WO2021029838A1

WO2021029838A1 - Multi-axial angular hip prosthesis for animals

Info

Publication number: WO2021029838A1
Application number: PCT/TR2020/050291
Authority: WO
Inventors: Ari SMIRYAN; Fatih ATAK
Original assignee: Efa Veterinerlik Hizmetleri Tic. Ltd. Sti.
Priority date: 2019-08-09
Filing date: 2020-04-08
Publication date: 2021-02-18
Also published as: TR201912235A1

Abstract

The present invention relates to a newly designed multi-axial angular hip prosthesis that is developed to be used in hip joints having decreased or lost motive function due to various reasons in animals in order to refunction the joint by achieving the closest hip joint angular values compatible with the anatomy of animals. The present invention particularly relates to a multi-axial angular hip prosthesis developed to be used in the field of medicine, and designed in compliance with the bone structure of animals in order to eliminate painful bone deformities as well as joint deformities in the hip joint, stemming from traumatic arthritis, fractures, and similar reasons in quadrupeds and particularly in feline and canine animal groups.

Description

MULTI-AXIAL ANGULAR HIP PROSTHESIS FOR ANIMALS

Technical Field of the Invention

The present invention relates to a newly designed multi-axial angular hip prosthesis that is developed to be used in hip joints having decreased or lost motive function due to various reasons in animals in order to refunction the joint by achieving the closest hip joint angular values compatible with the anatomy of animals.

The present invention particularly relates to a multi-axial angular hip prosthesis developed to be used in the field of medicine, and designed in compliance with the bone structure of animals in order to eliminate painful bone deformities as well as joint deformities in the hip joint, stemming from traumatic arthritis, fractures, and similar reasons in quadrupeds and particularly in feline and canine animal groups.

Prior Art

Trauma-related fracture cases are occasionally encountered in various bones of quadrupeds, and of feline and canine animal groups in particular. One of these fracture cases is hip joint fractures.

The excision arthroplasty technique which employed in the state of the art for segmental tibia fractures occurring in hip joints of quadrupeds, requires lapsing of a period of at least 60 days subsequent to surgery before the patient may walk again, and necessitates patients to undergo physiotherapy for at least 2 years at the end of this period. Since post- operative recovery periods are substantially long, it takes patients a rather long time to return to the state in which they can meet their daily needs.

Even though the excision arthroplasty technique applied to animals in the state of the art creates a functional pseudo joint, problems like shortening, pain, muscle atrophy and limping in respective leg may occur due to erroneous surgeries. The most prevalent complication that develops in dogs that undergo excision arthroplasty is sharp exostoses, namely bone projections occurring in collum femoris stemming from faulty angulation of the osteotomy line. The most prevalent complication that develops in dogs that undergo excision arthroplasty is sharp exostoses, namely bone projections occurring in collum femoris stemming from faulty angulation of the osteotomy line.

In Turkey, the general method implemented by veterinary surgeons in hip joint fracture cases is the excision arthroplasty performed by removing caput femoralis from the hip joint. This method, however, is proven to pose difficulties in terms of implementation in dogs that are weighing 15 kg and above, inducing problems such as the upwards elevation of the femur bone over the pelvic height, thereby causing distention in sciatic nerve and leaving the patient incapable of walking. As trochanter major receives no linear force, osteoporosis develops in the femur bone in excision arthroplasty method, and especially severe atrophy is observed in the quadriceps femoris muscle.

In the state of the art, hip prosthesis systems originally developed for humans have been tried to be adapted to animals by being scaled down, and there are already a number of major companies around the world that are trying out this particular method. All angular values and technical characteristics utilized by these companies are identical to prostheses intended for humans. However, hip angulations of animals vary 115° and 145° based on breed characteristics, and therefore cannot be fixed with a 135° angle as in human models. Furthermore, while a healthy joint motion mechanism is a total of 225° in animals, it is 160° in humans. Therefore, hip replacement systems originally produced and developed for humans cause problems such as luxations, loosening and fractures in animals. These fractures are usually observed as femur shaft fractures and extended periods are required for its treatment.

Objects of the Invention

In order to eliminate aforementioned problems existing in the state of the art, the present invention relates to a newly designed multi-axial angular hip prosthesis that is developed to be used in hip joints having decreased or lost motive function due to various reasons in animals in order to refunction the joint by achieving the closest hip joint angular values compatible with the anatomy of animals.

The main object of the present invention is to minimize prevalence of complications including non-union, union delay, or avascular necrosis that develop in the treatment of the hip joint fractures by using multi-axial angular hip prosthesis in the hip joint of the quadrupeds.

Another object of the present invention is to increase the hip motion mechanism up to 235° by means of the dual head system capable of moving in an embedded manner thereof. Hip luxations are prevented by means of this angulation, and shearing forces that may impose on the shaft and correspondingly fractures occurring as a consequence of biomechanical axial changes may be avoided. Thus, an artificial joint system has been developed having full functionality in hip joint replacement procedures performed subsequent to hip dysplasia, caput femoralis fractures, trauma-related luxations, ligamentum teres ruptures and pathological fractures which are highly likely to occur in cats and dogs.

Another object of the present invention is to equally create 1 mm adherence room for bone cement around the stem in case stems are to be used with cement, or to ensure bone that is formed towards the prosthesis is equal in every section thereof if stems are to be used without cement by means of centering the prosthesis to the medullary canal when placing the inventive multi-axial angular hip prosthesis to the 1/3 proximal region of the femur bone together with a centering element .

The present invention will ensure that animals can be treated without experiencing any anatomical or biomechanical complications subsequent to repairing impairments pertaining to hip joints of quadruped via surgical therapy.

Detailed Description of the Invention

In order to achieve the aforementioned objects of the present invention, the inventive multi-axial angular hip prosthesis designed in compliance with the anatomy of the hip joint of quadrupeds and to be used in the reconstruction of defects occurring in hip joints of quadrupeds due to any reason is illustrated in annexed figures, wherein; FIGURE 1 illustrates the full side view of the bipolar outer cup friction area.

FIGURE 2 illustrates the ventral view of the bipolar outer cup.

FIGURE 3 illustrates the bottom oblique view of the bipolar outer cup.

FIGURE 4 illustrates the full side view of the ball.

FIGURE 5 illustrates the bottom oblique view of the ball.

FIGURE 6 illustrates the bottom oblique view of the linear extension surface of the ball.

FIGURE 7 illustrates the top view of the femoral stem.

FIGURE 8 illustrates the full lateral view of the femoral stem.

FIGURE 9 illustrates the full medial view of the femoral stem.

FIGURE 10 illustrates the ventro-lateral oblique view of the femoral stem.

FIGURE 11 illustrates the mounted full side view of the inventive multi-axial angular hip prosthesis.

FIGURE 12 illustrates the mounted full lateral view of the inventive multi-axial angular hip prosthesis.

FIGURE 13 illustrates the 235° angular rotation movement of the inventive multi-axial angular hip prosthesis.

FIGURE 14 illustrates the full side view of the centering element.

FIGURE 15 illustrates the bottom oblique view of the centering element.

Reference Numerals

1.Bipolar Outer Cup Friction Area 2.UHMWPE (Ultra High Molecular Weight Polyethylene) Specifically Hardened Polyethylene

3.Steel-Polyethylene Lock Retaining Ring Area

4.Convex Ball Retaining Surface

5.Specifically Formed Ball Friction Area

6.Specific Ball Area manufactured from CoCrMo (Cobalt Chrome Molybdenum)

7.Ball Prosthesis Inverted Conical Locking Area

8.Ball Linear Extension Surface

9.1/3 Proximal Femur Lateral Radial Area

10. Ball Conical Seat Surface Angle

11. Collum Section Surface Seat Collar Area

12. 1/3 Proximal Femur Ventral Constricting Surface Area

13. Trochanter Minor Surface Seat Area

14. Centering Element Mounting Area

15. Distal Medullary Canal Feeding Area

16. Osseointegration Retaining Surface Area

17. Proximal Femur Anterior Cortex Rotation Seat Area

18. Proximal Femur Anterior Distal Minor Seat Rotation Area

19. Trochanter Minor Support Area

20. Centering Element UHMWPE Medullary Canal Diameter

21. Flexible Flap Structure

22. Femoral Stem Mounting Area

23. Multi-axial Angular Hip Prosthesis

24. Bipolar Outer Cup

25. Ball

26. Femoral Stem

27. Centering Element

Multi-axial angular hip prosthesis is placed to the 1/3 proximal of the femur so that it can be seated inside the femur bone. The inventive multi-axial angular hip prosthesis is comprised of four main elements which are; bipolar outer cup (24), ball (25), femoral stem (26) and centering element (27).

The first main element is the bipolar outer cup (24) wherein said cup comprises of outer cup friction area (1) as illustrated in Figure 1, steel-polyethylene lock retaining ring area (3) as illustrated in Figure 2 and convex ball retaining surface (4) as illustrated in Figure 3. Said convex ball retaining surface (4) has an angle in a range between - 2.55° and -5.75°, and it ensures that the bipolar outer cup (24) and ball (25) are interlocked with one another by being positioned inside the bipolar outer cup (24). Convex ball retaining surface (4) is manufactured from a plastic derivative material such as the UHMWPE (Ultra High Molecular Weight Polyethylene) specifically hardened polyethylene (2), and comprises a specifically formed ball friction area (5) having a width in a range between 16.15 mm and 36.65 mm. As UHMWPE is a micron-based flexible material, it causes the ball (25) to be inserted to the bipolar outer cup (24) with difficulty, however it prevents the ball from being dislocated. Furthermore, UHMWPE is system that does not release any particles during friction and does not cause degeneration. The outer cup friction area (1) is steel surface having a width in a range between 10.2 mm and 16.15 mm, and a steel- polyethylene lock retaining ring area (3) is required in order to ensure that it can get interlocked with the convex ball retaining surface (4) which is manufactured from UHMWPE (Ultra High Molecular Weight Polyethylene) specifically hardened polyethylene (2). Bipolar outer cup (24) is obtained by means of engaging convex ball retaining surface (4) into steel- polyethylene locking retaining ring area (3) and the outer cup friction area (1) respectively. The ball (25) which is the second main element, comprises of; specific ball area (6) having a width in a range between 10.2 mm and 16.15 mm, manufactured from CoCrMo (Cobalt Chrome Molybdenum) alloy with a diameter as wide as the resected caput or smaller as illustrated in Figure 4, ball prosthesis inverted conical locking area (7) having width in a range between 6.8 mm and 11.5 mm as illustrated in Figure 5, and ball linear extension surface (8) having a width in a range between 0.43 mm and 10.35 mm as illustrated in Figure 6. As a rounding area is determined based on the surface measurements, the specific ball area (6) which is manufactured from CoCrMo (Cobalt Chrome Molybdenum) alloy, may identically imitate the resected caput. The femoral stem (26) and the ball prosthesis inverted conical locking area (7) located below the ball (25) is interlocked with one another. Ball linear extension surface (8) has measurements varying based on the resected collum amount, capable of imitating the distance of the collum.

The femoral stem (26), which is the third main element, is the main carrying mechanism that provides integrity with the femur shaft. Femur stem is produced with an angulation value of 5° which is the femur axis value of cat and dog breeds. The femoral stem (26) is comprised of; 1/3 proximal femur lateral radial area (9) having an angle value in a range between 4.25° and 8.05° as illustrated in Figure 9, ball conical seat surface angle (10) having an angle value in a range between 0.85° and 5.75° as illustrated in Figure 7, collum section surface seat collar area (11) as illustrated in Figure 8, 1/3 proximal femur ventral constriction surface area (12) having an angle value in a range between 0.85° and 3.16° as illustrated in Figure 8, trochanter minor surface seat area (13) as illustrated in Figure 7, centering element mounting area (14) having a width in a range between 2.55 mm and 3.45 mm as illustrated in Figure 9, distal medullary canal feeding area (15) having a width in a range between 29.75 mm and 86.25 mm as illustrated in Figure 10, osseointegration retaining surface area (16) having a width in a range between 29.75 mm and 86.25 mm as illustrated in Figure 10, proximal femur anterior cortex rotation seat area (17) having a width in a range between 3.4 mm and 10.6 mm as illustrated in Figure 10, proximal femur anterior distal minor seat rotation area (18) having a width in a range between 3.4 mm and 10.6 mm as illustrated in Figure 10, and trochanter minor support area (19) having an angle value in a range between 1.7° and 2.3° as illustrated in Figure 9. The ball (25) is engaged with the femoral stem (26) by means of the ball conical seat surface angle (10) located on the femoral stem (26). Ball conical seat surface angle (10) is an inverted conical area, and comprises a conical area that expands from 8 mm to 10 mm. Resected section includes a side area in which the gluteus minimus muscle functions towards which the collum adheres inwardly, wherein collum section surface seat collar area (11) provides a recess-wise angulation in order to ensure that the muscle herein may function smoothly. By means of the collum section surface seat collar area (11), functioning of the gluteus minimus muscle is not hindered after the femoral stem (26) is implanted, and this muscle can function with the proper anatomical balance. Distal medullary canal feeding area (15) is located inside the femoral stem (26). Distal medullary canal feeding area (15) helps intramedullary feeding within the bone and ensures that bone maintains liveliness. Medullary canal situated inside the bone has a constricting structure from top to bottom. Said constricting structure is imitated on the front and rear positions by means of 1/3 proximal femur ventral constricting surface area (12) and the lateral and 1/3 proximal femur lateral radial area (9). The femoral stem (26) identically imitates the medullary canal by means of these angulations and allows prosthesis to adhere to the bone or proper distribution of the cement. Osseointegration retaining surface area (16) located inside the femoral stem (26) is an important area for ensuring a better adherence of prosthesis to the bone. Bone makes rotation through two different point angulations which are; the proximal femur anterior cortex rotation seat area (17) inside the interior surface of the femur bone and towards the underside of the trochanter minor, and proximal femur anterior distal minor seat rotation area (18). These angulations allow for imitating two different anatomical angles which are in the internal surface of the femur bone and under the trochanter minor. Said prosthesis must not descend within the bone from the height determined by us which is ensured by the trochanter minor support area (19) within a week-long period until the inventive multi-axial angular hip prosthesis (23) retains to the bone or until the cement is fully settled in case it is implemented with cement. Trochanter minor support area (19) is a surface that perfectly fits to the resected surface in the femur bone. When said prosthesis is placed on the bone along with the trochanter minor support surface (19), section line corresponds to the trochanter minor. A separate area is created in which the trochanter minor is seated by means of a separate trochanter minor surface seat area (13) in order to ensure the full load distribution in the trochanter minor.

Centering element (27) which is the fourth main element, is comprised of; centering element UHMWPE medullary canal diameter (20) having a length in a range between 4.25 mm and 12.65 mm as illustrated in Figure 14, flexible flap structure (21) having a width in a range between 0.85 m and 1.73 mm as illustrated in Figure 14, and femoral stem mounting area (22) having a width in a range between 2.55 mm and 3.45 mm as illustrated in Figure 15. To mention a representational embodiment of the present invention, caput and collum located in 1/3 proximal of the femur are resected in order to place the inventive multi-axial angular hip prosthesis into the femur bone, and it is ensured that the prosthesis imitates the anatomical structures of the bone. The inventive multi-axial angular hip prosthesis is impacted into the medullary canal after the resection is performed. The aim of this impaction is to linearly transfer the entirety of static and biomechanical loads to the shaft over the prosthesis. Centering element (27) is mounted to the centering element mounting area (14) located at the bottom end of the stem of the inventive multi-axial angular hip prosthesis

(23) through the femoral stem mounting area (22), and prosthesis is inserted into the bone together with said centering element (27) in order to ensure that the inventive multi-axial angular hip prosthesis (23) remains at the center inside the femur bone. Femoral stem (26) remains at the center of the medullary canal in compliance with the centering element UHMWPE medullary canal diameter (20) and the flexible flap structure (21) located on the centering element (27) by means of the room for flexibility available therein. After the femoral stem (26) is inserted to the femur bone, it is connected to the ball (25). After the ball (25) is placed on to the femoral stem (26) in inverted conical way, two-piece system called femoral component is complete. Bipolar outer cup

(24) which is an important element for the present invention, has the bipolar outer cup friction area (1) which corresponds to the friction area in which the femur bone moves inside the hip bone. Outer cup friction area (1) is the inner surface of the bipolar outer cup (24) where the ball (25) functions. Specific ball area (6) which is the outer surface of the ball

(25) and is manufactured from CoCrMo (Cobalt Chrome Molybdenum) alloy, moves inside the specifically formed ball friction area (5) having a surface inside the bipolar outer cup (24). In the inventive multi-axial angular hip prosthesis (23), femoral stem (26) and the specific ball area (6) which is manufactured from CoCrMo (Cobalt Chrome Molybdenum) alloy, are in an interlocked state. Outer cup friction area (1) is located at the outmost surface of the bipolar outer cup (24) element which is situated on the specific ball area (6) manufactured from CoCrMo (Cobalt Chrome Molybdenum) alloy. The inventive multi-axial angular hip prosthesis (23) gets in to contact with the hip bone by means of the outer cup friction area (1). As the ball (25) and the bipolar outer cup (24) are in impaction with one another, they move together, and when these interlocked pieces are moving, convex ball retaining surface (4) which is manufactured from UHMWPE (Ultra High Molecular Weight Polyethylene) specifically hardened polyethylene (2) and positioned inside the bipolar outer cup (24) also moves up to a certain angle. When the ball conical seat surface angle (10) leans on the convex ball retaining surface (4) up to 45° angle, outer cup friction area (1) located inside the hip bone begins to rotate around its own axis in a manner in which it is capable of making an angle of 190°, thereby providing a double stage rotational movement of 235° angle in total to the inventive multi-axial angular hip prosthesis (23) (Figure 13). In the state of the art, as the multi-axial angular hip prosthesis (23) is fixed to the hip bone through the outer cup friction area (1) by means of cement or screws, outer ball which is located on the head of said prosthesis, could perform a rotational motion with a maximum angulation of 135° inside the hip bone.

Femur bone and hip bone of quadrupeds along with cat and dog breed groups have an angulated structure. Therefore, in order to create a prosthesis that is compatible with the anatomy of animals, the respective laboratory works were conducted on specific area and angular values located on the hip joint, and accordingly minimum and maximum measurement pertaining to aforementioned angles and areas were determined. Concordantly, obtained results were optimized by means of both theoretical and practical applications, and utilized in the production of the inventive multi-axial angular hip prosthesis (23).

Claims

1. A Multi-axial angular hip prosthesis used in hip joint surgeries performed in animals characterized in that, it comprises;

• at least one bipolar outer cup friction area (1) located on steel-polyethylene lock retaining ring area

(3),

• at least one convex ball retaining surface (4) manufactured from UHMWPE (Ultra High Molecular Weight Polyethylene) specifically hardened polyethylene (2),

• at least one steel-polyethylene lock retaining ring area (3) located between bipolar outer cup friction area (1) and said convex ball retaining surface (4),

• at least one specifically formed ball friction area (5) located inside said convex ball retaining surface

(4),

• at least one ball conical seat surface angle (10) that is connectable with ball (25),

• at least one collum section surface seat collar area (11) located on femoral stem (26),

• at least one 1/3 proximal femur ventral constricting surface area (12) located on femoral stem (26),

• at least one trochanter minor surface seat area (13) located on femoral stem (26),

• at least one centering element mounting area (14) located on femoral stem (26),

• at least one osseointegration retaining surface area (16) located on femoral stem (26),

• at least one proximal femur anterior distal minor seat rotation area (18) located on femoral stem (26),

• at least one trochanter minor support area (19) located on femoral stem (26), • at least one centering element UHMWPE medullary canal diameter (20) located on centering element (27),

• at least one flexible flap structure (21) located on centering element (27),

• and at least one femur stem mounting area (22) located on centering element (27).

2 . Bipolar outer cup friction area (1) according to Claim 1 characterized in that, it has a width in a range between 10.2 mm and 16.15 mm.

3. Convex ball retaining surface (4) according to Claim 1 characterized in that, it is in a range between -2.55° and -5.75° .

4 . Specifically formed ball friction surface (5) according to Claim 1 characterized in that, it has a width in a range between 16.15 mm and 36.65 mm.

5 . Ball conical seat surface angle (10) according to Claim 1 characterized in that, it is in a range between 0.85° and 5.75°.

6. 1/3 proximal femur ventral constricting surface area (12) according to Claim 1 characterized in that, it is in a range between 0.85° and 3.16°.

7 . Centering element mounting area (14) according to Claim 1 characterized in that, it has a width in a range between 2.55 mm and 3.45 mm.

8.Osseointegration retaining surface area (16) according to Claim 1 characterized in that, it has width in a range between 29.75 mm and 86.25 mm.

9. Proximal femur anterior distal minor seat rotation area (18) according to Claim 1 characterized in that, it has a width in a range between 3.4 mm and 10.6 mm.

10 . Trochanter minor support area (19) according to Claim 1 characterized in that, it is in a range between 1.7° and 2.3° .

11.Centering element UHMWPE medullary canal diameter (20) according to Claim 1 characterized in that, it has a length in a range between 4.25 mm and 12.65 mm.

12. Flexible flap structure (21) according to Claim 1 characterized in that, it has a width in a range between

0.85 mm and 1.73 mm.

13. Femur stem mounting area (22) according to Claim 1 characterized in that, it has a width in a range between 2.55 mm and 3.45 mm.

14.Multi-axial angular hip prosthesis used in hip joint surgeries performed in animals according to Claim 1 characterized in that, it has curvatures in compliance with the anatomy of the hip bone.