Patellar Instability

Kneecap is a bone called Patella, which is attached to the thigh bone and shin bone by tendons. During knee bending and straightening, the patella performs a gliding movement in a groove that is present at the end of the thigh bone. When the Patella (kneecap) shifts out from this groove, this leads to patellar instability or patellar subluxation.

Causes of patellar subluxation

  • The weakness of muscles of the thigh (weak muscles are not able to hold the patella strongly in its groove).
  • The tightness of some thigh muscles (tight muscles pull the patella towards their side).
  • Direct trauma or injury to the knee, makes the kneecap unstable.
  • A shallow thigh groove (patella is unable to make smooth gliding).

Types of instability

Generally, there are two types of patellar instabilities, they are:

  • The kneecap (patella) slightly slides out from the groove, called a subluxation.
  • Dislocation of the kneecap (patella) due to any trauma or injury. When the patella is completely out of its groove (or dislocation).

Symptoms of patellar instability:

People can experience:

  • Knee pain especially under the kneecap.
  • Pain during knee bending.
  • Swelling around the knee joint.
  • Stiffness of the knee joint.
  • People may experience difficulty while walking and exerting weight on the affected leg.
  • Knee buckling or locking sensation of the kneecap.
  • Sometimes if instability is severe there are physical changes.

When the people get the feeling that the kneecap is not returning to its original position (i.e. groove) after the movement of the leg, immediate consultation with the doctor is needed.

Diagnosis for patellar instability:

  • Physical examination
  • Inquiry about any history of fall or injury to the knee
  • X-ray of the knee joint may be prescribed to evaluate the bony changes
  • If there is a suspicion that the damage may be due to soft tissue or cartilage damage, then MRI may be advised

Treatment for patellar instability:

  • If the patella doesn’t return to its natural position then it requires the doctor’s attention to fix the kneecap. Initial instability or dislocations can be treated conservatively with brace support and rest.
  • Physiotherapy is also helpful and starts with muscle strengthening exercises to prevent the kneecap sliding.
  • In some cases, surgical treatment is required, in people with recurrent dislocations or instability of kneecap. Open surgery or arthroscopy may be recommended to realign or stabilize the patella.
  • There are cases in which a small piece of cartilage gets detached (loose body) and rests in the joint. This should be removed because it causes movement restriction and further cartilage damage.
  • In the case of ligament injury, ligament reconstruction is required.

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