RU2262912C2 - Hip joint endoprosthesis pedicle - Google Patents

Abstract

FIELD: medical engineering.

SUBSTANCE: device has neck and collar members and a rod. Self-jamming inserts manufactured from mesoporous plates of osteocompatible biosital material shaped as pyramid having trapezium-shaped cross-section are fixed on lateral sides of proximal rod part in parallel to endoprosthesis pedicle collar member in slots not more than 2 cm far from the collar member.

EFFECT: high strength and reliability in fixing prosthesis pedicle.

2 dwg

Description

The invention relates to medicine, in particular to traumatology and orthopedics, in particular to the design of the leg of the hip joint prosthesis, and can be used in surgical treatment of degenerative-dystrophic and inflammatory joint diseases.

A known construction of a porous hip prosthesis (1). The prosthesis shaft is made of an inert material with the presence of pores, the pores having a through structure, the pore volume is filled with a preparation that stimulates regeneration.

Hip joint prosthesis designs are known (2, 3). The femoral and acetabular components of the implant are made of bioinert high-strength corundum ceramics.

In the hip joint prosthesis (4), the shaft is made of biocompatible carbon fiber (glassy carbon).

In the listed analogues, the endoprosthesis shaft is made of inert materials, which, according to the authors, have biocompatibility. The actions of the authors of these patents are aimed at enhancing the reparative stage of osteogenesis, since they are based on the ability of materials to germinate into the bone structure, but neither biocompatible carbon fiber, nor bioinert high-strength ceramics have the property of osteocompatibility, which ensures active reparative regeneration not only at the 1st stage of osteogenesis, but also and at the remodeling stages, i.e. the biomaterials used in the analogues do not ensure the coexistence of bone tissue with the material of the endoprosthesis during the entire period of operation.

The lack of osteocompatibility in materials used in the construction of analogues can lead to the formation of a fibrous capsule at remote stages of cyclic remodeling, which subsequently leads to impaired function of the product (5). Therefore, analogues cannot fulfill the function of a loaded biomechanical structure in the entire operation interval, since the prosthesis works under high loads and in conditions of multi-cycle fatigue.

A significant drawback of analogues is the lack of osseointegration, leading to unreliable fixation of the endoprosthesis at the remote stages of cyclic remodeling.

In article (6), an analysis is given of the mechanism for the development of instability of hip arthroplasty. The authors of the article note that one of the reasons for the loss of bone tissue of the endoprosthesis with cementless fixation is the incompatibility of the implant materials in biomechanical parameters, which causes intensive adaptive reconstruction of bone tissue. During this process, there is a mismatch between the rate of osteoclastic bone resorption and osteogenesis, which ultimately leads to osteopenia and osteolysis.

As a prototype for the closest technical essence, we have chosen an endoprosthesis of the hip joint (7). The leg of the hip joint consists of a neck, collar and rod, on the sides of the proximal part of which 8 porous plates with a pore size of 1 to 150 microns are installed on the shell.

The disadvantage of the design of the prototype is the mounting of the plates on the shell, which does not provide sufficiently strong fixation of the plates. The disadvantage of the prototype is also the implementation of porous plates of metal. Plates with a porous structure used in the design of the prototype provide bone germination in the microroughness of the plates, but only at the reparative stage, but not at the subsequent stages of osteogenesis, as a result of which the bone structures are not replenished during the operation of the endoprosthesis, and a fibrous capsule is formed, which violates the conditions of osteogenesis in the immediate area adjacent to the surface of the endoprosthesis, the consequence of which is the so-called "delimited" osteogenesis, which leads to a further deterioration of all parameters to stnyh structures, which subsequently leads to a deterioration in the functional properties of the implant, so called him from turning. The authors of the patent did not take into account that osseointegration is ensured not by bone tissue ingrowth during the repair phase in the microroughness of the surface of the plates, but by the formation of a strong connection of the implant material - bone at the remote stages of cyclic remodeling.

The objective of the invention is to increase the strength and reliability of the fixation of the leg of the endoprosthesis, not only at the stage of osteogenesis, but also at the stages of cyclic remodeling due to the formation of osteointegrative connection of bone structures with an implantable structure.

The problem is solved in that in the leg of the endoprosthesis of the neck, collar and shaft, on the lateral surfaces of the proximal part of the shaft parallel to the collar of the shaft of the endoprosthesis are fixed in grooves at a distance of no more than 2 cm from the collar of self-jammed inserts from mesoporous plates of osteocompatible bio-metal.

The plates of the biocompatible biositall are made in the form of a truncated pyramid, and in the section they have the shape of a trapezoid.

Osteocompatible biositall is a glass-crystalline material synthesized in a silicophosphate system containing oxides of calcium, magnesium, zinc, silicon, phosphorus, and having a biphasic structure, and a synthetic analogue of bone tissue biomineral, carboxyhydroxylate-dallite, is present in this material as a microcrystalline phase. Osteocompatible bio-metal has protective properties - it prevents the lost bone volume from being taken up by the connective tissues during regeneration, thereby restoring the full bone volume (8).

Distinctive essential features of the claimed device are:

1. The location of the plates is parallel to the collar of the endoprosthesis and at a distance of not more than 2 cm from the collar.

2. The form of the plates - self-jamming inserts of plates made in the form of a truncated pyramid and in the shape of a trapezoid.

3. Fastening the plates - in the grooves.

4. The material from which the plates are made is an osteocompatible bio-metal with a mesoporous structure.

Fixing the plates parallel to the collar of the endoprosthesis increases the strength of fixation of the legs of the endoprosthesis at the time of setting, since it increases the contact area of the plates with the prepared bone bed.

The location of the grooves at a distance of not more than 2 cm from the collar also increases the strength of the fixation of the leg of the endoprosthesis, since this area is the zone of action of the lowest stresses.

The insert inserts from the plates are self-locking, that is, with a friction angle of not more than 5 and in the form of a truncated pyramid, and in the shape of a trapezoid, as well as fixing the plates in the grooves, ensures reliable fixation of the plates in the endoprosthesis leg without additional fixing elements of glue, rivets, etc. d.

The implementation of plates of osteocompatible bisital with a mesoporous structure allows for a strong connection of the implant material - bone, not only at the reparative stage of osteogenesis, but also at the remote stages of cyclic remodeling, which eliminates the possibility of the appearance of a fibrous capsule. Due to the protective properties of biositall, the lost bone volume cannot be taken up by the connective tissue, thereby preserving the osteogenetic potential of the bone tissue throughout the entire volume of osteogenesis.

The set of essential distinguishing features of the claimed consruction is new and allows to increase the strength of fixation of the endoprosthesis not only at the reparative stage, but also at the subsequent stages of osteogenesis due to the provision of osseointegration.

The invention is illustrated by drawings, where in Fig.1 schematically shows the leg of the prosthesis, and in Fig.2 a section along aa.

Neck of the endoprosthesis leg - 1; femur - 2; collar - 3 plates - 4, 5, shaft - 6.

Sterilization of the endoprosthesis is carried out immediately before the surgical operation together with surgical instruments and the presence of plates in the design of the endoprosthesis is not an obstacle to sterilization, since the thermal expansion coefficients of the bio-metal and titanium alloy are close to each other.

Before the introduction of the leg of the endoprosthesis, the bone marrow space is treated with brines corresponding to the shape of the leg used, then the leg is introduced into the bone marrow space until it is in firm contact with the bone.

In the process of biodegradation under the influence of biological fluids (blood, lymph) and cellular influences, the initial mesoporosity of osteocompatible plates from bio-metal increases and optimizes the conditions of angeogenesis at the 1st stage of the reparative osteogenetic process.

The endoprosthesis leg is made of VT-6 titanium alloy (Ti-Al-4 V).

The claimed design in comparison with the prototype increases the strength and reliability of the fixation of the leg of the endoprosthesis in the bed of the medullary canal not only at the reparative stage of osteogenesis, but also at the stages of remodeling due to the formation of osseointegrative connection of the bone structures of the skeleton segment with the implanted structure.

LIST OF REFERENCES

1. RU 2137442 C1, 09/20/99.

2. RU 2120257 C1, 10.20.98.

3. RU 02117460 C1, 08.20.98.

4. SU 1813425 A1, 05/07/93.

5. Lysenok L.I. Osteogenesis and the possibility of osteosubstitution // Clinical implantology and dentistry // 2001, 1-2 (15-15), p.107-111.

6. Abrosimov V.G. and other Tribological mechanisms in the development of instability of the hip joint endoprosthesis // New directions in plastic and reconstructive surgery // 2001, 1, September, pp. 65-69.

7. US patent 4888022, 12.19.1965.

8. Orlov V.P. Reconstructive surgery for injuries and diseases of the spine using glass-crystal implants (abstract of a thesis for the degree of doctor of medical sciences) St. Petersburg. VM.A them. S.M. Kirova, 2002.

Claims (1)

Hip joint prosthesis leg, consisting of a neck, collar and shaft, characterized in that on the shaft parallel to the collar legs of the endoprosthesis at a distance of not more than 2 cm from the collar, self-locking inserts from mesoporous plates of an osteocompatible biosetal in the form of a truncated pyramid are fixed, trapezoid shape.

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