Patella (Kneecap) Dislocations and Reconstruction/Repair 2016-10-12T12:39:55+00:00

Patella (Kneecap) Dislocations and Reconstruction/Repair

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The patella, or kneecap lies in front of the knee joint. The patella glides up and down a groove called the patellofemoral groove located at the front of the thigh bone or femur as the knee bends. The patella is attached to the quadriceps muscle by way of the quadriceps tendon and acts to increase the leverage from this muscle group when straightening the knee.

The patella normally lies within the patellofemoral groove and is designed to slide vertically within the groove. Dislocation of the patella occurs when the patella moves or is moved to the outside of this groove and onto the bony head of the femur. The patella may also sublux rather than fully dislocate, meaning it moves partially out of position (subluxation). A patella dislocation is not the same as a dislocation of the knee joint. A dislocated knee joint is a more severe traumatic injury.

Symptoms of Patella Dislocation

Symptoms of kneecap dislocation include:

  • Knee appears to be deformed.
  • Knee is bent and cannot be straightened out.
  • Kneecap (patella) dislocates to the outside of the knee.
  • Knee pain and tenderness.
  • Knee swelling.
  • “Sloppy” kneecap — you can move the kneecap too much from right to left (hypermobile patella)

Patella Reconstruction/Repair

The most advanced procedure being performed for patellar dislocation addresses an important ligament called the medial patellofemoral ligament, or MPFL. The MPFL is the connecting ligament between the end of the thigh bone (femur) and the inner side of the kneecap (patella). When the kneecap dislocates, the MPFL is always torn.

In acute injuries, it may be possible to repair the MPFL. This is only true in first-time dislocations that are addressed with immediate surgery. Many surgeons advocate immediate surgery after an initial patella dislocation to repair the MPFL.

After repeat kneecap dislocations, a new ligament must be constructed in order to fix the MPFL. This is performed using a ligament or tendon from another place in your body, or from a donor. The new MPFL ligament is created and attached to the thighbone and kneecap. The newly reconstructed MPFL securely holds the kneecap in a proper position.

If boney alignment needs corrected a tibial tubercle osteotomy or trochleoplasty is completed.

Treatment of Patella Dislocation

Use the RICE principles on the injured knee or rest, ice, compression and elevation. Ice can be applied for 10 to 15 minutes every hour initially reducing to 2 or 3 times a days as swelling and symptoms reduce. Rest from any sporting activities and seek medical attention. Having one episode of patella dislocation often makes you susceptible to another. A knee support can provide protection for the joint. Patella stabilizing braces have been specifically designed to provide support for the knee cap.

When the acute symptoms resolve, a full knee strengthening rehabilitation program is required to help avoid future recurrence. Specifically exercises for the vastus medialis muscle on the inside of the quadriceps are important.

Patella stability depends on the boney alignment of the knee and depth of the groove. The MPFL provides the stabilized soft tissue support to prevent lateral translation of the patella. Recurrent dislocation requires evaluation of the structures using exam x-rays, MRI or CT.

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