RU2752712C1 - Implant for subtalar arthroereisis - Google Patents

Abstract

FIELD: medicine.SUBSTANCE: implant for subtalar arthroereisis includes a body in form of a truncated cone with threads along the surface. The diameter of the larger base of the cone is 9.5 mm to 17.5 mm, the diameter of the smaller base of the cone is 7.5 mm to 15.5 mm. A central hole with a diameter of 1.6 mm for installing a spoke is made along the entire length of the cone. Three equidistant cuts for growth of the cicatricial fibrous tissue are made along the outer side of the body. A blind hole with a depth of up to 0.5 cm for a hexagonal cannulated screwdriver is made at the base of the cone. The body is made of a biodegradable material, wherein a calcium phosphate coating is applied over said material.EFFECT: invention ensures anatomically correct placement of the implant and maximum reduction of possible risks of migration of the subtalar implant from the subtalar sinus to the outside, minimising incorrect installation and post-operative complications in form of migration of the implant, wherein repeated surgical intervention for removing the proposed subtalar implant is not required due to complete biological degradation thereof in the subtalar space.1 cl, 3 dwg

Description

The technical field to which the invention relates

The invention relates to medical devices and can be used in the surgical treatment of planovalgus deformity of the feet in children and adults.

State of the art

Known subtalar implant (US 8628582, publ. 01/14/2014). The truncated cone-shaped implant contains a low domed distal end, a V-threaded surface and a flat proximal end, with the internal thread located adjacent to the cannulation along the longitudinal axis of the specified implant and communicating with the specified internal thread, a seating notch and a cylindrical notch of the implant.

The disadvantage of the known subtalar implant is that the implant and the installation tool are made of metal, which excludes the possibility of biodegradation of this implant, i.e. complete disintegration of the installed implant after it has performed the function of temporarily limiting the hyperpronation of the foot for a certain period of time, and requires additional surgical intervention to remove the implant

Also known subtalar implant (Patent RU 2601658, publ. 10.11.2016), which is made in the form of a truncated cone of porous composite titanium nickelide with a porosity of 81% with an average pore size of 420 μm.

The disadvantages of the known implant include the impossibility of installing this implant in patients with mobile planovalgus deformity of the feet and connective tissue dysplasia, the impossibility of removing, if necessary, this implant from the placement site due to the formation of fusion with the bones of the foot surrounding the implant. It is also possible to note a longer period of immobilization of the foot in the postoperative period for the need for the formation of arthrodesis of the joints of the foot in the area of implantation.

Known subtalar implant (patent RU 2514550, publ. 04/27/2014), which contains a body in the form of a truncated cone with a thread on the outer surface and an axial hole for a key. Three longitudinal grooves are made on the body, located at the same distance from each other and dividing the body into three equal parts. The grooves in the direction of unscrewing have platforms that are lowered by the height of the thread tooth, and the teeth on the opposite side of the groove are rounded with a radius.

The disadvantage of the technical solution is that implantation is not provided for the entire depth of the subtalar sinus, since the anterior base is made in the form of a flat platform. In addition, this implant is also made of metal, which excludes the possibility of its biodegradation and requires additional surgical intervention to remove the implant.

The essence of the invention

The technical problem is aimed at creating an implant with a longer (up to 18 months) period of biodegradation, namely, complete resorption at the place of its installation upon reaching a certain period of time, as well as increasing the reliability of fixation in the subtalar joint.

The technical problem is achieved by the fact that in the implant for subtalar arthroereisis, which includes a body in the form of a truncated cone with a thread along its surface, according to the proposed solution, the diameter of the larger base of the cone is 9.5 mm - 17.5 mm, the diameter of the smaller base of the cone is 7, 5 mm - 15.5 mm, while along the entire length of the cone, a central hole with a diameter of 1.6 mm is made for installing the spoke and along the outer side of the body there are three cuts for the germination of scar-fibrous tissue, located at the same distance from each other, and in The base of the cone has a blind hole up to 0.5 cm deep for a hexagonal cannulated screwdriver, while the body is made of a biodegradable material, on top of which a calcium phosphate coating is applied.

Figure 1 shows a general view of the implant in section, figure 2 - view A, figure 3 - bottom view.

Implementation of the invention

The body 1 of the implant is made in the form of a truncated cone with threads along its surface. The diameter of the larger base of the cone is 9.5 mm -17.5 mm, the diameter of the smaller base of the cone is 7.5 mm-15.5 mm, a central hole with a diameter of 1.6 mm is made along the entire length of the cone, and three slots are made along the outer side of the body 3 A blind hole 2 up to 0.5 cm deep for a hexagonal cannulated screwdriver is made at the base of the cone. A calcium phosphate coating is applied to the body surface. A biodegradable biocomposite material can be used as the material of the implant body.

The minimum implant size is 7.5 mm by 9.5 mm, and the maximum - 15.5 mm by 17.5 mm, was selected experimentally. The implant maximally repeats the conical shape of the subtalar sinus of the foot, which ensures anatomically correct placement of the implant and minimizes the possible risks of migration of the subtalar implant from the subtalar sinus outward, which minimizes the possibility of incorrect installation and postoperative complications in the form of implant migration. In the cuts 3, scar-fibrous tissue grows, which subsequently provides a more reliable fixation of the implant in the subtalar sinus and minimizes the risk of migration in the postoperative period. Slots 3 throughout the body of the implant also ensure the symmetry of the subsequent fixation over the entire area of the subtalar space.

The implant is installed as follows.

The operation is performed in the operating room under intravenous anesthesia or sevoran inhalation anesthesia. The position of the patient is lying on his back. A pneumatic tourniquet is applied to the upper third of the lower leg of the operated lower limb. The operated lower extremity is squeezed out with an elastic bandage, the pneumatic turnstile is pumped, minimizing blood loss. The lower limb is treated with an antiseptic solution three times. The search for the entrance to the subtalar space is performed on palpation, namely, the retraction of soft tissues is palpated slightly anterior to the external ankle. An oblique arcuate skin incision is performed slightly anteriorly and distally to the outer ankle in the length of up to 2-3 cm, depending on the size of the foot and the expected size of the implant, a layer-by-layer access to the subtalar joint is performed, removing the cutaneous nerve aside, and then spreading it out using a mosquito-type clamp »A connective tissue membrane at the entrance to the subtalar space. Further, in an oblique direction from front to back, from top to bottom, an instrument is inserted into the subtalar sinus to eliminate the subluxation of the talus in relation to the calcaneus, moderate downward pressure on the handle of the instrument is performed to obtain elevation of the neck and head of the talus, the foot at this moment moderately rotates inward with the second hand. The assistant performs excessive inward rotation of the forefoot to stretch the metatarsal-sphenoid ligament and make the forefoot more mobile. The reposition instrument is removed from the subtalar sinus. The foot is brought to the position of norm correction. In the area of the subtalar joint, using the instrument, the implant size is selected, starting from a size of 9.5 mm to a size of 17.5 mm. After selecting the optimal size conical implant with the maximum possible degree of correction of the foot deformity, a metal wire 1.5 mm in diameter is installed in the subtalar joint from bottom to top front to back, passed through the entire subtalar sinus to the opposite side of the foot with the wire going out to the opposite side of the foot percutaneously, on The implant is put on through the central through hole with a diameter of 1.6 mm; behind the implant, a hexagonal channeled 3.5 mm screwdriver with a 1.6 mm hole in the center is put on the wire. The diameter of the central through hole in the implant and in the screwdriver, equal to 1.6 mm, is selected based on the most tight contact between the implant and the guide wire, the screwdriver and the guide wire to reduce possible backlash to a minimum and achieve the most accurate placement of the implant in the subtalar sinus of the foot ... The implant is screwed in clockwise rotational movements into the subtalar sinus cavity with a narrow oval base inward, and a wide base facing the outside of the foot at an angle of up to 10-15 degrees to the frontal plane, until it stops. The screwdriver is removed from the spoke, the spoke is removed. Test movements with the foot are performed to check that the implant is firmly in the joint, there is no tendency to migration. The wound is tightly sutured in layers with Vicryl without leaving drainage. Intradermal cosmetic sutures with vicryl are applied to the skin and an aseptic bandage is applied to the area of the postoperative suture. Pneumozhgut dissolve. A support is applied to the lower limb under a plaster cast, then a circular plaster-polyurethane bandage is applied to the lower limb from the upper third of the lower leg to the tips of the toes, the foot is fixed at a right angle.

A control X-ray is performed 3-5 days after the operation in frontal and lateral projections in a plaster cast.

The stay in the plaster-polyurethane bandage is 21 days after the operation, control images - 6 weeks after the operation, the plaster bandage is removed provided there is no pain or discomfort in the projection of the subtalar joint of the foot. After removing the plaster cast, the obligatory wearing of orthopedic shoes or insoles with an inner raised edge is prescribed in order to maximize the unloading of the medial part of the foot, wearing these shoes - within 6 months from the date of surgery. After 6 months, a control X-ray of the foot is performed in frontal and lateral projections.

Further, control radiographs of the foot in frontal and lateral projections are performed once every 12 months, followed by consultation with an orthopedic surgeon.

The subtalar implant, the size of the larger base of which varies from 9.5 mm to 17.5 mm, is installed in patients from 5 to 50 years old.

The combination of features of the proposed invention allows for the anatomically correct placement of the implant and to minimize the possible risks of migration of the subtalar implant from the subtalar sinus outward, which minimizes incorrect installation and postoperative complications in the form of implant migration.

Repeated surgery to remove the proposed subtalar implant is not required due to its complete biodegradation in the subtalar space.

Claims (1)

An implant for subtalar arthroereisis, including a body in the form of a truncated cone with a thread along its surface, characterized in that the diameter of the larger base of the cone is 9.5 mm - 17.5 mm, the diameter of the smaller base of the cone is 7.5 mm - 15.5 mm , while along the entire length of the cone, a central hole with a diameter of 1.6 mm is made for installing the spoke, and along the outer side of the body, three cuts are made for the germination of scar-fibrous tissue, located at the same distance from each other, and a blind hole is made at the base of the cone with a depth of up to 0.5 cm for a hexagonal cannulated screwdriver, with the body made of a biodegradable material over which a calcium phosphate coating is applied.

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