Neutral zone is also described as loose pack position. That position in which the capsule andligaments are the freeest in all direction, the position in which motion in all directions is freeest which includes accessory and traditional motions. In the hip and the SI the loos-pack position is with hip in about 30 degree flexion and abduction and slight external rotation (approximate figures from memory). The opposite to loose pack is closed pack in which ligaments and capsule are tightest and motion in any direction has greatest restricition.
Jerry Hesch, MHS, PT