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:
CONSTRAINED LINER

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 a medical implant. More particularly, the present disclosure relates to a constrained liner.
BACKGROUND OF INVENTION
[2] Hip arthroplasty is a surgical procedure to address hip pain caused by failure of individual hip joint mechanism either due to old age, pressure due to daily activities or due to medical conditions such as osteoporosis or rheumatoid arthritis. The hip joint is a ball and socket joint. The procedure of hip replacement includes replacement of one or both parts of the hip anatomy. This allows the patient to resume daily activities and relieve pain.
[3] The hip replacement systems are typically made up of four major components namely, a modular shell, a modular liner, a femoral head and a femoral stem. The modular shell and the modular liner form an acetabulum part of a hip implant, whereas the femoral head and the femoral stem forms a femoral part of the hip implant. The acetabulum part is further coupled to the femoral part to act and function like a human hip joint.
[4] Hip replacement surgeries may, however, to serious complications. One of the most common complications is dislocation of the total hip endoprosthesis. Conventionally available hip replacement systems are more prone to dislocation of the femoral head from the modular liner, which may lead to anterior dislocation. Further, excessive retroversion may result in posterior dislocation or excessive abduction may result in lateral dislocation.
[5] This type of dislocation normally causes severe pain in the patient. To treat such condition, a revision surgery is performed. However, repeated revision surgeries are traumatic for the patients and increase their medical costs.
[6] Hence, there requires a need of a hip replacement system to overcome the problems associated with conventionally available hip replacement systems.
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 a prosthesis. In an embodiment , the prosthesis includes a liner and a locking member. The liner includes a wall having a top surface and an annular slot provided on the top surface of the wall. The annular slot defines an inner section and an outer section of the wall. The inner section includes a plurality of cuts and is configured to move radially. The locking member is configured to be disposed in the annular slot and restrict the radial movement of the inner section when the locking member is disposed in the annular slot.
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 exploded isometric view of a liner assembly 100, according to the embodiment of the present disclosure.
[11] Fig. 2 depicts a sectional view 200 of the coupling of the liner assembly 100 with a femoral head 300, according to the embodiment of the present disclosure.
DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS
[12] 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.
[13] 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.
[14] 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.
[15] 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.
[16] The present disclosure relates to a hip prosthesis (or prosthesis). The prosthesis includes a liner assembly including a liner and a locking member. The liner assembly can be deployed as a part of the hip prosthesis in a total hip arthroscopy. The liner is inserted into and coupled with an acetabular shell of the hip prosthesis. A cavity of the liner receives a femoral head of the hip prosthesis. The locking member locks the femoral head within the liner. The proposed liner assembly eliminates the failure of the hip prosthesis due to the dislocation of the femoral head from the liner and increases longevity of the hip prosthesis. Consequently, no revision surgeries are required, thereby improving the patient outcome. Further, the liner assembly helps in achieving joint stability.
[17] In an embodiment, the liner includes a wall having a top surface and an annular slot provided on a top surface of the wall. The annular slot defines an inner section and an outer section of the wall. The inner section is configured to move radially inward and outward direction during the insertion of the femoral head within the cavity. The inner section includes a plurality of cuts. The locking member is configured to fit in the annular slot. The plurality of cuts makes insertion and removal of the locking member easier than conventional liners. Further, the plurality of cuts facilitates the radially inward and outward movement of the inner section. Thus, assembling the proposed liner assembly with the femoral head is easier, thereby decreasing time for the implant procedure and improving the patient outcome.
[18] Fig. 1 depicts an exploded isometric view of a liner assembly 100, according to an embodiment of the present disclosure. The liner assembly 100 includes a liner 101 and a locking member 102. In an embodiment, the liner 101 is a constrained liner. The liner assembly 100 is inserted into an acetabular shell of a hip prosthesis and coupled with the acetabular shell using, for example, a press-fit mechanism, thread locking, taper locking or any other suitable technique. The liner assembly 100 is designed to hold a femoral head of the hip prosthesis securely with the help of a locking mechanism.
[19] The liner 101 may be made of a material including, but not limited to, Ultra-High Molecular Weight Polyethylene (UHMWPE), polymethyl methacrylate (PMMA), high cross-linked polyethylene (HXLPE) including vitamin E, etc. In an embodiment, the liner 101 is made of HXLPE with vitamin E. The liner 101 may have a shape, such as, without limitation, hemispherical, dome, elevated wall, 10° oblique, 15° oblique etc., or any suitable shape based upon patient’s requirements. In an exemplary embodiment, the liner 101 is dome-shaped with a circular top surface and a taper towards a distal end of the liner 101. The dimensions of the liner 101 may vary depending upon the patient.
[20] Further, the liner 101 includes a plurality of protrusions 101n extending from an outer surface of the liner 101. In the depicted embodiment, the liner 101 includes four protrusions 101n, though any number of protrusions 101n may be provided. The plurality of protrusions 101n may be extruded from the outer surface of the liner 101. The plurality of protrusions 101n are configured to engage with corresponding slots of the acetabular shell for locking the liner 101 with the acetabular shell and provide rotational stability.
[21] The liner 101 includes a wall 104 extruded from a top surface 101a of the liner 101. The wall 104 has a top surface 104a. In an embodiment, the wall 104 is cylindrical. The dimensions of the wall 104 may vary depending upon the patient’s anatomy and requirements. The liner 101 includes a cavity 120 extending from the top surface 104a. The cavity 120 is configured to receive the femoral head during assembly of the hip prosthesis. The shape of the cavity 120 generally matches a proximal portion of the femoral head. In an embodiment, the cavity 120 has a shape greater than hemispherical (as shown in Fig. 2).
[22] The top surface 104a of the wall 104 is provided with an annular slot 106 (or slot 106) forming an inner section 108 and an outer section 110 of the wall 104. The slot 106 is configured to receive the locking member 102. The size and shape of the slot 106 corresponds to the size and shape of the locking member 102.
[23] The inner section 108 includes an inner rim 108a and an outer rim 108b. The outer section 110 includes an inner rim 110a. The diameter of the inner rim 108a is smaller than the diameter of the femoral head component. The inner section 108 is configured to move radially inward and outward during assembly of the liner 101 with the femoral head as explained later. The inner section 108 includes a plurality of cuts 109.The cuts 109 enable the movement of inner section 108 radially inwards and outwards. Though the depicted embodiment shows four cuts 109, it should be appreciated that the inner section 108 may have any number cuts 109.
[24] The locking member 102 is configured to fit in the slot 106. The locking member 102 restricts the movement of the inner section 108 upon assembling the liner 101 with the femoral head, as explained later. The locking member 102 may have a shape such as a ring, a disc, a donut, a band, etc. The locking member 102 may have any suitable cross-section such as, circular, oval, rectangular, etc. In the depicted embodiment, the locking member 102 is a ring having a circular cross-section. The locking member 102 may have diameter corresponding to width of the slot 106. The locking member 102 may be made up of a material including, but not limited to, titanium, cobalt chromium, SS316 etc. or any other medical grade, biocompatible metal. In an embodiment, the locking member 102 is made of titanium.
[25] Fig. 2 depicts a sectional view 200 of the coupling of the liner assembly 100 with a femoral head 300, according to an embodiment. The femoral head 300 is generally spherical in shape and includes an opening coupled to a trunnion portion 400 of a femoral component.
[26] To assemble the femoral head 300 with the liner assembly 100, the femoral head 300 is inserted into the liner 101. During the insertion of the femoral head 300 into the liner 101, a portion of the femoral head 300 having a larger diameter than the diameter of the inner rim 108a contacts the inner rim 108a. As a result, the femoral head 300 pushes the inner section 108 in the radially outward direction as the femoral head 300 is continued to be inserted into the liner 101. The cuts 109 on the inner section 108 facilitate the movement of the inner section 108 in the radially outward direction. The movement of the inner section 108 causes the movement of the outer rim 108b of the inner section 108 towards the inner rim 110a of the outer section 110.
[27] When the femoral head 300 is further inserted into the liner 101, a portion of the femoral head 300 having a diameter equal to or lower than the diameter of the inner rim 108a contacts the inner rim 108a. As a result, the outward pressure on the inner section 108 is reduced and the inner section 108 moves radially inward to its original position. Once the femoral head 300 is fully inside the cavity 120 (i.e., an outer surface of the femoral head 300 aligns with and contacts an inner surface of the cavity 120), the locking member 102 is inserted into the slot 106 as shown in Fig. 2. The locking member 102 restricts the radial movement of the inner section 108. The cuts 109 make the insertion and removal of the locking member 102 easier.
[28] Since the diameter of the inner rim 108a of the inner section 108 is comparatively smaller than the diameter of the femoral head 300 and the locking member 102 restricts radially outward movement of the inner section 108, the femoral head 300 is locked securely inside the cavity 120 of the liner 101. This avoids any dislocation of the femoral head 300 from the liner assembly 100. As a result, failure of the hip prosthesis due to the dislocation of a femoral component from a liner is prevented. Consequently, no revision surgeries are needed, thereby improving the patient outcome.
[0072] 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 prosthesis comprising:
a. a liner (101) comprising a wall (104) having a top surface (104a) and an annular slot (106) provided on the top surface (104a) of the wall (104), the annular slot (106) defining an inner section (108) and an outer section (110) of the wall (104), the inner section (108) comprises a plurality of cuts (109) and is configured to move radially; and
b. a locking member (102) configured to be disposed in the annular slot (106) and restrict the radial movement of the inner section (108) when the locking member (102) is disposed in the annular slot (106).
2. The prosthesis as claimed in claim 1, wherein the wall (104) is extruded from a top surface (101a) of the liner (101).
3. The prosthesis as claimed in claim 1, wherein the liner (101) is coupled with an acetabular shell of the prosthesis.
4. The prosthesis as claimed in claim 3, wherein the liner (101) comprises a plurality of protrusions (101n) extending from an outer surface of the liner (101) and configured to engage with corresponding slots of the acetabular shell.
5. The prosthesis as claimed in claim 1, wherein the inner section (108) comprises an inner rim (108a) having a diameter smaller than a diameter of a femoral head (300) of the prosthesis.
6. The prosthesis as claimed in claim 5, wherein the inner section (108) is configured to move in a radially outward direction in response to a portion of the femoral head (300) having a diameter greater than or equal to the diameter of the inner rim (108a) contacting the inner rim (108a).
7. The prosthesis as claimed in claim 5, wherein the liner (101) comprises a cavity (120) configured to receive the femoral head (300).
8. The prosthesis as claimed in claim 1, wherein the cuts (109) are configured to facilitate the radial movement of the inner section (108).