RU2802431C1 - Method of simulation of posttraumatic compression bone defect - Google Patents

Abstract

FIELD: medicine; experimental traumatology and orthopedics.

SUBSTANCE: invention can be used to simulate a post-traumatic compression bone defect. On the anterior-outer surface of the distal metaepiphysis of the rabbit femur, a rectangular cortical plate with sides of 10 mm and 5 mm is cut with the help of a disk cutter. By simultaneous displacement of the resulting bone fragment to a depth of 8 mm, a zone of compression of the underlying cancellous bone tissue is created. The cortical fragment is lifted, placed and fixed in its original position with the formation of a metaepiphyseal bone defect with a volume of 400 mm³.

EFFECT: method ensures complete repetition of pathophysiological mechanisms for obtaining delimited compression metaepiphyseal bone defects in experimental animals, allows to standardize their shape and size and exclude the penetration of connective tissue elements from the surrounding soft tissues due to the formation of a cortical plate notch, compression of the underlying bone and its elevation and fixation to the maternal bone.

1 cl, 8 dwg, 1 ex

Description

The demand for osteotropic materials in the modern world is growing every year. According to the Research Institute of Rheumatology of the Russian Academy of Medical Sciences, currently about 2 million patients require bone replacement surgery. Injuries and surgical interventions for tumor and inflammatory processes require doctors to search for new approaches to replacing bone tissue defects or optimizing osteogenesis processes, including the use of special materials. The relevance of the development of this method of modeling a post-traumatic defect is due to the high frequency of occurrence of post-traumatic compression defects of bone tissue; this method can also be used to study the processes of osseointegration and reparative osteogenesis, since conditions are recreated as close as possible to the conditions of bone formation in the trauma zone.

There is a method for modeling fractures of spongy tissue to study osseointegration and regeneration of bone tissue (patent number G09B 23\28 “Method for modeling a bone tissue defect to study osseointegration of osteoplastic material and regeneration of spongy bone tissue in an experiment on rabbits” patent holder Federal State Budgetary Educational Institution of Higher Education “ Privolzhsky Research Medical University" of the Ministry of Health of the Russian Federation. Application 20211109643, application 04/07/2021, publ. - 10.29.2021, Bulletin No. 31), which created a model for studying the processes of osseointegration of osteoplastic materials and bone tissue regeneration by forming a marginal osteotome rectangular defect 7x5x4mm in the rostral half of the iliac crest, without resection of the internal cortical layer and with subsequent implantation of osteoplastic material into the formed area. A significant disadvantage of this method is the mechanical removal of bone structures during its implementation, which does not correspond to the pathogenetic mechanisms of development of compression and impression fractures of cancellous bone, and therefore distorts the mechanisms of subsequent reparative regeneration and prevents the receipt of reliable information about the organotypic replacement of the resulting defect.

Known is the “Method for modeling a bone defect of the femur” (patent number G09B 23\28 patent holder Federal State Institution Central Research Institute of Traumatology and Orthopedics named after N.N. Priorov Rosmedtekhnologii. Application 2007122659\14, application 06/19/2007, published 27.01 .2009, Bulletin No. 3). The essence of this method is to form a diaphyseal bone defect of the femur of a laboratory animal with a length of 0.5-0.7 cm using a milling cutter by resection of ¾ of its diameter. The authors claim that this method makes it possible to assess the formation of bone tissue during the healing of diaphyseal comminuted fractures of long tubular bones, including the use of various options for bone grafting. The disadvantages of this method are the absence of an osteoclastic component when modeling a defect and fracture, as well as the impossibility of obtaining a bone tissue defect of identical size in laboratory animals.

There is a known method for modeling a bone defect of the femur (patent RU2345423C1), which consists in forming a milling defect with a diameter of 2 mm and a depth of 3 mm in the femur of a rat, into which osteoplastic material is subsequently implanted. The disadvantages of this modeling method are the small volume of the experimental defect, which makes it difficult to install a sufficient amount of osteoplastic material into it, and the high probability of spontaneous organotypic replacement, which hinders the objective study of the processes of reparative osteogenesis. It should also be noted that this method of defect formation is not pathogenetically similar to the mechanism of fracture, since the defect is formed by mechanical action by an external device (Matveev A.G. Ensuring radicality using new options for bone grafting in the treatment of benign tumors. Dissertation for Ph.D. .med.sci.Moscow, 2000, p.125).

The closest to the proposed method is a method for modeling an intra-articular impression fracture of the proximal tibia, taken as a prototype (Patent A61B 17\00008 “Method for modeling an intra-articular impression fracture of the proximal tibia.” Patent holder Federal State Budgetary Educational Institution of Higher Education “Ural State Medical University” of the Ministry healthcare of the Russian Federation. Application 2017136912, application 10/19/2017, published 10/05/2018, bulletin No. 28). The method makes it possible to simulate an intra-articular condylar fracture with incongruent articular surfaces. When modeling a defect, after accessing the proximal part of the tibia and forming a four-sided cut, the sawed fragment is removed, then a part of the condyle is broken and displaced in the distal direction, which makes it possible to create an impression intra-articular fracture. However, this method does not allow creating a standardized cavity bone defect. In addition, this method is very traumatic, since destruction occurs not only of the bone, but also of the cartilaginous structures of the knee joint, which leads to prolonged impairment of motor function in this segment of the musculoskeletal system.

To create a model of a post-traumatic cavity metaepiphyseal bone defect that maximally replicates the pathophysiological mechanisms of its formation, layer-by-layer access to the distal metaepiphyseal portion of the femur from the lateral side is performed. After exposing the bone, using a cutter (diameter - 20 mm, thickness 1 mm), a rectangular cortical plate is cut with side dimensions of 10 mm and 5 mm, length and width, respectively. Next, the cortical plate is displaced to a depth of 8 mm, as a result of which a compression fracture of the underlying metaepiphyseal cancellous bone is formed, then, using an elevator, the “depressed” fragment is raised and fixed to the parent bone in its original position. As a result, a post-traumatic bone defect of standard size and shape, separated from the surrounding soft tissues, is formed, the volume of which is 400 mm ³ .

The invention is illustrated by drawings, which show in stages the formation of a delimited metaepiphyseal defect of bone tissue resulting from a compression fracture.

In FIG. 1 – sawed section of bone tissue (size 10×5 mm).

In FIG. 2 – displacement of the cortical plate (to a depth of 8 mm).

In FIG. 3 – formed compression zone of spongy tissue.

The method for modeling a post-traumatic compression bone defect is illustrated by the following clinical example.

As a clinical example, modeling of a post-traumatic bone defect in experimental animals (rabbits) in the amount of 36 pieces was performed. The experiment was carried out in compliance with the principles of humanity, which are set out in the directives of the European Community (86/609//EEC) and the Declaration of Helsinki. The authors also received permission to conduct an experimental study from the ethical committee of Omsk State Medical University No. 128 dated 02/03/2021. In the operating room, in the position of the animal on its back with fixed limbs under intramuscular sedation with a solution of zoletil, after 3 times treatment of the surgical field with an antiseptic solution, hydropreparation of soft tissues Sol. Novocaini 0.25%-3.0. After dissection of the skin and underlying tissues, access was made to the distal metaepiphysis of the right femur. The quadriceps femoris tendon and the patella were retracted to the medial side. Using a disk cutter, a rectangular cut of the cortical plate in the area of the metaphyepiphysis of the femur with dimensions of 10 mm by 5 mm was formed. Next, the cortical plate was “embedded” into the metaepiphyseal bone to a depth of 8 mm, after which it was lifted and subsequently fixed to the mother bone using an elevator. The intervention area was covered with the tendon of the quadruple femoris muscle, and the wound was sutured in layers. An aseptic dressing was applied and no external immobilization was performed. To perform a standardized defect, 36 rabbits of the “white giant” breed, weighing 3700-4000 g, were selected. The duration of the operation was 10 minutes, blood loss was within 2-3 mm. It is worth noting that in the postoperative period, motor activity was restored in all animals after 2 days. No femoral fractures, contractures, or infectious complications were recorded in any of the animals.

In FIG. 4 – sawed section of bone tissue (size 10×5 mm).

In FIG. 5 – displacement of the cortical plate (displacement depth 8 mm).

In FIG. 6 – formed compression zone of spongy tissue.

In FIG. 7 – view of the wound after elevation and fixation of the cortical plate.

During the experiment, to objectify the formation of a metaepiphyseal bone defect, an MSCT study was performed to confirm the location, size of the post-traumatic defect and restoration of the osteotomized cortical plate (Fig. 5).

Fig. 8 - MSCT image in sagittal projection. The image highlights the formed area of the bone tissue defect.

Thus , this invention allows us to completely repeat the pathophysiological mechanisms of producing limited compression metaepiphyseal bone defects in experimental animals, standardize their shape and size, exclude the penetration of connective tissue elements from the surrounding soft tissues, which further provides conditions for a detailed study of the processes of reparative regeneration of bone tissue, and also osseointegration when replacing a defect with osteoinductive and osteoconductive materials.

Claims (1)

A method for modeling a post-traumatic compression bone defect, which consists in cutting a rectangular cortical plate with side dimensions of 10 mm and 5 mm along the anterior outer surface of the distal metaepiphysis of the femur of a rabbit using a disk cutter, after which, by simultaneously displacing the resulting bone fragment to a depth of 8 mm create a compression zone of the underlying cancellous bone tissue, then the cortical fragment is lifted, placed and fixed in its original position to form a metaepiphyseal bone defect with a volume of 400 mm ³ .