Discomfort or pain experienced in the lower back is incredibly common, with there being several different potential causes that all have similarities in symptoms. Sacroiliitis is less commonly diagnosed due to this fact but ends up being the cause of anywhere from 10-25% of the cases of lower back pain. Some other conditions that are commonly mistaken for sacroiliitis or are just difficult to differentiate without proper in-depth diagnostic tools include a herniated disk in the lower back, lumbar spinal stenosis, sciatica, osteoarthritis (though this can also be a cause for sacroiliitis), stress fractures, and more.