You may have heard this one before: 50 percent of all normal and asymptomatic adults have at least one herniated disc (sometimes referred to as a slipped disc.) However, unlike many other buzzy medical “factoids,” this one is more myth than truth.

In 1984, a paper was published in Spine, a biweekly peer-reviewed medical journal that covers the research field of orthopedics. In the paper, it noted that in the over-40 age group, more than half of the MRI scans of people who had no complaints of back pain were “abnormal.”

Over time, this statistic took on a different meaning, getting interpreted and reinterpreted to mean “50 percent of all normal people have a disc bulge or disc herniation.” However, this interpretation is quite a stretch of the facts.

The original authors of this paper described “abnormalities” in a very broad sense, including frequently benign findings such as facet arthrosis and spondylosis under the umbrella of abnormal.

In fact, disc herniations were found in only 19 percent of the over 40 age group.This statistic was in line with other reports of asymptomatic disc bulge/herniation.

It is also important to keep in mind that there is another common medical/legal misconception that the presence of spinal degeneration is generally always 1) abnormal, 2) likely to be painful, and 3) the likely source of the patient’s pain—as opposed to a claimed injury. In reality, degeneration is such a common finding that is it generally considered a normal part of the aging process, and it correlates very poorly with pain or disability.