I was experimenting with the pose you have in the full body shot on the previous page and determined that it is likely due to how you have the hip positioned, that is causing so much distortion at the thigh. Rotating the hip on the -X axis a bit (about 10 degrees) helps to remove that distortion, at least with M4 in his default shape, as it requires less bending of the thigh to get to the sitting pose and keeps the pelvis in a more natural position (i think). But this might depend on whether or not you have done any custom sculpting on the body or if you're just using the morphs++ (or one of the other stock daz morph sets).

Apologies for the crappy lighting.