Used to determine whether the sacrum has developed a flexion or extension dysfunction​

Have patient lie prone and find the lumbosacral junction. Find L4 at the level of the iliac crests. Move down to just past L5 but remain cephalad to sacral base – this is the lumbosacral junction (BETWEEN the lumbar and sacral vertebrae) 

Place the heel of your hand on the lumbosacral junction and firmly push down towards the table and release. Repeat one or two times to appreciate the effect

If you feel rebound/springing, the spring test is NEGATIVE.

With a negative spring test, it means that you are diagnosing a flexed sacrum (right on right OR left on left)

If you feel no give at all (like you’re pushing into a wall) or if the patient experiences increased pain, the spring test is POSITIVE.

With a positive spring test, it means that you are diagnosing a extended sacrum (right on left OR left on right) 

A good mnemonic: Nice Normal Negative vs. Painful Positive Posterior