Dear Alophysio,

Thanks very much for replying. I am a medical doctor -an endocrinologist, so not much experience of the biomechanics of the back or pelvis. I hope I haven't put too many people off by saying I am a doctor -thought it might allow people to use medical terminology more freely as I will understand it. I hope that me being a doctor doesn't put people off -allied health professionals and all that!
I hope if I can address each point you made you may be able to expand a little -I find this area very complex.

2.) The areas that I mentioned are tight, a term relayed by my physio -but may indeed be overactive. That makes better sense. However I seem to have two main problems 1.) relaxing off the left sided (contralateral back muscles ) through friction or release techniques seem to create more instability in the right Wikipedia reference-linkSIJ, and that does all sorts of things -anterior rotation/upslip/sacral torsion 2.) when I stretch my quads in prone lying I seem to get pain in the contralateral SIJ(ie if I stretch my left I get pain in my right SIJ.) Would you know why this could be?

3.) You mention that this could be myofascial/neural control problems if this alternates. Excuse my stupidity but can both of these be addressed by rehabilitation?

5.) The test they use is the stork test, where the ilium rises on the "unlocked side", with one leg lifted at 90 degrees in standing.. This seems to be my biggest frustration. It seems no matter how much core exercise/reformer training I do this occurs which creates pain and stiffness.

I guess my real question is, this has been going on for quite a while now, and is it just possible that you cannot gain motor/neural control of this after years of faulty motor patterns. or is it a case of finding the right rehabilitation? I am presuming that the fact my SIJ can "lock" after exercise is a good sign, but I can't seem to keep it there..

Any further thoughts would be appreciated. Thanks.