RU2307615C2 - Device for osteosynthesis - Google Patents

Abstract

FIELD: medicine; traumatic surgery; orthopedics.

SUBSTANCE: device is made of shape memory effect titanium nickelide and it has elongated frame made of two wires, twisted into bundle. Pairs of half-wave curves of any wire are distributed along length of frame. Curves together and opposite stay apart from bundle. Wires have ends for intraosteal fixation; ends are bend to meet each other in same plane. Planes of one-sided half-wave curves are oriented in plane of device to have the same direction as bend ends of wires for intraosteal fixation and they intend to be placed inside bone. Opposite half-wave curves of any pair are oriented in orthogonal to plane of device, alternatively to different sides along length of frame. Angle of bend of wire ends equals to 100-120°. Device provides prevention of risk of letting device for osteosynthesis go from bone in case when oblique and comminuted fractures of tubular bones have to be treated.

EFFECT: prevention of axial instability of bone fractures.

Description

The invention relates to medicine, namely to traumatology and orthopedics, and can be used in the treatment of fractures of tubular bones.

Osteosynthesis - the operation of restoring the integrity of a broken bone - a process differentiated by the stages of execution and the list of subtasks at each stage. Fragments of the bone must be correctly aligned, closed, squeezed, fixed, and provided with a rest regimen for a rather long period of time. The complexity of each subtask depends on the characteristics of the fracture. For example, with oblique fractures of the tubular bones, when the sliding effect acts upon compression of the fragments, the technical means, in addition to compression, must provide both radial and axial immobility of the fragments.

A device for osteosynthesis in the form of an open ring of titanium nickelide with shape memory effect [Medical materials and shape memory implants. Ed. Tomsk University, Tomsk, 1998, p.214-215]. Its use in the surgical treatment of oblique and comminuted fractures of the diaphyseal sections of the tubular bones is beneficial due to the relative simplicity of the surgeon's actions.

A ring with an inner diameter (in the cold state) is selected 5-10% less than the average bone diameter at the fracture site. After reposition of the fragments, the device is superimposed using the shape memory effect (Fig. 1). For long oblique fractures, an overlay of several autonomous or combined rings is used (FIG. 2).

The disadvantage of this device is the narrow scope. The success of the operation depends on the type of fracture, and the appropriateness of its use requires good thought and great caution.

In case of fractures of tubular bones with a short plane of fracture, a device with an intramedullary fixator is used [Medical materials and shape memory implants. Ed. Tomsk University, Tomsk, 1998, p.234]. The compression of the closed fragments is carried out by the effect of the shape memory meander-like portion of the staple (Fig. 3), which is inserted into the bone with counter-curved legs. One leg is significantly elongated and, being located inside the bone along it, serves as a retainer to prevent fragments from slipping off. Thus, the device combines the actions of fixation and compression. The disadvantage is the possible migration of the intramedullary peduncle, i.e. the unreliability of fixing slipping fragments.

Known technologically simple and, with the correct choice of tactics of operation, quite effective device for osteosynthesis [Medical materials and implants with shape memory. Ed. Tomsk University, Tomsk, 1998, Fig. 4.54], selected by the greatest similarity as a prototype of the invention. It contains an elongated skeleton formed by two twisted into a bundle wires of titanium nickelide (Fig. 4) with counterbent ends - legs for intraosseous fixation. Half-wave bends of each wire, locally aligned and oppositely directed, thus forming loops, are made along the length of the core. The loop planes are oriented orthogonally to the plane of the device and serve together with the skeleton of the osseous support of the device. Another function of the loops is to create compression in the fracture zone. For this, the cooled device is deformed by longitudinal stretching of the loops, imposed on the fracture by transcortical implantation of the legs and left to heat and trigger the effect of thermodynamic restoration of the original form.

Osteosynthesis with such a device does not require wide operational access and skeletonization of broken bones. However, the absence of a separate element of axial stabilization of fragments creates a risk of slipping and forces one to carefully choose the position of the installed device (or several devices) according to the fracture configuration.

The technical result of the invention is to increase the fixing ability of the device in the treatment of oblique and comminuted fractures of the tubular bones.

The specified technical result is achieved by the fact that in the device for osteosynthesis of titanium nickelide with a shape memory effect containing an elongated skeleton of two twisted wires in a bundle with pairs of half-wave bends of each wire distributed along its length, together and opposed to the bundle, and the ends of the elongated skeleton bent in one plane, counter, at an angle of 100-120 ° for intraosseous fixation, the plane of one-sided standing half-wave bends intended for placement inside the bone is oriented in the plane of the device, co-directional bent ends intraosseous fixing bends opposed half-wave of each pair are oriented orthogonally to the plane of the device, alternately in opposite directions along the length of the core.

The proposed device depicted in figure 5, is used as follows.

During osteosynthesis of an oblique fracture of the tubular bone during surgery, the site of fracture 7 is exposed (Fig. 6), scar tissue is removed (in case of a late fracture) and bone fragments 5 and 6 are compared. In both bone fragments, a groove is cut through the line 7 of the lateral projection of the fracture in the longitudinal direction 8, the length of which corresponds to the length of the core between the extreme bends, and the width corresponds to the tight fit of half-wave bends into it 2.

Openings are made on the virtual groove extension line, symmetrically, at a distance of 5-10% longer than the core length in the cortical layer. 9. A selected osteosynthesis device is irrigated with chloroethyl for 5-10 seconds, cooling it to a temperature below + 10 ° С. Using, for example, krampon forceps, the core is stretched in the longitudinal direction due to deformation of half-wave bends, and the bent ends of the core are deformed to a right angle. Then the device is immediately immersed in the prepared holes and groove and held in this position for 20-30 s.

During this time, in connection with the contact heating of titanium nickelide to 35 ° C, a shape memory effect is manifested, while stretched half-wave bends 2, 3 reduce the longitudinal size of the core, providing dynamic compression of fragments. The device is fixed in the bone and the desired position of the fragments is fixed by tensioning the bent ends 4, which tend to the initial, bent, state, and rigidly connecting the fragments to the device by pinching the half-wave bends 2 in the groove 8 and the osseous restriction of migration by half-wave bends 3.

After the joint of the fracture, the device is removed as follows. Its extraosseous part is exposed and irrigated with chloroethyl in the wound, as a result of which titanium nickelide becomes plastic. By the traction, the ends and half-wave bends are extracted from the bony holes and groove.

Thus, the specified technical result is achieved due to the implementation of the details of the skeleton in the bone groove and the formation of a rigid frame that blocks the slipping of fragments of the oblique fracture. For long oblique and multi-fragmented fractures, several devices are used to counter the displacement of fragments in all possible directions. Individual selection and fitting of a device for a specific fracture prescribes the "piece" nature of the technology. Under these conditions, the production of the product should be as close as possible to the operating room.

The design of the device meets these conditions, because the starting material is a trivial wire, and hot bending fabrication does not require highly skilled performer and sophisticated metalwork tools.

The illustrations show:

figure 1 - external view of the ring device for osteosynthesis and the scheme of its installation;

figure 2 - device for osteosynthesis with paired rings;

figure 3 - device for osteosynthesis with intramedullary fixation;

figure 4 - device for osteosynthesis (prototype);

figure 5 - the proposed device for osteosynthesis of fractures of tubular bones: 1 - the skeleton, 2 - intraosseous half-wave bends, 3 - osseous half-wave bends, 4 - bent ends of the skeleton - legs for intraosseous fixation;

6 is a diagram of the imposition of a device for osteosynthesis with oblique fractures of the tubular bones: 5, 6 - bone fragments, 7 - fracture line, 8 - bone groove, 9 - holes for fixing the device.

The device after experimental tests is used in a clinical setting.

An example of a specific use.

Patient K., 25 years old, was admitted to the clinic of the Kemerovo State Medical Academy with a closed fracture of the second metacarpal bone in the middle third with displacement of fragments. In aseptic conditions under local anesthesia, the patient underwent an osteosynthesis operation using the proposed device (Fig. 5).

The manufactured device contains an elongated skeleton made of two twisted into a bundle of nickel-titanium wires with a diameter of 1.0 mm The ends of the elongated skeleton for intraosseous fixation are bent at an angle of 100 ° each from its distal direction, facing each other, in the same plane. The overall length of the device is 25 mm, the length of the bent ends of the core is 8 mm. Half-wave bends made locally pairwise aligned and spaced 10 mm symmetrically from the ends of the core at the center of the bends along the length of the core. A pair of combined bends forms an opal loop with dimensions of 5 × 10 mm. The planes of unilaterally standing half-wave bends are oriented in the plane of the device, with the bent ends bent for intraosseous fixation, and are designed to be placed inside the bone in a groove specially prepared for them. The planes of the opposite half-wave bends are oriented orthogonally to the plane of the device in opposite directions. The material of the device is titanium wire nickelide ТН - 10 with a phase transition temperature of 0 ÷ 10 ° С.

The device during the operation works as follows. An open reposition of the selected fragments was carried out and in the longitudinal direction through the fracture line a groove was made in the cortical layer 1.0-1.2 mm wide, 20 mm long. Holes were drilled symmetrically along its edges at a distance of 27 mm from each other to accommodate the bends of the core to a depth equal to the diameter of the bone.

The device is cooled with chloroethyl to a temperature of + 10 ° C and with the help of crampon forceps is stretched in length, up to about 27 mm, when the ends of the core are bent to a right angle. In this form, it is inserted into the holes and the groove until the skeleton and the osseous half-wave bends touch the surface of the bone. After heating the device with the heat of the patient’s body, it, aspiring to its original form, fixed in the bone and squeezed the fragments to the necessary compression of osteosynthesis.

External immobilization after surgery was not performed. Active development of movements began on the second day. After 3 weeks, a full functional recovery was obtained.

After the joint of the fracture, the device was removed by cooling with naked chloroethyl, protruding above the bone of the skeleton and easy traction from the holes and groove.

Successful use of the device in clinical conditions, its technological readiness for widespread use, indicate that the proposal meets the criterion of "industrial applicability".

Claims (1)

A device for osteosynthesis of titanium nickelide with a shape memory effect containing an elongated skeleton of two twisted into a bundle, wires with pairs of half-wave bends of each wire distributed along its length, jointly and oppositely extending from the bundle, and with ends for intraosseous fixation, the latter being bent counter in one plane, characterized in that the planes of the unilaterally standing half-wave bends are oriented in the plane of the device, with the bent ends bent for intraosseous fixation, and are intended for placement inside the bone, the opposite half-wave bends of each pair are oriented orthogonally to the plane of the device, alternately in opposite directions along the length of the core, and the angle of bending of the ends for intraosseous fixation is 100-120 °.

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