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Patella

Name of bone

Patella

Location/Articulation

The patella, also known as the knee cap or kneepan, is a thick, circular-triangular bone that articulates with the femur and covers and protects the knee joint. The largest sesamoid bone in the human body, the patella is attached to the tendon of the quadriceps femoris muscle, which contracts to extend/straighten the knee. The vastus intermedialis muscle is attached to the base of patella. The vastus lateralis and vastus medialis are attached to lateral and medial borders of patella respectively.

The patella is stabilized by the insertion of vastus medialis and the prominence of the anterior femoral condyles, which prevent lateral dislocation during flexion. The retinacular fibers of the patella also stabilize it during exercise.

Muscle and ligament attachments

Surface anatomy

The primary functional role of the patella is knee extension. The patella increases the leverage that the tendon can exert on the femur by increasing the angle at which it acts.

The patella ossifies between the ages of 2 and 6 years, although in some people, the patella may be absent congenitally or hypoplastic. About 2% of the population has a bipartite patella, which is usually asymptomatic. Direct trauma, however, may produce symptoms that mimic those of a fracture.


Figure 1. Anatomy of the patella

Radiography

Physical examination

Embryology

Anomalies

Injuries/Disorders

  • Patella tendonitis
  • Patella fracture

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Related Content

Resources on Patella and related topics in OrthopaedicsOne spaces.

Page: Patella (OrthopaedicsOne Articles)
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Page: Screw-home mechanism (OrthopaedicsOne Articles)
Page: Torque (OrthopaedicsOne Articles)
Page: Femoral condyles (OrthopaedicsOne Articles)
Page: Metaphysis (OrthopaedicsOne Articles)
Page: Cartilage (OrthopaedicsOne Articles)
Page: Tibial plateau (OrthopaedicsOne Articles)
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