RU182229U1 - Anterior cruciate ligament transplant fixator - Google Patents

Abstract

The utility model relates to medicine and medical equipment used in traumatology. The latch consists of a screw and washer. The screw has a through central channel for the guide, a head in the form of a spherical element, flattened from above, a longitudinally elongated working part with an external thread. In the screw head from the side of its upper part, a groove for a screwdriver is made. The working part of the screw has a conical shape. The washer is made with the possibility of installation in the area of the screw head. On the inner side of the washer along its periphery are pointed protrusions for implantation in bone tissue. The inner hole of the washer has a rounded chamfer, corresponding in shape to the lower spherical part of the head with the possibility of drowning inside the washer. A gap is made between the washer and the head, which allows rotation of the lower part of the head inside the washer with the possibility of changing the angle of locking the position of the screw. Using the utility model allows for simultaneous attachment of the anterior cruciate ligament graft inside the transossal canal and from the external surface of the bone through a minimum number of foreign bodies used. 1 ave .; 2 ill.

Description

The utility model relates to medicine and medical equipment used in traumatology, namely, implants for fixing the position replacing the damaged anterior cruciate ligament of flexible plastic materials inside the formed transossal channels during surgical restoration of the anatomy and functionality of the knee joint.

Currently, there is a variety of interference screws produced by various firms in the market for medical devices used in plastic cruciate ligament [RF patents for invention No. 2600284 and utility model No. 169955, patent for invention ZA No. 2015565680, see Inion Hexalon ™ catalog, Internet resource: http://inion.su/images/inion_images/PDF_katalog/Inion-Hexalon.pdf, ChM® Artroskopia catalog, Internet resource: http://www.bioretec.com/products/ ActivaScrew-Interference /]. All of them have the same conical shape with a central through channel for the guide and an external thread to provide adhesion to the side wall of the formed channel. Their structural differences with respect to each other are insignificant and, basically, consist in different threading of the external thread or a change in the angle of the solution of the conical shape of the screw. The execution of thread turns smaller and more rounded leads to poor adhesion in the screw-transplant-bone system. In such cases, when the loads are applied to the knee joint, the graft can simply break out, while the screw will remain in its former place in the formed transossal canal. The manufacture of a screw with large and sharp threaded turns provides more reliable adhesion to the side walls of the bone canal, but can lead to unintentional destruction of a flexible plastic material, namely its complete or partial rupture. Moreover, the presence of any type of thread on the outer surface of the screw can lead to winding the graft on it when screwing it into the bone canal, and, consequently, to mechanical damage to the graft and a violation of the technology of its installation. But, in general, the technical characteristics of each of the screws are not inferior to each other, and the choice of surgeon in the application of a particular design is determined only by personal preferences.

To exclude the possibility of graft slipping, elements for fixing the ends of the graft outside the transossal canal were developed. One of these elements are additional screws with clamping washers, on the periphery of which there are spikes on the inside for insertion into the bone [Cross Pins versus Endobutton Femoral Fixation in Hamstring Anterior Cruciate Ligament Reconstruction: Minimum 4-Year Follow-Up / Chae-Gwan Kong, MD, Yong In, MD, Geon-Hyeong Kim, MD and Chi-Young Ahn, MD // Knee Surg Relat Res, Vol. 24, No. 1, Mar. 2012. R. 34-39; US patent for the invention No. 2003/0105465].

However, these screws with a washer are inserted just below the outlet formed in the bone of the channel perpendicular to the longitudinal axis of the latter. Thus, they fix only the ends of the graft on the outside of the bone, pressing them in a stretched position to the bone structures with a downward direction. The technical features of the execution of the screw head and completely corresponding to its shape and dimensions of the reciprocal groove in the washer do not allow changing the angle of introduction of this design, and therefore they cannot be installed inside the formed transossal channel, such as interference screws.

If only this screw with a washer is used to fix the graft with the bone, then a friction section arises in the graft bend area when leaving the hole with transition to the outer surface of the bone. Since the knee joint is one of the joints, the main movements in which are the flexion-extension processes, accompanied by pulling and loosening of the anterior cruciate ligament or its substitute, this area will be subject to severe mechanical injury to the graft when moving in the joint, namely its “grinding” . If an interference screw or some other fixing element is installed together with the screw and washer described above, this will significantly complicate the installation process, increase the presence of foreign bodies in the human body, increasing the risk of developing infectious and inflammatory complications in the postoperative period.

The closest analogue of the claimed utility model is the design of a screw with a washer [see Biomet Sports Medicine “WasherLoc ™” catalog, Internet resource: http://www.biomet.co.uk/resource/2022/WasherLoc%20

Tibial% 20Fixation.pdf], which has spikes of various lengths on the inside, which works just like the previous devices, with the only difference being that its insertion point is aligned with the canal outlet in the tibia, excluding the graft bending (friction) zone.

However, the use of this technical solution minimizes the area of fixation of the transplant, bringing it to one point at the exit of the transplant from the transossal canal. This significantly increases the load force at the fixation point, and therefore increases the risk of transplant rupture.

The objective of the claimed utility model is the development of transosseous fixator, providing simultaneous fastening of the transplant of the anterior cruciate ligament inside the transossal canal and from the outer surface of the bone through a minimum number of used foreign bodies.

The essence of the claimed utility model is that in the transosseous transplant fixator of the anterior cruciate ligament, consisting of a screw with a head having a groove for a screwdriver and turning into a working longitudinally elongated part with an external thread, and installed on it in the area of the washer head, from the inside which along its periphery are pointed protrusions for implantation in bone tissue, a through central channel for the guide is formed along the screw, its working part is cone-shaped, and the head ulation a spherical element, flattened top; the inner hole of the washer has a rounded chamfer corresponding to the shape of the lower spherical part of the head with the possibility of drowning inside the washer, while a gap is made between the washer and the head, which allows rotation of the lower part of the head inside the washer with the possibility of changing the angle of blocking the screw position.

The technical result of the claimed utility model.

The technical features of the execution of the faces of the inner hole of the washer and the shape of the screw head, which are not used in any of the analogues, allow you to install the screw with the washer in the transosseous canal of the bone at an angle without loss of fixation strength of the anterior cruciate ligament graft, with the possibility of varying the value of this angle depending on the individual anatomical features. This allows both external and intracanal fixation of the anterior cruciate ligament graft using only one screw, while reducing the number of foreign bodies, complications associated with them and eliminating the occurrence of additional zones of trauma to bone structures. The implementation of the screw head spherical shape, flattened on top, also eliminates the possibility of mechanical injury to nearby soft tissues, thereby reducing the risk of inflammatory reactions. With this type of fixation, a friction section is not formed in the area of the transplant kink when leaving the hole with the transition to the outer surface of the bone, which, in turn, eliminates the possibility of mechanical injury in this area of the graft and minimizes the risk of inflammatory reactions.

The inventive utility model is illustrated using FIG. 1-2, in which: FIG. 1 is a general view of the latch, in FIG. 2 is a cross-sectional view of a retainer. In FIG. 1-2 positions 1-9 are indicated:

1 - screw;

2 - washer;

3 - through the central channel of the screw;

4 - screw head;

5 - working part of the screw;

6 - external thread of the working part of the screw;

7 - groove for a screwdriver in the screw head;

8 - pointed protrusions of the washer for implantation into the bone;

9 - a facet of a washer.

The transosseous transplant fixator of the anterior cruciate ligament consists of screw 1, washer 2. Screw 1 has a through central channel 3 for the guide, a head 4 in the form of a spherical element, flattened from above, a longitudinally extended working part 5 with external thread 6. In the head 4 of the screw 1 with the side of its upper part has a groove for a screwdriver 7, for example a hexagonal shape. The working part 5 of the screw 1 has a conical shape. The washer 2 is made with the possibility of installing in the area of the head 4 of the screw 1. On the inner side of the washer 2 along its periphery there are pointed protrusions 8 for insertion into bone tissue. The inner hole of the washer 2 has a rounded chamfer 9, corresponding in shape to the lower spherical part of the head 4 with the possibility of drowning inside the washer 2. Between the washer 2 and the head 4 there is a gap allowing rotation of the lower part of the head 4 inside the washer 2 with the possibility of changing the angle of blocking the screw position one.

Transosseous transplant fixator of the anterior cruciate ligament is used as follows.

Due to the possibility of changing the screw insertion angle due to the design features, the claimed utility model can be used to fix the ends of the anterior cruciate ligament transplant in the transossal canal formed both in the femur (single-beam technology) and in the tibia (single-beam and double-beam technologies). The method of installing the clamp does not have any differences when changing the location of the screw. In this regard, we consider the process of using the claimed utility model using an example of anterior cruciate ligament plasty using the two-beam method according to the RF patent for invention No. 2506057, which includes graft fixation in the transossal tibial canal.

The patient is placed on the operating table with the legs hanging down. Anterolateral access to the knee joint is performed, through which an arthroscope is inserted and a cavity is examined. Then anteromedial access is performed through which a transtibial guide is inserted into the knee joint under the control of an arthroscope. The latter is guided by a guide needle to the site of the anatomical exit of the anterior cruciate ligament at the height of the tibia. The transtibial guide is removed. At the insertion point of the guide needle, a skin incision of 5-7 mm is performed to insert a cannulated drill. A guide channel is formed along the guide pin by drilling. When bending at the knee joint 100-110 °, a femoral guide is inserted into the formed channel, along which a guide needle is inserted into the external condyle of the femur from its inner surface through the anatomical attachment of the anterior cruciate ligament. The femoral guide is removed. Through the guide needle, a cannulated drill forms a through first channel in the epiphysis of the femur, while ensuring the location of its inner hole at the site of anatomical attachment of the anterior cruciate ligament. When bending at the knee joint of 80-90 ° using the same femoral guide, a guide needle is inserted 1-1.5 cm higher in height to the outer condyle of the femur. The femoral guide is removed. A second canal is formed on the spoke with a cannulated drill in the epiphysis of the femur so that the longitudinal axes of the first and second channels form an angle of 30-40 °. The first and second channel in the epiphysis of the femur are formed with equal diameters, and the channel in the epiphysis of the tibia with a diameter equal to the sum of the diameters of the first and second channels. In most cases, the diameter of the canals in the epiphysis of the femur is 4-5 mm. Guide spokes are removed. In the projection of the external openings of the canals in the epiphysis of the femur, a skin incision is made to visualize them, corresponding to the shortest distance between them. Then, an anterior cruciate ligament graft is made from auto- or synthetic material. To do this, a graft is carried out using a flexible nitinol ear of a knitting needle - a conductor through the tibial canal into the joint cavity, then through one of the femoral canals with access to its outer side. In a similar manner, the graft is carried back to the joint through the free canal of the femur, allowing the graft to pass through the cortical layer between the external openings of the canals in the epiphysis of the femur, and the graft is brought out through the canal of the tibia. A guide needle is placed in the transossal canal of the tibia. Stretch the graft and fix its position. To do this, an interferential screw is inserted into the transosseal channel along the spoke guide, ensuring a tight fit of the inner surface of the washer to the tibia with the introduction of its pointed protrusions into the bone structures, additionally fixing the ends of the graft from the outer surface of the tibia. The guide pin is removed. Use a screwdriver to tighten the screw. The arthroscope is removed. Wounds are sutured.

Example.

The product was made in the form of a prototype. The fixation technology was tested on a simulation model of the knee joint. All constructive solutions of the fixator, in particular, the specific features of the screw head and the washer’s inner hole, were justified and made it possible to install it with a tight fit of the washer to the surface of the tibia without loss of strength characteristics of the fixator-transplantation system. Using the finite element method implemented in the ANSYS system, two biomechanical systems were developed: “femur - fixator / graft - tibia”. An interferential screw was used as a retainer in the first system, and the inventive interferential screw with a washer in the second. All elements of this system were designed as three-dimensional realistic geometric models. The materials of bone tissue, fixative and graft were isotropic perfectly elastic. When modeling, large (final) deformations of the models were taken into account. Using mathematical modeling, the displacement (displacement) and effective stress indicators of all elements of biomechanical systems were determined. By comparing the results of the analysis of biomechanical systems under load, corresponding to the “flexion-extension” of the knee joint during movement, it was confirmed that it is the combination of the use of intrachannel and external fixation of the graft that allows the formation of a reliable and maximally secure system of fixation of the anterior cruciate ligament transplant, eliminating the possibility of it destruction.

Claims (1)

Transosseous transplant fixator of the anterior cruciate ligament, consisting of a screw with a head having a groove for a screwdriver and turning into a working longitudinally elongated part with an external thread, and mounted on it in the area of the washer head, on the inside of which there are pointed protrusions for insertion into bone tissues, characterized in that a through central channel for the guide is formed along the screw, its working part is cone-shaped, and the head is a spherical element, puppy on top; the inner hole of the washer has a rounded chamfer corresponding to the shape of the lower spherical part of the head with the possibility of drowning inside the washer, while a gap is made between the washer and the head, which allows rotation of the lower part of the head inside the washer with the possibility of changing the angle of blocking the screw position.

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