RU2261681C2 - Plate for carrying out bone fracture osteosynthesis in bones after endoprosthetic repair - Google Patents

Abstract

FIELD: medical engineering.

SUBSTANCE: device has plate having canals for inserting screws and optional epimetaphyseal fixing member. The canals for inserting screws are arranged along plate boundary and made divergent at an angle of 40-60° to pass through cortical layer without affecting medullary canal.

EFFECT: reliable high-strength fixation.

4 dwg

Description

The invention relates to medical equipment, namely to traumatology and orthopedics, and can be used in the surgical treatment of fractures of a long bone containing an endoprosthesis leg.

The traditional treatment of such injuries is hindered by the endoprosthesis leg, which fills the entire bone marrow cavity of one of the fragments and, as a rule, reaches the fracture level. There are several generally accepted devices for treatment, each of which is characterized by known disadvantages.

A device for external fixation of fractures is known — the apparatus of G. A. Ilizarov [1], which is less traumatic, allows you to achieve the necessary fixation and even activate the patient. The disadvantages of this device is that the leg of the endoprosthesis serves as an obstacle to the passage of the spokes through the fragment containing the implant. Therefore, for the success of this method, it is necessary to bypass the endoprosthesis leg with knitting needles so as to completely exclude not only contact with it, but also to prevent the passage of the spoke channel through the bone marrow cavity, since this creates the risk of infection of the endoprosthesis, which is a more dangerous complication than the fracture itself . Even with the passage of the needle inside the cortical wall of the bone, infection of the spoke wound directly threatens the endoprosthesis. Therefore, the use of such a device is considered quite dangerous.

Known devices for intramedullary osteosynthesis of fractures - intramedullary nails and rods [1]. Their disadvantage is that it is impossible to introduce a nail into a fragment with an endoprosthesis, since its place is already taken by a metal leg. The principles of intramedullary fixation are applied when using the revision leg of an endoprosthesis having a length sometimes reaching the opposite third of the bone. For a major endoprosthetics center, this solution is standard. However, the operation is effective mainly in cases where the leg present in the broken long bone is short, that is, not revision. In the case of a long revision leg, the fracture is localized in the opposite third, almost always - comminuted, and the intramedullary fixation method is in principle unpromising. In addition, help with such fractures often has to be provided to the doctors of the peripheral hospitals at the place of residence of patients who may have gone to a remote republican center for endoprosthetics and broken a bone at home. In local hospitals, revision arthroplasty is as difficult as delivering a patient to the capital. The following drawback is associated with the quality of fixation of the endoprosthesis leg: for intraosseous fixation, the revision leg has to remove the well-standing (that is, without any signs of loosening) primary leg, which they try to save with other methods of osteosynthesis.

A specialized device is known - The Mennen Plate - containing the actual plate, on both sides of which there are legs with sharp teeth, which are designed to cover the diaphysis of the bone. The teeth are immersed in fragments surrounded by grafts using special nippers. A disadvantage of the plate, besides the price (the device is much more expensive than traditional bone plates), is its low fixation strength - thin legs with teeth can bend and cause permanent deformation of the consolidating bone with a random load [2], and a change in the biomechanical axis of the limb quickly leads to loosening of the endoprosthesis and audit intervention.

The prototype of the claimed device was chosen an AO-ASIF [3] osseous plate containing a plate with channels for fastening to the bone with screws and an epiphyseal fixing unit (T-shaped, L-shaped blade, “clover leaf”, “spoon”, “fork” ) or without it.

The disadvantage of the prototype is that when the osseous fixation of the plate to one of the fragments prevents the leg of the endoprosthesis located intramedullary. It is very difficult to go around the endoprosthesis leg with screws during bone osteosynthesis using modern plates, since, according to the methodology, the holes in the fixators are oriented to hold the screws through two cortical layers, and the space between the cortical layers is occupied by the endoprosthesis leg. Only occasionally is it possible to bypass screws with a particularly thin leg of the endoprosthesis, however, some screws almost always come into direct contact with it, which can cause undesirable effects (for example, an electrochemical conflict of alloys leading to metallosis).

The technical result of the present invention is to ensure the reliability of fixation in case of any fracture of the endoprosthetic long bone, including multi-split, as well as an increase in the strength of fixation.

The technical result is achieved by the fact that in the known device containing a osseous plate with or without epimetaphyseal fixation node and channels for screws, the latter are located at the edges of the plate and are made diverging at an angle of 40-60 ° for the passage of screws inside the cortical layer around the bone marrow canal.

The significance of the distinguishing feature is determined by the fact that the displacement of the channels in the plate to its edges and their diverging at the specified angle made it possible to ensure compatibility of a bone fragment, the medullary cavity of which is filled with a hard leg, with bone fixators with a practically unchanged surgical procedure. The orientation of the diverging channels allows you to direct the screws so that they pass inside the cortical layer, bypassing the medullary cavity. Moreover, the contact of the screws with the leg of the endoprosthesis is not only excluded, which is undesirable, for example, from the point of view of metal compatibility (the brand of metal of the endoprosthesis is unknown to the patient, and the alloy of the bone set is usually not identical to the endoprosthesis). In addition, the screws inside the cortical layer pass along a very long path (along the chord), crashing into the compact bone not by 5-7 turns, as in the central passage of the screw, but by the entire thread along almost the entire length of the screw, i.e. 10-15 turns that are 2 times stronger. For osteoporotic bone (the main contingent of such victims are elderly and old patients), this effect was quite beneficial, since the ability to dose the load on the operated limb in such patients was reduced, and the effect achieved in the inventive device provided increased rigidity and reliability of fixation.

The compliance of the technical solution with the criterion of "novelty" is determined by the absence in the prior art of an identical technical solution to achieve the claimed result.

Compliance with the criterion of "inventive step" was determined by the fact that in our simple solution, which was initially aimed at circumventing an obstacle, an unexpected additional effect was revealed that created the result of a multiple increase in the fixation stability of screws, which until then had been a weak link in the entire bone method. This effect is not known from the prior art and has not been previously used by orthopedic traumatologists.

Compliance with the criterion of "industrial applicability" is determined by the effectiveness of the treatment of fractures of the endoprosthetized long bone, which is achievable everywhere by the claimed device, and without it only in the endoprosthetics centers, and not with all types of fractures. This effectiveness determines the interest of healthcare in the proposed device. The willingness of the enterprise that made the prototypes to switch to mass production of this latch requires patent protection for this development.

In figure 1. a plate (straight) for osteosynthesis of fractures of an endoprosthetized long bone is shown, front view.

Figure 2 is a plate for osteosynthesis of fractures of an endoprosthetized long bone, a side view in a transverse section (bone and retainer).

Figure 3 - plate (straight) for osteosynthesis of fractures of the endoprosthetic long bone, top view.

Figure 4 - plate for osteosynthesis of fractures of the endoprosthetics bone in axonometric projection on the bone with a low hip fracture containing a long leg revision endoprosthesis. An option with an epimetaphyseal fixing node is shown, in this case with a classic L-shaped blade. A sectional plane corresponding to FIG. 2 is shown.

The plate for osteosynthesis of fractures of the endoprosthetic bone (Figs. 1-4) consists of a bone plate 1 with channels 2. The axis of the 3 channels for screws 4 is made diverging at an angle of 40-60 °. The external configuration of the latch is traditional and may contain an epimetaphyseal fixing node 5 (Fig. 4) of any configuration (T-shaped, “spoon”, “fork”, “clover leaf”, L-shaped blade).

This device is used as follows. After surgical access to the bone 6 is made, the fragments are compared, temporarily fixed with a bone holder, a plate 1 is placed on the bone and fixed with screws 4. When drilling 6 channels under the screws for 4 channels, 3 channels 3 of the plate 1 act as conductors orienting the drill along the chord passing in thicker than the cortical layer of the bone 6. This allows you to insert the screws 4 inside the cortical wall to bypass the legs 7 of the endoprosthesis- "NE", located in the center of the bone marrow cavity (Fig.2 and 4). The use of an epimetaphyseal fixing node (for example, an L-shaped blade, etc.) and compression are carried out according to the indications and principles of ASIF, adopted in the basic techniques of bone osteosynthesis.

The device allows you to:

- perform bone osteosynthesis of any closed fracture of the endoprosthetic long bone, regardless of the level of damage, the type of fracture and the length of the leg of the endoprosthesis;

- increase the stability of osteosynthesis due to a stronger fixation of the screws in the cortical layer of the bone;

- to refuse revision arthroplasty in case of a bone fracture next to the leg of the endoprosthesis, both in the absence of indications for replacing the leg (no loosening), and when implantation is impossible for organizational reasons (in a peripheral hospital that has no experience in arthroplasty).

List of references

1. V. Golyakhovsky, V. Frenkel. Guide to transosseous osteosynthesis by the method of G.A. Ilizarov. - St. Petersburg: Nevsky dialect, 1999, 272 p.

2. Mennen. Prtof Ulrich. Ten Years Experiencenwith the Clamp On Plate. Orthopedic Product News. Oct / Nov / Dec 1989, p. 23-25.

3. Müller M.E., Allgover M., Schneider R., Willenegger X. Guidelines for internal osteosynthesis (technique recommended by the group of joint-stock companies Switzerland). - Springer - Verlag. - Berlin -... Moscow. - from. 232-281.

Claims (1)

A plate for osteosynthesis of endoprosthetic bone fractures, including the plate itself with screw channels, an epimetaphyseal fixation node or without it, characterized in that the screw channels are located at the edges of the plate and are made diverging at an angle of 40-60 ° for passing inside the cortical layer bypassing bone marrow canal.

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