RU2309706C2 - Hip joint implant and device for installation - Google Patents

Abstract

FIELD: medicine; traumatic surgery; orthopedics.

SUBSTANCE: device intends exclusively for mounting the implant, provides ability of adjustment of depth of implant's leg immersion during process of installation. Implant has acetabular component, head, neck, hip department, leg consisting of proximal and distal parts connected together, and rest made in form of rod provided with threaded head with splint. Fragments of channel for rest, which rest is disposed in eccentricity, are made in any part of leg. Proximal and distal parts are made onto external surfaces with threads being opposite in direction to each other. Proximal part of leg carries joint department and neck with head. There is dead threaded opening in edge along axis. Direction and step of thread of opening coincide with parameters of thread onto external surface of proximal part of leg. Threaded rod has square cross-section shaped protrusion for screwing into blind threaded opening; threaded rod is mounted at edge of distal part of leg. Threaded jack for threaded head with splint is made in joint department. Device for installing of implant has rod with cylindrical envelope and handle. Envelope is made with internal diameter which is smaller than internal diameter of thread onto surface of parts of implant's leg. There is jack in form of stepped smooth-walled opening, which shape and sizes correspond to external diameter of thread of threaded rod as well as to shape and sizes of square-shaped protrusion. Free end of handle is equipped with spherical head for test correction and it is declined from axis of rod for value of neck-diaphysar angle of hip joint implant.

EFFECT: prevention from turning through and from longitudinal shifts of leg; ability of screwing o f leg into bone-brain channel.

2 cl, 2 dwg

Description

The invention relates to medicine, specifically to orthopedics traumatology. It is used to replace a pathologically altered, destroyed, as a result of trauma or orthopedic disease, hip joint.

One of the problems of modern arthroplasty is the conflict in the metal-bone system, which leads to the loosening of the implant and nullification of the result of the operation. This necessitated the search for new constructive solutions providing a more stable position of the elements of the prosthesis of the hip joint, in particular, its legs in the bone tissue.

Such technical solutions include hip joint endoprosthesis [1]. The essence of this device is that by means of a spring-loaded rod having a variable cross-section, spring-loaded petals are pulled out from the windows of the tubular leg. The end sections of the petals are equipped with corrugation, which they abut against the inner surface of the medullary canal. This, in turn, leads to a lodging of bone tissue, which for some time is compensated by the springing of the stem and petals. But, in the end, bone resorption that is not compensated by the springs and loosening of the implant leg occurs.

Compensating the endoprosthesis of the hip joint can be given as another analogue [2]. In this device, thrust elements made in the form of hollow bodies of elongated shape with longitudinal slits are strung on a leg, which is a tube. By axial compression of the thrust elements, achieved by tightening the nut and compressing the spring at the proximal end of the leg, these elements are circularly stretched, in close contact with the inner surface of the medullary canal. However, this device retains its effectiveness until the compensating capabilities of the spring elements are exhausted.

Closest in terms of its technical solution to the claimed is the hip joint endoprosthesis [3]. The spit part of this prosthesis is equipped with a cylindrical part with a channel. The end section connected to it with a threaded rod is also a cylinder, but with a pointed end and a blind threaded hole for the threaded rod. Both cylindrical sections are equipped with anti-rotation scallops. A cylindrical compression spring is installed on the rod, expanding when squeezed by its approaching proximal and distal cylindrical sections. The expansion of the spring during compression creates an emphasis on the inner surface of the medullary canal. In this device, the effectiveness of fixation is maintained as long as the resorption of bone tissue compensated by the spring is maintained. In addition, antirotational scallops must penetrate deep enough into bone tissue to maintain their functional purpose. To reduce this traumatic moment, it is also necessary that the anti-rotation scallops of the trochanteric section are installed strictly in the alignment of those of the terminal section, using grooves cut by them in the bone tissue and, thus, avoiding additional trauma.

The invention consists in a combination of essential features sufficient to achieve the desired technical result, namely, to prevent the cranking and longitudinal displacements of the legs in the medullary canal, if possible screwing the legs into the medullary canal.

This essence lies in the fact that the hip joint implant contains an acetabular component, a head, a neck, a trochanteric section and a leg, consisting of interconnected proximal and distal parts. It is equipped with a stopper in the form of a rod with a threaded head with a slot. In each part of the legs are made coaxially compatible fragments of an eccentrically located channel under the stopper. The proximal and distal parts are made on external surfaces with threads opposite in direction. The proximal part of the leg carries the trochanteric part and the neck with the head and has a blind threaded hole in the end along the axis, the direction and thread pitch of which coincide with the thread parameters on the outer surface of the proximal part of the leg. A threaded rod with a square protrusion at the end is installed on the opposite end of the distal part of the leg along the axis for screwing into a blind threaded hole. Moreover, in the spit section, a threaded socket for a threaded head with a slot is made.

The essence of the device for installing a hip joint implant is a combination of essential features sufficient to achieve the desired technical result, consisting in the fact that this device is intended solely for installing a hip joint implant according to claim 1, with the possibility of adjusting the immersion depth of the legs of this endoprosthesis during installation .

This essence lies in the fact that the device for installing the hip joint implant contains a rod with a cylindrical cage and a handle. The cage is made with an outer diameter smaller than the inner diameter of the thread on the surface of the parts of the leg of the endoprosthesis, with a socket in the form of a stepped smooth-walled hole, corresponding in shape and size to the outer diameter of the thread of the threaded rod, as well as the shape and dimensions of the protrusion of the square section. The handle at the free end is equipped with a spherical head for trial adjustment and is deviated from the axis of the rod by the size of the cervical-diaphyseal angle of the hip joint endoprosthesis.

The presence on the external surfaces of the proximal and distal parts of the leg of the endoprosthesis of opposite threads in the direction excludes the possibility of turning the legs in the medullary canal. The presence of these threads eliminates the possibility of longitudinal movements of the legs. Both of these factors provide high stability in the metal-bone system.

The presence of a blind threaded hole at the end of the proximal part of the leg and a threaded rod with a mating thread at the end of the distal part of the leg provides a reliable connection between both parts of the leg.

The coincidence of the direction and the pitch of the threads of the outer surface of the proximal part of the leg and the blind threaded hole provides the possibility of simultaneously screwing the proximal part of the leg into the medullary canal and screwing it with a blind threaded hole onto the threaded rod of the distal part of the leg.

The presence in the leg of an eccentrically located channel coaxially passing through both parts of the leg connected together and the placement of a stopper in it ensures reliable fastening of the parts and the functioning of the leg as a whole, preventing rotational displacements of the proximal and distal parts.

The presence of a protrusion of a square section at the end of the threaded rod, and the reciprocal shape of the hole in the socket of the holder of the device, for installing the hip joint prosthesis (with a smooth-walled cylindrical section under the threaded rod), provide the possibility of screwing (and, if necessary, unscrewing) into the medullary canal of the distal part of the leg endoprosthesis.

The correspondence of the length of the rod with the clip of the device for installing the hip joint prosthesis to the length of the proximal leg, and the handle with the head to the length of the neck with the endoprosthesis head, makes it possible to use the device as a test to determine the fit and the optimal size of the proximal leg before screwing it into the bone marrow canal .

The smaller diameter of the thread of the cylindrical ferrule of the device for installing the hip joint compared to the internal diameters of the threads on the surfaces of the leg parts provides free movement of the rod of the device with the ferrule along the processed bone marrow canal.

The endoprosthesis of the hip joint is presented in figure 1 (the leg is given in disassembled form in longitudinal section, its cross sections are also shown here.)

The device for installing the endoprosthesis is shown in figure 2 (the cage is shown in longitudinal and cross sections)

The endoprosthesis of the hip joint contains a head 1, a neck 2, a trochanteric section 3, a proximal part of the leg 4 with a thread 5 on the surface, a blind threaded hole 6, the direction and pitch of the thread of which coincides with the thread 5. The endoprosthesis also contains the distal part of the leg 7 with an external thread 8 opposite thread 5 direction. At the end of the distal part of the leg 7, facing in the direction of its proximal part 4, a threaded rod 9 with a thread corresponding to the thread of the blind threaded hole 6 and a protrusion of square section 10 is placed along the axis.

After the proximal 4 and distal 7 parts of the leg are connected, when the first threaded hole 6 is screwed onto the threaded rod 9, an eccentrically located channel is formed along the entire length of the leg due to the coaxial alignment of its fragments made in each part of the leg. A stopper 11 is placed in the channel, made in the form of a rod equipped with a threaded head 12 with a slot, under which a threaded socket is made in the spit section 3. The endoprosthesis of the hip joint contains an acetabular component 13.

A device for installing an endoprosthesis of the hip joint is made in the form of a rod 14 with a handle 15, deviated from the axis of the rod 14 by the value of the cervical-diaphyseal angle of the endoprosthesis. A spherical head 16 is placed at the free end of the handle 15, and a cylindrical ferrule 17 is provided at the end of the shaft 14. It has a smooth-walled socket 18 corresponding to the shape and dimensions of the outer diameter of the thread of the threaded rod 9, as well as to the shape and dimensions of the protrusion of square section 10.

Hip endoprosthesis is used as follows. Lateral surgical access reaches the area of the hip replacement. In the course of the operation, cicatricial joint capsule and paraarticular tissues are excised. The femoral head is dislocated from the articular cavity, after which it is resected together with the neck. The acetabulum is resected, and then the acetabular component of the endoprosthesis 13 is installed in it. A clip 17 is inserted into the threaded rod 9 by the quadrangular socket 18 and the square protrusion 10 of the leg 7. The latter is inserted into the bone marrow canal processed by scanning and screwed in by rotating the rod 14 of the device for the installation of the endoprosthesis with the handle 15. The immersion depth of the distal part of the legs 7 is controlled, focusing on the position of the head 16, using it as a test. When the head 16 reaches the position necessary for the head 1, a test reduction of the head 16 into the acetabular component 13 is performed, the device for installing the endoprosthesis is removed, if necessary, after preliminary correction of the immersion depth of the distal part of the leg 7. Next, the proximal part of the leg of the endoprosthesis 4 is immersed, screwed its threaded hole 6 on the threaded rod 9. When the ends of the parts 4 and 7 of the leg contact, coaxial matching of fragments of the eccentrically located channel occurs in them la A stopper 11 is inserted into the channel by screwing its head 12 into a socket made in the spit section 3, ensuring a reliable connection of the parts 4 and 7 of the leg to each other.

The wound is sutured in layers. Postoperative management is common, as is the case for patients undergoing hip replacement surgery.

Information sources

1. RF patent No. 2066153, BI 23, 1996.

2. RF patent No. 2086210, BI No. 22, 1997.

3. RF patent No. 2185799, BI No. 21, 2002.

Claims (2)

1. An endoprosthesis of the hip joint containing an acetabular component, a head, a neck, a spit and a leg, consisting of interconnected proximal and distal parts, characterized in that it is equipped with a stopper in the form of a rod with a threaded head with a slot, in each part of the legs are made coaxially aligned fragments of an eccentrically located channel under the stopper, the proximal and distal parts are made on external surfaces with threads opposite in direction, the proximal part of the leg carries an integral part and a neck with a head, and has a blind threaded hole in the end along the axis, the direction and thread pitch of which coincide with the thread parameters on the outer surface of the proximal part of the leg, a threaded rod with a square protrusion at the end is installed on the opposite end of the leg of the leg along the axis for screwing into a blind threaded hole, and in the spit section a threaded socket for a threaded head with a slot is made. 2. A device for installing a hip joint endoprosthesis according to claim 1, comprising a rod with a cylindrical cage and a handle, the cage is made with an outer diameter smaller than the internal diameter of the thread on the surface of the parts of the endoprosthesis leg, with a socket in the form of a stepped smooth-walled hole corresponding in shape and size the outer diameter of the thread of the threaded rod, as well as the shape and dimensions of the protrusion of the square section, the handle on the free end is equipped with a spherical head for trial adjustment and deviated from the axis of the rod by the size of the cervical-diaphyseal angle of the hip joint endoprosthesis.

Images