Patellar Instability/Dislocation

‘Dislocation’ of the patella (knee cap) often involves a traumatic incident where there is a powerful force to the kneecap, or a powerful quadriceps contraction.

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This causes the kneecap to move out of its usually position within the groove of the knee, usually moving to the outer side.


‘Patellar instability’ can occur after a dislocation, or if a client has risk factors that make them more susceptible (such as hypermobility, a high rising patella called ‘patella alta’, a shallow trochlear or groove). Patellar instability means the kneecap is less stable and more susceptible to dislocate.


  • If an acute injury – can see the kneecap displaced to the side. Rapid swelling, bruising and pain can follow.
  • Tenderness around the kneecap.
  • Apprehensive to move knee – feelings of instability, or like the kneecap is going to pop out of place.
  • Muscle imbalance – tight outer leg muscles, weaker inner leg muscles (especially a quadriceps muscle called VMO).


  • In the case of a dislocation, spontaneous reduction of the patella is common (where is goes back into place by itself).
  • A physiotherapist will often recommend R.I.C.E (rest, ice, compression, elevation) immediately post injury.
  • Rehabilitation is recommended to regain full knee range of motion and strengthen weaker muscles (particularly VMO and hip control).

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