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Patellar Dislocation


Patellar (knee cap) dislocation is commonly referred to as knee dislocation. The actual term knee dislocation refers to the displacement of the joint between the thigh bone and the leg bone which is less common and more grevious injury. Here we will be addressing the issue of patellar dislocation alone in this page. Patella or the knee cap is a sesamoid (small bone found in the muscle or tendon) bone which remains in the front of the knee. It forms the extensor mechanism (the pulley action which straightens the knee from the bent position). This bone is restrained by multiple restraints. However when it jumps out of its place to the outer side of the knee, one would feel severe pain and loss of confidence to move.  

Why & how does it happen?

Patellar dislocation can occur due to either the developmental abnormalities in the bones and tendon or alternatively due to injury. Often it can be a combination of both. It is also commonly seen in people who are double jointed (lax joints). The first dislocation often happens at an early age of around 14 to 18. 

Who gets this injury?

This injury is common when dancing or playing contact sports, when there is a sudden twist asnd pivot movement. It is more  common in girls than boys and particularly in the late teens. It is rare after the age of 30. 


  • Sudden severe pain

  • In some loud POP sound

  • Inability to walk

  • Feeling that knee will give away and not supporting

  • Swelling appears usually few hours later

  • Within a week most patients with MPFL tear will be able to walk with a slight limp

  • Persistence of instability sensation and pain in certain movements and activities

When to seek medical help?

Initial assessment with an x-ray, pain relieving medicines and RICE therapy is needed as an immediate remedy. Further assessment by an expert Arthroscopy Surgeon and MRI scan are necessary to analyze the extent of injury.

What happens to MPFL if no treatment is undertaken?

MPFL ligament injury alone may not result in any further dislocations unless there are other bone and supporting structure abnormalities as well. Hence careful assessment of all the parameters supporting the patella need to be assessed. In addition, if the first dislocation has happened in someone who is over the age of 30, it is very unlikely for them to have further dislocations. 

What happens when I visit the Consultant?

You will be asked about the nature of injury, symptoms further to that so far. Consultant will examine you and discuss the treatment modalities. 

What are the treatment options?

The treatment modalities range from physiotherapy to MPFL Ligament reconstruction to bone procedures as well to correct the alignment. 

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