Patellar alignment is the position of the kneecap relative to the groove in the underlying femur bone into which it slides when the knee is bent and straightened.

Patellar alignment

 

The patella is normally V-shaped at the back and snugs into the V-shaped groove of the underlying femur.

What factors affect patellar alignment

Normally the articular cartilage at the back of the patella aligns perfectly with the articular cartilage in the underlying trochlea, which is a nice V-shape. The patella is normally held in this position by restraints from:

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What factors cause patellar malalignment

Abnormal patellar alignment may affected by structural abnormalies patella or trochlea:

or by abnormal tension on the patella from other structures:

  • Tight lateral retinaculum
  • Tibial tubercle in poor alignment
  • Torsion of femur or tibia
  • Weak MPFL
  • Weak quadriceps, especially VMO

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Synonyms: 
kneecap alignment
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Dr Sheila Strover (Editor)
BSc (Hons), MB BCh, MBA

See biography...