RU230003U1 - Device for temporary retention of fragments during bone osteosynthesis - Google Patents

Abstract

The utility model relates to the field of traumatology and orthopedics, namely to a medical instrument, and is intended for temporary retention of repositioned fragments during bone osteosynthesis from the moment of reposition until fixation with a bone plate. The device for temporary retention of fragments during bone osteosynthesis contains a rod consisting of a working part with a thread and a non-threaded part. The non-threaded part is made L-shaped. The technical result is to ensure retention of fragments in the correct repositioned position due to the creation of sufficient force during screwing, which leads to an optimal tightening force of the fragments. In addition, the technical result consists in the possibility of repeated unimpeded fitting of the bone plate, subjected to the required intraoperative bending in order to ensure a high degree of congruence to the bone surface, with the provision of convenience of subsequent bone osteosynthesis.

Description

The utility model relates to the field of traumatology and orthopedics, namely to a medical instrument, and is intended for temporary retention of repositioned fragments during bone osteosynthesis from the moment of reposition until fixation with a bone plate.

A method is known for fixing fragments in oblique and helical fractures using a lag screw, which provides counter compression and maintains the correct position of the fragments until a plate is applied [1].

However, when fixed with the described screw, its head protrudes from the bone by several millimeters, which prevents the plate from being correctly placed on the bone. The plate, once on the screw head, cannot be placed on both fragments at the same time. When attempting to insert screws into the plate, either displacement or a fracture occurs at the site of insertion of the lag screw, which is an iatrogenic mechanical complication. Surgeons are forced to move the plate to the biomechanically unfavorable side or to sink the head into the cortical layer using a countersink, which also creates risks of iatrogenic fracture at the site of the lag screw. If it is not used, surgeons are faced with the need for an almost acrobatic transition from repositioning forceps to the plate, during which the loss of reposition can occur dozens of times with an increase in the duration of this stage of the operation by half an hour or more.

The device "Provisional fixation pin" is known - a pressure screw [2], which is used in a number of kits for bone osteosynthesis. The device is a straight rod consisting of a working part with a thread and a non-threaded part. The working part with a thread is designed for screwing into the bone. At the border of the threaded and non-threaded parts there is a thickening similar to the head of a screw, which (the thickening) presses the plate to the bone through the hole of the bone plate for their temporary mutual fixation.

However, according to the osteosynthesis technique, the first reposition and fixation is performed with repositioning forceps or a lever bone holder, which, when grasping from the bone of both sides, has one of the jaws in the place where the plate needs to be placed, and after repositioning it becomes an insurmountable obstacle to the placement of the plate. An attempt to momentarily release the lever bone holder and make room for the plate leads to a displacement of the fragments due to muscle tone, which cannot be suppressed even by anesthesia with muscle relaxants. A paradox arises: the bone holder must be there (reposition and temporary retention) and it must not be there (so as not to interfere with the placement of the plate). The described device does not solve this problem: fixation of the plate to the fragment is possible only after some interfragment fixation that does not interfere with the placement of the plate or with minor displacements. In these cases, the action of this device will be identical to the action of any screw that is inserted through the plate into the bone first. That is, the device only provides an extra unnecessary action for the surgeon.

The technical problem is the creation of a reliable and effective device for temporary retention of repositioned fragments during bone osteosynthesis from the moment of their reposition until fixation with a bone plate, devoid of the above-mentioned disadvantages.

The technical result consists in ensuring the possibility of repeated unhindered fitting of an extra-bone plate, subjected to the required intraoperative bending in order to ensure a high degree of congruence to the bone surface, with ensuring the convenience of subsequent extra-bone osteosynthesis.

The technical result is achieved due to the fact that in the device for temporary retention of bone fragments for fitting and installing an extra-bone plate during extra-bone osteosynthesis of an oblique, screw-shaped fracture, containing a rod, according to the utility model, the working part of the rod is made with a thread for screwing into both bone fragments, and the threadless part is made L-shaped with the possibility of using it as a handle and putting an extra-bone plate on it with advancement.

In specific embodiments of the device, the rod is made with a diameter of 3.5 mm or 4.5 mm.

The claimed device is used after repositioning and temporary fixation of the fragments has been performed using repositioning forceps: the claimed device is inserted into the center of the oblique component of the fracture in the same way as a lag screw is inserted, while the L-shaped threadless part is used as a lever to ensure sufficient torsional force when screwing in, which, in turn, ensures optimal and reliable tightening of the fragments for further osteosynthesis.

The essence of the device for temporary retention of fragments during bone osteosynthesis is explained by drawings, which show the following images:

Fig. 1 - Device for temporary retention of bone fragments during bone osteosynthesis, front view, where: 1 - rod; 2 - working part; 3 - thread; 4 - middle third; 5 - posterior third (shank); 6 - arc bend.

Fig. 2 - Device for temporary retention of bone fragments during bone osteosynthesis, side view, where: 1 - rod; 2 - threaded part; 3 - thread; 4 - middle third; 5 - posterior third (shank); 6 - arc bend.

Fig. 3 - Device for temporary retention of bone fragments during bone osteosynthesis, in axonometry, where: 1 - rod; 2 - threaded part; 3 - thread; 4 - middle third; 5 - posterior third (shank); 6 - arc bend.

Fig. 4 - Device for temporary retention of bone fragments during bone osteosynthesis, filming during surgery (clinical example). The fragments are aligned and temporarily fixed with the claimed device for retaining bone fragments, inserted into a canal that is drilled through both fragments along a thread cut in the bone canal, while the threaded part of the device and the thread in the fragments are not visible, since they are immersed in the bone, where: 1 - the rod itself; 4 - middle third; 5 - posterior third (shank); 6 - arc bend; 7 - proximal fragment; 8 - distal fragment; 9 - oblique or spiral fracture line.

Fig. 5 - Device for temporary retention of bone fragments during bone osteosynthesis (schematic drawing, in longitudinal section), the fragments are aligned and held by the claimed device inserted into a bone canal drilled in both aligned fragments, where: 1 - rod; 2 - threaded part; 3 - thread; 4 - middle third; 5 - posterior third (shank); 6 - arc bend; 7 - proximal fragment; 8 - distal fragment; 9 - oblique or helical fracture line; 10 - channel for the device for temporary retention of bone fragments; 11 - thread cut in the bone of channel 10; 12 - plate; 13 - hole in the plate; 14 - cortical screw.

Fig. 6 - Device for temporary retention of bone fragments during bone osteosynthesis (shooting in the operating room), the fragments are aligned and held by the claimed device inserted into the bone canal drilled in both aligned fragments, and a plate is put on the shank through one of the holes for a trial fit on the bone, while the threaded part and the bone thread are not visible, since they are hidden by the bone, where: 1 - rod; 4 - middle third; 5 - posterior third (shank); 6 - arc bend; 7 - proximal fragment; 8 - distal fragment 12 - plate; 13 - hole in the plate.

Fig. 7 - Device for temporary retention of bone fragments during bone osteosynthesis (diagrammatic drawing in conditional straight section), when after fixation of fragments with the claimed device, one screw is inserted into the proximal and distal fragments, and the device itself has not yet been removed, where: 1 - rod; 2 - threaded part; 3 - thread; 4 - middle third; 5 - posterior third (shank); 7 - proximal fragment; 8 - distal fragment; 9 - oblique or screw fracture line; 10 - channel for threaded bone holder; 11 - thread cut in the bone of channel 10; 12 - plate; 14 - cortical screw.

Fig. 8 - Device for temporary retention of bone fragments during bone osteosynthesis, where all screws have been installed and the claimed device has been replaced with a cortical screw (diagram). The claimed device is held by the surgeon over the place from which it was removed and where the screw replacing it has been inserted, where: 1 - rod; 2 - threaded part; 3 - thread; 4 - middle third; 5 - posterior third (shank); 12 - plate; 14 - cortical screw.

Fig. 9 - Device for temporary retention of bone fragments during bone osteosynthesis, where all screws have been installed and the claimed device has been replaced with a cortical screw (shot in the operating room). The fragments and the fracture line are not visible, as they are hidden by the plate. The claimed device is held by the surgeon over the place from which it was removed and where the replacing screw has been inserted, where: 1 - rod; 2 - threaded part; 3 - thread; 4 - middle third; 5 - posterior third (shank) 12 - plate; 13 - hole in the plate; 14 - cortical screw.

A device for temporary retention of bone fragments during bone osteosynthesis comprises a rod 1, preferably made with a diameter of 3.5 mm or a diameter of 4.5 mm. The rod 1 includes a working part 2 with a thread 3 and a threadless part consisting of a middle part 4 and a rear part 5 (shank). The threadless part is made L-shaped so that the rear part 5 is located at an angle in the middle part 4, optimally at an angle of 90°.

The device is used as follows.

Based on the type of plate and the diameters of screws required for its fixation (3.5 mm or 4.5 mm), a device for temporary retention of bone fragments with the corresponding diameter is selected. After surgical access and alignment of bone fragments 7 and 8 along the oblique or screw-shaped components of fracture 9, they are mutually compressed in the transverse direction and a channel 10 is drilled into the bone through both fragments 7 and 8. In channel 10, a bone cortical thread 11 is cut, corresponding to thread 3 of rod 1. Then, working part 2 of rod 1 is screwed into channel 10 until it stops, using rear part 5 as a handle (crank). Insertion of threaded part 2 until it stops provides temporary fixation with counter compression of the “lag screw” type [1, pp. 220-224], as in the prototype. Next, a bone plate 12 is put on the rod 1, which is advanced along the rod through the opening 13 in such a way that the plate first passes the back part 5, the bend 6 and the middle part 4 until it contacts the fragments 7 and 8. The quality of contact of the plate 12 with the bone fragments 7 and 8 is assessed. If the contact is unsatisfactory, then the plate 12 is removed by sliding back along the rod, bent, put on the rod 1 until it contacts the fragments 7 and 8, with a repeated assessment of the quality of contact. The bending of the plate 12 and repeated fitting are performed until its optimal contact with bone fragments 7 and 8 are achieved. Upon achieving acceptable contact of the surfaces of bone fragments 7 and 8 and the plate 12, the plate 12 is fixed. For this purpose, screws 14 are inserted through openings 13 in the plate 12 into bone fragment 7 (proximal) and bone fragment 8 (distal), achieving their resistance to displacement along the oblique or helical surface of the fracture 9. The working part 2 of the rod 1 is unscrewed from the channel 10 and the cortical screw 14 is screwed in instead, ensuring absolute stability of the system fixation. After this, the remaining screws are inserted into the fragments according to the operation plan to optimize the final strength of the fixation. The operation is completed in accordance with the current regulations.

Clinical example

Patient B., 37 years old, underwent osteosynthesis for a fracture of the distal tibial epiphysis at the R.R. Vreden National Medical Research Center of Traumatology and Orthopedics [3], which traditionally has low congruence to the surface of the lower third of the tibia and requires mandatory intraoperative bending. The plate required the use of cortical screws with a diameter of 3.5 mm. A device for temporary retention of bone fragments with a rod diameter of 3.5 mm was selected for the operation, which corresponds to the diameter of the screws intended for use to fix the plate. The operation was performed exactly according to the method described above, and its stages are shown in the pictures on the operating table presented in the illustrations: Figs. 4, 5 and 9. By rotating the device by the shank, sufficient force was achieved for transverse interfragment compression, and the shape of the device and its orientation relative to the bone ensured convenience when placing the plate on the bone. This made it possible to perform bone osteosynthesis without technical errors and without the use of temporary fixation with pins, without errors and with savings in operating time (saving up to approx. 30 min). During the operation, the plate was tried on three times by putting it on through the hole on the shank of the device and placing it on the bone. The device maintained the reposition position of the bone fragments during each manipulation and, accordingly, ensured the possibility of precise adjustment of the working surface of the plate to the anterior surface of the tibia. The treatment result was favorable: timely consolidation of the fracture and restoration of limb function.

References

1. Rudi T.P., AO Principles of Fracture Treatment / T.P. Rudi, R.E. Baklit, K.G. Moran; trans. from English. A.A. Sitnik. - 2nd ed., revised and supplemented. - Volume 1. Principles. - Berlin: B.I., 2013 - 556 p. (pp. 220-224).

2. US Patent No. 5 968046, Provisional fixation pin, David Castelman, “Smith & Nephew C ^o ”, 10/19/1999, priority from 07/04/1998.

3. DEOST product catalog. Moscow, Pushchino, 2012, p. 35.

Claims (3)

1. A device for temporary retention of bone fragments for fitting and installing a bone plate during bone osteosynthesis of an oblique screw fracture, comprising a rod, characterized in that the working part of the rod is made with a thread for screwing into both bone fragments, and the threadless part is made L-shaped with the possibility of using it as a handle and putting a bone plate on it with advancement. 2. The device according to item 1, characterized in that the rod has a diameter of 3.5 mm. 3. The device according to item 1, characterized in that the rod has a diameter of 4.5 mm.