Dynamic stabilization exercises including those that activate glut max are the gold standard. In most cases the Si is hyper mobile from genetics or pregnancy, rarely unstable from trauma. This is common in gymnasts and dancers but with balnced exercise
they are able to function at a high level.

Consideration must also be given to avoiding end range positions.

If this approach fails prolotherapy should be considered but all the same principles apply re exercise and education in conjunction with prolotherapy and it is not a quick fix. It frequently requires a series of injections over several months and if people are
deconditioned it will be a very slow process of recovery.

Diane Lee and LJ Lee have an excellent book that includes many exercise ideas and is available through Diane Lee's website. Be patient.