RU2294178C2 - Device for holding foot and compensating extremity shortening - Google Patents

Abstract

FIELD: medical engineering.

SUBSTANCE: device has base, instep insole and flexible control rods attachable to Ilisarov apparatus. Threaded guiding pins are vertically mounted on the base and rigidly fixed therein. One of rods is placed near the edge in the middle of short base side and two other rods are placed in the corners along the second short side. Spacers, sensitive element unit and supination member are available on the control rods. The number of spacers is determined to make total height match extremity shortening length to be compensated. The sensitive element unit has base plate, bearing strain gage fixed in its center, and rectangular bending leaf spring connected to each other with bent base plate legs. The instep insole has rigid plate provided with members for fastening it on leg and three vertical projections on three sides having opening for fixing flexible control rods and instep insole. The instep insole is fixed on nut rods with reciprocation movement being allowed without stressing bending spring. The leaf springs have oval slots for receiving guiding rods.

EFFECT: full spring straightening under loading; improved treatment outcome.

3 cl, 1 dwg

Description

After applying the Ilizarov apparatus, for various injuries and diseases of the lower limb (in particular, when shortening a segment of the lower limb), a frequent complication is the development of equinus deformity of the foot. Especially often this occurs when the segments of the lower limb are lengthened when they are shortened. Prevention of this type of postoperative complication is the installation of all kinds of footstops using elastic rods [1]. In the case of shortening the segment, the height of the foot rail is equal to shortening, usually, foam is used to reduce the weight of the structure for this purpose. At the same time, with the compensation of shortening due to the cultivation of the distraction regenerate in the Ilizarov apparatus, the height of the buttress is reduced by cutting the thickness of the foam. However, after applying the Ilizarov apparatus, patients are allowed to walk with a dosed load (15-20 kg) for 4-5 days. Patients work out the feeling of such a load on the scales.

As the closest technical solution we adopted as a prototype stopper to a compression-distraction apparatus [2], which is designed to keep the foot in a functionally advantageous position in the postoperative period after osteosynthesis. This device contains a base that is attached to the lower ring of the Ilizarov apparatus using rods, one of which is made elastic. The device is used only for injuries of the ankle joint and is not intended for use in other injuries of the limb (lower leg, knee joint and femur). It does not have the ability to control the load on the limb, its shortening is not compensated.

The essence of the invention lies in the combination of distinctive features sufficient to achieve the desired technical result, namely: improving treatment outcomes, reducing its time, reducing complications (post-traumatic flatfoot, pelvic distortion, development of compensatory scoliosis) and increasing patient comfort.

This essence consists in the fact that the stopper for compensating for shortening of the limb and keeping the foot in the correct position in the postoperative period after osteosynthesis contains a base, a supination insole and elastic traction for attachment to the Ilizarov apparatus. On the base, threaded guide pins are installed vertically and rigidly fixed in it, one of which is located at the edge in the middle of the short side of the base, and the other two at the corners along the second short side. Spacers are placed on the pins, the number of which is selected so that the total height corresponds to the value of the compensated shortening of the limb. The block of the sensing element consists of a substrate, in the center of which a strain gauge is fixed, and a rectangular bent leaf spring. The strain gauge and the leaf spring are interconnected by the bent legs of the substrate. The supination insole consists of a rigid plate with fastening elements to the foot and three vertical protrusions on three sides for attaching elastic rods, and the supination insole itself. At the same time, the supination insole is fixed on the pins with nuts, with the possibility of reciprocating movements, without bending spring tension. Leaf springs have oval grooves along their short sides for guide pins oriented along their long sides, ensuring full spring straightening under load.

The stopper has a set of calibrated leaf springs, designed for use in various postoperative periods.

The strain gauge is connected to the earphone through a signal converter.

A vertical installation on three sides with rigid fastening at the base of the threaded guide pins is provided to impart stability to the structure and the possibility of changing the height of the foot, depending on the magnitude of the shortening of the limb segment.

Stacked spacers are installed on the pins, eliminate the misalignment of the pelvis, and their height is selected and corresponds to the magnitude of the compensated shortening of the limb.

The execution of the spacer, used with minimal shortening of the limb of the composite, consisting of two identical, small parts, makes it universal, which allows it to be made of a material more durable than polystyrene and used repeatedly.

The presence of a block of a sensitive element consisting of a substrate with a strain gauge fixed to it and a leaf spring of bending allows you to dose the load on the limb by selecting the appropriate spring and notify the patient about the excess load on the operated limb.

The use of a supination insole construction, consisting of a rigid plate with fastening elements to the leg and protrusions with holes on three sides, and the supination insole itself, is a preventive measure to prevent the development of post-traumatic flatfoot. A rigid plate eliminates deformation of the supination insole during operation. Vertical protrusions with holes are provided for fastening elastic rods that fix the insole relative to the rings of the Ilizarov apparatus, which eliminates sagging of the foot, and prevents the development of the equine position of the foot in the postoperative period.

The use of threaded pins, rigidly mounted on the base, for fixing the insole with nuts, ensures the unity of the structure without bending spring tension, i.e. the possibility of reciprocating movements of the insole with a different number of spacers on the pins.

Fixing the insole without tension of the flat spring, with the possibility of reciprocating movements, provides dosing of the load on the limb: when the body weight is transferred to the operated leg, the leaf spring is straightened, which provides grooves for the rods along its long sides. At the maximum dosed value of the load, the spring straightens and acts on the load cell, which gives a warning signal to the earpiece.

The stopper has in its kit a set of calibrated leaf springs, designed for use in various postoperative periods. This is due to the fact that after the formation of primary bone callus or the formation of regenerate, the load on the limb must be increased.

The stopper is equipped with a strain gauge and is connected to the headphone through a signal converter. The use of a strain gauge with an earpiece frees the patient from the process of memorizing the dosed load.

General view of the stopper with spaced nodes in the space shown in the drawing.

The stopper consists of a base 1, on which the threaded guide pins 2 are rigidly mounted. On the pins 2, the stacking spacers 3, the sensing element unit 4 and the insole 5 are sequentially mounted.

The block of the sensing element 4 consists of a substrate 6 with a strain gauge 7 fixed to it and a leaf spring 8 with grooves 9 connected to each other by bent tabs 10 of the substrate 6.

The supination insole 5 consists of a rigid plate 11 with fastening elements to the foot 12 and three vertical protrusions with holes 13 and the supination insole 14 itself.

Stop holder to compensate for shortening of the limb and foot retention is used as follows.

In the preoperative period, after comparative radiographs of the healthy and shortened segments, the magnitude of the shortening of the damaged segment is determined. Given the magnitude of the shortening, the stopper is assembled according to the following scheme. The required number of type-setting spacers 3 is put on the pins 2 of the base 1 so that their total height together with the substrate 6 and the rigid plate 11 is equal to the value of the shortening of the limb segment. After that, on the pins 2 with oval grooves 9, a sensor unit 4 is installed, consisting of a substrate 6 with tabs 10, a leaf spring 8 and a strain gauge 7. After that, a supination insole 5 consisting of a rigid plate 11 s is installed on the sensor unit 4 on the pins 2 fastening elements to the foot 12, vertical protrusions 13 and the supination insole 14 itself. The foot holder is attached to the patient’s foot with the help of fastening elements to the foot 12, and to the ring of the Ilizarov apparatus - by elastic rods (not shown) for verti cial protrusions 13 with holes 11 of the rigid plate.

Information sources

1. Rationalization and invention in orthopedics, issue 2, Sverdlovsk, 1975, from 60-62.

2. Auth. testimonial. USSR No. 556794, A 61 B 17/18, 1977, BI No. 17.

Claims (3)

1. Stop holder to compensate for shortening of the limb and keeping the foot in the correct position in the postoperative period after osteosynthesis, containing a base, supination insole and elastic traction for attachment to the Ilizarov apparatus, characterized in that the base is installed vertically and rigidly fixed therein, threaded guides pins, one of which is located at the edge in the middle of the short side of the base, and the other two at the corners along the second short side, spacers are placed on the pins, the number of which shaved so that the total height corresponds to the compensated shortening of the limb, the sensor block consisting of a substrate in the center of which a strain gauge is fixed, and a rectangular bend leaf spring connected by bent legs of the substrate, as well as a supination insole containing a rigid plate with fastening elements to the leg and three vertical protrusions on three sides with holes for attaching elastic rods, and the supination insole itself, while supination insole fixed on pins nuts with the possibility of reciprocating movement, without the bending stress of the spring, and the leaf springs have at their short sides of the oval slots for the guide pins oriented along their long sides to ensure complete straightening of the spring under load. 2. Stop holder according to claim 1, characterized in that it has a set of calibrated leaf springs, designed for use in various postoperative periods. 3. Stop holder according to claim 1, characterized in that the strain gauge is connected to the headphone via a signal converter.