Can Spinal Arthritis Falsely Raise Your DXA T-Score?

Yes, spinal osteoarthritis and other age-related changes can make your bone density scan look better than it actually is. It is a common situation for conditions like arthritis in the lower back to create falsely high results on a DXA scan, which can sometimes mask underlying osteoporosis.

Discovering you might have osteoporosis can be worrying, and confusing test results do not help. Understanding how DXA scans work can empower you to ask the right questions about your bone health and your scan report.

What is a T-Score?

A DXA scan estimates your bone mineral density and reports it as a T-score. This number compares your bone density to the average bone density of a healthy young adult. In general, a normal T-score is -1.0 or higher, low bone mass (osteopenia) is between -1.0 and -2.5, and osteoporosis is -2.5 or lower. However, when extra bone or calcification is present in the scanned area, this score can become artificially inflated, making the bones look denser than they truly are ^{[1] [2]}.

How Arthritis and Artifacts Interfere with the Measurement

When you get a DXA scan, the machine takes a two-dimensional picture to estimate how much mineral is in your bones. The machine cannot easily tell the difference between healthy, strong bone and extra, irregular bone or calcifications that form due to other conditions.

As we age, it is common to develop wear-and-tear arthritis (osteoarthritis or degenerative spondylosis) in the spine. This often causes the body to grow osteophytes, commonly known as bone spurs. Because the DXA scan measures all the X-ray-blocking material in its path, these dense bone spurs are added to your total measurement ^[1].

As a result, your spine’s T-score can be artificially raised ^[2]. In some cases, a normal-looking DXA T-score in the lower spine does not rule out osteoporosis and might underestimate your real risk for fractures ^[3].

Other conditions can also cause this diagnostic pitfall, including:

• Scoliosis (a sideways curvature of the spine) or positioning problems during the scan ^{[2] [1]}.
• Vascular calcification (calcium buildup in the large blood vessels near the spine) ^[1].
• Previous spinal compression fractures. Important note: While a collapsed vertebra (spinal bone) adds dense, compressed material that artificially inflates the reading ^[1], a fragility fracture is itself a major sign of osteoporosis. You should not disregard sudden back pain, loss of height, or pain after a minor fall just because your scan looks “normal.”

Why Doctors Look at Multiple Areas

Because degenerative changes in the spine are so common, spine-hip discordance—where the spine score looks normal or high, but the hip score shows osteoporosis—is a frequent finding as people age ^{[4] [5]}.

This discordance can sometimes just be a natural difference in your skeleton, but often it means the spine measurement is compromised ^[1]. Because of this, doctors do not rely on just one area. The total hip or the femoral neck (the top of the thigh bone) are usually less affected by the specific bone spurs that form in the spine, making them a very useful standard for diagnosis ^[6]. The hip can, however, be affected by its own arthritis, positioning problems, or surgical hardware. If neither the spine nor the hips can be interpreted accurately, doctors may look at the 1/3 radius (a specific measurement in the forearm).

Getting an Accurate Picture

If your doctor suspects that your spine T-score is affected by arthritis or artifacts, they will not just rely on a single number. They can take several steps to ensure your bone health is accurately assessed:

• Review the images: The clinician can look at the DXA images to identify bone spurs or fractures. They will often exclude specific vertebrae from the final score calculation if those bones are clearly distorted by an artifact (something that interferes with the measurement) ^{[1] [2]}.
• Rely on valid sites and overall risk: Your care team will determine which scan sites are actually valid for diagnosis, because measurements across different skeletal sites are not always interchangeable ^[7]. Treatment decisions are based on your lowest valid T-score along with your age, medical history, medications, and any previous fragility fractures.
• Consider other tests: In cases of advanced degenerative changes where the DXA is completely uninterpretable, a doctor might suggest Quantitative Computed Tomography (QCT) ^{[8] [9]}. QCT takes a 3D image and measures the inner spongy bone separately from the outer bone spurs. However, QCT has different diagnostic thresholds, does not directly measure bone strength, involves more radiation and cost, and is not required for most patients.