RU2593224C1 - Hip joint endoprosthesis - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: invention refers to medicine, namely to surgical orthopaedics, and can be applied to total hip joint replacement. Hip joint endoprosthesis consists of acetabular component, insert, spherical head, neck, and endoprosthesis stem. Neck base has shape of cylinder with ledge at bottom and inner thread along base, and is located in cylindrical channel located in upper part of endoprosthesis stem, and located along axis of stem. In channel, parallel to it, along its whole length, there are slots at outer side connected to each other into one slot in lower part of channel. Neck base ledge is in one of slots. Middle part of stem has first cavity located along axis of stem. Lower part of stem has second cavity of rectangular parallelepiped form, located along axis of stem. Second cavity is connected to first chamber and cylindrical channel in top part of stem by top and bottom cylindrical through holes arranged along axis of stem. In lower through hole and in second cavity there is rod of rectangular cross-section. Magnet in parallelepiped form with rectangular opening at center is located on rod in second cavity and has clamping spring at its bottom located on rod. When no effect upon magnet is exerted by external magnetic field, it stays in locking slot of rectangular parallelepiped form, located perpendicular to axis of stem in upper part of second cavity, and in upper through hole there is pin, screwed into thread of neck base. In first cavity there is reducer connected to upper end of rod and to lower end of pin.

EFFECT: increased range of joint motion, possibility to change extremity length and recover length with maximum accuracy after operation, possibility to change antetorsion of endoprosthesis neck and, accordingly, prevention of joint dislocations after operation, creating conditions for optimum tension of pelvic and trochanter muscles, optimisation of biomechanical parameters, and improved treatment results.

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Description

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

Various endoprostheses of the hip joint are known which, when installing the femoral component, allow you to change parameters such as offset, endoprosthesis neck anthetorsia, and limb length (tension of the pelvio-trochanteris muscles).

So, for example, in the leg of the endoprosthesis (RF patent №2245690) there is a cylindrical channel in which the base of the neck having a cylindrical shape corresponding to a cylindrical channel is placed with the possibility of vertical movements and fixing. This allows you to change the tension of the pelvio-trochanteris muscles and, accordingly, the length of the limb during the installation process (after setting the head). The disadvantage of this endoprosthesis is that it provides only a change in the length of the limb, offset (through the use of different heads), and there is no possibility of changing the antetorsion of the neck of the endoprosthesis.

Known endoprosthesis of the hip joint (RF patent 2265419), the base of the neck of which is made in the form of a segment of the gear. A cylindrical worm is installed in the cylindrical channel of the leg itself along its axis. The worm makes a worm gear with the base of the neck, due to which it is possible to change the cervical-diaphyseal angle, indirectly changing the offset and length of the limb. The disadvantage of this endoprosthesis is the inability to change the antetorsion of the neck of the endoprosthesis.

Known hip endoprostheses with modular necks, for example, the Zimmer ® M / L Taperwith Kinectiv ® Technology endoprosthesis with modular necks (http://www.zimmer.com/medical-professionals/products/hip/ml-taper-kinectiv-technology .html, accessed 05.05.2015).

An endoprosthesis of this type is a system consisting of a modular femoral component and a set of necks of various configurations. Due to the selection of the appropriate neck, it is possible to change the offset, limb length, neck antetorsia. The disadvantage of this endoprosthesis is the need for a set of necks.

The disadvantage of all of these endoprostheses is that the change in offset, limb length, neck antetorsia is provided only during surgery. After the operation, changing these parameters is not possible.

At the same time, in modern traumatology and orthopedics there are implants that allow you to change your parameters, for example, length under the influence of an external electromagnetic field, see, for example, A. Gupta, J. Meswania, R. Pollock, S.R. Cannon, T.W.R. Briggs, S. Taylor, G. Blunn, Non-invasivedistalfemoralexpandableendoprosthesisforlimb-salvagesurgeryinpaediatrictumours. - thejournalofboneandjointsurgeryvol. 88-B, No. 5, may 2006. Most often, such constructions are used in pediatric oncology when there is a need to increase the length of the affected limb in the process of child growth.

The closest known hip endoprosthesis to the claimed is the RF patent No. 2296536, A61F 2/32. The endoprosthesis contains a head, a cylindrical neck with a thread, a trochanteric section, a leg, a locking screw, a lock nut and a spherical body. A cylindrical glass with a threaded channel under the neck is fixed on its spherical body with its base. The lock nut is installed on the neck between the end of the glass and the spherical body with the possibility of fixing the level of immersion of the neck in the glass. The locking screw is made with a socket under the socket wrench and a surface congruent to the spherical body for contact with the latter. The locking screw is mounted on the thread from the outside of the trochanteric section. This endoprosthesis during the installation process allows you to change the offset, the antetorsion of the neck of the endoprosthesis, the length of the limb (the tension of the pelviotrochanter muscles). However, all these manipulations, as well as the above counterparts are possible only during the operation.

The objective of the invention is the provision in the postoperative period of the possibility of changing the length of the limb, changing the antetorsion of the neck of the endoprosthesis and, accordingly, preventing dislocations in the joint, increasing the amplitude of movements in the joint, creating conditions for optimal tension of the pelvio-trochanter muscles.

To solve the problem in a known hip joint implant consisting of an acetabular component, an insert, a spherical head, neck and leg of the endoprosthesis, the base of the neck has the shape of a cylinder with a protrusion at the bottom, also has an internal thread along the base and is located in the cylindrical channel located in the upper part the legs of the endoprosthesis and located along the axis of the leg, in the channel parallel to it along its entire length from the outside there are grooves that connect to each other in the lower part of the channel into one single groove, p whereby the protrusion of the neck base is in one of the grooves, in the middle part of the leg there is a first cavity located along the axis of the leg, in the lower part of the leg there is a second cavity in the form of a rectangular parallelepiped located along the axis of the leg, while the second cavity is connected to the first cavity and the cylindrical channel of the upper part of the leg by means of the upper and lower cylindrical through holes located along the axis of the leg, in the lower through hole and the second cavity there is a rod of rectangular cross section, a magnet in a parallelepiped with a rectangular hole in the center, located on the rod in the second cavity, and a spring clamping it from below, located on the rod, and in the absence of an external magnetic field, it is in a blocking groove in the form of a rectangular parallelepiped located perpendicular to the axis of the legs in the upper part of the second cavity, and in the upper through hole there is a stud screwed into the thread of the neck base, and in the first cavity there is a gearbox connected to the upper end of the rod and to the bottom they pin end.

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 a hip joint prosthesis (acetabular component, liner, head, neck base thread not shown), scale, in FIG. 2 is a structural diagram of the femoral component of the endoprosthesis (neck, gear, magnet, spring not shown), scale 1: 1, in FIG. 3 - neck of the endoprosthesis, scale 1: 1, in FIG. 4 - a visual image (volumetric drawing) of the gearbox, 4: 1 scale, in FIG. 5 - section of the endoprosthesis leg (secant plane runs along the longitudinal axis, in the center), scale 1: 1, in FIG. 6 is a diagram of the rotation of the neck of the hip joint endoprosthesis, scale 2: 1, in FIG. 7 is a diagram of a change in limb length and location of a magnetic system.

In FIG. 1 adopted the following notation:

1 - neck;

2 - the base of the neck;

3 - protrusion of the base of the neck;

4 - leg;

5 - leg groove;

6 - a single groove;

7 - the first cavity;

8 - upper cylindrical through hole;

9 - cover of the upper cavity;

10 - gear;

11 - lower cylindrical through hole;

12 - the second cavity;

13 - cover of the lower cavity;

14 - magnet;

15 - spring;

16 - blocking groove.

In FIG. 2 adopted the following notation:

4 - leg;

5 - leg groove;

6 - a single groove;

7 - the first cavity;

8 - upper cylindrical through hole;

11 - lower cylindrical through hole;

12 - the second cavity;

16 - blocking groove.

In FIG. 3 adopted the following notation:

1 - neck;

2 - the base of the neck;

3 - protrusion of the base of the neck;

17 - neck channel;

18 - internal thread of the base of the neck.

In FIG. 4 the following notation is accepted:

10 - gearbox.

In FIG. 5 adopted the following notation:

1 - neck;

2 - the base of the neck;

3 - protrusion of the base of the neck;

4 - leg;

5 - leg groove;

7 - the first cavity;

8 - upper cylindrical through hole;

10 - gear;

11 - lower cylindrical through hole;

12 - the second cavity;

14 - magnet;

15 - spring;

16 - blocking groove;

19 - hairpin;

20 - the rod.

In FIG. 6 the following notation is accepted:

1 - neck;

4 - leg;

18 - internal thread of the base of the neck;

19 - hairpin;

In FIG. 7 the following notation is accepted:

21 - a magnetic system;

22, 23 - the direction of movement;

24 - electromagnets.

The inventive endoprosthesis of the hip joint consists of an acetabular component, an insert, a spherical head (not shown in the figures), neck 1, legs of the endoprosthesis 4. The base of the neck 2 is made in the form of a cylinder with a protrusion of the base of the neck 3 at the bottom. At the base of the neck 2 there is a channel of the neck 17 with an internal thread of the base of the neck 18 (see Fig. 3). The base of the neck 2 is located in the cylindrical channel of the upper part of the leg of the endoprosthesis, located along the axis of the leg of the endoprosthesis 4. In the channel parallel to it along its entire length from the outside there are grooves of the leg 5, connected to each other in the lower part of the channel into one single groove 6, and the protrusion of the base of the neck 3 is located in one of the grooves of the legs 5 (see Fig. 1, 2). In the middle part of the leg 4 there is a first cavity 7 located along the axis of the leg, in the lower part of the leg 4 there is a second cavity 12 in the form of a rectangular parallelepiped located along the axis of the leg 4, while the second cavity 12 is connected to the first cavity 7 and to the cylindrical channel of the upper parts of the legs through the upper cylindrical through hole 8 and the lower cylindrical through hole 11 located along the axis of the leg 4 (see Fig. 1, 2, 5). Outside, these cavities are closed by the cover of the upper cavity 9 and the cover of the lower cavity 13, respectively. In the lower through hole 11 and the second cavity 12 there is a rod of rectangular cross section 20 (see Fig. 5). On the rod 20 is a magnet 14, made in the form of a parallelepiped with a rectangular hole in the center corresponding to the rod. The magnet 14 is located in the second cavity 12. At the bottom of the magnet 14 there is a spring 15 clamping it, located on the rod 20, and when it is free, the magnet 14 is in the blocking groove 16 in the form of a rectangular parallelepiped located perpendicular to the axis of the legs 4 in the upper part of the second cavity 12 (see Figs. 1, 5). In the upper through hole 8 there is a pin 19 screwed into the internal thread of the base of the neck 18, with a gearbox 10 in the first cavity connected to the upper end of the shaft 20 and to the lower end of the pin 19 (see Figs. 4, 5).

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

The acetabular component of the endoprosthesis 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. Holes may be present in the acetabular component of the endoprosthesis for additional fixation by screws. The material for the manufacture can be any alloy used for the manufacture of endoprostheses, for example, CoCrMo. All components of the endoprosthesis are made of paramagnets.

The insert may be made of materials commonly used in endoprosthetics, for example, the so-called “cross-link” polyethylene.

An endoprosthesis head is a standard metal head commonly used in endoprosthetics. Various variants of friction pairs are possible, for example, ceramic-ceramic, ceramic, polyethylene and others.

The neck 1 and leg 4, the cover of the upper cavity 9 and the cover of the lower cavity 13 are made of special medical alloys used for the manufacture of endoprostheses. Fixation of the caps of the cavities is possible by mechanical clamping in the corresponding grooves of the legs. Fixation by welding is possible.

The cervical-diaphyseal angle is usually 135 degrees, and may also be less, for example 125, for the endoprosthesis replacement of chronic injuries of the femoral neck associated with significant shortening of the limb.

It is advisable to make the number of leg grooves 5 from 3 to 5 in connection with the need to change the position of the neck antetorsia in values from 30 degrees of antetorsion to 30 degrees of retrotorsion, since the neck antetorsia is normally 10-15 degrees.

Gear 10 is a typical micro gear used in micromotors, consisting of a set of spur gears making up a spur gear. The total gear ratio of the gearbox is 1: 298, for example, the gearbox from the ZGRM12FT20-298 motor, see, for example, http://chipster.ru/catalog/robotech/1627.html, accessed May 21, 2015.

The spring 15 may be made of spring steel.

Magnet 14 is a typical ferrite magnet.

Magnetic system 21 is a special medical magnetic system, see, for example, A. Gupta, J. Meswania, R. Pollock, S.R. Cannon, T.W.R. Briggs, S. Taylor, G. Blunn Non-invasivedistalfemoralexpandableendoprosthesisforlimb-salvagesurgeryinpaediatrictumours // Thejournalofboneandjointsurgery (Eng.). - 2006. - VOL. 88-B, No. 5, may. - P. 649-654.

Thus, the implementation of the claimed endoprosthesis is not in doubt, since for its manufacture typical designs, parts and materials used in arthroplasty are used.

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

Preoperative planning and preparation of the endoprosthesis.

The required value of the femoral neck antetorsia is determined, as well as the estimated limb length. In the case of conventional primary arthroplasty, the length and neck antetorsion are set on the leg before surgery. In the initial position (see Fig. 5), the base of the neck 2 is in its lowest position. In this case, the protrusion of the base of the neck 3 is located in a single groove 6. In this position, the neck 1 can rotate around the axis of the pin 19 (together with the pin or thread) within a sector that is limited by the protruding parts of the legs 4 (see Fig. 5, 6) . Next, the leg 4 is placed next to the magnetic system 21 so that their longitudinal axes coincide (see Fig. 7). When the power of the magnetic system 21 is turned on, a constant magnetic field is created by the electromagnets 24. In this case, the magnet 14 is extended from the blocking groove 16 due to the attraction to the electromagnets 24 (see Fig. 7 arrow 22). Then begins the rotation of the electromagnets 24 located in the magnetic system 21 clockwise or counterclockwise (depending on the necessary movement of the neck). Due to the attraction of the magnet 14 to the electromagnets 24, it rotates around the axis O similar to the rotation of the electromagnets 24 (see Fig. 7 arrow 23).

Since the rod 20 has a rectangular section, and the magnet 14 has a rectangular hole, the rotation from the magnet 14 is transmitted to the rod 20, it is also possible to move the magnet 14 along the rod with its exit from the blocking groove 16. The rotation of the rod 20 is transmitted to the gearbox 10, and from it to the pin 19. When the stud 19 is rotated, the base of the neck 2 is extended along the axis of the leg 4. In this case, the protrusion of the base of the neck 3 falls into one of the grooves of the leg 5. When the stud is rotated, the neck 1 is manually set to the desired antetorsion position, i.e. the protrusion of the base of the neck 3 is installed in one of the grooves. In this way, the estimated antetorsion and the distance by which the neck 1 will protrude are established. After the necessary antetorsion parameters and limb lengths are set, the magnetic system 21 is turned off, and by stretching the spring 15, the magnet 14 returns to the blocking groove 16.

Endoprosthesis Installation

One of the known methods, for example antero-lateral, is access to the hip joint. During the operation, after removal of the femoral head, the acetabulum is treated with standard scans. The acetabular component of the endoprosthesis is installed using one of the known methods, for example, “press-fit”, then the insert is installed. Next, the femoral canal is treated with special sweeps, legs 4, and heads are installed. The head is reduced and the wound is sutured in layers.

In the case of endoprosthetics for chronic injuries of the femur, for example, a fracture of the femoral neck, when there is a significant shortening of the lower limb and the proximal femur is displaced upward, practice shows that it is almost impossible to restore the length of the limb during surgery without significant damage to surrounding soft tissues and formed scars . In this case, the preparation of the endoprosthesis leg is either not carried out at all or the neck 1 extends to the minimum distance necessary for the protrusion of the base of the neck 3 to enter the supposed groove of the leg 5 so that the length of the entire leg is minimal. Thus, the minimum length of the protruding part of the neck and, accordingly, the possibility of less traumatic installation of the endoprosthesis in a position in which the length of the limb increases minimally is achieved. An increase in the length of a limb to its normal length is performed in the postoperative period similarly to the technique described above.

The postoperative period.

With an insufficiently accurate intraoperative installation of the leg 4 of the endoprosthesis or the acetabular component of the endoprosthesis, it may be necessary to correct the length of the limb, for example, when shortening or lengthening the operated limb. It may also be necessary to correct the neck antetorsia 1, for example, when the lower limb is rotated outward or inward for proper installation, or if there are dislocations in the joint due to improper installation of the acetabular component (with excessive anteversion of the acetabular component, it is possible to correct it by increasing the neck retrotorsion 1.

Correction of limb length is as follows.

The operated lower limb of the patient is placed in the magnetic system 21 so that the system is located in the middle third of the thigh (the lower end of the legs 4 should not reach the beginning of the magnetic system 21). Next, the magnetic system 21 is turned on, followed by the rotation of the electromagnets 24 clockwise or counterclockwise (depending on the necessary change in the length of the limb) and extension or retraction of the neck 1 (see Fig. 7, the mechanism of movement of the neck is described above in preoperative planning). It is advisable to perform this manipulation under x-ray control to assess the degree of increase or decrease in the length of the limb (see Fig. 5).

If arthroplasty is necessary for chronic injuries of the femur, for example, a fracture of the neck of the femur, when there is a significant shortening of the lower limb, performing restoration of the length of the limb in one step will lead to significant muscle overstrain, as a result of which it is advisable to restore the length of the limb in several stages, increasing it by 1 -2 mm in one step, which will make it possible to evenly stretch the formed scars and maintain an adequate degree of muscle tension.

The restoration of the required limb length, respectively, of the center of rotation in the artificial joint allows us to achieve the optimal range of motion in the joint.

Correction of cervical antetorsia after surgery is as follows.

First, the neck 1 is set to its initial position (see Fig. 5). The mechanism of movement of the neck 1 is described above. In this case, the protrusion of the base of the neck 3 falls into a single groove 6, it becomes possible to rotate the neck 1 within the sector limited by the protruding parts of the leg 4. By mechanical rotation of the lower limb of the patient, the doctor’s hand rotates it to the required angle (see Fig. 7). Next, the electromagnetic system 21 is turned on, the extension of the neck 1 to the required length begins (in this case, the protrusion of the base of the neck 3 falls into the necessary groove of the leg 5. It is also advisable to perform this manipulation under x-ray control to restore the required length of the limb.

Since the correction of the antetorsia requires the installation of the neck in the initial position, i.e. such that the length of the limb is minimal, then after setting the necessary antetorsion, restoration of the previous limb length is required.

Thus, in the postoperative period, this endoprosthesis allows you to correct errors that can be made during surgery to replace the joint, restore the rotation center, limb length as accurately as possible, and achieve maximum range of motion in the joint.

The technical result of the claimed invention is:

- increase in the range of motion in the joint;

- the ability to change the length of the limb and restore the length with maximum accuracy after surgery;

- the possibility of changing the neck antetorsion of the endoprosthesis and, accordingly, preventing dislocation in the joint after surgery;

- creation of conditions for optimal tension of pelvio-trochanteris muscles, optimization of biomechanical parameters and improvement of treatment results.

Claims (1)

An endoprosthesis of the hip joint, consisting of an acetabular component, an insert, a spherical head, neck and legs of the endoprosthesis, characterized in that the base of the neck has the shape of a cylinder with a protrusion at the bottom, also has an internal thread along the base and is located in a cylindrical channel located in the upper part of the leg of the endoprosthesis and located along the axis of the legs, in the channel parallel to it along its entire length from the outside there are grooves that connect to each other in the lower part of the channel into one single groove, and the protrusion of the base The hook is located in one of the grooves, in the middle part of the leg there is a first cavity located along the axis of the leg, in the lower part of the leg there is a second cavity in the form of a rectangular parallelepiped located along the axis of the leg, while the second cavity is connected to the first cavity and to the cylindrical channel of the upper parts of the legs through the upper and lower cylindrical through holes located along the axis of the legs, in the lower through hole and the second cavity there is a rod of rectangular cross section, a parallelepiped magnet with with a rim hole in the center, located on the rod in the second cavity, and a spring clamping it from below, located on the rod, and in the absence of an external magnetic field, it is in the blocking groove in the form of a rectangular parallelepiped located perpendicular to the axis of the legs in the upper part of the second cavity and in the upper through hole there is a stud screwed into the thread of the base of the neck, and in the first cavity there is a gearbox connected to the upper end of the rod and to the lower end of the stud.

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