If someone has a wide, flat back, tests with a lot of hip internal rotation and limited external rotation, I would look ABOVE the pelvis. The entire pelvis is likely oriented forward, making it normal to have increased flexion, adduction, and internal rotation in the hips. Here’s another video where we talk about the different types of anterior pelvic tilt. [link]
If the axial skeleton is in an exhaled position, then the rib cage might adopt a wide shape to relieve some of the pressure. Think flat back position: lumbar flexion, thoracic extension, cervical flexion. Consider all of the concentric muscle activity in front of and above the pelvis. Also, look hard at the posterior upper thorax.
This happens a lot and it doesn’t fit a normal presentation, so it can be confusing.