Does medical imaging really help you with your aches and pains?

You are in pain and would like to have an X-ray or an MRI (magnetic resonance imaging), a test that produces detailed images of the inside of the body. You hope to understand what is causing the pain. This is a natural desire. Imaging can provide a helpful answer, but its role depends on the suspected problem and treatment decisions.

An imaging test is not always necessary to begin treatment. For low back pain, the healthcare professional’s evaluation first looks for warning signs: a major accident, fever, loss of strength or sensation, or unexplained weight loss. In the absence of these signs, routine immediate imaging generally does not improve pain or a person’s ability to perform daily activities. ¹

In a study that followed 3,369 people for six years, most lumbar changes seen on MRI were not associated with future pain intensity. Some associations were found, but they were generally weak. ² The imaging findings should therefore be interpreted in conjunction with your symptoms and the physical examination.

• Changes seen on an MRI of the back are common in people without pain. ³
• A change in the image may occur without causing any pain. ³
• The way an MRI result is explained can affect a patient’s level of concern. ⁴
• For low back pain without any concerning signs, routine immediate imaging generally does not improve treatment outcomes. ¹

This guide helps you understand when imaging is truly useful. To learn more about the relationship between what is seen and what is felt, read our article on osteoarthritis and pain.

Do imaging tests always show where it hurts?

Imaging does not always reveal the cause of pain: some changes also occur in people who are not in pain. However, an abnormality may contribute to the symptoms. Its significance depends on the overall evaluation.

When we have an injury or pain, it's in our nature to want to know the exact structure that is hurting us.

Not knowing what the problem is can be worrisome, such as when you're trying to figure out the cause of a water leak in the basement.

X-rays, ultrasounds, CT scans, and MRIs show different parts of the body. An ultrasound uses sound waves to produce images; a CT scan uses X-rays. These tests can reveal a fracture or other injury, but an image does not directly measure the pain a person feels.

For back, knee, or shoulder pain that is not the result of an accident or impact, guidelines generally advise against routine imaging at the start of treatment. The healthcare professional can often determine the appropriate initial treatment based on the interview and physical examination. ⁵ For low back pain without a specific cause, routine imaging offers no significant benefit and may lead to unnecessary interventions. ⁶

Does an imaging test change the treatment plan?

An imaging test may alter the treatment plan if its results reveal a problem that requires a different course of treatment. However, its routine use for lower back pain and certain knee problems generally provides little or no benefit in terms of pain, daily activities, satisfaction, or quality of life. ⁷ The plan is based primarily on the physical therapy evaluation and on the specific question that the imaging is intended to answer.

The decision depends on what the review can actually change. These two situations illustrate the difference:

A study examined the timing of imaging in 782 people who had already been referred to an orthopedist or neurosurgeon—doctors who, among other things, evaluate conditions that may require surgery. Overall treatment outcomes were similar whether imaging—such as an MRI or CT scan—was performed early or reserved for needs that arose later. However, the early-imaging group showed a slight improvement in certain outcomes at eight and twenty-four months. ⁸ The choice therefore also depends on the clinical situation.

An unnecessary imaging test can lead to additional tests or treatments with no expected benefit. ⁶ How the results are explained also matters. In a trial involving 44 people with back pain, one group received a factual explanation of the MRI report. The other group received a reassuring explanation presenting the results as normal changes. After six weeks, the first group had a more negative perception of their back, less improvement in pain, and more difficulty with daily activities. ⁴ This small trial suggests that results should be explained in context. It does not show that any imaging worsens back pain.

Interpretations of MRI results can also vary. In one study, a 63-year-old woman with back pain and symptoms in one leg underwent MRIs at ten different centers over a three-week period. None of the 49 distinct findings appeared in all ten reports. ⁹ This case illustrates variability among reports; it does not measure the reliability of all exams for all patients.

Three limitations help explain why a picture isn't always enough.

What are the three concepts that explain this discrepancy?

Three limitations explain this discrepancy: the image does not directly measure pain, the body changes with age, and some abnormalities exist without symptoms.

First, pain is a personal experience. A medical image does not directly show what you are feeling. The healthcare professional listens to your description and correlates it with the physical examination. ^{10, 11} Just as with sadness, one can observe symptoms without actually experiencing what the other person is going through. A normal image therefore does not invalidate your pain.

Second, the body changes with age. The discs—the cushions between the bones of the spine—and the joints can change in appearance. These changes become more common with age, even in the absence of pain. ³ Osteoarthritis refers to changes affecting the entire joint; its presence on an image does not necessarily explain the symptoms.

In a study involving 3,110 people with no history of back pain, researchers estimated the prevalence of changes by age. At age 40, the estimated prevalence of disc degeneration was 68%. This term refers, among other things, to changes in the disc’s water content and height. At age 30, the estimated prevalence of disc bulging was 40%: in this condition, the disc protrudes more significantly beyond its normal space. ³ These estimates do not mean that all changes observed in a person experiencing pain are insignificant.

Troisièmement, une anomalie peut exister sans douleur. Des personnes présentent de l’arthrose dans le bas du dos sans avoir mal. Cela n’exclut pas une contribution de l’arthrose aux symptômes chez une autre personne.³ Pour les maux de dos, la physiothérapie et l’exercice font partie des traitements qui peuvent aider à retrouver des activités plus confortables. Le service public de santé britannique (NHS) décrit ces options de traitement du mal de dos¹².

For knee osteoarthritis, a 2024 review found short-term improvements in pain and physical function with exercise. Compared to no treatment, standard care, or limited counseling, the average improvement was about 13 points out of 100 for pain and 13 for physical function. The uncertainty surrounding the averages did not allow for the conclusion that the benefits consistently exceeded the thresholds chosen for a substantial change. ¹³ These results pertain to the knee; they do not directly measure the effect of exercise on lumbar osteoarthritis.

In another study, 98 adults without back pain underwent an MRI. The researchers found bulging in 52% of the participants, protrusion in 27%, and extrusion in 1%. Protrusion and extrusion are two forms of a herniated disc, in which the disc’s contents locally extend beyond their normal space. ¹⁴ These findings do not automatically indicate the cause of pain in another person.

Les chiffres précédents concernent le bas du dos.³ Des changements à l’IRM sont aussi présents dans le cou (notre guide sur la Neck pain) de personnes sans symptômes. Une revue cervicale en confirme la présence, tout en trouvant certains changements plus fréquents chez les personnes atteintes d’une maladie de la moelle épinière, le faisceau nerveux qui relie le cerveau au corps.¹⁵ L’évaluation reste donc nécessaire.

When is medical imaging truly useful?

Medical imaging is useful when it is used to identify a specific cause or provides information that may change the course of treatment. A suspected fracture, a serious accident, a possible infection, or a decision to undergo surgery may warrant it. Progressive weakness, spreading numbness, fever, or unexplained weight loss require evaluation. ⁶ The healthcare professional determines the next steps based on these signs before selecting a treatment plan.

Le physiothérapeute recherche les éléments qui peuvent justifier une image pour déterminer le meilleur plan de traitement. Au Québec, un physiothérapeute détenant l’attestation requise peut prescrire une radiographie après une blessure des muscles, des os ou des articulations survenue depuis moins de 72 heures. Il doit être le premier professionnel à évaluer la blessure, sans consultation médicale préalable, et respecter les critères de prescription. Pour les autres examens d’imagerie, il vous dirige vers un médecin. L’interprétation des radiographies est réservée aux médecins. Ces règles sont celles de l’Ordre professionnel de la physiothérapie du Québec¹⁶.

For non-traumatic pain in the lower back, knee, and shoulder, guidelines generally recommend imaging only for suspected specific or serious problems. Imaging may also be considered if initial non-surgical treatment is ineffective and if the results are likely to change the course of treatment. ⁵ Age-related changes must be interpreted in conjunction with the symptoms. ³

Don’t delay seeing a doctor while waiting for test results. Back pain, a sensation of heat or cold, fever, chills, or general malaise are all reasons to seek urgent medical attention. Severe pain that begins suddenly, or pain that worsens rapidly, also warrants urgent care. Unexplained weight loss also requires medical attention.

Go to the emergency room if your back pain is accompanied by any of the following symptoms:

• Pain, tingling, weakness, or numbness in both legs.
• Loss of sensation around the genitals or anus.
• New difficulty urinating or leakage of urine or stool.
• Changes in genital sensation during sexual intercourse, difficulty achieving or maintaining an erection, or an inability to reach orgasm.
• Chest pain.
• Back pain began after a serious accident.

Le NHS décrit ces signes d’alerte¹².

Is a herniated disc detected on an imaging test a death sentence?

A herniated disc detected on imaging alone does not determine the severity of your pain or your functional abilities. In a study of 56 people with a lumbar herniated disc, the relative size of the herniation was not associated with leg pain or difficulties with daily activities. People with urgent nerve involvement affecting bladder or bowel function were excluded. ¹⁷

Hernias can also change over time as seen on imaging. In a Danish study, 140 herniated discs in 106 people were monitored between the ages of 41 and 49. Over an eight-year period, 65% of the hernias remained stable, 17.5% decreased in size, 12.5% increased in size, and 5% fluctuated. These changes in size do not, on their own, account for the progression of symptoms. ¹⁸ To learn more about this condition and possible treatments, visit our page on lumbar disc herniation.

To learn more

Physical therapist Alexis Gougeon hosts the podcast *Parle-moi de santé*. In Episode 27, he discusses medical imaging with physical therapist Tatiana Vukobrat and family physician René Wittmer.

Episode #27 of Parle-moi de santé (medical imaging)

• Écouter l'épisode 27 de Parle-moi de santé sur l'imagerie médicale, sur Podbean

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Nos physiothérapeutes ont défini la stratégie de recherche, le plan et le contenu clinique de cet article. Un outil d’IA a soutenu la recherche documentaire et la révision du texte pour assurer une cohérence du contenu et du style d’écriture.