206. Similarly, the second tab 229 at the free end of the second leg 221 of the boss 206 is placed inside the first recess 213 provided adjacent to an anchored end of the first leg 209 and is carved in the proximal portion of the stem extension 201. The mechanism of coupling acts as a lock and prevents any unwanted movements of the two portions.
[0051] Once placed, the first hole 215 and the second hole 215 present in the first joint portion 207 overlap with the first slot 223 and the second slot 223 of the second joint portion 219 of the boss 206. At step 264, the screws 231 pass through the respective holes 215 and are tightened in the respective slots 223. During tightening, the first screw 231 and the second screw 231 may be rotated in a clockwise direction to fix the screws in the respective slots 223. Thus, the threads of the first screw 231 and the second screw 231 are coupled with the internal threads of the first slot 223 and second slot 223. The length and diameter of the one or more screws 231 is designed in such a way that the screws 231 can easily fit into the respective holes 215 and slots 223.
[0052] Further, the structural and functional details of the like components of the first joint portion 207 provided with the stem extension 201, second joint portion 219 provided with the femoral component 203 may be referred from FIG’s.1b-1d and is not repeated herein for the sake of brevity. As in the method of attachment with respect to the tibial component, the method of attachment of the stem extension 201 and the femoral component 203 via the joint of the present disclosure is the same. The coupling of the first and second joint portions 207, 219 forms a reciprocal L-shaped joint between the femoral component 203 and the stem extension 201 that provides functional stability by preventing dislocation or breakage between these components.
[0053] 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 joint for coupling a first component and a second component of a prosthesis (100), comprising:
a. a first joint portion (107) provided with a first component, the first joint portion (107) including:
i. a first leg (109) having an anchored end and a free end;
ii. a first recess (113) adjacent to the anchored end of the first leg (109); and
iii. a first tab (117) provided at the free end of the first leg (109); and
b. a second joint portion (119) provided with a second component, the second joint portion (119) including:
i. a second leg (121) having an anchored end and a free end;
ii. a second recess (125) adjacent to an anchored end of the second leg (121); and
iii. a second tab (129) provided at a free end of the second leg (121);
wherein, upon coupling, the first leg (109) of the first joint portion (107) overlaps with the second leg (121) of the second joint portion (119);
wherein, upon coupling, the first tab (117) is seated in the second recess (125) and the second tab (129) is seated in the first recess (113).
2. The joint as claimed in claim 1, wherein, the first component is a stem extension (101).
3. The joint as claimed in claim 1, wherein, the second component is one of a tibial keel (105) or a femoral component (203).
4. The joint as claimed in claim 1, wherein, the first leg (109) and the second leg (121) include a D-shaped cross-section (109a, 121a) and an inner wall (109b, 121b).
5. The joint as claimed in claim 4, wherein, the inner wall (109b, 121b) is one of straight or tapered in construction.
6. The joint as claimed in claim 1, wherein, the first leg (109) includes one or more holes (115).
7. The joint as claimed in claim 1, wherein, the second leg (121) includes one or more slots (123).
8. The joint as claimed in claims 5 and 6, wherein, at least one of the holes (115) or slots (123) are either threaded or non-threaded.
9. The joint as claimed in claims 5 and 6, wherein, the holes (115) or slots (123) are one of circular or oblong shaped.
10. The joint as claimed in claim 1, wherein, the first recess (113) and the second recess (125) are rectangular cut-outs.
11. The joint as claimed in claim 1, wherein, the first leg (109) is attached to the second leg (121) by fixing screws (131) in one or more holes (115) or slots (123).