Strong bones matter for your spine. Weak bones from osteoporosis can lead to painful compression fractures, and they can affect how well screws and implants hold after spine surgery. A DEXA scan is a quick, simple test that measures how strong your bones are.
DEXA stands for dual-energy X-ray absorptiometry. It uses two very low-dose X-ray beams to measure the mineral content, or density, of your bones, usually in the lower spine and hips. You simply lie on an open, padded table while a scanning arm passes over you. DEXA is the standard test doctors use to diagnose osteoporosis and low bone density, and it is also how bone strength is tracked over time.
Bone density screening guidelines generally recommend a DEXA scan for:
Other risk factors include low body weight, smoking, heavy alcohol use, a family history of hip fracture, early menopause, and conditions such as rheumatoid arthritis or an overactive thyroid or parathyroid.
Spine patients are a special group. Dr. Grunch also checks bone density when it will help plan treatment, such as after a compression fracture or before spine surgery, even if you are younger than the usual screening ages.
A DEXA scan gives you a T-score, which compares your bone density to that of a healthy young adult:
Dr. Grunch orders a DEXA scan:
If your bones are weak, treating osteoporosis before or after surgery can improve your results. Note: arthritis and old fractures in the spine can make the spine score look better than it really is, so Dr. Grunch also looks at the hip scores.
Your report lists several numbers. Here is what the most important ones mean:
Why the hip matters so much for spine patients. Arthritis, bone spurs, calcium deposits in nearby blood vessels and old fractures all add density in the spine without adding real strength, which can make your spine score look better than it truly is. If you have had a spinal fusion, the fused vertebrae are generally left out of the measurement. For these reasons, Dr. Grunch looks closely at your hip scores, and sometimes at bone density clues on your CT scan, instead of relying on the spine number alone.
A score is not the whole story. Having low bone density does not automatically mean you will break a bone. A broken spine or hip bone from a minor fall generally points to osteoporosis even when the T-score is not below -2.5. Doctors often combine your T-score with a calculator called FRAX, which uses your age, sex, weight, past fractures, medicines and other risk factors to estimate your chance of a hip or other major osteoporosis-related fracture over the next 10 years. Some scanners also offer a trabecular bone score (TBS), an add-on that estimates the quality of the bone’s inner structure from the same spine image.
Spine surgery often depends on strong bone. Screws and implants need healthy bone to grip, and a fusion needs good bone to grow together. Weak bone is a recognized risk factor for screws loosening, a fusion that is slow to heal, and fractures in the bones next to a fusion. Studies do not agree on exactly how large these risks are for every patient, which is why your whole situation is considered and not just one number.
When a DEXA scan shows weak bone, Dr. Grunch may:
Bone quality also matters for motion-preserving surgery such as disc replacement, because the implant sits against the vertebrae. Very weak bone can make a fusion or other approach a better fit than a disc replacement. Before surgery, you will meet with Dr. Grunch or one of her physician assistants to review your scan results and talk through the plan that fits you.
You lie on your back on a padded table, usually with your legs resting on a cushioned box. The scanner arm passes slowly over your lower spine and then your hip. You need to hold still, but there is nothing to feel. The test takes about 10 to 20 minutes.
There are no restrictions afterward. Your results will be reviewed with you. The report is usually sent to Dr. Grunch’s office by the imaging center, so ask the center how long it takes to be finalized.
If your bone density is normal, no special treatment is needed. If it is low, see the section below on what comes next.
A low result is common, and it is treatable. Dr. Grunch may recommend one or more of the following, often together with your primary care doctor or a bone health specialist:
If you already have a painful compression fracture, see compression fractures and kyphoplasty.
There is no single schedule. Most people do not need a repeat DEXA scan sooner than about two years, and people with normal results may wait much longer. Your doctor may repeat it sooner if you have had a fracture, started a medicine that thins bones, or have another reason for fast bone loss. For people on osteoporosis medicine, repeat scans are usually spaced out too, and are most helpful when the result could change your care.
A DEXA scan is one of the safest imaging tests. The radiation dose is very low, much lower than a standard chest X-ray.
Weak bones raise the risk of compression fractures and can affect how well screws hold and bones fuse after spine surgery. Knowing your bone density helps Dr. Grunch plan safer surgery and prevent future fractures.
It compares your bone density to that of a healthy young adult. A T-score of -2.5 or lower means osteoporosis.
Yes. Skip calcium supplements, including multivitamins and calcium antacids, for 24 hours before the test.
Guidelines generally recommend one for women 65 and older, men 70 and older, and younger adults with risk factors such as a past fracture, long-term steroid use or a condition that causes bone loss. Dr. Grunch may also order one before spine surgery or after a compression fracture.
Yes. Arthritis, bone spurs and old fractures can make the spine score look higher than the true bone strength, and fused vertebrae are generally left out of the measurement. That is why Dr. Grunch also looks at your hip scores.
No. It means the plan needs to account for your bone quality. Dr. Grunch may adjust the operation, treat your osteoporosis before or after surgery, or recommend a different procedure. Weak bone can make some options, such as disc replacement, less suitable.
It varies. Many people do not need a repeat scan sooner than about two years. Your doctor decides based on your results, risk factors and treatment, and a repeat is most useful when it could change your care. Use the same imaging center when possible.
No. A DEXA scan measures bone density using very low-dose X-rays. A bone scan uses a small amount of radioactive tracer injected into a vein to find areas of active bone change, such as a fracture, infection or tumor. See the page on bone scans for details.
If Dr. Grunch has ordered a DEXA scan for you and you have questions, call 470-293-9800 or contact us. You can also ask general questions any time through our “Ask Us Anything” chat. For questions about scheduling, cost or arrival time for the test itself, call the imaging center where it is booked.
Related: All imaging and diagnostic tests · Compression fractures · Kyphoplasty
This information is for educational purposes only and is not medical advice. It does not replace individualized care from a licensed physician. Please talk to your provider about your symptoms and follow the instructions from your imaging center.
