Odd body deformation

Any idea why this model deforms horribly when the lower body is rotated left?

Thanks for looking.

Looks like a B-bone problem, sometimes that comes up if the bones on both sides of the B-bone aren’t rolled to face the same way. If you change the armature to B-bone view, you might see that the trouble bone is twisted when the armature is in the rest position. If that’s what’s up, an easy fix is to select the problem bone and both the bones on either side, and use ctrl-N and pick an axis to align them all with.

Thanks for the reply Captain.
I’m not using B-Bones on the rig. I can’t explain it, but the model isn’t doing this after reloading the file.

Oh! I didn’t realize the waist was several different bones, I assumed it was one bone with subdivisions. Well, if it appears to be fixed I suppose that’s good news!