Hello Elizabeth!
This one has me stumped a little bit too. I tried looking up the reference in the Campbell text (Basciani 1995) but I was not able to get the full PDF. Campbell uses the terminology “habitually positioned away from the involved arm” which makes me wonder if they mean flexed away or turned away. The APTA clinical summary is a little more clear in stating that the child will tilt towards the side of the injury. The APTA information’s reference is from 2006 but the information referenced within that reference is from 1984…ugh! Other search results didn’t help me clarify this topic any further. My best guess would be that the child would likely develop a tilt in the direction of the BPI, like the APTA states, with the head turning away from the injury (similar to what you might expect from a child with hemiplegia). Sorry I’m not able to clarify this any further for you, but hopefully this reasoning will help a little bit!
Jessica