WO2020035883A1

WO2020035883A1 - Elbow implant

Info

Publication number: WO2020035883A1
Application number: PCT/IN2019/050600
Authority: WO
Inventors: Dinesh Kalyanasundaram; Dilpreet Singh; Pulak Mohan Pandey
Original assignee: Indian Institute Of Technology Delhi
Priority date: 2018-08-16
Filing date: 2019-08-16
Publication date: 2020-02-20

Abstract

The present subject matter relates to an elbow implant (100). The elbow implant (100) comprises a humerus part (102) having a humerus stem (104) penetrable into a humerus medial canal of a humerus, and an ulna part (108) having an ulna stem (110) penetrable into an ulnar medial canal of an ulna. The humerus part (102) and the ulna part (108) are linkable with each other via a connecting pin (114) to form an elbow joint. The elbow implant (100) is of reduced size and includes a minimum number of parts to ensure minimal bone loss with ease of assembly during a total elbow arthroplasty (TEA).

Description

ELBOW IMPLANT

TECHNICAL FIELD

[0001] The present subject matter relates, in general, to a prosthetic implant, in particular, to elbow implant.

BACKGROUND

[0002] In general, a metal or polymer implant joint is used to facilitate painless elbow joint motion, when a natural elbow joint is replaced with the metal or polymer implant in case of a total elbow replacement. The total elbow replacement is necessitated when cartilage of a natural elbow joint wears down and the movement of the elbow joint becomes very painful and affects the daily life of a patient.

BRIEF DESCRIPTION OF DRAWINGS

[0003] The detailed description is described with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the figures to reference like features and components. Some implementations of the system(s), in accordance with the present subject matter, are described by way of examples, and with reference to the accompanying figures, in which:

[0004] Fig. 1 illustrates a front perspective view of an elbow implant in an assembled state, in accordance with an implementation of the present subject matter.

[0005] Fig. 2 illustrates a rear perspective view of the elbow implant in the assembled state, in accordance with the implementation of the present subject matter.

[0006] Fig. 3 illustrates an isometric view of the elbow implant in the assembled state, in accordance with the implementation of the present subject matter.

[0007] Fig. 4 illustrates a side view of the elbow implant, in accordance with the implementation of the present subject matter. DETAILED DESCRIPTION

[0008] Elbow joint gets affected in trauma patients and patients with rheumatoid arthritis. In rheumatoid arthritis, the cartilage of the elbow joint wears down, due to which the movement of the joint becomes very painful and affects the daily life of the patient. In trauma patients, the elbow joint may get damaged and the movement of the joint may be completely stopped in severe cases. Analgesics are a temporary solution for such conditions. However, considering the severity of the elbow joint condition, a total elbow arthroplasty (TEA) may be required.

[0009] In general, the elbow joint is replaced with a metal or polymer implant to facilitate painless elbow joint motion. The existing metal or polymer implant includes a number of parts, which are assembled after implantation. Such assembling after implantation increases the complexity of the surgery to perfectly fit and assemble the number of parts. Further, the existing metal or polymer implants are oversized and bulky and therefore more bone mass has to be removed to perfectly fit the metal or polymer implant in the bone.

[0010] To this end, an elbow implant is proposed, which is of reduced size and includes a minimum number of parts to ensure minimal bone loss with ease of assembly during a total elbow arthroplasty (TEA) in accordance with the implementations of the present subject matter.

[0011] In an implementation of the present subject matter, the elbow implant includes a humerus part having a proximal end and a distal end. The proximal end of the humerus part includes a humerus stem, which is penetrable into a humerus medial canal of a humerus. The minimal bone material from the humerus medial canal of the humerus may be removed for penetrating the humerus stem into the humerus medial canal of the humerus. In one example, the spongy bone or the cancellous bone material from the humerus medial canal of the humerus may be removed. Further, the distal end of the humerus part includes a first U-shaped component, which is penetrable into a trochlea portion of an epicondyle of a human elbow.

[0012] The elbow implant further includes an ulna part having a distal end and a proximal end. The distal end of the ulna part includes an ulna stem, which is penetrable into an ulnar medial canal of an ulna. The minimal bone material from the ulna medial canal of the ulna may be removed for penetrating the ulna stem into the ulna medial canal of the ulna. Further, the proximal end of the ulna part includes a second U-shaped component, which is penetrable into the trochlea portion of the epicondyle of the human elbow. In particular, the second U-shaped component is penetrable through a trochlea notch portion of the ulna bone. The second U-shaped component is articulable with the first U-shaped component, which may enable movement of the elbow joint. The humerus part and the ulna part are linkable with each other via a connecting pin to form an elbow joint.

[0013] In one implementation of the present subject matter, the first U-shaped component includes two condylar portions. Each condylar portion of the two condylar portions includes a receptacle disposed on an inner surface thereof. The second U-shaped component includes two bearing surfaces. Each bearing surface of the two bearing surfaces is complementing the respective condylar portion and includes a hole extending there through.

[0014] In one implementation of the present subject matter, the connecting pin can be passed through the respective hole of each bearing surface. Further, respective end of the connecting pin may be received in the respective receptacle of each condylar portion.

[0015] In one implementation of the present subject matter, the humerus part has a length in a range of 65 mm to 75 mm. Further, the humerus stem has a length in a range of 35 mm to 50 mm, a width in a range of 4 mm to 8 mm, and a thickness in a range of 4 mm to 8 mm. [0016] In one implementation of the present subject matter, the ulna part has a length in a range of 65 mm to 80 mm. Further, the ulna stem has a length in a range of 35 to 55 mm a width in a range of 4 mm to 8 mm, and a thickness in a range of 4 mm to 8 mm.

[0017] The elbow implant of the present subject matter can restore the working of a human elbow joint with normal flexion and extension of 140° to 0°. Further, the elbow implant can be used to facilitate the normal daily tasks of the patients such as pick and place of the objects, eating food etc.

[0018] The implementations of the present subject matter offer the elbow implant that is reduced in sizes and therefore leads to less bone mass loss for inserting the elbow implant into the humems. The shape of the ulnar stem and humeral stem are designed to fit perfectly within the humems medial canal of the humems and ulna medial canal of the ulna respectively. Since, each patient can have different sizes of bone, the current design is accustomed to adopt to these dimensional changes. Further, the elbow implant of the present subject matter provides perfectly curved surfaces designed to distribute stresses and avoid any stress concentration. The elbow implant of the present subject matter is designed with reduced number of parts as compared to conventional elbow implants and therefore ensures ease of assembly during surgery. The elbow implant is designed to use as pre-assemble or assembly after implantation of the elbow implant.

[0019] These and other advantages of the present subject matter would be described in a greater detail in conjunction with Figs. 1-4 in the following description. The manner in which the elbow implant is implemented and used shall be explained in detail with respect to Figs. 1-4.

[0020] It should be noted that the description merely illustrates the principles of the present subject matter. It will thus be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described herein, embody the principles of the present subject matter and are included within its scope. Furthermore, all examples recited herein are intended only to aid the reader in understanding the principles of the present subject matter. Moreover, all statements herein reciting principles, aspects and implementations of the present subject matter, as well as specific examples thereof, are intended to encompass equivalents thereof.

[0021] Fig. 1 illustrates a front perspective view of an elbow implant 100 in assembled state, in accordance with an implementation of the present subject matter. The elbow implant 100 can be understood as a medical device manufactured to replace a natural elbow joint. The elbow implant 100 includes a humerus part 102. The humerus part 102 can be understood as a part of the elbow implant 100, which can be penetrated into a humerus (not shown). The humerus can be understood as a long bone in an upper arm (not shown) and is located between the elbow joint (not shown) and the shoulder (not shown). The shape of humerus part 102 complements to the shape of the humerus. The humerus part 102 has a length in a range of 65-70 mm. In one example, the length of the humerus part 102 can depend on a length of the humerus, in which the humems part 102 is to be penetrated during a total elbow arthroplasty (TEA). The humerus part 102 can be made of a biocompatible metallic material such as Ti6Al4V Grade 5 Titanium alloy or a polymeric material such as Polyether ether ketone (PEEK) or Ultra high density polyethylene (UHMWPE). Further, the humerus part 102 includes a proximal end and a distal end. In one example, the proximal end and the distal end of the humerus part 102 are referenced from a trochlea portion (not shown) of an epicondyle (not shown) of a human elbow (not shown).

[0022] The proximal end of the humerus part 102 includes a humerus stem 104. The humerus stem 104 has a length in a range of 35 mm to 50 mm, a width in a range of 4 mm to 8 mm, and a thickness in a range of 4 mm to 8 mm. The humerus stem 104 may be penetrated in a humerus medial canal of the humerus bone (not shown) of the humerus after sectioning an olecranon (not shown). After the penetration of the humerus stem 104 in the humerus medial canal of the humerus, a bone cement (not shown) can be injected into the humerus medial canal to fix the humeral stem 104 in the humerus. In one example, the bone cement can be injected into the humerus medial canal to fix the humeral part 102 in the humerus. In one example, the bone cement can be polymethylmethacrylate.

[0023] The distal end of the humerus part 102 includes a first U-shaped component 106. The first U-shaped component 106 may be penetrated into the trochlea portion of the epicondyle of the human elbow. The first U-shaped component 106 has a width, at the distal end, in a range of 22 mm to 27 mm and thickness in a range of 8 mm to 12 mm.

[0024] Further, the elbow implant 100 includes an ulna part 108. The ulna part 108 can be understood as a part of the elbow implant 100, which can be penetrated into an ulna (not shown). The ulna can be understood as a long bone found in the forearm that stretches from the elbow joint to the wrist, and when in anatomical position, is found on the medial side of the forearm and runs parallel to the radius bone, the other long bone in the forearm, and is the larger and longer of the two. The shape of ulna part 108 complements to the shape of an ulna (not shown). The ulna part 108 has a length in a range of 65 mm to 80 mm. In one example, the length of the ulna part 108 can depend on a length of the ulna, in which the ulna part 108 is to be penetrated during the total elbow arthroplasty (TEA). The ulna part 108 can be made of a biocompatible metallic material such as Ti6Al4V Grade 5 Titanium alloy or a polymeric material such as Polyether ether ketone (PEEK) or Ultra high density polyethylene (UHMWPE). Further, the ulna part includes a proximal end and a distal end. In one example, the proximal end and the distal end of the ulna part 108 are referenced from the trochlea portion of the epicondyle of the human elbow.

[0025] The distal end of the ulna part 108 includes an ulna stem 110. A natural carrying angle is adopted in the design of the ulna stem 110. In one example, the ulna stem 110 of the elbow implant 100 is designed to accommodate a normal carrying angle of the ulna. The ulna stem 110 has a length in a range of 35 mm to 55 mm, a width in a range of 4 mm to 8 mm, and a thickness in a range of 4 mm to 8 mm. The ulna stem 110 may be penetrated in an ulnar medial canal (not shown) of the ulna after sectioning the olecranon. After the penetration of the ulna stem 110 in the ulnar medial canal of the ulna, the bone cement can be injected into the ulnar medial canal to fix the ulna stem 110 in the ulna. In one example, the bone cement can be injected into the ulnar medial canal to fix the ulna part 108 in the ulna.

[0026] The proximal end of the ulna part 108 includes a second U-shaped component 112. The second U-shaped component 112 may be penetrated into the trochlea portion of the epicondyle of the human elbow. The second U-shaped component 112 has a width, at the proximal end of the ulna part, in a range of 10 mm to 14 mm.

[0027] In one example the humeral stem can adopt to an optional angle to fit perfectly into the humeral medial canal. After the fixation of the humerus stem 104 in the humerus medial canal of the humerus and the fixation of the ulna stem 110 in the ulnar medial canal of the ulna, the humerus part 102 and the ulna part 108 may be linked with each other using a connecting pin 114. In one example, the connecting pin 114 may be an assembly pin. In one example, the first U-shaped component 106 and the second U-shaped component 112 may be linked using the connecting pin 114. In one example, the humems part 102 and the ulna part 108 may be linked with each other using the connecting pin 114 before or after penetration of the humerus part 102 and the ulna part 108 in the humerus and the ulna respectively. The second U-shaped component 112 is articulable with the first U-shaped component 106 over the connecting pin 114, which may enable movement of the elbow joint.

[0028] In an implementation of the present subject matter, the first U-shaped component 106 includes two condylar portions 116-1, 116-2, collectively referred to as 116 hereinafter. Each condylar portion 116 of the two condylar portions 116-1, 116-2 includes a receptacle (not shown in Fig. 1 ) disposed on an inner surface (not shown in Fig. 1) thereof. The second U-shaped component 112 includes two bearing surfaces 118-1, 118-2, collectively referred to as 118 hereinafter. Each bearing surface 118 of the two bearing surfaces 118-1, 118-2 is complementing the respective condylar portion 116 and includes a hole (not shown in Fig. 1) extending there through.

[0029] Fig. 2 illustrates a rear perspective view of the elbow implant 100 in the assembled state, in accordance with the implementation of the present subject matter, and Fig. 3 illustrates an isometric view of the elbow implant 100 in the assembled state, in accordance with the implementation of the present subject matter. Fig. 2 and Fig. 3 are explained hereinafter in conjunction with each other. The elbow implant 100 includes two receptacles 202-1, 202-2, collectively referred to as 202 hereinafter. Each receptacle 202 of the two receptacles 202- 1 , 202-2 is disposed on the respective condylar portion 116 of the first U-shaped component 106. The receptacle 202-1 is disposed on the condylar portion 116-1. The receptacle 202-2 is disposed on the condylar portion 116-2. Further, the elbow implant 100 includes two holes 204-1, 204-2, collectively referred to as 204 hereinafter. Each hole 204 of the two holes 204- 1, 204-2 is extending through the respective bearing surface 118 of the second U- shaped component 112. The hole 204-1 is disposed on the bearing surface 118-1. The hole 204-2 is disposed on the bearing surface 118-2. Further, the connecting pin 114 can be passed through the respective hole 204 of each bearing surface 118 and the respective end (not shown) of the connecting pin 114 may be received in the respective receptacle 202-1, 202-2 of each condylar portion 116 for linking the first U-shaped component 106 with the second U-shaped component 112 for formation of the elbow joint.

[0030] Fig. 4 illustrates a side view of the elbow implant 100 in the assembled state, in accordance with the implementation of the present subject matter. An exemplary position of the elbow implant 100 is represented, in which the each condylar portion 116 of the humerus part 102 mates with the respective bearing surface 118 of the ulna part 108 via a connecting pin 114.

[0031] In an implementation of the present subject matter, the elbow implant 100 is designed to use as an assembly after the implantation of the elbow implant 100 during TEA. In such an implementation, the humems medial cavity of the humerus is rasped to remove the bone mass of the humerus for penetrating the humerus stem 104 into the humerus medial cavity of the humerus in such a manner that the first U- shaped component 106 is penetrated into the trochlea portion of the epicondyle of the human elbow. After penetration of the humerus stem 104 into the humerus medial cavity of the humerus, the humerus medial cavity of the humerus is injected with the bone cement so that the humerus stem 104 firmly fixes into the humerus medial cavity. Further, the ulnar medial cavity of the ulna is rasped to remove the bone mass of the ulna for penetrating the ulna stem 110 into the ulna medial cavity of the ulna in such a manner that the second U-shaped component 112 is penetrated into the trochlea portion of the epicondyle of the human elbow. After penetration of the ulna stem 110 into the ulnar medial cavity of the ulna, the ulnar medial cavity is injected with the bone cement so that the ulna stem 110 firmly fixes into the ulnar medial cavity. Furthermore, the connecting pin 114 is inserted into the holes 202 and 204 of the bearing surfaces 116 and 118 of the humerus part 102, and ulna part 108 and ends of the inserted connecting pin 114 are respectively received on respective receptacle 202-1, 202-2 of each condylar portion 116 of the humerus part 102.

[0032] In another implementation of the present subject matter, the elbow implant 100 is designed to use as pre-assembled before the implantation of the elbow implant 100 during the TEA. In such an implementation, the humerus part 102 and the ulna part 108 are linked with each other by passing the connecting pin 114 through the holes 204 of the bearing surfaces 118 of the ulna part 108 in such a manner that ends of the inserted connecting pin 114 are respectively received on respective receptacle 202-1, 202-2of each condylar portion 116 of the humerus part 102. The humerus part 102 and the ulna part 108 when linked by the connecting pin 114 form an assembly of the elbow implant 100. During the TEA, the assembly of the elbow implant 100 is inserted into the elbow joint area in such a manner that the humerus stem 104 of said assembly is penetrated into the humerus medial cavity of the humerus and the ulna stem 110 of said assembly is penetrated into the ulnar medial cavity of the ulna. During said insertion of said assembly, a connecting region of the first U-shaped component 106 and the second U-shaped component 112 along with the connecting pin 114 is penetrated into the trochlea portion of the epicondyle of the human elbow.

[0033] Although examples for the present disclosure have been described in language specific to structural features and/or methods, it should be understood that the appended claims are not necessarily limited to the specific features or methods described. Rather, the specific features and methods are disclosed and explained as examples of the present disclosure.

Claims

We claim:

1. An elbow implant (100) comprising:

a humerus part (102) having a distal end and a proximal end, wherein the proximal end of the humerus part (102) comprises a humerus stem (104) penetrable into a humerus medial canal of a humerus, and wherein the distal end of the humerus part (102) comprises a first U-shaped component (106) penetrable into a trochlea portion of an epicondyle of a human elbow; and

an ulna part (108) having a distal end and a proximal end, wherein the distal end of the ulna part (108) comprises an ulna stem (110) penetrable into an ulnar medial canal of an ulna, and wherein the proximal end of the ulna part (108) comprises a second U-shaped component (112) penetrable into the trochlea portion of the epicondyle of the human elbow and articulable with the first U-shaped component (106);

wherein the humerus part (102) and the ulna part (108) are linkable with each other via a connecting pin (114) to form an elbow joint.

2. The elbow implant (100) as claimed in claim 1, wherein the first U-shaped component (106) comprises two condylar portions (116), each having a receptacle (202-1, 202-2) disposed on an inner surface thereof, and wherein the second U- shaped component (112) comprises two bearing surfaces (118), each complementing the respective condylar portion (116) and having a hole (204) extending there through.

3. The elbow implant (100) as claimed in claim 2, wherein the connecting pin (114) is passable through the respective hole (204) of each bearing surface (118), and wherein respective end of the connecting pin (114) is receivable in the respective receptacle (202-1, 202-2) of each condylar portion (116).

4. The elbow implant (100) as claimed in claim 1, wherein the humerus part (102) has a length in a range of 65 mm to 75 mm.

5. The elbow implant (100) as claimed in claim 1, wherein the humems stem (104) has a length in a range of 35 mm to 50 mm, a width in a range of 4 mm to 8 mm, and a thickness in a range of 4 mm to 8 mm.

6. The elbow implant (100) as claimed in claim 1, wherein the ulna part (108) has a length in a range of 65 mm to 80 mm.

7. The elbow implant (100) as claimed in claim 1, wherein the ulna stem (108) has a length in a range of 35 mm to 55 mm, a width in a range of 4 mm to 8 mm, and a thickness in a range of 4 mm to 8 mm.

8. The elbow implant (100) as claimed in claim 1, wherein the first U-shaped component (106) has a width, at the distal end, in a range of 22 mm to 25 mm and thickness of 8 mm to 12 mm.

9. The elbow implant (100) as claimed in claim 1, wherein the second U-shaped component (112) has a width, at the proximal end, in a range of 10 mm to 14 mm and thickness of 8 mm to 12 mm.

10. The elbow implant (100) as claimed in claim 1, wherein the shape of the humerus part (102) complements to the shape of the humerus, and wherein the shape of the ulna part (108) complements to the shape of the ulna.