RU2523622C1 - Method for simulation of false joint in shin fractures and device for implementing it - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: external fixation apparatus (EFA) is applied on a rabbit's shin, then an osteoperforation and an osteoclasis are performed between the 2^nd and 4^th levels. Shin bone fragments are separated at 1 cm and fixed with EFA pins in this position for 14 days; that is followed by a one-stage compression between supports of the 4^th and 5^th levels until resist completely. Ends of the separated fragments are combined and fixed; the EFA is stabilised. A device for simulating the false joint in an experimental animal's shin fracture comprises proximal and distal bases in the form of a sector equal to 3/4 of a ring. Proximal base consists of 2^nd and 4^th levels, distal base consists of 5^th and 7^th levels, sectors of levels 2, 4 and 5 are placed one below the other while 7^th level sector is flipped through 180° in a horizontal plane in relation to the sectors of levels 2, 4 and 5. Two threaded fixing rods connect the 2^nd and 4^th, 4^th and 5^th, 5^th and 7^th levels, and one fixing rod connects the 2^nd level with 4^th and 5^th levels. Each base comprises two pairs of bolted pin fixators. Model reproducibility makes 100%.

EFFECT: simulating the false joint having the characteristics maximum close to the real clinical process.

2 cl, 8 dwg, 1 ex

Description

The alleged invention relates to medicine, namely to experimental surgery, traumatology and orthopedics, and can be used to study the course of reparative processes in fractures of the lower leg.

It is known that nonunion fractures and “false joints” of tubular bones are formed after treatment of open fractures in 8-35% of cases (Sidorova G.V., Arsentyeva N.I., Arsentiev L.I. Prediction of injury in the Irkutsk region // Bull. VSSC SB RAMS. - 1999. - No. 1. T.2. - S.121-123) and in 5-11% note nonunion after closed fractures (Bauer I.V., Kazarezov M.V., Velichko A.Ya Improving the efficiency of rehabilitation of people with disabilities with pseudoarthrosis when choosing a reasonable operational standard depending on the type of nonunion // Medicine and Education in Siberia. - 2010. - 5. - S.38-47).

Various methods are known for modeling bone loss and consolidation.

So there is a known method of modeling fracture nonunion with the formation of a false joint by prolonged traction of conjugated bones (Lopukhin Yu.M. Experimental Surgery / Moscow: Moscow, 1971. p. 285-287). In this method, dogs are used as experimental animals, which under general anesthesia perform a resection of a 1-cm-long section of the bone with envelope of the ends of the fragments by the fascia, and then carry out a long (up to 1 month) traction of the conjugated bones. By the 30th day, non-fracture with the formation of a false joint is obtained.

The disadvantages of this method include the fact that the known method cannot be used for an experimental animal rabbit, because this is due to the hocking movement of this animal. Reliance on the hind legs in the absence of fixation leads to various complications - fragment migration, bleeding, skin perforation, secondary infection, and innervation disturbance. The use of dogs as experimental animals does not provide standardization and reproducibility of the model, because different breeds of dogs have different weight, height, immunity, healing time, etc.

In addition, the lack of fixation of the fracture site leads to additional pain shock, the risk of bleeding and the possibility of transition to an open fracture, which increases the risk of infection.

The closest in technical essence to the proposed is a method for modeling delayed osteogenesis (Kononovich N.A., Dyuryagin E.V., Dyachkov A.N. Method for modeling delayed osteogenesis. Application 2005104529/14, 02/18/2005., Published on 07.27.2007 g., RF Patent No. 2301457, published on 06/20/2007, Bull. No. 17). The essence of the known method consists in the fact that in the middle third of the bones of the leg of the dog open fracture is performed using the Jigli file, then the contents are removed from the bone marrow cavities of the proximal and distal fragments to a depth of at least 1 cm, after which the fragments are accurately compared and fixed in the external apparatus fixation.

A known device for modeling delayed osteogenesis during fracture of the tibia is an external fixation device (AVF), which contains the proximal and distal bases (subsystems), each of which consists of 2 supports with holes evenly spaced along the entire length. The supports are parallel to each other and interconnected by threaded locking rods, at the ends of which there are nuts and locknuts,

The disadvantages of the known method and device include the fact that they do not provide the possibility of obtaining a model of a false joint, because intended only for modeling delayed osteogenesis. An even bone cut does not correspond to the clinical picture of the fracture and is accompanied by crushing, burns and restructuring of the beam structure of the bone in the damaged area. Removing the contents of the medullary canal is also an artificial technique that violates the homogeneity of the model and does not correspond to the clinic.

The disadvantages of this method include a large amount of surgical intervention, extensive soft tissue trauma and open access, which increases the risk of infection.

As in the analogue method, the use of dogs as experimental animals does not provide standardization and reproducibility of the model.

The objective of the proposed technical solution is to develop a method for modeling a false joint and device for its implementation.

The technical result of the proposed method is to enable the formation of a false joint in the experiment, which is close to the clinic in its characteristics and is formed due to violations of surgical tactics and rehabilitation in case of fracture of the tubular bone.

The technical result of the method is achieved in that the simulation of the false joint in case of fracture of the bones of the lower leg of the experimental animal is carried out by violating the integrity of the bone tissue and fixing bone fragments by applying an external fixation apparatus (AVF).

Distinctive techniques of the proposed method consist in the fact that AVF is first applied to the rabbit's shin, then osteoperforation and osteoclasia are carried out between the 2nd and 4th levels, the fragments of the leg bones are bred 1 cm apart and fixed with 14 knots of the AVF in this position days. After that, carry out simultaneous compression between the supports of IV and V levels to full resistance. The ends of the diluted fragments are compared and fixed, AVF stabilize.

The technical result of the claimed device is to ensure stable fixation of bone fragments in a diluted and biodynamic position, taking into account the anatomical bending of the bones of the leg of the rabbit.

The technical result is achieved by the fact that the device for modeling a false joint in fracture of the tibia of an experimental animal contains a proximal and distal base, each of which consists of 2 supports with holes evenly spaced along the entire length. The supports are parallel to each other and interconnected by threaded locking rods, at the ends of which there are nuts and locknuts.

Distinctive features of the claimed device are that each base is made in the form of a sector equal to 3/4 of the ring, while the proximal base is II and IV levels, the distal one is V and VII levels. Sectors of the II, IV and V levels are located one below the other, and the sector of the VII level is rotated 180 degrees in the horizontal plane in relation to the sectors of II, IV and V levels. 2 threaded locking rods connect the 2nd and 4th, IVth and Vth, Vth and VIIth levels, and one fixing rod connects the 2nd level with the 4th and 5th levels. Also, at each base, 2 pairs of bolt spoke fixators are installed, which are placed according to the scheme:

. $$\frac{II2-\mathrm{8,}\mathrm{four}-10}{3/\mathrm{four}}-\frac{IV2-\mathrm{8,}\mathrm{four}-10}{3/\mathrm{four}}-\frac{V2-\mathrm{8,}\mathrm{four}-10}{3/\mathrm{four}}-\frac{VII2-\mathrm{8,}\mathrm{four}-10}{3/\mathrm{four}}$$

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A comparative analysis of the claimed technical solutions with the prototype made it possible to establish their compliance with the criterion of "novelty."

In the study of other well-known technical solutions in the field of medicine and experimental surgery, signs that distinguish the claimed invention from the prototype were not detected.

The use of the above features of the proposed method using the proposed device allows to obtain a model of a false joint in fracture of the bones of the lower leg of an experimental animal.

The authors of the proposed technical solution found that in the defect zone by the 10th day of the experimental study, connective-cartilaginous tissue is formed, which is the initial stage of the formation of the false joint.

An X-ray examination on day 20 revealed signs of delayed formation of "bone callus", osteolysis of the edges of the fracture, a decrease in the density of the cortical plate along the entire length, and histological examination revealed the appearance of a large number of fibroblasts, the formation of connective tissue, chondroblasts and single chondrocytes. The changes in the X-ray and histological patterns revealed on day 20 were noted in all experimental animals with equal severity.

In all animals, the completion of the experimental study, i.e. on day 50, a slight compaction of the edges of the fracture with enlightenment between the fragments is observed radiologically, which indicates the absence of bone density tissue formation, i.e. no fusion in the area of the bone defect; histologically, the enlightenment zone is represented by cartilaginous connective tissues, and the densities at the ends of the fragments in the form of bone callus are represented by spongy bone.

The imposition of the claimed apparatus of external fixation allows you to standardize damage according to the specified parameters: 1 cm between fragments, preservation of the biological axis, rigid fixation of fragments. Stabilization of fragments in the proposed external fixation apparatus reduces pain, which makes it possible for the operated animal to use the damaged limb for movement.

The proposed method and device can eliminate complications associated with the migration of fragments and damage to soft tissues, blood vessels, nerves, and thereby prevent the process from turning into an open fracture, which excludes the possibility of an infectious complication and subsequent rejection of animals from the experiment.

The advantages of the proposed technical solution compared to the prototype should also include a closed method of obtaining a model, which leads to a minimum amount of surgery and soft tissue trauma.

Therefore, the proposed method and device ensure the achievement of the technical result perceived by the applicant, namely, the formation of a false joint in an experiment that is close to the clinic in its characteristics and is formed due to violations of surgical tactics and rehabilitation of a fractured tubular bone.

The analysis of the known technical solutions showed a lack of information about the influence of the distinctive features of the proposed method on the achievement of the technical result perceived by the applicant. This allows us to consider the claimed technical solutions meet the criterion of "inventive step".

The method and device that make up the claimed invention are intended for use in medicine. The possibility of implementing the inventive method using the inventive device is confirmed by the methods and means described in the application. Therefore, the claimed invention meets the condition of patentability "industrial applicability".

The essence of the invention is illustrated by figure 1, which shows a General view of the inventive device for modeling a false joint (see Appendix to the description of the application), where: 1 - sector II level; 2 - sector IV level; 3 - sector V level; 4 - sector of the VII level; 5 - threaded rod connecting the sectors of II and IV levels; 6 - threaded rod connecting the sectors of II and IV levels; 7 - a threaded rod connecting the sectors of IV and V levels; 8 - threaded rod connecting the sectors of IV and V levels; 9 - a threaded rod connecting the sectors of V and VII levels; 10 - threaded rod connecting sectors of V and VII levels; 11 - threaded rod connecting the sectors of II, IV and V levels; 12 - nuts; 13 - locknuts; 14 - special fixators; 15 - nuts of special fixators; 16, 17, 18, 19, 20, 21, 22, 23 - knitting needles.

The inventive device consists of four sectors equal to ¾ of the ring (Fig.1-1, 2, 3, 4), seven threaded locking rods of different sizes (Fig.1-5, 6, 7, 8, 9, 10, 11), 16 bolt spoke fixators (Figs. 1-14) and 16 nuts for them (Figs. 1-15), each of which in Fig. 1 is indicated by 14 and 15, respectively; 15 nuts (Figs. 1-12), 15 lock nuts (Figs. 1-13) and 8 spokes (Figs. 1-16).

The implementation of the proposed method using the inventive device is illustrated by an example of a specific implementation. The following example is intended to illustrate but not limit the invention.

The study was conducted on 6-month-old male Chinchilla rabbits weighing 3,000 g. Animals were kept in a vivarium with free access to water and food, which complies with GOST Standards "Keeping experimental animals in research institutes nurseries" (category 1 vivarium, vet certificate 238 No. 0015220 dated March 25, 2009, the Veterinary Service of the Irkutsk Region). Animal experiments were carried out in accordance with the rules for the humane treatment of animals, regulated by the "Rules for the use of experimental animals", approved by Order of the Ministry of Health of the USSR No. 742 of 11/13/84, "On the approval of the rules for working with experimental animals" and No. 48 from 01/23/85, "On the control of work using experimental animals."

All surgical interventions were performed under sterile conditions under general anesthesia. X-ray studies were performed before and after surgery, and then on the 20th and 50th days. Morphological studies were performed on the 20th and 50th days.

1 hour before the operation, sedation was performed followed by anesthesia. Then, under aseptic conditions and under general anesthesia, the animal was fixed on the table of A.I. Sechenov in the supine position, the forelimbs and the right hind limb were fixed to the operating table. Hair was cut from the left hind limb, the skin was treated with a soap solution, dried and treated with Veltosept solution, 70% alcohol, three times. The rabbit was covered with a sterile sheet with an incision into which the left hind limb was passed.

Using a device for dividing a segment into levels, the locations of transosseous elements were determined. The authors used a set of elements for transosseous osteosynthesis according to Ilizarov. The weight of the device in assembled form was 140 g, i.e. 4.6% of the rabbit's body weight. The inventive device is made taking into account the anatomical features of the rabbit tibia, while the inner surface of the segments at the level of the upper third of the tibia of the animal is 1 cm away from the skin.

The external fixation device was imposed according to the scheme:

$$\frac{II2-\mathrm{8,}\mathrm{four}-10}{3/\mathrm{four}}-\frac{IV2-\mathrm{8,}\mathrm{four}-10}{3/\mathrm{four}}-\frac{V2-\mathrm{8,}\mathrm{four}-10}{3/\mathrm{four}}-\frac{VII2-\mathrm{8,}\mathrm{four}-10}{3/\mathrm{four}}$$

To do this, retreating distally from the condyle 2.0 cm through the tibia carried 2 spokes (Figs. 1-16, 17). The spokes 16 and 17 were fixed in a taut position to sector 1 (figure 1). Next, two knitting needles were carried out (Figs. 1-18, 19). and fixed in a taut position to sector 2 (figure 1).

Next, two knitting needles were carried out (Figs. 1-20, 21) and fixed in a taut position to sector 3 (Fig. 1). Next, two knitting needles were carried out (Figs. 1-22, 23) and fixed in a stretched position to sector 4 (Fig. 1). Three threaded fixing rods 5, 6 and 11 were inserted into the holes of the external support sector 1 (Fig. 1), which were secured with nuts 12 and locknuts 13 with a wrench (Fig. 1). On the distal ends of the rods 5, 6 and 11 put on the next sector 2 (figure 1). Three threaded fixing rods 7 and 8 (Fig. 1) were inserted into the holes of the external support of sector 2, which were secured with nuts 12 and locknuts 13 (Fig. 1) with a wrench. On the distal ends of the rods 7, 8 and 11 put on the next sector 3 (Fig. 1). Two threaded fixing rods 9 and 10 were inserted into the holes of this external sector 3, which were fixed with nuts 12 and locknuts 13 (Fig. 1). The next sector 4 (FIG. 1) was put on the distal ends of the rods 9 and 10 and secured with nuts 12 and a lock nut 13 (FIG. 1).

To implement the method in the inventive device used needles with a diameter of 1 mm; tension was carried out by a calibrated spreader.

After additional processing of the surgical field with 70% alcohol, between sectors 2 and 3 (Fig. 1), osteoperforation was performed with a spoke with a diameter of 1.5 mm (Fig. 2). For this, a knitting needle (φ = 1.5 mm) was inserted through two cortical layers of the tibia, then without leaving the first cortical layer of the tibia, the direction of the knitting needle was changed and only the opposite cortical layer of this bone was perforated. Then, the nut 12 and the lock nut 13 were relaxed, after which the osteoclasia of both bones of the lower leg of the rabbit was performed and the middle sectors 2 and 3 were disconnected (Fig. 1). Clinically noted the complete mobility of bone fragments in all planes. Sectors of the transosseous apparatus were connected, giving the apparatus an initial state with simultaneous dilution of 1 cm between the middle sectors 2 and 3 (figure 3). Aseptic dressings were applied around the exit of transosseous elements. Compression was carried out on the 14th day until full resistance using nuts 12 and locknuts 13.

According to the results of the study, it was found that on the 1st day of the experiment, the external fixation apparatus is stable, animals are active, and appetite is preserved. When x-ray examination revealed a transverse defect between fragments of the bones of the leg up to 1 cm. The axis of the limb is preserved, the edges of the fragments with a smooth contour in a straight and lateral projection (figure 4).

After 14 days, simultaneous compression was performed between sectors 2 and 3 (Fig. 1) to full resistance, after which the external fixation apparatus was stabilized.

On the 20th day after the compression: the external fixation apparatus is stable in the fixation mode; animals are active, the appetite is not disturbed, with hock movements partially rely on the operated limb.

All animals on the 20th day after the compression was performed x-ray (figure 5). In this case, a transverse defect between the fragments of the shin bones up to 0.1 cm was revealed. Seals at the ends of the fragments were noted. During histological examination (Fig.6) in the defect zone, a large number of chondroblasts (A), connective fibers (B) and the formed islands of the spongy bone structure (C) were noted.

On the 50th day of the experiment, external fixation is stable in the fixation mode. The animals are active, the appetite is not impaired, with hock movements reliance on the operated limb.

On the 50th day, all animals underwent radiography (Fig.7). In this case, a transverse defect between the fragments of the leg bones up to 0.1 cm was revealed, compaction was noted at the ends of the fragments with the closure of the medullary canal around the fragments. The formation of tissues of different density, denser around the cortical plate and less dense between fragments in the defect zone. X-ray conclusion - an overgrown fracture of the leg bones. During histological examination, a large number of chondrocytes (A) and a small number of chondroblasts (B), connective fibers (C) and the spongy bone structure (D) are noted in the defect zone (Fig. 8). This histological picture characterizes the presence of a false joint and corresponds to the clinical course.

Thus, the proposed method allows to obtain a model of a false joint in fracture of the bones of the leg. The inventive device ensures the preservation of 1 cm between fragments, preservation of the bio-axis and the rigid fixation of fragments. Violation of the processes of consolidation of the lower leg bones causes the formation of connective-cartilage tissue in the defect zone by the 10th day and the absence of bone fusion up to 50 days, i.e. the formation of a “false joint”. The developed model in its characteristics is as close as possible to the real clinical process. The reproducibility of the model is 100%. The standardization of the resulting model is achieved using the same type, breed, sex, age and weight of the animals, as well as due to the set parameters provided by the claimed device.

The model can be used in a chronic experiment to study the mechanisms of formation and development of the pseudoarthrosis during fracture of the tubular bones of the lower leg in laboratory animals.

Claims (2)

1. A method for modeling a pseudoarthrosis during a fracture of the tibia of an experimental animal, including violation of the integrity of the bone tissue and fixation of bone fragments by an external fixation device (AVF), characterized in that AVF is first applied to the rabbit's shin, then between II and IV osteoperforation and osteoclasia are carried out by the levels, fragments of the leg bones are bred to a distance of 1 cm and fixed with AVF spokes in this position for 14 days, after which they are simultaneously compressed between the supports of IV and V levels to the full resistance, the ends of the fragments corresponded divorced and fix, stabilize the AMF. 2. A device for modeling a false joint in fracture of the tibia of an experimental animal, containing a proximal and distal base, each of which consists of 2 supports with holes evenly spaced along the entire length, the supports are parallel to each other and interconnected by threaded fixing rods, at the ends of which there are nuts and locknuts, characterized in that each base is made in the form of a sector equal to 3/4 of the ring, while the proximal base is II and IV levels, the distal one is V and VII levels, sectors II , IV and V levels are located one below the other, and the sector of the VII level is rotated 180 degrees in the horizontal plane with respect to the sectors of II, IV and V levels, moreover, 2 threaded fixing rods connect the II and IV, IV and the Vth, Vth and VIIth levels, and one fixing rod connects the 2nd level with the IVth and Vth levels, also at each base there are 2 pairs of bolt spoke fixators, which are placed according to the scheme:
$$\frac{II2-\mathrm{8,}\mathrm{four}-10}{3/\mathrm{four}}-\frac{IV2-\mathrm{8,}\mathrm{four}-10}{3/\mathrm{four}}-\frac{V2-\mathrm{8,}\mathrm{four}-10}{3/\mathrm{four}}-\frac{VII2-\mathrm{8,}\mathrm{four}-10}{3/\mathrm{four}}$$

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