RU2589612C1 - Hip joint endoprosthesis - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: invention refers to surgical orthopaedics, and can be used for total hip replacement. Hip joint endoprosthesis consists of acetabular component in form of a hemisphere with lock ring polyethylene insert with rom, spherical head, web and endoprosthesis leg. In the flat part of the acetabular component with its outer side there are perpendicular blind holes equidistant from each other. In top polyethylene insert with its lower side there is a blind threaded hole in its lower part, in which the locking ring screwed inside this hole along its axis there is a metal cylindrical holder of Ferromagnet to interact with magnet brought close to body surface with T-shaped section and above it the spring. Lower part of spring metal cylindrical holder is located inside one of the holes of acetabular component. All elements of the endoprosthesis except said retainer are made of a sample.

EFFECT: invention ensures increased service life of the endoprosthesis.

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Description

The invention relates to medicine, namely to operative orthopedics, and can be used for arthroplasty of the hip joint.

After the installation of an artificial joint during its operation, over time, the components of the friction pair wear, and therefore, the center of rotation in the joint shifts and the length of the limb decreases. With complete wear of the components of the friction pair (the liner most often wears out), the friction of the endoprosthesis head against the inner surface of the acetabular component begins, which requires repeated surgical intervention - revision of the hip joint.

Endoprostheses with the so-called alternative friction pair ceramic-ceramic, ceramic-polyethylene, for example, DePuyCorail®HipSystem are known.

(http://emea.depuysynthes.com/hcp/hip/products/qs/corail-hip-system-emea, accessed March 17, 2015), which have good tribological properties.

The disadvantages of endoprostheses with a ceramic-ceramic friction pair are: increased stiffness of the ceramic-ceramic pair, tendency to fracture, including spontaneous failure in violation of implantation technology, as well as brittleness (toughness), respectively, inadmissibility of impedance between the edge of the insert and the neck of the endoprosthesis.

A disadvantage of ceramic-polyethylene friction pair endoprostheses is that the appearance of ceramic debris leads to a catastrophically increasing wear of the friction pair, increased formation of fracture products with the induction of osteolysis processes in bone implant beds and fibrosis in soft tissues. In revision operations, a separate problem is the impossibility of completely removing ceramic particles from the primary endoprosthesis, which increase the wear of the revision friction pair. The disadvantage of these endoprostheses is also their high cost (Orthopedics: national leadership / under the editorship of S.P. Mironov, G.P. Kotelnikov. - M.: GEOTAR-Media, 2008. - P. 220-224. Manual for endoprosthetics of the hip joint / under the editorship of PM Tikhilov, V.M. Shapovalov. - SPb .: RNIITO named after PP Vredena, 2008. - P. 43-45).

Known hip arthroplasty containing between the acetabular component and the endoprosthesis head various elements (balls), for example, patents of the Russian Federation 2290137, 2207084. The disadvantage of these endoprostheses is that as the balls are erased with large amplitudes of movements, the balls may fall out of the recesses, as well as jamming. balls in the sharp corners of the recesses, which will prevent rotation, blocking movement in the joint.

The closest known hip endoprosthesis to the claimed one is the Zimmer endoprosthesis with the Trilogy acetabular component (Guidance on hip joint replacement / edited by R.M. Tikhilov, V.M. Shapovalov. - St. Petersburg: PP Vredena RNIITO, 2008 . - p. 63-64). This implant contains a pair of metal-polyethylene friction. The disadvantage of the endoprosthesis is that when the endoprosthesis is functioning, the polyethylene liner is worn (worn out) at the place of the highest load (with a slight erasing of the remaining part of the liner), which leads to a shortening of the limb, a change in the center of rotation in the joint, see, for example, x-ray in figure 6 , which in turn leads to limitation of movements in the joint, impaired limb function. Upon achievement of complete abrasion, the friction of the metal head of the endoprosthesis against the metal acetabular component begins, which is accompanied by the ingress of metal debris into the surrounding tissue, contributes to the development of osteolysis and requires revision endoprosthetics of the hip joint. This factor is the main reason for the limited life of the implant.

In the event that the insert has an anti-luxation visor, in case of dislocations in the joint after surgery, for example, with incorrect orientation of the components of the endoprosthesis, there is also no possibility of non-invasive orientation of the antiluxation visor so that it prevents dislocation.

The objective of the invention is to increase the life of the endoprosthesis of the hip joint, and if there is an anti-luxation visor in its composition, to prevent dislocation in the joint.

To solve this problem, in the well-known hip joint implant consisting of an acetabular component in the form of a hemisphere with a retaining ring, a polyethylene insert with a rim, a spherical head, neck and legs of the endoprosthesis, in addition to the flat part of the acetabular component, from its outside there are non-through equidistant to each other from another hole, in the rim of the polyethylene liner on its lower side there is a through hole with a thread in its lower part, into which a locking ring is screwed For example, inside this hole along its axis there is a metal cylindrical retainer of a T-shaped section and a spring above it, and in the free state of the spring, the lower part of the metal cylindrical retainer is inside one of the holes of the acetabular component.

The objective of the invention is achieved by enabling non-invasive rotation of the liner at a certain angle, in order to move the least worn part of the liner to the zone of greatest load, and, accordingly, its most worn part, to the zone of least load.

In the study of other well-known structural and technical solutions in this field of medicine, the specified set of features that distinguishes the invention from the prototype was not identified.

In FIG. 1 is a structural diagram of an acetabular component of an endoprosthesis (insert not shown) at a 3: 1 scale; FIG. 2 - polyethylene insert (retainer not shown), scale 3: 1, in FIG. 3 - a fragment of the rim of a polyethylene liner (incision at the location of the non-through hole), a fragment of the acetabular component of the endoprosthesis (section at the location of one of the non-through holes), scale 3: 1, in FIG. 4 - locking ring, scale 5: 1, in FIG. 5 is a diagram of the rotation of the liner, a visual image (three-dimensional drawing), scale 2: 1, in FIG. 6 is a diagram of an endoprosthesis of a hip joint with an unworn insert; FIG. 7 - radiograph of the hip joint, the corresponding scheme of the endoprosthesis of the hip joint with a worn liner.

In FIG. 1 adopted the following notation:

1 - acetabular component of the endoprosthesis;

2 - thread of the acetabular component of the endoprosthesis;

3 - through hole;

4 - a lock ring;

5 - antennae of a lock ring;

6 - a groove of a lock ring.

In FIG. 2 adopted the following notation:

7 - polyethylene liner;

8 - the rim of the polyethylene liner;

9 - through hole;

10 - thread non-through hole of the liner (the locking ring is not shown).

In FIG. 3 adopted the following notation:

1 - acetabular component of the endoprosthesis;

3 - through hole;

8 - the rim of the polyethylene liner;

11 - a cylindrical clamp T-shaped section;

12 - spring;

13 - a locking ring.

In FIG. 4 the following notation is accepted:

13 - a locking ring;

14 - thread locking ring;

15 - groove for a screwdriver.

In FIG. 5 adopted the following notation:

1 - acetabular component of the endoprosthesis;

7 - polyethylene liner;

10 - a cylindrical clamp T-shaped section;

16 magnet;

In FIG. 6 the following notation is accepted:

17 - the pelvic bone;

18 - femur;

19 - head of the endoprosthesis of the hip joint;

20 - unworn (new) polyethylene liner.

In FIG. 7 the following notation is accepted:

17 - the pelvic bone;

18 - femur;

19 - head of the endoprosthesis of the hip joint;

21 - worn polyethylene liner.

The inventive hip joint implant consists of a spherical head, neck and leg of the endoprosthesis (not shown in the figures), the acetabular component 1, which is a hemisphere, in the lower part of which there is a hole with a threaded acetabular component of the endoprosthesis 2. In the flat part of the acetabular component 1 with its on the outer side there are holes 3. perpendicular to it, through holes equidistant from each other. From the inner surface of the hemisphere there is a groove of the retaining ring 6, in which the retaining ring 4. is located the retaining ring 5 are located in a special cutout from the outer surface of the hemisphere (see Fig. 1).

A polyethylene insert 7 is installed in the acetabular component of the endoprosthesis 1, in the rim of which 8 there is a through hole 9 with a thread in its lower part 10 from the lower side (see Fig. 2). A locking ring 13 is screwed into the thread of the through hole of the liner 9, having an outside thread of the locking ring 14. Inside the through hole 9 of the liner 7 there is a metal cylindrical lock of the T-shaped section 11 along its axis and a spring 12 on top, and the lower part in the free state of the spring 12 a metal cylindrical retainer of a T-shaped section 11 is located inside one of the through holes of the acetabular component 3. (see Fig. 1, 4).

The principle of operation of the proposed endoprosthesis is as follows.

One of the known methods is access to the hip joint, for example, antero-lateral. During the operation, after removal of the femoral head, the acetabulum is treated with standard scans. The acetabular component of the endoprosthesis 1 is installed using the press-fit method. Insert 7 is inserted into it as follows. The lower part of the insert 7 protruding from the bottom is installed in the central hole of the acetabular component of the endoprosthesis 1. Then, using a special guide (impactor) installed in the insert 7, the insert 7 is driven into the acetabular component of the endoprosthesis 1. At the same time, the antennae of the retaining ring 5 diverge in different directions, together with this, the snap ring 4 expands. After the liner is installed, the snap ring 4 enters the special groove of the liner 7, the antennae of the snap ring 5 are closed, along which the installation of the insert 7 is checked (see Fig. 3, position 1). Then, the insert 7 rotates smoothly until one of the through holes 3 of the acetabular component coincides with the through hole 9 in the lower part of the insert, while the spring 13 pushes out the metal cylindrical lock 11 and fixes the insert 7. (see Fig. 2, position 2) . Next, the femoral canal is treated with special scans, the femoral component, the head are installed, and the wound is sutured in layers.

It was noted above that during the operation of the endoprosthesis in the zone of the greatest load, the polyethylene liner wears out, which leads to a change in the length of the limb, the center of rotation in the joint, see, for example, the x-ray in figure 7.

Upon reaching a certain degree of wear of the liner 7 to restore the normal center of rotation and limb length, as well as to prevent complete wear of the liner 7, the following is performed.

In the patient’s position on the healthy side with relaxed muscles of the operated lower limb with slight traction along the axis of the limb (so that the endoprosthesis head does not rest against the insert and does not interfere with rotation) under X-ray control using magnet 16, the insert 7 is rotated at a certain angle so that it reaches the zone of greatest load “move” the least worn part of the liner, and, accordingly, “move” the most worn part in the zone of least load. The principle of operation is that the magnet 16 is initially brought to the surface of the body in the projection of the acetabular component of the endoprosthesis 1. Since the components of the endoprosthesis are made of paramagnets, and the cylindrical retainer of the T-shaped section 11 is made of ferromagnets, then due to the attraction of the latter to magnet 16, it comes out through the holes 3 of the acetabular component 1, as a result of which the insert can rotate around the axis O (see Fig. 5). Then, when the magnet 16 is rotated around the circumference (shown by an arrow in Fig. 6), the insert 7 rotates along with it. When the magnet is rotated to a certain planned angle when the magnet is removed, the cylindrical clamp of the T-shaped section 11 is again pushed by the spring 12 into one of the through holes 3 X-ray examination is performed to monitor its position.

In the event that the insert 7 has an anti-luxation visor, in case of dislocations in the joint after surgery, for example, when the components of the endoprosthesis are incorrectly oriented, it is also possible to non-invasively turn the insert 7 and position the anti-luxation visor so that it prevents dislocation.

The practice of revision endoprosthetics shows that the least wearing part of the insert (to be rotated) usually wears out by 10-20%, therefore, as a result of using the claimed invention, the service life of the hip joint endoprosthesis will increase by 80-90%.

The components of the claimed device of the hip joint endoprosthesis can be implemented as follows.

The acetabular component of the endoprosthesis 1 is a typical acetabular component of the endoprosthesis made in the form of a hemisphere with a different coating for ingrowth of bone tissue, for example, with plasma spraying. The acetabular component of the endoprosthesis may have additional holes for additional fixation with screws. The material for the manufacture can be any alloy used for the manufacture of endoprostheses, for example, CoCrMo.

The retaining ring 4 can be made of spring steel.

Polyethylene liner 7 may be made of the so-called "cross-link" polyethylene, usually used for the manufacture of liners.

The cylindrical retainer of the T-shaped section 11 can be made of medical steel with ferromagnetic properties.

The spring 12 may be made of spring steel.

The locking ring 13 can be made of the same material as the acetabular component of the endoprosthesis.

Magnet 16 can be represented by any kind of magnet.

Thus, the implementation of the claimed endoprosthesis is not in doubt, since its manufacture uses standard materials and parts used in endoprosthetics.

The technical result of the present invention is:

extension of the life of the endoprosthesis. In the presence of an anti-luxation visor - ensuring the possibility of preventing dislocations in the joint.

Claims (1)

An endoprosthesis of the hip joint, consisting of an acetabular component in the form of a hemisphere with a retaining ring, a polyethylene insert with a rim, a spherical head, neck and legs of the endoprosthesis, characterized in that in the flat part of the acetabular component from its outer side there are openings perpendicular to it equally equidistant from each other , in the rim of the polyethylene liner on its lower side there is a through hole with a thread in its lower part, into which a locking ring is screwed, inside this hole along its si there is a metal cylindrical retainer made of a ferromagnet to interact with a magnet brought to the surface of the body, having a T-shaped cross section and a spring on top of it, and in the free state of the spring, the lower part of the metal cylindrical retainer is inside one of the holes of the acetabular component, all elements of the endoprosthesis in addition to the said retainer are made of paramagnets.

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