I've seen jump work sometimes on interrupting a knock back, generally I use spineshatter or elusive though. Basically as soon as your character starts to move you'll want to use a jump. If you use it too early you'll still end up being knocked back. I find elusive and spineshatter far more reliable, plus jump deals more potency than spine so I try not to use it for odd purposes like that. Either elusive sits there not being used, or I use it.