Sacroiliac Joint pain can often be inappropriately treated or mistaken as lower back pain. There are several conditions that simulate sacroiliac joint pain.
1. Myofascial Pain
This is a chronic pain caused by multiple trigger points and fascial constrictions. This particular condition involves the muscles and fascial areas of the back. The patient may feel knots or hardening of the muscle with weakness and tenderness. Myofascial pain syndrome and fibromyalgia may present the same clinical picture but, they are different problems. The site location is close to the SI joint and can be confused with SI joint pain.
2. Trochanteric Bursitis
Inflammation of the greater trochanter bursa. This condition causes tenderness and pain 
in the hip. Trochanteric bursitis occurs in middle aged women. The area of pain may overlap with the SI joint area of pain and can radiate close to the sacroiliac joint. The pain from this condition is sometimes severe and associated with iliotibial band syndrome. Trochanteric Bursitis is occasionally overlooked. This condition may present with arthritis of the hip and low back pain and other conditions.
3. Piriformis Syndrome
This condition occurs when the sciatic nerve is compressed by the piriformis muscle in the buttocks. Piriformis Syndrome may be associated with lower lumbar radiculopathy similar to spine pathology. It occasionally develops due to blunt trauma to the buttocks. Localized buttocks pain will increase with sitting or driving. Tenderness is commonly found in the sciatic notch.
4. Cluneal Nerve Entrapment
The superior cluneal nerve has three branches. The medial branch of this nerve is confined within a tunnel which may cause impingement of the nerve producing pain close to the SI joint.
5. Lumbosacral Disc Herniation or Bulge
The disc may move out of place (herniate) or break open (rupture) from injury or strain. Disc herniation of the lumbosacral region could involve the nerve roots, creating lower back pain. The pain is usually found in the midline and can go down the leg.
6. Lumbosacral Facet Syndrome
The facet provides stability for the spine and contain a joint. This joint may be affected by inflammations or degeneration which causes pain that can be mistaken for SI joint pain.
7. Lumbar Radiculopathy
Lumbar Radiculopathy is a major source of back pain. This condition occurs from inflammation, irritation, or impingement of the nerve root. It is commonly confused for SI joint pain.
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