📌 When the MPFL Tears Without Patellar Dislocation

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Direct-impact MPFL tears: subtle, rare, and easy to miss.

Isolated MPFL Tear from Direct Medial Contusion — Extremely Rare

The MPFL almost always tears due to transient lateral patellar dislocation,
accompanied by the classic bone bruise pattern
(medial patella + lateral femoral condyle).

 

But in this case?

The patient had no dislocation, only a direct medial impact.

Key MRI clues suggesting a true contusion-only MPFL tear:

• Focal MPFL tear at the femoral side
  
  
• Hoffa’s fat pad edema / subcutaneous edema at the impact site
  
  
• Local bone contusion that does not match the dislocation pattern
  
  
• Medial patellomeniscal ligament (MPML) intact
  
  
• No medial patella–lateral trochlea bone bruise pair
  
  
• History fits a direct blow, not instability
  
  

 

Why it matters:

This mechanism is biomechanically possible but extremely underreported.
Diagnosis requires excluding transient dislocation, not just seeing the tear.

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