Diagnosing a meniscus tear: from clinical examination to MRI

Clinical examination: the first step that imaging cannot replace

Before any imaging, a clinical examination of the knee is essential. The doctor or surgeon evaluates several factors: pain upon palpation of the joint line (near the affected meniscus), the presence of an effusion (swollen knee), the range of flexion-extension, and the response to standardized rotation tests. These tests, including the McMurray test, trigger characteristic pain or clicking when a meniscus tear is involved.

Patient history is equally decisive. The knee surgeon gathers the context in which symptoms appeared: was there a trauma or an identifiable twist? Is the pain mechanical (worsened by exertion, relieved by rest)? What is the patient's athletic activity, profession, and history of joint issues? This information directly influences the interpretation of the subsequent imaging tests.

This is precisely what analyzing a complete file allows for: MRI, clinical report, and lifestyle context together constitute the necessary elements for a rigorous assessment. An opinion based solely on an MRI, without knowledge of the clinical picture, is insufficient to guide a treatment decision.

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X-ray, MRI, arthro-CT: what each exam provides

The diagnostic process generally follows a progression of three exams, depending on the clinical picture:

• Knee X-ray is prescribed as a first-line test. It does not visualize the meniscus, which is soft, non-bony tissue. Its role is to immediately rule out other causes of pain: fractures, joint space narrowing (a sign of osteoarthritis), or associated bone abnormalities. It is a prerequisite, not a diagnostic exam for a meniscus tear. ‍
• MRI (Magnetic Resonance Imaging) is the gold standard for visualizing the meniscus. It identifies the type, location, and extent of the injury. It is important to be aware of its limitations: in patients over 50, it frequently reveals meniscal abnormalities that are not necessarily the cause of the pain being felt. ‍
• CT arthrography is a second-line examination. It is prescribed in cases where an MRI is contraindicated (due to a metal implant or claustrophobia) or when doubt persists after an MRI. It combines an X-ray with the injection of a contrast agent into the joint to visualize its fine structures.

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MRI findings and pain: establishing a careful correlation

This is often the stage where doubt sets in. The MRI shows a meniscal tear, but the doctor expresses a reservation: is this really the lesion responsible for the pain? This is not a rhetorical question. It is at the heart of the therapeutic decision.

The radiologist provides a morphological description of what they observe in the images: the location of the tear, its type, and its extent. It is the specialized knee surgeon who determines the clinical significance of this description: is this lesion active, unstable, and linked to the patient's symptoms? Or is it an old degenerative abnormality that plays no role in the current pain?

This distinction is all the more delicate because several knee conditions can coexist with a meniscal tear and explain all or part of the symptoms:

• Early-stage osteoarthritis, with joint space narrowing visible on an X-ray
• A popliteal cyst (Baker's cyst) at the back of the knee, often secondary to joint effusion
• Pes anserine tendinopathy on the inner side of the knee, which is common in patients over 50

When this correlation between lesion and pain remains uncertain, a hasty surgical decision carries the risk of operating on a structure that is not the true source of the problem. It is precisely in these situations that a second opinion from a specialized knee surgeon is invaluable: not to contradict a diagnosis, but to refine its clinical scope and therapeutic implications. If diagnostic uncertainty persists after the tests have been performed, this approach provides greater clarity before considering treatment.

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