JP6640286B2 - Kit used for hip arthroplasty - Google Patents

Description

  The present invention relates generally to implants used in orthopedic surgery.

  Joints in the human body form the junction between two or more bones or other skeletal parts. Ankles, hips, knees, shoulders, elbows and wrists are just a few of the many joints found in the body. As can be seen from the above list of joints, many of the joints allow for relative movement between the bones. For example, a joint may have sliding, sliding, hinged movement, or spherical movement. For example, the ankle allows for hinged motion, the knee can combine sliding and hinged motion, and the shoulders and hips allow for motion with a spherical arrangement.

  Joints in the body can be stressed or damaged in a variety of ways. For example, the continued use of a joint over the years has resulted in gradual wear and tear on the joint. The joints that allow movement have cartilage located between the bones, which provide lubrication to the movement and also absorb some of the forces directed at the joint. Over time, normal use of the joints may cause cartilage wear and direct contact between working bones. In contrast, trauma to the joint in normal use, the application of large forces due to an accident such as a motor vehicle accident, can cause considerable damage to bone, cartilage or other connective tissue such as tendons or ligaments.

  Arthrosis, a term that refers to joint disease, is another means by which joints can become damaged. Probably the best known joint disease is arthritis, which is commonly referred to as joint disease or inflammation that results in pain, hypertrophy, stiffness, instability, and often deformity.

  There are many different forms of arthritis, and osteoarthritis is the most common, which results from the wear and tear of cartilage in joints. Another type of arthritis is osteonecrosis, which results in the loss of part of the bone due to loss of blood supply. Other types of arthritis result from trauma to the joint, while other arthritis, such as rheumatoid arthritis, lupus and psoriatic arthritis, destroy cartilage and are associated with inflammation of the joint lining.

  The hip joint is one of the joints commonly suffering from arthropathy. The hip joint is a spherical joint that connects the femur or femur to the pelvis. The pelvis has a hemispherical socket called an acetabulum for receiving a spherical head in the femur. Both the femoral head and the acetabulum are coated with cartilage, allowing the femur to move easily within the pelvis. Other joints that commonly suffer from arthropathy include the spine, knee, shoulder, carpal, metacarpal, and phalanges of the hand. As opposed to arthropathy, arthroplasty generally refers to the creation of artificial joints. In some cases of arthritis or other forms of arthropathy, such as when pain is severe or when the range of motion of the joint is limited, partial or total replacement of the joint within a prosthesis is warranted. In some cases. The procedure for joint replacement will, of course, vary according to the particular joint in question, but in general, it is necessary to replace the end of the diseased bone with an artificial joint implant and insert a member that will serve as a cartilage substitute. Including.

  The prosthetic implant is formed of a rigid material that is bonded to the bone and provides strength and stiffness to the joint, and the cartilage substitute is selected to provide lubrication to the joint and absorb some of the compressive force. Is done. Suitable materials for the implant include metals and composites such as titanium, cobalt chromium, stainless steel, ceramics, and suitable materials for the cartilage substitute include polyethylene. Cement may also be used to secure the prosthetic implant to the host bone.

  For example, a total hip replacement involves removing the ball-shaped femoral head and inserting a stem implant into the center of the bone called the medullary canal or bone marrow. The stem implant may be cemented within the medullary canal or may have a porous coated surface to allow the implant to heal bone directly. The stem implant has a neck and a ball-shaped head that are intended to perform the same functions as a healthy femur neck and a ball-shaped head.

  The cup or shell may be placed directly in the acetabulum. The cup or shell may include a porous coating to promote bone ingrowth to secure the shell to the acetabulum. Alternatively or additionally, the shell may include one or more openings for receiving bone screws to assist in attaching the shell to the acetabulum. The cup may be formed from a metal, for example, cobalt chrome, stainless steel or titanium. Alternatively, the cup may be formed from ceramic or polyethylene. In some embodiments, the cup engages directly on the head. In another embodiment, certain liners are inserted into the cup to articulate against the head. The liner may be formed from metal, ceramic or polyethylene.

  Metal and ceramic liners are often locked into the shell through taper locks, ie, the shell includes a taper, and the liner includes a corresponding taper that fits within the taper of the shell. When properly seated, the taper of the shell and the taper of the liner engage each other, locking the liner within the shell. However, during insertion, the conical taper of the liner can become misaligned with the conical taper of the shell, thus preventing surface-to-surface locking of the intended conical taper. This is called cross-locking and is characterized by relatively less stable ends or multipoint locks. If misalignment occurs during insertion, the risk of implant destruction and other complications increases during surgery.

  If the liner becomes cross-locked, the surgeon must decide whether to leave the liner in the cross-locking position, attempt to remove the liner from the shell, or remove the entire implant structure. . Leaving the cross-locked liner within the shell presents a number of risks to the patient, including increased wear, degradation of the implant structure, suboptimal range of motion, and implant failure. Removing the liner from the shell or the entire structure also poses a risk and complicates the operation.

  Therefore, there is a need for a liner that eliminates or substantially reduces the occurrence of cross-locked tapered joints.

  According to one embodiment of the present invention, there is provided a liner adapted to be inserted into an acetabular shell used in hip arthroplasty. The liner includes a concave inner surface adapted to engage the femoral head. The liner further includes an outer surface adapted to engage the acetabular shell, and an edge extending between the inner and outer surfaces. The outer surface includes a locking portion extending from the edge, a compound curved portion extending from the locking portion at a first transition point, and a dome portion extending from the compound curved portion at the first transition point. The shaped part is tangent to the locking part.

  In another embodiment, a kit for use in arthroplasty is provided. The kid includes a shell and a liner adapted to be inserted into the shell. The liner includes an inner surface and an outer surface. The inner surface is generally concave and the outer surface is adapted to engage the acetabular shell. The outer surface includes a locking portion and a compound curved portion, and the compound curved portion includes a radial portion and a straight tangent portion.

  In yet another embodiment of the present invention, a liner is provided. Liners are used in arthroplasty and include an inner surface and an outer surface. The outer surface is adapted to engage the acetabular shell and includes a locking portion and a compound curved portion. The compound curved portion extends tangentially from the locking portion.

For a more complete understanding of the present invention and its advantages, reference will now be made to the following description, taken in conjunction with the accompanying drawings.
1 is a perspective view of a liner according to an embodiment of the present invention. FIG. 2 is a sectional view of the liner of FIG. 1. FIG. 2 is an enlarged view of a part of the liner of FIG. 1. FIG. 2 is a cross-sectional view of the liner of FIG. 1 superimposed on a liner according to the prior art. FIG. 2 is a cross-sectional view of the liner of FIG. 1 coupled to a shell, with the liner misaligned. FIG. 2 is a cross-sectional view of the liner of FIG. 1 coupled to a shell, with the liner properly positioned within the shell. FIG. 4 is a perspective view of a liner according to another embodiment of the present invention. 5 is a flowchart illustrating a method of using a liner and shell according to the present invention. FIG. 2 is a partial cross-sectional view of the liner of FIG. 1 showing various dimensions between regions according to one embodiment of the present invention.

  Embodiments of the present invention and their advantages are best understood by referring to the following description and drawings. In the following description and in the drawings, like reference numerals have been used for like and corresponding parts of the drawings.

  Referring now to FIGS. 1 and 2, there is shown a liner 10 according to one embodiment of the present invention. Liner 10 includes an inner surface (ie, a support surface) 12. As shown, in this embodiment, the support surface 12 is substantially concave. The bearing surface 12 is designed to articulate with a femoral head (not shown). Liner 10 also includes an outer surface 14. Outer surface 14 is designed to fit within shell 16 (FIGS. 5 and 6). The support surface 12 and the outer surface 14 bond to an edge 18 extending between the support surface 12 and the outer surface 14. In other words, the edge 18 is between the support surface 12 and the outer surface 14. In this embodiment, the support surface 12, outer surface 14, and edge 18 are all formed from a single piece. In another embodiment, these components are modular and may be locked together.

  The outer surface 14 will be described in more detail with reference to FIGS. Outer surface 14 includes a locking portion 20, a compound curved portion 22 and a dome portion 24. In this embodiment, the dome portion 24 includes a flat top portion 24a, as is common in some prior art liner designs. However, it should be understood that some liners 10 may not have a flat top portion. Lock portion 20 extends from edge 18 and has a size and shape to engage shell 16 as described in more detail below. In this embodiment, the locking portion 20 is a conical tapered wall, but other known locking mechanisms may be used.

  In the embodiment illustrated in FIGS. 1 and 2, the composite curvilinear portion 22 includes two portions, a radial portion 25 and a tangential portion 26. In the illustrated embodiment, the radial portions are curved and the tangent portions 26 are straight. In another embodiment, the tangent portion 26 may also be curved with a radius different from the radius of the radial portion. As shown in FIG. 3 which is an enlarged view of the liner 10 near the compound curved portion 22, the locking portion 20 is tangent to the radial portion 25 at the transition point 28. In other words, radial portion 25 extends tangentially from locking portion 20. Since the radial portion 25 is tangent to the lock portion 20, there is no end and there is continuity between the lock portion 20 and the radial portion 25. Radial portion 25 defines a center thereof because it is curved with a radius of a circle tangent to locking portion 20.

  As shown in FIG. 2, compound curved portion 22 starts at the point where lock portion 20 ends and extends from lock portion 20. In some embodiments, the dome portion 24 is absent and the compound curved portion 22 extends to the top of the liner 10.

  Referring again to FIG. 3, the radial portion 25 transitions tangentially into the tangential portion 26 at the transition point 30. In other words, tangential portion 26 extends tangentially from radial portion 25 at transition point 30. Radial portion 25 is tangent to the tangent portion at point 30, so there are no ends or sharp points on liner 10. The tangent portion 26 is a straight line that also makes a tangent to the dome portion 24 at the transition point 32. In other words, the tangent portion 26 is a straight line tangent to both the radial portion 25 and the dome portion 24. By having a tangent portion 26 tangent to both of these two curved regions 24, 25, there are no edges or corners and the rough surface is reduced. The tangent portion 26 is a straight line in the embodiment shown in FIGS. In another embodiment, tangent portion 26 may be curved. In yet another embodiment, the tangent portion may not be present, as further shown in FIG. The compound curved portion 22 may include only the radial portion 25.

  Turning to FIG. 4, liner 10 is shown superimposed on a prior art liner (line 34). As can be seen, the compound curvilinear portion 22 extends outwardly from a corresponding outer portion 34 of the prior art liner. This additional material is represented by the unshaded portion 35 in FIG. The additional material in liner 10 reduces the amount of clearance between the two parts when liner 10 and shell 16 are assembled, as further described in FIGS. 5 and 6 below.

  In some embodiments, the curvature of the radial portion 25 is determined by maximizing the radius of the radial portion 25, but the tangential portion 26 tangent to both the radial portion 25 and the dome portion 24 is still Can be formed. However, in other embodiments, other parameters may determine the curvature of the radial portion 25.

  Referring now to FIGS. 5 and 6, the liner 10 inserted within the shell 16 is shown. Shell 16 includes an inner surface 36 and an outer surface 38. The outer surface 38 is designed to fit into a surgically prepared acetabulum (not shown). Inner surface 36 includes a locking portion 40 designed to mate with locking portion 20 of liner 10. In the present embodiment, the lock portion 40 is a taper that fits with the tapered lock portion 20 of the liner 10. In this embodiment, the locking portions 40, 20 of the shell 16 and the liner 10 are self-locking tapers, as is known in the art.

  First, when the liner 10 is introduced into the shell 16 and the locking portions 20 and 40 are misaligned, as shown in FIG. 5, the liner 10 "floats" within the shell 16 and faces within the shell 16. Not one. In other words, the edge 18 of the liner 10 is not flush with the edge 42 of the shell 16. This allows the user to ensure alignment between the locking portion 20 of the liner 10 and the locking portion 40 of the shell 16 before placing the liner 10. As described above, the compound curved portion 22 includes additional material (the unshaded portion 35 of FIG. 4) to reduce the clearance between the liner 10 and the shell 16. Thus, unless the locking portion 20 of the shell 16 and the locking portion 40 of the liner 10 are aligned, the compound curved portion 22 will strike the shell and prevent the liner from falling into place. Once the liner 10 and the shell 16 are aligned, the locking portions 20, 40 are engaged and the locking portion 20 of the liner 10 is in full taper contact with the locking portion 40 of the shell 16, as shown in FIG. Liner 10 may be completely contained within shell 16. When the liner 10 is completely contained within the shell 16, the edge 18 of the liner 10 is parallel to the edge 42 of the shell 16.

  FIG. 7 shows another embodiment of the present invention. This embodiment includes a liner 50. Liner 50 includes a locking portion 52, a compound curved portion 54 and a dome portion 56. In the present embodiment, compound curved portion 54 includes a single curved portion 58. In other words, there is no straight tangent portion described in the embodiment of FIGS. The curved portion 58 of the compound curved portion 54 extends from a point 55 where the locked portion ends. In some embodiments, the dome portion 56 is absent and the compound curved portion 54 extends to the top of the liner 10. In another embodiment where the dome portion 56 is present, the compound curved portion 54 transitions into the dome portion 56 at a point 59. In this embodiment, the curved portion 58 extends tangentially from the lock portion 52 and the dome portion 56.

  Referring now to FIG. 8, a method of using one embodiment of the present invention will be described. In step s60, the shell 16 is inserted into an acetabulum (not shown). The liners 10, 50 are arranged in the shell (s62). If the liners 10, 50 are floating, the user rotates the liners 10, 50 until the shell 16 slides into the shell 16 as shown in FIG. 6 (step s64). In some embodiments, step s60 may be performed after inserting the liners 10, 50 into the shell. In other words, the liner / shell combination may be assembled in an operating room or may be obtained pre-assembled, such as a monolithic shell with a pre-assembled liner and shell. The user may be a surgeon who assembles the shell and liner during the operation, or a person who pre-assembles the device and then supplies the shell and liner assembly to the surgeon in a pre-assembled state. .

  Referring now to FIG. 9, a partial cross-sectional view of the liner 10 is shown. In this embodiment, the liner 10 has an outer surface 14 that includes a locking portion 20, a compound curved portion 22, and a dome portion 24. The compound curved portion 22 includes two portions, a radial portion 25 and a tangential portion 26. FIG. 9 illustrates one embodiment that specifies those portions and regions having various dimensions. As shown, the locking portion 20 has a height 70 of about 0.250-0.300 inches. Lock portion 20 has a taper gauge diameter 72 of about 3.05 cm (1.2 inches) to 5.08 cm (2.0 inches) and a diameter of about 0.483 cm (0.190 inches) to 5.59 cm (2.20 inches). ) And the taper gauge position 74 of FIG. Lock portion 20 also has a taper angle 76 of 5-6 degrees.

  Radial portion 25 has a mixing radius 78 of 0.250-0.750 inches (0.635-1.91 cm). The tangential flat extends between an angle 80 of about 9.0 to 10.0 degrees and has a length 82 of about 0.10 to 0.15 inches.

  While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and will herein be described in detail. However, it is not intended to limit the invention to the particular forms disclosed, but on the contrary, all modifications that come within the spirit and scope of the invention as defined in the appended claims. It is to be understood that they are intended to cover all equivalents and alternatives.

(Embodiment)
(1) A liner adapted to be inserted into an acetabular shell used for hip arthroplasty,
A concave inner surface adapted to engage the femoral head;
An outer surface adapted to engage the acetabular shell;
An edge extending between the inner surface and the outer surface, the outer surface having a locking portion extending from the edge, a compound curvilinear portion extending from the locking portion at a first transition point; A dome portion extending from the compound curved portion; and an edge, wherein the compound curved portion is tangent to the locking portion at the first transition point.
(2) The liner according to embodiment 1, wherein the compound curved portion includes a radial portion and a tangent portion.
(3) The liner of embodiment 2, wherein the radial portion extends from the locking portion at the first transition point.
(4) The liner according to embodiment 2, wherein the tangent portion is a straight line.
(5) The liner of embodiment 4, wherein the tangent portion extends from the radial portion at a second transition point.
(6) The liner according to embodiment 5, wherein the tangent portion is tangent to the radial portion at the second transition point.
(7) The liner of embodiment 2, wherein the dome portion extends from the tangent portion at a third transition point.
The liner of claim 7, wherein the tangent portion is tangent to the dome portion at the third transition point.
(9) The liner according to embodiment 1, wherein the dome portion extends from the compound curved portion at a transition point, and the compound curved portion is tangent to the dome portion at the transition point.
(10) A kit used for arthroplasty,
Shell and
A liner adapted to be inserted into the shell, the inner liner including an inner surface and an outer surface, wherein the inner surface is substantially concave and the outer surface is adapted to engage an acetabular shell; A liner, wherein the outer surface includes a lock portion and a compound curved portion, wherein the compound curved portion includes a radial portion and a straight tangent portion.

The kit of claim 10, wherein the shell includes a locking portion adapted to engage the locking portion of the liner.
The kit of claim 11, wherein the locking portion of the shell and the locking portion of the liner are self-locking tapers.
(13) The kit according to embodiment 10, wherein the compound curved portion extends tangentially from the lock portion.
(14) The kit of embodiment 10, wherein the liner further comprises a dome portion extending tangentially from the compound curved portion.
(15) The kit according to embodiment 14, wherein the dome portion includes a flat top portion.
(16) A liner for use in arthroplasty, wherein the liner includes an inner surface and an outer surface, the inner surface is generally concave, and the outer surface is adapted to engage an acetabular shell. A liner, wherein the outer surface includes a locking portion and a compound curved portion, the compound curved portion extending tangentially from the locking portion.
(17) The liner of embodiment 16, wherein the outer surface further comprises a dome portion extending tangentially from the compound curved portion.
18. The liner of claim 17, wherein the compound curved portion includes a radial portion and the dome portion extends tangentially from the radial portion.
(19) The liner according to embodiment 16, wherein the compound curved portion includes a radial portion having a radius and a tangent portion.
(20) The liner of embodiment 19, wherein the tangent portion has a length of 0.15 to 0.15 inches.

(21) The liner of embodiment 16, wherein the locking portion is tapered and has a tapered height of about 0.250 to 0.300 inches.
(22) The liner of embodiment 16, further comprising an edge between the inner surface and the outer surface.

Claims (5)

A kit used for hip arthroplasty,
A shell having a shell lock portion;
A liner adapted to be inserted into the shell;
The liner is
An inner surface and an outer surface,
The inner surface is generally concave, the outer surface is adapted to engage the shell,
The outer surface includes a liner lock portion and a compound curved portion including a curved portion having a curvature,
The shell lock portion and the liner lock portion are adapted to engage each other;
The shell lock portion and the liner lock portion have a self-locking taper,
The compound curved portion extends tangentially from the liner lock portion at a first transition point in a cross-section through the centerline of the liner ;
The kit according to claim 1, wherein the cross section passing through the center line of the liner includes all the center lines passing through the center portion of the liner .   2. The compound curved portion includes a tangent portion extending from the curved portion at a second transition point in a cross-section through the centerline of the liner, wherein the tangent portion is tangent to the curved portion. The kit according to 1. The kit according to claim 2, wherein the tangent portion has a linear structure in a cross section passing through a center line of the liner .   The kit according to claim 2, wherein the tangent portion has a curved portion having a curvature, and the curvature of the tangent portion is different from the curvature of the curved portion.   4. The kit of claim 3, wherein the liner includes a dome portion extending from the tangent portion at a third transition point in a cross-section through a centerline of the liner.

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