Curvature angle

losblancos3

New member
Joined
Jan 19, 2021
Messages
3
Hi all,

I am trying to figure out an accurate way of determining the angle of curvature for a bone. Wondering if any of you could provide some advice on how to achieve it. I was following Feduccia (1993) example (see attached). Any help would be greatly appreciated!

Feduccia 1993 claw curvature.pngVentral acetabular expansion and ilial shaft VSA.png
 
I don't think "angle of curvature" is a proper mathematical term; searching for it, it appears to just mean the change in direction from one end to the other, commonly measured in terms of the angle between perpendiculars. What they are doing here is using two chords (of what you are assuming to be a circle) to find the center of that (approximate) circle, and measuring the angle at the center.

But the key idea in such a measurement would be to decide what to consider the two ends, which I suppose is a practical matter of agreement among people in that field, and not something for math to decide.

In your first illustration, they seem to have chosen a point that is beyond the claw proper, and in the second, they arbitrarily chose not to go further. "Accuracy" is in the mind of the definer.
 
I am trying to figure out an accurate way of determining the angle of curvature for a bone.

define "curvature"? do you mean 'K' curvature?

I would fit a quadratic polynomial like x^2 +x + c and then find the curvature of the polynomial at a given t.
The curvature is defined as

1611268409602.png

but curvature can mean many things so please define what you are trying to do.
 
Last edited:
Top