MRI is a magnificent machine and, for back pain, a frequent mistake. Patients arrive at our clinic carrying scans that show bulging discs and "degeneration", frightened by words that describe normal ageing, and sometimes already booked for operations their spine never needed. The scan is rarely wrong. The way it gets used is.
The Role of MRI in Modern Medicine
Unlike X-rays or CT scans, MRI uses powerful magnets and radio waves to create detailed images without exposing patients to ionising radiation. This makes it especially valuable for soft tissue conditions. In low back pain, it can reveal disc herniations, spinal stenosis, degenerative disc disease, spondylolisthesis and facet joint arthritis. The detail is the point, and the detail is also the problem: the sharper the picture, the easier it is to find something to blame.
Patients love MRIs for the same reason clinicians order them too readily: the promise of a definitive answer to "what is causing my pain?" But that promise quietly shifts the job from examining the patient to reading the picture, and pictures are very good at showing things that do not matter.
Red Flags Come First
There is one thing imaging must never skip: the clinical check for red flags first, the small set of warning signs that point to serious underlying conditions. In low back pain, those are:
- Unexplained weight loss: may suggest malignancy or systemic disease
- Severe or progressive neurological deficits: possible spinal cord compression or cauda equina syndrome
- History of cancer: raises suspicion for metastatic disease
- Recent significant trauma: increases likelihood of fracture
- Prolonged steroid or immunosuppressant use: associated with infection risk and fractures
When red flags are present, advanced imaging is warranted. When they are absent, most acute low back pain is self-limiting and responds well to conservative treatment. Yet imaging is frequently ordered anyway.
Clinical Guidelines Are Clear
The American College of Physicians (ACP) and the American Academy of Family Physicians (AAFP) both recommend against routine imaging for low back pain without red flags. Their guidelines recommend starting with history, physical examination, and conservative management, reconsidering imaging only if symptoms persist beyond 4–6 weeks without improvement.
The Pitfall: "Normal Abnormalities"
One of the most significant problems with MRI overuse is the detection of findings that are common in people with no symptoms at all. Research shows:
- Up to 76% of asymptomatic individuals aged 20–80 show some form of disc bulge or herniation on MRI
- Nearly 90% of people over 60 have some degree of disc degeneration, even if pain-free
- Spinal stenosis and facet joint arthritis are common ageing findings that do not necessarily correlate with pain
Without careful correlation with clinical history and examination, these incidental findings get attributed to the patient's symptoms, leading to overdiagnosis and overtreatment.
The Psychological Impact: "Scanxiety"
Beyond the clinical harm, there is the psychological kind. Abnormalities on a scan can trigger what some call "scanxiety": heightened anxiety, a fixation on structural "damage", and a belief that surgery is the only way out. In reality, many of these findings are benign and have nothing to do with the patient's actual pain.
The Domino Effect Toward Unnecessary Surgery
This is how a harmless finding becomes an operation. The scan creates urgency, urgency drives a specialist referral, the referral drives a surgical recommendation, and the patient ends up under anaesthesia for something that was never the source of their pain. All the risks of surgery, and no guarantee of relief.
What to Do Instead
The alternative is not complicated: a proper clinical examination first, to screen for red flags. If none are present, conservative care comes first: education, physiotherapy, activity modification and appropriate analgesia. Imaging is reserved for cases that do not respond, or where suspicion of serious pathology is genuinely high.
"Image what you cannot examine. Examine what you cannot image."
Patients and clinicians both have to hold the line here. The machine is not the enemy; reaching for it first is.