RU2039530C1 - Osteosuture clamping device - Google Patents

Abstract

FIELD: medical engineering; orthopedic surgery. SUBSTANCE: device has a plate made of material with shape memory. One end of the plate has the form of a fork with sharp bent ends. The other end is sharp and crooked. The longitudinal groove wall is not less than two thicknesses wide. EFFECT: reliable immobilization of tubular bone fragments without using plaster bandage. 2 dwg

Description

 The invention relates to medical equipment, in particular to devices used to provide compression osteosynthesis of bone fractures without additional immobilization with a plaster cast.

 A device for osteosynthesis is known, consisting of a plate with petals on one of the sides curved in different directions, made of a material with a shape memory effect (EPF). The device can correct the angular deformation of the tubular bones and increases the fixation of fragments.

 However, this device is used for osteosynthesis in fractures of only tubular bones.

 Closest in technical essence to the proposed one is a latch, which is a plate with a longitudinal groove and screw holes, one end of which is made in the form of a fork with pointed bent ends.

However, during operation, a gap between the metal and the bone is created at the site of insertion of the end of the plate into the bone tissue due to compaction of the latter as a result of a large difference in the elastic moduli of the bone and the titanium alloy from which the device is made (2000 and 11000 kgf / mm ^2, respectively), which worsens bone fusion conditions.

 The aim of the invention is to provide a device for osteosynthesis of periarticular fractures.

 The technical effect of the claimed device is the fixation of fractures of solid bones and ensuring their constant compression, and at the same time, facilitating the operation process.

 For this, in a device for hip osteosynthesis containing a monolithic plate with a groove and screw holes on the diaphyseal part and with an intraosseous part bent at an angle, the plate is made of a memory effect material, while its other end is pointed and curved towards the intraosseous part, and the width of the jumpers formed by the groove is at least two plate thicknesses.

Due to thermoelastic martensitic transformation during mold restoration, the alloy develops a force of up to 50 kgf / mm ² , which will constantly provide compression of the bones at the fracture site.

It was established experimentally and theoretically that in order to provide the alloy with forces up to 50 kgf / mm ² under a load of 100 kg and a stability margin of not ≅ 3, the residual cross section of the diaphyseal part in the groove should be at least two plate thicknesses.

 In FIG. 1 shows the latch in the initial position; in FIG. 2 the same in working position.

 The latch contains a monolithic plate with a groove 2 and holes 3 for screws on the diaphyseal part 4, the width of the jumpers formed by the groove is indicated by 5.

 PRI me R. The clamp for hip osteosynthesis is made of an alloy plate with an EPF TN-20 thickness 3 and a width of 12 mm. The diaphyseal part (working) has a length of 70 mm and is equipped with a groove 2 with a length of 42 and a width of 6 mm and two holes 3 with a diameter of 2 mm for screwing in. The upper part of the device is made in the form of a fork with pointed ends with a width of 6 mm, intended for insertion into the bone head. The lower part is made in the form of a single pointed 6 mm wide pin and is intended for insertion into the diaphysis of the bone.

The device, taken in its initial position, is attached with the geometry shown in FIG. 2. Thereafter, in the same heat-set mandrel predetermined device geometry at a temperature of 500 ^{° C} for 1 h, then cooled to a temperature of minus 50-0 ^{° C} and is deformed by stretching in the tensile testing machine diaphyseal portion 4 in the groove 2 in place of 7-9% Then the device without heating, placed in a dewar at a temperature of -50 ^{° C,} where it is stored until its use.

 The device operates as follows.

After the preparation of the slots for the introduction of the bent ends of the device and the screw holes in the bone fragments (according to the corresponding template), the device with the upper end 6 and lower end 7 is inserted into the slots made in the head and diaphysis of the bone, and fasten with screws on both parts of the fragments. After introduction into the fracture site device is heated to body temperature (37 ° ^C), the material passes through the device temperature reverse martensitic transformation range (30-35 ° ^C) and restores the original (before expansion) okolopaznogo dimensions diaphyseal portion of the device, while developing this correspondingly reactive compression stress. With the correct introduction of the device into the bone tissue, these stresses will provide constant compression of bone fragments at the fracture site with an effort of up to 30-50 kgf / mm ² .

где Р_кр критическая сила, кгс;
Е модуль упругости сплава ТН-20, равный 11000 кгс/мм²;
I момент инерции сечения;
l_пр предельная длина рабочего сечения, мм.To confirm the reliable operation of the device under load, which can reach 100 kg, the stability of the device was calculated using the Euler formula
P _cr

where R _cr critical force, kgf;
E modulus of elasticity of the alloy TN-20, equal to 11000 kgf / mm ² ;
I moment of inertia of the section;
l _{CR the} maximum length of the working section, mm

For this device design, the section width is 3 mm; h section thickness, 3 mm; l _cr 70 mm.

150 кгс
Отсюда коэффициент запаса устойчивости
H_у

3
Таким образом, предлагаемое устройство способно обеспечивать компрессионное соединение отломков костей (без образования люфта) и эксплуатационную надежность.Substituting the parameter values in the formula, we obtain
P _cr

150 kgf
Hence the safety factor
H _y

3
Thus, the proposed device is able to provide a compression connection of bone fragments (without the formation of backlash) and operational reliability.

Claims (1)

 FASTENER FOR OSTEOSYNTHESIS, made in the form of a plate with a longitudinal groove and holes for screws, one end of which is made in the form of a fork with pointed curved ends, characterized in that the plate is made with a shape memory effect, while the other end is pointed and bent, and the width the longitudinal wall of the groove is at least two of its thicknesses.

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