Prevalence of abnormal findings in 230 knees of asymptomatic adults using 3.0 T MRI

Key points

1. 01Nearly all asymptomatic knees scanned showed at least one MRI abnormality
2. 02Meniscal tears, cartilage damage, and bone marrow changes were common despite no symptoms
3. 03Even findings usually considered serious, like bucket-handle and complex meniscal tears, appeared in pain-free knees
4. 04Imaging findings poorly predict symptoms, so MRI results need clinical correlation

How it was conducted

Design

Cross-sectional prevalence study using 3.0 T MRI

Participants

115 uninjured sedentary adults, median age 44, both knees imaged (230 knees)

Imaging

Bilateral 3.0 T knee MRI graded by two radiologists

Symptom measure

KOOS knee questionnaires to confirm asymptomatic status

Outcome

Prevalence of structure-specific abnormalities across all knees

What they found

• Abnormalities were present in 97% of knees
• Meniscal tears occurred in 30% of knees, with horizontal tears the most common at 23%
• Patellofemoral cartilage abnormalities were found in 57% of knees and bone marrow abnormalities in 48%
• Moderate cartilage lesions occurred in 19% of knees and severe lesions in 31%
• Moderate bone marrow edema occurred in 19% of knees and severe in 31%
• Partial ACL ruptures were seen in 2% of knees
• Bucket-handle and complex meniscal tears were reported in asymptomatic knees

Limitations

• Cross-sectional design shows prevalence at one time point and cannot prove findings cause or predict symptoms
• Participants were sedentary adults with a median age of 44, so results may not transfer to athletes or other age groups
• No symptomatic comparison group is described, limiting conclusions about how these findings differ from painful knees
• Radiologist grading of structures can carry interpretation variability

Why it matters

For patients

An abnormal knee MRI does not by itself mean your pain has been explained, since many pain-free people have the same findings.

For clinicians

Knee MRI findings should be interpreted in the context of symptoms and examination rather than treated as the cause of pain on their own.

For readers

This study shows how common incidental MRI abnormalities are in healthy knees, a key caution against over-relying on imaging.