Nice reply Jerry.

Also useful to read Peter O'Sullivan's "clinical Instability" model of Low back pain with respect to flexion/lateral shift pattern of pain. Bascially it is a mal-adaptibe behaviour that feeds into the pattern of instability and causes the problem to become chronic.

I was always taught that a list to the ipsi side was protection of the disc (shortening), a list to the contra side was protection of the joint (locking it open) and an alternating list was an unstable disc lesion. I think this still holds up in general but I am willing to be shown why this may not be so.