What is the statistical likelihood that a young adult woman (~22 years old) with an MRI‑proven labral tear in one hip also has a labral tear in the opposite hip?

Bilateral Labral Tears: Statistical Likelihood in Young Women

In a young woman (~22 years old) with an MRI-proven labral tear in one hip, there is approximately a 40-45% chance that the contralateral hip also has a labral tear, though it is likely asymptomatic. 1

Key Evidence on Contralateral Hip Involvement

The most relevant study directly addressing your question examined 100 patients with unilateral symptomatic FAI who underwent MRI of both hips 1. In this cohort:

• 41-43% of asymptomatic contralateral hips had labral tears on MRI (depending on which radiologist's interpretation was used)
• The interobserver reliability was almost perfect (κ ≥ 0.85), indicating these findings were consistent
• Only 9% of these initially asymptomatic hips became symptomatic over 2 years of follow-up

This finding is reinforced by broader population studies showing labral tears are remarkably common in asymptomatic individuals:

• 69-86% of young asymptomatic adults have labral tears on MRI 2, 3
• 38.6% prevalence in a cohort of 70 young asymptomatic volunteers (mean age 26 years, 67% women) 4

Critical Clinical Context

The presence of a labral tear on MRI does not equate to clinical significance. The 2020 International Hip-related Pain Research Network consensus guidelines emphasize that 5:

• Incidental intra-articular findings are common in asymptomatic individuals
• Diagnostic imaging has "very limited ability to confirm the diagnosis of a particular condition as the cause of pain"
• Diagnosis should never be made using imaging alone but must combine symptoms, clinical signs, and imaging findings

Age-Related Considerations

For your 22-year-old patient specifically:

• Labral tears increase with age, but even in younger populations the prevalence is substantial
• Participants older than 35 years are 13.7 times more likely to have chondral defects 2, suggesting your patient's age may be somewhat protective against progression

Clinical Implications

If the contralateral hip is asymptomatic, no intervention is warranted despite the high likelihood of an MRI-detectable labral tear. The evidence shows:

1. Low conversion rate: Only 9% of asymptomatic labral tears became symptomatic over 2 years 1
2. High false-positive rate: The majority of labral tears visible on MRI never cause symptoms
3. Poor predictive value: The presence of an asymptomatic labral tear does not reliably predict future symptoms

When to Image the Contralateral Hip

Only obtain contralateral hip imaging if:

• The patient develops anterior groin pain in the opposite hip
• Pain occurs with hyperflexion or sharp catching with rotation 6
• A positive FADIR test is present (though this has limited diagnostic accuracy) 5

Common pitfall to avoid: Do not routinely image or treat the asymptomatic contralateral hip based solely on the presence of a unilateral symptomatic labral tear. This leads to overdiagnosis and potential unnecessary intervention given the 40-45% prevalence of asymptomatic tears and only 9% conversion to symptomatic disease.