RU2703876C1 - Method for preoperative planning of surgical correction of foot deformation at the level of midfoot - Google Patents

Abstract

FIELD: medicine.SUBSTANCE: invention refers to medicine, namely to traumatology and orthopedics, and can be used for preoperative preparation of patient for surgical correction of deformation of middle foot. An X-ray image of the foot is made with a load in the forward projection. On the X-ray image of the foot, a point "a" corresponding to the transverse tarsal joint medial border is placed, and a point "b" corresponding to the lateral edge of the transverse tarsal joint. Line 1 is passed through points "a" and "b", in the middle of which point "c" is marked and line 2 is drawn from it at angle of 89° to line 1. Further, line 3 corresponding to mechanical axis of 2nd metatarsal bone is drawn. Cross point of lines 2 and 3 is the apex of deformation of middle foot. When performing virtual osteotomy, distal bone fragment is moved so that lines 2 and 3 are aligned.EFFECT: method enables accurate determination of the apex of deformation of the middle foot and, accordingly, higher reliability of preoperative planning and surgical correction due to geometrical constructions.1 cl, 10 dwg

Description

The invention relates to medicine, namely to traumatology and orthopedics, and can be used for preoperative preparation of a patient for surgical correction of deformation of the middle part of the foot, when the components of the deformation are determined by a radiograph made in direct projection.

Known methods of planning correction of deformations of the middle part of the foot:

1. Kirienko A. Ilizarov Technique for Complex Foot and Ankle Deformities, Marcel Dekker, New York, 2004.

2. Bradley M. Lamm, Paul A. Stasko. Normal Foot and Ankle Radiographic Angles, Measurements, and Reference. The Journal of Foot & Ankle Surgery. 2016

According to these methods, the reference angles of the bones of the middle section are found, as well as their location from the axis of the talus. However, these methods have certain disadvantages:

1. When finding the location of the mechanical axis of the second metatarsal bone (M2) relative to the Shoparov joint, the possibility of their deformation is not taken into account, which leads to inaccurate planning.

2. If there is deformation at the level of the ankle joint or hindfoot, then the mechanical axis of the second metatarsal bone relative to Shoparov’s joint will not be true.

3. In the described methods for planning correction of deformations of the middle part of the foot, it is not provided for determining the peak of deformation at which correction should be carried out.

The technical result of the claimed invention is the ability to accurately determine the apex of deformation of the middle part of the foot and, accordingly, on the basis of this is to increase the reliability of preoperative planning and surgical correction.

The result is achieved due to the fact that they put a point “a”, which is located on the inner edge of the Shoparov’s joint, on the medial edge of the ram-navicular joint, and a point “b”, which is located on the outer edge of the Shoparov’s joint, i.e. on the lateral edge of the heel-cuboid joint. Through points "a" and "b" draw line 1 and find its middle - point "c". From the middle of line 1, line 2 is drawn at an angle of 89 ° (± 3.7) to line 2. Then, line 3, which is the mechanical axis of the 2nd metatarsal bone, is drawn. The intersection point of lines 2 and 3 is the peak of deformation. The next step is to perform a virtual corrective osteotomy and move the distal fragment so that line 2 and line 3 coincide.

The figures depict:

FIG. 1. Scheme of building the Shoparov line of the joint (line 1) on the lateral and medial points (ab). Finding point c on line 1.

FIG. 2. Scheme for constructing the line 2. The pattern of the angle between line 1 and line 2 is 89 ° (± 3.7). The location of the mechanical axis of the second metatarsal bone coincides with line 2.

FIG. 3. The scheme of the deformed foot and the construction of points a and b on it, the construction of the Shoparov line of the joint (line 1), the location of points c on it.

FIG. 4. Scheme of plotting line 2 from point c.

FIG. 5. The scheme for determining the "correct" location of the mechanical axis of the second metatarsal bone (line 3) and the determination of the deformation peak at the intersection of line 2 and line 3.

FIG. 6 Schematic representation of the dosage correction of deformation of the middle section (line 2 coincides with line 3)

FIG. 7. X-ray of the direct projection of the foot with deformation at the level of the middle section with the construction of line 1 and the definition of point c.

FIG. 8. X-ray of the direct projection of the foot with the construction of line 2, determination of the mechanical axis of the second metatarsal bone, finding the apex of deformation.

FIG. 9. Sciagram in the X-ray photograph - a representation of the correction of deformation of the middle section at the osteotomy level when combining line 2 and line 3.

FIG. 10. The skygram in the X-ray photograph — after correction of the deformation of the middle section (line 2 coincides with line 3).

To implement the method, through line a and b (the edges of the head of the talus and calcaneus) draw line 1 and measure the distance from a to b millimeters (figure 1, figure 3). From the middle of line 1 (point "C") at an angle of 89 °, draw line 2 (figure 2, figure 4). In the absence of deformation, line 2 should coincide with the mechanical axis of the 2nd metatarsal bone (figure 2). In the presence of deformation, these lines intersect (figure 5). The intersection of the axis of the second metatarsal bone and line 2 is the peak of deformation (figure 5). At this level, corrective osteotomy is performed. To correct the deformation, it is necessary that line 2 coincides with the mechanical axis of the second metatarsal bone - line 3 (figure 6).

In figures 3-6 schematically shows the application of the method with a deformed foot.

In figures 7-10 demonstrated the application of the described method for correction of deformation. The relationship between bone structures before and after correction is shown.

To obtain the angle at which lines 1 and 2 intersect, which is 89 ° (± 3.7), 90 x-rays of undeformed feet of people aged 20 to 62 years were analyzed. All radiographs were performed with a load in direct projection. When analyzing the roentgenograms, the location of the Shoparov line of the joint (talon-scaphoid and calcaneo-cuboid) was determined, from the middle of this line a second line was drawn to the center of the metatarsal head 2, the angle formed by these lines after the average treatment was 89 ° (± 3.7).

The data obtained allowed us to develop a new method of analysis and planning of correction of deformations of the middle part of the foot in direct projection.

Claims (1)

A method for preoperative planning of surgical correction of foot deformity at the midfoot, including performing an x-ray of the foot with a load in direct projection, determining reference lines and angles of the midfoot from it, the totality of which determines the degree of deformation of the foot, characterized in that the radiograph of the foot performed in a direct projection, point “a” corresponding to the medial edge of the Shoparov joint is put, and point “b” corresponding to the lateral edge of the Shoparov joint is drawn through the points “ a ”and“ b ”line 1, in the middle of which mark point“ c ”and from it draw line 2 at an angle of 89 ° to line 1, then draw line 3 corresponding to the mechanical axis of the 2nd metatarsal bone, while the point of intersection of the lines 2 and 3 is the peak of deformation of the middle part of the foot, and after performing a virtual osteotomy, the distal bone fragment is moved so that lines 2 and 3 are aligned.

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