Last updated on July 6 2022
Description
Roof arc concept started with Matta (1986). It helps to determine the amount of intact acetabular dome and it is a useful method to evaluate the need for surgery. It can be calculated using three different kinds of radiographic views: AP, obturator and iliac oblique views.
The Roof Arc procedure helps to identify fracture stability. The angle is measured between the femoral vertical line parallel to Perkin’s line that crosses the center of the femoral head and a line from the fracture to the center of the femoral head.
Measurements
The measurement made by the procedure is displayed in the image:
- Roof Arc Angle (RAA): angle between the femoral vertical line and the fracture line.
Auxiliary references
To show this procedure, PeekMed® needs additional references:
- Hilgenreiner’s line: a horizontal line through the teardrops (or triradiate cartilage in children) of the acetabulum;
- Femoral vertical line: a perpendicular line to Hilgenreiner’s line that crosses the center of the femoral head;
- Fracture line: a line from the fracture to the center of the femoral head.
How to perform
After selecting this procedure in the sidebar, as well as, the side where you will perform the procedure, you must mark the points to conclude it. To see the caption of each point you need to click on this button 
Beware: you can change the position of the points at this stage or later. To do this, simply click on each handle with the left mouse button and move them to the most suitable position.
This procedure has no advanced configuration.