Mechanical implants for hip and shoulder arthroplasty

Abstract

The present invention relates to a mechanical implant for hip and shoulder arthroplasty. The mechanical implant comprises a neck (1) and an end (2), the end (2) which enters into a cavity in the patient's bone and terminates with a movable mechanical part (3) which fits into the metaphysis of the femur or humerus, and the end (2) terminates with two movable parts (4) to fit the end (2) into the neck (1). The two parts of the neck (1) and the movable mechanical part (3) are joined by a screw (5). The present invention enhances stability and facilitates the replacement of the neck (1) in the event of revision.

Description

Detailed Description of the Invention

[0001] 〔Technical Field〕 The present invention relates to the technical field of surgical instruments, devices or methods, and more specifically, to those that artificially replace or substitute a part of the body. Even more specifically, it relates to hip joint replacement implants for the femoral head region and shoulder joint replacement implants for the humeral head region.

[0002] 〔Background of the Invention〕 The mechanical implants for partial or total replacement hip and shoulder arthroplasty disclosed in the present invention have not been disclosed in the prior art.

[0003] In a normal state, the femoral head of a healthy person forms a joint with the acetabulum of the pelvis, enabling a wide range of movement of the hip joint in multiple planes. Many diseases such as osteoarthritis can cause joint function disorders due to degeneration of articular cartilage and accompanying pain, deformation, and loss of function. Total hip arthroplasty usually involves the complete replacement of the femoral head, the neck of the bone, and the acetabulum of the pelvis using implants made of metal and polyethylene alloy. This orthopedic surgery aims to reduce the severe pain caused by the friction of degenerated cartilage and to restore function and improve the quality of life.

[0004] Until now, when patients suffering from chronic joint pain due to arthritis chose to undergo joint replacement surgery, orthopedic surgeons replaced the existing joint surface with artificial implants. These implants must adhere to the patient's natural bone. The methods of adhering implants to bone are broadly classified into two main types: methods that use cement and methods that do not require the use of cement. When using cement during implant installation, an additional layer of bone cement made of an acrylic polymer usually called polymethylmethacrylate (PMMA) is required between the patient's natural bone and the artificial joint components.

[0005] The disadvantages of using bone cement include the fact that it deteriorates over time, causing cement fragments to detach and potentially leading to problems. Cement breakdown can cause loosening of the artificial joint, potentially requiring another joint replacement surgery (revision surgery). Residual cement can irritate surrounding soft tissue and cause inflammation. Although rare, cement can enter the bloodstream and reach the lungs, potentially leading to a life-threatening condition. Furthermore, the application of bone cement to closed bone cavities such as the femur is associated with the development of cement application syndrome, characterized by rapid hypotension, hypoxia, and even cardiac arrest due to embolism of fat globules and bone marrow components in the lungs. Finally, necrosis and fever are frequent occurrences in patients undergoing related surgeries involving the use of cement.

[0006] On the other hand, cementless implant placement (also known as press-fit implantation) requires implants with a rough or porous coating that promotes the growth of natural bone on top of them. Since new bone growth is limited to 1-2 mm, the surgeon must use special tools to shape the natural bone to comfortably fit the implant.

[0007] Some implants have screws or plates that fix the bone and prosthesis in place until natural bone growth creates more secure fixation. The disadvantage of these cement-free methods is that they require healthy bone. Patients with low bone density due to osteoporosis, for example, may not be suitable for these methods. Furthermore, an additional disadvantage is that it can take up to three months for bone tissue to grow around the new implant. Because it takes time for natural bone to fully integrate with the implant, experts discuss whether or not patients should delay putting full weight on the new joint. Another potential drawback that frequently occurs is from impact during implant placement, which can even cause bone fracture. Moreover, over time, the ends of the implant may sink into the bone, leading to loss of function. Another common undesirable complication is that the implant may loosen due to opening of the bone cavity, resulting in unwanted mobility within the lumen. Finally, femoral prostheses with collars can prevent complete interlocking of the femoral prosthesis, resulting in satisfactory vertical stability but causing rotational instability.

[0008] Therefore, the object of the present invention is to advantageously solve the aforementioned drawbacks and disadvantages of the prior art by proposing a mechanical implant for partial or total hip and shoulder arthroplasty.

[0009] Furthermore, an object of the present invention is to provide a mechanical implant for partial or total hip and shoulder arthroplasty that fits into the lumen of the bone and provides stability both during application and throughout the lifespan of the implant.

[0010] Another object of the present invention is to provide a mechanical implant for partial or total hip and shoulder arthroplasty, having a movable mechanical part that fits into the metaphysis of the femur or humerus.

[0011] Furthermore, an object of the present invention is to provide a mechanical implant for partial or total hip and shoulder arthroplasty that ensures that the end of the implant does not sink into the bone lumen over time.

[0012] A further object of the present invention is to provide a mechanical implant for partial or total hip and shoulder arthroplasty that facilitates the replacement of an entire segment in the event of revision.

[0013] An additional advantage of the mechanical implant of the present invention is that it is fully adjustable, adaptable to all known types of bone, and ensures excellent fit.

[0014] These objectives, features, and advantages of the present invention, as well as other objectives, features, and advantages, will become apparent in the following detailed description. [Brief explanation of the drawing]

[0015] The present invention will become apparent to those skilled in the art by reference to the accompanying drawings, which illustrate the invention in an illustrative and non-limiting manner. Figure 1 shows an exploded view of the mechanical implant of the present invention and its constituent parts. Figure 2 shows exemplary embodiments of mechanical implants for partial or total hip and shoulder arthroplasty. Figures 3(a)-(b) show plan and side views of a mechanical component with its end inserted into a bone lumen. Figure 4 shows the neck portion which forms part of the mechanical implant of the present invention. [Detailed description of preferred embodiments]

[0016] Exemplary embodiments of mechanical implants used in partial or total hip and shoulder arthroplasty will be described with reference to the attached drawings.

[0017] The mechanical implant of the present invention consists of two parts: a neck (1) shown in Figure 4 and an end (2) shown in Figure 3(a) which is inserted into a cavity in the patient's bone. The end (2) is terminated by a movable mechanical part (3) that fits into the metaphysis of the femur or humerus and two movable parts (4) used to fit the end (2) into the neck (1). The two parts, the neck (1) and the movable mechanical part (3), are joined by a screw (5) shown in Figure 1.

[0018] The end portion (2) has a cruciform structure (6) with four holes (7). The movable mechanical part (3) is fitted into a hole (7a) perpendicular to the end portion (2) (Figure 3(b)). On the other hand, two movable parts (4) are fitted into holes (7b) horizontal to the end portion (2). The cruciform structure (6) has slits (8) on each side for the mechanical part (3) and the movable part (4) to be fitted and adjusted to the metaphysis of the bone, respectively. To make a mechanical implant (Figure 2), the lower part of the neck portion (1) has a configuration that fits into the cruciform structure (6) so that the neck portion (1) is integrated into the end portion (2) and into the movable mechanical part (3) which has the movable parts (4), respectively.

[0019] The end portion (2) and neck portion (1) are made of titanium in an advantageous but not limited manner, and the movable mechanical portion (3) has a hydroxyapatite coating.

[0020] It should be noted that the description of the present invention has been made with reference to, but is not limited to, exemplary embodiments. Accordingly, any changes or modifications relating to shape, dimensions, form, materials used, structure, and assemblies are considered to be included in the scope and object of the present invention, provided that they do not constitute a new inventive process and do not contribute to the development of the known art. [Brief explanation of the drawing]

[0021] [Figure 1] The mechanical implant of the present invention and its constituent parts are shown in an exploded view. [Figure 2]Exemplary embodiments of mechanical implants for partial or total hip and shoulder arthroplasty are shown. [Figure 3a] This shows a plan view of a mechanical component with its end inserted into a bone canal cavity. [Figure 3b] This shows a side view of a mechanical component with its end inserted into the bone canal cavity. [Figure 4] This shows the neck portion that forms part of the mechanical implant of the present invention.

Claims

1. It comprises a neck portion (1) and an end portion (2), The aforementioned end (2) enters the cavity of the patient's bone and terminates at the movable mechanical part (3), The movable mechanical part (3) fits the metaphysis of the bone and has two movable parts (4), The end portion (2) has a cross-shaped structure (6) with four holes (7), The movable mechanical part (3) is fitted into a hole (7a) perpendicular to the end portion (2), and the two movable parts (4) are fitted into holes (7b) horizontal to the end portion (2). The cross-shaped structure (6) has slits (8) on each side, and the movable mechanical part (3) and the two movable parts (4) are attached to the slits (8), and are adjusted based on the metaphysis of the bone. A mechanical implant for hip and shoulder arthroplasty, characterized in that the lower part of the neck portion (1) has a notch (9) that fits into the cross-shaped structure (6) so that the neck portion (1) is integrated into the end portion (2) and into the movable mechanical portion (3) which has the two movable parts (4).

2. The mechanical implant for hip and shoulder arthroplasty according to claim 1, characterized in that the end portion (1) and the neck portion (2) are made of titanium.

3. The mechanical implant for hip and shoulder arthroplasty according to claim 1, characterized in that the movable mechanical part (3) has a hydroxyapatite coating.

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