The number one question we get as physical therapists is some version of: “Don’t I need an MRI to know what’s wrong?” It makes sense. Being in pain is hard enough, but not knowing why can feel even worse. So let’s take a real look at what an MRI actually shows us.
MRIs are excellent at doing exactly what they’re designed to do: finding every defect and abnormality in tissue. That sounds like a good thing, but research on what those abnormalities actually mean tells a more complicated story.
What research on “normal” spines shows
In one well-known set of findings, researchers scanned people with no back pain at all, and found evidence of degenerative disc disease in 37% of people in their 20s, 52% in their 30s, 68% in their 40s, and 88% by their 60s. All of these people were healthy, with no history of back pain.
They found something similar with bulging discs: present in 30% of people in their 20s, 40% in their 30s, 50% in their 40s, and 77% by their 60s, again, in people with zero pain.
The conclusion: bulging discs and degenerative disc disease are largely just normal signs of aging, more like wrinkles or gray hair on the inside. They don’t necessarily mean something is wrong or needs to be surgically fixed.
Why an early MRI can backfire
When people are told an MRI shows their spine is “broken” or fragile, it changes how they see themselves, and how they move. They start moving stiffer, cutting back on activity, and self-limiting. That self-restriction leads to more stiffness and weakness, which can make back pain worse, not because of what the MRI found, but because of how it changed their behavior.
Research has also looked at cost: people who get an MRI before starting physical therapy tend to see meaningfully higher total costs of care. And areas with a higher concentration of MRI machines correlate with higher rates of back surgery, without better outcomes to show for it.
When an MRI actually makes sense
There are a few situations where getting an MRI sooner rather than later is genuinely the right call:
- Significant trauma or injury to the spine, like a severe car accident, fall, or blunt force
- Progressive muscle weakness
- Any change in bowel or bladder function
- Unrelenting pain, especially pain that’s worse at night or isn’t improving with good physical therapy
If you’re not sure whether your situation fits one of these, a physical therapist can usually tell you fairly quickly whether an MRI makes sense right now or whether it’s worth holding off. If your physician has told you to wait on imaging, it’s often because they understand that jumping straight to an MRI can raise your risk of ending up in surgery, along with the cost of your care.