Your expectations during a doctor’s visit are clear — you want to know what’s wrong and how to fix it. Each year in the USA, about 31 million patients visit a doctor for lower back pain.

“Diagnosis is extremely hard, there are 10,000 diseases and only 200 to 300 symptoms.” 

 — Mark L. Graber, founder of the Society to Improve Diagnosis in Medicine.

But according to a John Hopkins Hospital study, chronic pain is misdiagnosed 40–80% of the time. Many claim that the main reasons for this are:

  • Doctors not spending enough time with their patients.
  • Ordering the wrong tests and therefore missing key information.

There are limits to imaging tests such as X-rays and MRIs. They can capture images of structures inside the body. What they can’t capture is an image of the pain.

1. Sacroiliac (SI) Joint Pain

The sacroiliac joint (or SI joint) is the cause of low back pain 14-22% of the time, according to recent studies.

The SI joint is the pelvic joint that connects the lower spine and the pelvis. 

  • The sacrum. Five vertebrae below the lumbar spine (lower back). They are fused together and function as a single bone.
  • The ilia. The pair of large, broad “hip bones” on each side of the pelvis.

In the early part of the 20th Century, doctors looked to the SI joint as the source of low back pain.

But in 1934, Dr. William Jason Mixter and Dr. Joseph S. Barr published findings that one or more lumbar discs are often the source of pain. Since then, doctors have regarded the lumbar spine as the chief suspect for lower back pain.

A study finds that in half of failed lumbar fusion surgeries, the SI joint was the real source of pain.

Testing For SI Joint Pain

SI joint pain is a common symptom that could indicate many medical conditions. That’s why doctors use a variety of different tests to identify the root of the pain. 

Manual Tests

  • FABER test. Lying on your back, cross the leg of the painful side over the knee of the other leg. Your legs will form the shape of the number “4.” The doctor or specialist will press down on the crossing leg’s knee and pelvis on the opposite side at the same time. If it brings on pain, it’s likely the SI joint is the source. This is also called Patrick’s test.
  • Gaenslen’s test. Lie face up. Let one leg dangle off the side of the exam table. The doctor presses on this leg and bends the other knee toward your chest. Again, if it elicits pain, it’s a problem in the SI joint.
  • Cranial shear test. While you’re lying on your stomach on the exam table, the doctor presses on your coccyx (tailbone), checking for pain.
  • Sacroiliac shear test. Similar to the cranial shear test. The doctor presses down on the tailbone, looking for movement.
  • Pelvic compression test. Lie down on your side. The doctor presses down on your hip.
  • Pelvic distraction test. Lie on your back while the doctor presses both sides of your pelvis.
  • Thigh thrust test. You lie face up on the table. With one hand under your buttock, the doctor raises your leg to a 90-degree angle, knee bent.

Imaging Tests

  • X-ray. The doctor can look for changes in the low back and pelvis.
  • Computerized tomography (CT) Scan. A more powerful x-ray that shows more details.
  • Magnetic resonance imaging (MRI). With the aid of a computer, powerful magnets and radio waves show images of the structures inside your body.

Injection Test

The specialist injects a cortisone steroid into the SI joint. If it eases the pain, the SI joint is the source.

There are some risks with the SI joint injection test, such as infection and nerve trauma. About 24% of patients temporarily feel an increase in pain afterward.

Serious complications are rare, but most doctors won’t order an injection test unless the others are inconclusive.

2. Lumbar Disc Herniation

Between each vertebrae lies a flat, round disc. Each disc is about ½ inch thick and has a gelatin-like center. These discs act as cushions for the spine’s joints.

But sometimes, the discs become herniated. A herniated disc means that it has formed a bulge that extends outside of the spinal joint. 

Herniated discs don’t always cause back pain. A lot of people have herniated discs and don’t know it. But sometimes the bulge presses against spinal nerves causing severe pain.

Even if imaging tests reveal a damaged disc, it might not be the pain source. Other conditions have similar symptoms and it’s important to rule them out.

3. Piriformis Syndrome

The muscle that connects the lower spine to the upper part of the leg is called the piriformis. It travels through the sciatic notch, an opening in the pelvis which lets the sciatic nerve travel to the leg.

When the muscle presses the sciatic nerve against the pelvic bone, a sharp pain radiates to the lower back, buttocks, and legs.

It’s usually due to inflammation of muscles or tendons, after vigorous exercise or tasks involving heavy lifting. In such a case, it should get better in a few days.

But sometimes there are abnormal bone formations that can cause piriformis syndrome:

  • Abnormal curving of the spine (scoliosis).
  • One leg is longer than the other.
  • Bone spurs forming after an injury or hip surgery.

Gluteus Medius Muscle Pain

The gluteus medii (plural) are the muscles in the buttocks that give support to the pelvis and upper legs while walking, running or balancing on one leg. It can create lower back pain when it presses against the sciatic nerve.

Tarsal Tunnel Syndrome

The tibial nerve, branches from the sciatic nerve and runs to the ankle. It gets compressed at the ankle and sends a pain signal up the sciatic nerve.

4. Entrapment Neuropathy

Entrapment neuropathies are when peripheral nerves get compressed. That is, surrounding tissue squeezes or pinches them.

Since they branch from the sciatic nerve, they sometimes send pain signals to the lower back. Here are some entrapment neuropathies that can mimic low back pain: 

  • Superior cluneal nerve. Runs from the lower back to the hip bone.
  • Lateral femoral cutaneous nerve. Branches off from lumbar nerves and runs through the hip bone to the femur (thigh bone).
  • Common peroneal nerve. Branches from the lower thigh and runs to the knee joint.
  • Superficial peroneal nerve. Branches from the common peroneal nerve at the knee joint.

There’s a lot of misunderstanding about sciatica. It’s not a medical condition. It’s a set of symptoms that indicate sciatic nerve compression.

The sciatic nerve runs from the lower spine to the feet. When it gets pinched or squeezed by surrounding tissue (compression), it causes sharp pain that travels to the buttocks. Sciatica pain can travel to the back of the thighs and even down to the feet.

Bone degeneration in the lumbar spine is often the cause of sciatica, but not always. Sometimes bone abnormalities show up on an x-ray, but the sciatic pain is coming from somewhere else.

Sometimes when the sciatic nerve is compressed in another location, the pain travels to the lumbar spine.

By pressing the joint of the 4th and 5th vertebrae in the lumbar, the doctor can tell whether or not it’s the source of sciatic pain.

Final Thoughts

When you have low back pain that radiates, it’s not often obvious where it’s coming from. That’s why you need thorough testing to find the real source.

If you have back pain that travels to your buttocks and the backs of your legs, the professionals at Oasis can help.

Start your diagnosis with our Condition Assessment Tool.