I'm trying to use pin bones for an arm rig, for the sake of positioning them better and being able to do perspective better, and I'm attempting to follow along with various tutorials I've seen by veteran animators such as MoeU33 and Poptoogi, but there's a complication that none of the videos I've watched have actually addressed: all of the tutorials I've watched use characters with arms that are perfectly straight, whereas my character's arms - both her forearm and upper arm - have points in the middle to add more detail to the shape so she doesn't just look like a stick figure. You can see what I mean here:

The specific issue is that even after following the tutorials to the letter, her arms balloon/warp out if the bones go too far back, which the following image demonstrates:

Is this just a limitation of the technique and/or software, or is there something specific I need to be doing?