Regarding articulation, it is true that the femur would be mostly disarticulated. Cracraft (1971) however indicated that in retraction, if the facies articularis antitrochanterica of the femur disarticulates from the antitrochanter, it can be abducted a maximum of 35° in pigeons.
Well... I haven't read the paper yet, but in their 2008 SVP talk and in the NOVA episode, Burnham et al. showed 90°.