Patella fracture


  • Occurs via direct blow or forceful contraction of quadriceps muscle
  • Do not confuse a bipartite patella with a fracture (bipartite patellas are usually bilateral so may image contralateral knee to confirm)

Clinical Features

  • Focal patellar tenderness, swelling, effusion
  • Check integrity of knee extensor mechanism by having patient perform straight-leg raise

Differential Diagnosis

Knee diagnoses

Acute knee injury




  • AP and lateral
    • Lateral view: Distance from tibial tubercle:lower pole of patella ~ length of patella +/- 20%
      • If greater than this suspect patellar ligament rupture
  • Consider skyline (sunset) view if suspect fracture of articular surface


  • Nondisplaced with intact extensor mechanism: knee immobilizer, rest, ice
  • Displaced >3mm or disruption of extensor mechanism: above + early referral for ORIF


  • Outpatient

See Also


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