EBRAGRAF – User InstructionsEBRAGRAF – User Instructions

Peter Mayrhofer, April 2001, rev. February 2006

Dept.of Engineering Mathematics,

Geometry and Computer Science

University of Innsbruck, Austria

EBRA-CUP measurement program

Datafile *.dat EBRAGRAF graphics program

One patient‘s x-ray series

DATAFLOW

Display of patient‘s data

Select time limit (in months) up to which serial radiographs are compared

Scale ordinate of diagramsSelect DAT-file

Dual comparability checks rotations around x- AND y-axis (will exclude more x-rays!). Map shows comparisons

EBRAGRAF Main Window

SIMUL-Graphics is a way-oriented display of migration showing a variable cup-symbol (not in scale!) moving according to x- & y-directed migration and varying according to inclination & anteversion of the cup.

Select comparability limit (in mm) up to which comparable x-rays may differ

Angular values in degrees

1°

Ascending curve = cranial migration

1 year1mm

1mm

Wear-x

Wear-y

Descending curve = medial migration

1mm

cup

head

KEEP IN MIND !KEEP IN MIND !

EBRA-Migration < 1mm is not significant.

EBRA - Wear CalculationEBRA - Wear Calculation

Wear is NOT computed as the difference between head- and cup-migration!

EBRA uses the projections of head- and cup-center in the film plane to analyse wear according to the method of Scheier/Sandel.Scheier, H. ans Sandel, J. (1976): Wear affecting the plastic cup in metal plastic endoprostheses, in Total Hip Prostheses (edited by Gschwend, N.G. and Debrunner, H.U.), pp. 186-190. Huber, Bern.

This way of wear calculation proved to be more accurate in comparison to RSA.

EBRA - Results in TableEBRA - Results in Table

Switch for cup-symbol in SIMUL-Graphics

Export data to EXCELL

Dots mark excluded x-rays

Flag (0/1) for continuity of diagram Flag = 1 means interrupted curve!

Absolute values for angles

Relative values for migration

NOTICE !NOTICE !

In case of bad comparability EBRAGRAF - migration diagrams may be disconnected, i.e. may have gaps or be cut off at the beginning or the end.

Such diagrams (usual percentage =12% with comparability limit=3mm) could become continuous again if new x-rays are added to the series.

There are x-ray series even NOT EVALUABLE by EBRA because of too bad comparability! Especially if the number of x-rays per series is near the required minimum of 4.

Disconnected DiagramDisconnected Diagram

Gap will close with either higher comp. limit or addition of new comparable radiographs.

Symbol will be rotated according to inclination and anteversion

Set scale and origin position in main window

1mm

Use buttons below to get tables

Cup symbol may be switched off in Main Window or selectively in Tables Window Head-migration:

continuous line, cup-migration: dashed line

A utility for A utility for visualization visualization of migration of migration

patternpattern

Vector oriented migration diagramVector oriented migration diagram

Assessing the quality of a seriesAssessing the quality of a series

not comparable

x-comparability y-comparability

comparable

The smoother the graph the better the series!

WARNING !WARNING !

The DAT-file produced by the EBRA-CUP measurement program must not contain double data records for reanalysed x-rays.

If any x-ray measurement is to be repeated after having saved this x-ray to the DAT-file, the corresponding data record has to be deleted manually from the DAT-file!

Data record for one x-ray in datafile *.dat

Interpretation of diagramsInterpretation of diagrams

Reliable EBRA-results depend mainly on precise landmark setting with the EBRA-CUP measurement program.

But also a correct reading of the EBRAGRAF output is very important.

The following examples should help you to avoid frequently made mistakes.

Example 1

No significant migration of head and cup!

Measured migration within the inaccuracy of the method - The implant seems to be stable.

2,5° change of anteversion

0,7mm lateralisation of head

Example 2

Comparability map showing the number of comparisons per interval of time

1mm medialisation of head and cup

Rotation of cup

Results not unusual!

Example 3

MISTAKE: The series was measured twice, but the data records were written to the same DAT-file!

In case of reinput chose a different file name for saving or delete the old data records manually.