COMPUTER BASED PARAMETRIC NAVIGATION METHOD RELATED TO CIRCULAR FIXATOR APPLICATION

Technological Background:

Computer based external fixator system is related to a method including providing to get images by a software online by using radioscopic images of fixator parameters and coordinate parameters related to bones that is need to get fixed and providing to change the position of the rings where the bones are related to and to send the obtained parameters to software which will calculate the differences between rod heights for changing the position of the bones according to treatment. Known Status of this Technique:

The "Distraction Osteogenesis" method is used for a lot of treatments applied for processes such as extremity prolongation, replacing the bone losses, fixing the curvatures called deformity and bonding the broken bones. This method was founded by Professor Gavriil Abramovich ilizarov that was born in Caucasia (Union of Soviet Socialist Republics) in 1921. Professor ilizarov made a revolution by destroying the opinion related to impossibility of the prolongation process in bones for many centuries. For this process, the bone is cut by applying surgical intervention for prolonging it gradually and new bone tissue (osteogenesis) is observed in prolongation area. The bone can be prolonged between 15 % and 100 % of the length by applying this method. Traction process is applied to bone on circles by using wires and screws in this method which is called ilizarov technique. Prolongation or shortening processes are applied by moving the circles placed on screwed rods that exist between two big circles with a specified angle. But the applications that needed to be performed are not only two processes including shortening and prolongation. The requirement for the bones moving in 3D between each other is an important characteristic for treatments about formal disorders or aligning the broken pieces of bones according to themselves. For this reason, the circles bounded on bones may move angularly and/or provide the horizontal alignment with lateral moves. A lot of mechanical auxiliary equipment such as hinges or rotating devices is required for performing these movements between two rings. In this period either planning the work that needed to be applied and ranging the processes or choosing the parts that will be used or positions require a serious effort and experience.

Although all advantages that come with ilizarov system, the troubles that we face in application prevent this technique to be used commonly and wrong planning may occasionally cause wrong or long treatment periods. For getting over these troubles and mistakes, Charles Taylor has developed Taylor Spatial Frame (TSF) (Smith & Nephew, Memphis, TN, ABD) suitable to basic ilizarov rules in 1994 with his brother who is an engineer. This system has been very successful for most of the problems faced in conventional circular external fixators. TSF is an evolved status of conventional ilizarov system by using a hexapod. The changes made in rod lengths provide circular movement that are required for positioning the bones to deserved coordinates and these length values are obtained by using a complex mathematical formula with the help of a computer program. The operator does not have to think about the form of fixator nor has experience due to combining developed Hexapod system with circular fixators. In this system, a fixator with six telescopic rods that bounds two rings to each other by using a special geometry and a computer program that will perform the calculation process are used. The system gets information about bone coordinates due to parameters measured through radioscopic image of the patient and then plans the movement between themselves for providing the recovery process. A prescription is obtained by entering different measurement values such as deformity values, sizes of rod-ring that were used and coordinate of TSF on extremity to computer program. The program prepares a prescription that describes what speed value and direction will be used by creating a hinge system virtually. After the formula in prescription was applied, a recovery is observed. The most important problem on system called TSF is calculating the required measures correctly to make the reliable calculation. Calculation may be incorrect because of too much parameter that have to be measured and the differences between the reference points while specifying the data for these processes. Otherwise, having too much parameters make learning the system and measurement period harder. In our invention, introducing parameters related to fixator, radioscopy images and also the parameters related to bone axis on radioscopic images and preventing the user to make any mistakes by returning the obtained data for verification into images visually and also confirming all processes done are all possible applications.

Description of Drawings: This invention is described in more details as described in the drawing attached hereinafter for purposes only, wherein;

Figure 1 Flow chart that shows the operating method of the invention

The drawing that will help for describing the invention has been numbered as described in the attachment and given with their names.

Description for References:

1. Creating radiography image model in coordinate plane

2. Adjusting the contrast control for radiography image

3. Rotating the radiography image

Being able to change the length and width values for radiographic image as combined and individually

5. Being able to switch radiographic image horizontally and vertically on coordinate plane

6. Specifying the axis from center (middiafizel) point of the bone

7. Being able to calculate the coordinates of the center by a software after choosing two outer point on the bone

8. Specifying the coordinates of the center by a guideline

9. Modeling the recovery steps calculated by the software and displaying it in animated style on radiographic image. Description of the Invention:

This invention is related to a Computer Based External Circular Fixator Application that provides getting the radioscopic images of parameters about fixator and bone parameters that is wanted to be recovered, calculating the required rod length values for coordinates on which the rings placed on by a calculating software and a computer based external circular fixator application that provides the bones to form into deserved shape

In our invention, introducing parameters related to fixator, radioscopy images and also the parameters related to bone axis on radioscopic images and preventing the user to make any mistakes by returning the obtained data for verification into images visually and also confirming all processes done are all possible applications.

Specifying the coordinates of bone axis after taking the images for radioscopic process and relating them with the position of the fixator is highly important. In this step, axis coordinates of the bone pieces and coordinates of fixator's position are specified by graphic interface due to user's choice and the relations between these two coordinate groups is provided by using a calculating software. Process steps are respectively:

^• Introducing the images taken from front-back and side of the bone and placing (1) the fixator to coordinate plane by template image made by software

^• During this recovery process, to match the radioscopic image with the template there are switching buttons for;

a. The length and width of the radioscopic image (4),

b. Image opacity (2),

c. Rotating (3),

d. Switching on vertical and horizontal planes (5)

And it is possible to make all adjustments with these buttons.

For recovery process you need to choose one of the two different bones mentioned below;

^• For top (proximal) bone over Ostheotomy/broken line;

a. Distal (bottom) edge near to Ostheotomy/broken line,

b. Proximal (top) edge placed on a coordinate far enough to specify the direction, · For bottom (distal) bone over Ostheotomy/broken line;

c. Proximal (top) edge near to Ostheotomy/broken line,

d. Distal (bottom) edge placed on a coordinate far enough to specify the direction, The center (middiafizel) of the bone must be chosen for this process. Coordinates of the points are obtained due to these choices and they are transferred to calculating software as a parameter.

There are two separate methods for finding the center (middiafizel) of the bone to find (6) bone axis. Sometimes it is not easy to find the center point because of placement of the bone behind the fixator image and the problem which is occurred by asymmetrical image towards two directions. We can classify the methods that are used as described below;

a. Choosing the coordinate of the center point on the bone with specifying by the user (7),

b. Calculating the coordinate by software after choosing the two outer points of the bone (8).

Drawing the lines that specify the bone axis shorter and not able to see the difference because of short lines may cause serious problems on recovery planning so modeling the recovery steps that was calculated by software and displaying (9) it in animated style on radiographic image make it possible to compare axis line and bone axis.