Dorsal defect of the patella

Dorsal defect of the patella is a benign subchondral lesion of unknown aetiology and a normal developmental anomaly of the patella, which can be mistaken for a pathological process such as a focus of infection or osteochondritis dissecans.

Dorsal defect of patella occurs in males and females with equal frequency and is most frequently found in adolescents. It is bilateral in up to one-third of individuals.

This condition often is asymptomatic and an incidental finding on knee imaging, but it occasionally may be the cause of knee pain.

Plain radiograph and CT

A rounded focus of radiolucency surrounded by a sclerotic margin in the upper, outer quadrant of the patella.

MRI

On MR, this defect is similar to many other bony lesions:

  • T1: low signal 
  • T2: high signal

Dorsal defect of patella is one of the skeletal "do not touch" lesions, therefore because of its characteristic location, it should not undergo biopsy. 

Lower limb anatomy
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Article information

rID: 23004
Section: Anatomy
Tag: cases
Synonyms or Alternate Spellings:
  • Dorsal defect of patella

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Cases and figures

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    Case 1
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    Case 2
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