Kneecap Instability or Dislocation

What is Kneecap instability or Dislocation?

Patellar instability means the patella (kneecap) slips out of the femoral groove in the thighbone. An unstable kneecap can lead to a dislocated knee. Physical therapy and leg braces can help. Some people have chronic (ongoing) patellar instability. This condition increases the risk of dislocated knees, ACL tears and arthritis in the knee.

What Causes Kneecap instability or Dislocation?

Some of the causes are –

  • Hypermobility
  • Weakness or muscle imbalance
  • Obesity
  • Poor muscle flexibility and strength
  • Uneven groove or space in femur (thighbone)
  • Defect in alignment of bone or kneecap
  • Dislocation or injury
  • Soft tissue abnormality such as torn patellofemoral ligament
  • Previous injury

How is Kneecap instability or Dislocation diagnosed?

Even if your kneecap moves back into place on its own, you should see your healthcare provider for a diagnosis and potential treatment. Your provider will perform a physical exam to assess symptoms, including your range of motion.

You may also get:

  • X-rays to see if the kneecap is out of place and check for broken bones.
  • MRI to check for injuries like anterior cruciate ligament (ACL) tears, meniscal tears and loose bone fragments.

How is Kneecap instability or Dislocation treated?

For partial knee dislocations and patellar instability, your provider may recommend:

  • Knee brace to immobilize the knee and keep the kneecap in place.
  • Physical therapy to strengthen muscles that hold the kneecap in place and improve range of motion.

If you have chronic patellar instability or a complete kneecap dislocation, your healthcare provider may recommend surgery.

  • Medial patellofemoral ligament (MPFL) repair to strengthen and repair the ligaments that hold the kneecap in place.
  • MPFL reconstruction
  • Knee replacement