RU2271776C2 - Hip joint endoprosthesis - Google Patents

Abstract

FIELD: medical engineering.

SUBSTANCE: device has spherical head, neck, trochanteric portion and pedicle manufactured as tube. Longitudinally movable and fixable rod is enclosed in the tube. The rod is threaded on its lower end that is mounted with the thread in lower blind externally sharp-pointed tube end. The upper rod end, positioned in the trochanteric portion, has gag having a cut crown. The gag is fitted on the rod so that its cylindrical part is plungeable into tube opening. Bushings equidistant from each other and from the cylindrical gag part and lower tube end are tier-by-tier arranged in pairs on the rod. The bushings are retained in the initial position by means of compressed spiral springs arranged between them on the rod. Each bushing carries three U-shaped loops. Straps are pivotally mounted with one set of ends in the loops. The straps are pivotally connected in turn with their other ends having wavy surface to the like strap ends mounted on neighboring bushing joining the bushings in pairs. Longitudinal slots arranged tier-by-tier are available in the tube. The slots are arranged with their longitudinal axes along the pedicle surface at an angle of 120° relative to each other and shifted by 60° relative to neighboring tier. Pivotally bound strap ends having wavy surface are arranged in the initial position in the longitudinal slots of each tier flush with tube surface.

EFFECT: improved fixation stability in medullary femur canal; improved treatment results.

3 dwg

Description

The device relates to medicine, specifically to traumatology, orthopedics, and is used for arthroplasty of a pathologically altered or destroyed hip joint. From the literature it is known that after 8-10 years after the endoprosthesis replacement, the legs of the artificial joint are loosened in 50% of the operated. This happens regardless of what its fixation was (cement or cementless). Therefore, researchers continue to research in the direction of creating reliable contact in the metal-bone system, including by reconstructing renewable compression in cases of bone-sagging of the bone metal.

Known devices are, for example, “Hip Endoprosthesis” [1], the leg of which is equipped with prestressed, deflected from its axis rods embedded in the bone tissue of the hip diaphysis. But this is not enough for stable fixation of the legs in a given position. The long free ends of the rods cannot sufficiently prevent the occurrence of instability, including rotational. They also cannot prevent the axial displacement of the leg of the endoprosthesis up.

Another analog of the device can be the leg of the “Hip Joint Endoprosthesis" [2], which is a rod with a head installed in the holes of the spacer sections, the large bases of the skirts of which are made of gears. However, this design does not provide a sufficiently reliable fixation.

The closest in technical solution to the claimed should be considered adopted for the prototype "Endoprosthesis of the hip joint" [3], the leg of which has the greatest number of signs common with the claimed. However, the prototype leg, as well as the axial channel made therein, have a variable section. This requires when installing it in the medullary canal of the thigh using a special scan that repeats the stepped shape of the leg of the prosthesis. The same circumstance makes it impossible to correct the change in the degree of immersion of the leg of the prosthesis in the medullary canal of the thigh. In addition, the petals that fix the leg in the medullary canal are directed by their ends to one (distal) side of the thigh, which does not provide reliable preservation of the position of the leg at a given depth.

The essence of the invention lies in the combination of common with the prototype and distinctive features that ensure the achievement of the desired technical result, namely: increasing the stability of fixation of the leg of the endoprosthesis in the bone marrow canal of the thigh and improving treatment outcomes.

The essence of the invention lies in the fact that the endoprosthesis of the hip joint contains a spherical head, neck, trochanteric section and leg, made in the form of a tube. A rod is placed in the tube with the possibility of longitudinal displacements and fixation, equipped with a thread at the lower end and mounted on the thread in the lower, blind, end of the tube pointed from the outside. The upper end of the rod, located in the spit section, is equipped with a cap with a faceted nimbus and mounted on the rod with the possibility of immersing its cylindrical part in the lumen of the tube. On the rod, in pairs, in tiers, bushings are placed equally spaced from each other, also from the cylindrical part of the plug and the lower blind end of the tube and held in their original position by spiral compression springs placed between them on the rod. Each sleeve carries three U-shaped hinges in which strips are pivotally mounted at one end, and, in turn, pivotally connected with their other ends equipped with a groove, with the same ends of adjacent strips mounted on an adjacent sleeve, thus connecting bushings in pairs. Longitudinally grooved longitudinal grooves are made in the tube, and in each tier the grooves are located with their longitudinal axes on the leg surface at 120 degrees relative to each other, and with respect to adjacent tiers the grooves are offset by 60 degrees. At the same time, in the initial position, the ends of the strips are pivotally connected, equipped with a groove, placed in the longitudinal grooves of each tier and flush with the surface of the tube.

The use of a tube of constant cross section as the leg of an endoprosthesis does not require the use of a special tool for processing the bone marrow canal, which simplifies the procedure for installing the endoprosthesis.

The presence of tiered grooves with longitudinal axes displaced relative to each other provides high stability of fixation of the endoprosthesis leg in the bone marrow canal of the thigh when the articulated, grooved ends of the strips abutting against the bone tissue of the bone marrow are pulled out from the grooves.

The presence of spiral compression springs on the rod between the bushings, the cylindrical part of the plug and the lower blind end of the tube provides (in the initial position) the corrugated ends of the slats in grooves flush with the surface of the tube.

Compression of the coil springs ensures uniform extension of the grooved ends of the planks from the grooves with their focus on the wall of the medullary canal and the achievement of renewable compression due to the tendency of the compressed springs to return to their original position, in the case of bone sagging.

The endoprosthesis of the hip joint is presented in figure 1 ... 3. Figure 1 shows a device with a longitudinal section of one half of it along the axis, figure 2 - pairwise pivotally connected strips of the sleeve of one tier, placed on the rod (axonometry, compression springs not shown) and figure 3 shows a view A of figure 2 .

The device comprises a head 1, a neck 2, a spit section 3 and a leg 4 made in the form of a tube. A rod 5 is placed in the tube, equipped with a thread 6 at the lower end. The lower end 7 of the legs 4 is externally pointed, closes the tube tightly and is equipped with a thread 8, a mating thread 6 of the rod 5. On the rod 5 are placed axially movable bushings 9, equipped with U-shaped loops 10, in which the straps are pivotally mounted 11. Free ends of the straps 11 are connected in pairs by hinges 12, and their rounded ends are equipped with a groove 13. The upper end of the rod 5 is equipped with a plug 14 having a faceted nimbus, and its cylindrical section 15 is installed in the spit section 3 with the possibility of immersion in it. Between the bushings 9, the cylindrical section of the plug 15 and the lower blind end 7 of the legs 4 are located spiral compression springs 16 (not shown in FIGS. 2, 3). The grooves 17 are located in the leg 4 in tiers of three in each of them. Moreover, in each tier, the grooves are located with their longitudinal axes at 120 degrees relative to each other, and with respect to adjacent tiers - at 60 degrees.

The device is used as follows. One of the well-known surgical approaches exposes the area of the hip joint. The surrounding capsule of the joint and paraarticular tissues surrounding the scar are excised, and the head and neck are resected. The bone marrow canal of the thigh is drilled according to the diameter of the leg of the endoprosthesis and introduced into the prepared bone bed to a predetermined depth. The neck of the endoprosthesis is set in the position of physiological antetorsia. Using the key, rotate the cap head. In this case, the lower threaded end of the rod is screwed into the thread of the lower end of the leg, compressing the springs, which brings the bushings closer together. The planks are extruded from the grooves by corrugated ends, which are embedded in the tissue of the medullary canal, creating a reliable fixation of the endoprosthesis.

Information sources

1. RF patent N2089136, A 61 F 2/32, BI 1997, N25.

2. RF patent N2066153, A 61 F 2/32, BI 1996, N25.

3. RF patent N2045247, A 61 F 2/36, BI 1995, N28.

Claims (1)

An endoprosthesis of the hip joint containing a spherical head, neck, spit and leg made in the form of a tube, characterized in that the rod is placed with the possibility of longitudinal movement and fixation of the rod, equipped at the lower end with a thread and mounted on the thread in the lower blind end sharpened from the outside end tube, the upper end of the rod, located in the spit section, is equipped with a cap with a faceted nimbus and mounted on the rod with the possibility of immersing its cylindrical part in the lumen of the tube, on the rod pop The sleeves are arranged in a tiered fashion, equidistant from each other, as well as from the cylindrical part of the plug and the lower blind end of the tube and held in their initial position by spiral compression springs placed between them on the rod, each sleeve carries three U-shaped loops in which one the ends are pivotally mounted strips, in turn, pivotally connected by their other ends equipped with corrugated ends with the same ends of the strips mounted on an adjacent sleeve, thus connecting the bushings in pairs, in the tube are made longitudinal grooves are arranged in tiers, and in each tier, the grooves are located with their longitudinal axes on the leg surface at 120 degrees relative to each other, and with respect to the adjacent tier, the grooves are offset by 60 degrees, while in the initial position, the ends of the strips articulated with corrugation are placed in the longitudinal the grooves of each tier and flush with the surface of the tube.

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