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Displaced patella

The function and location of the patella

Knee anatomy - Medicover Hospital Hungary
Knee anatomy - Medicover Hospital Hungary

The knee or knee joint (articulatio genus) connects the thigh to the leg. The knee joint is the largest, most complex and most vulnerable joint of our body. The role of the knee joint between the tibia and the femur is to create the load transfer, so that controlled, but still free movement takes place. The knee joint plays a decisive role in the energy transmission of the quadriceps muscle. The back surface of the kneecap is covered by a layer of hyaline cartilage, and it mainly moves up and down during bending the knee. This movement is basically totally painless, silent.

One of the most sensitive and most vulnerable parts of the knee joint is the area of the kneecap, which is also known as a patello-femoral joint. Both painful and instability-related disorders can originate, mainly due to the displacement of the knee joint.

Displaced patella

Normally, the kneecap fits neatly into the recess on the front surface of the thighbone so both sides are equally burdened. If the shape of the kneecap or the thighbone is different, the load is uneven, which can lead to cartilage damage.

The kneecap is held by laterally strong bands. Anatomical abnormalities or insufficient placement of the bands may cause the knee to move in relation to the center line. This is most common in lateral (outward) directions because the bony flange is lower here.

What are the symptoms of displaced patella?

The leading symptom of the problem is the pain of the knee’s front, behind the kneecap, which is mainly arises at strong bending:

  • downhill walking,
  • squatting,
  • walking on uneven ground
  • running.
Displaced patella - Medicover Hospital Hungary

It is a typical symptom when a long sitting period causes a knee pain (“car cinema phenomenon”), because kneecap is heavily compressed into the joint recess when bending, which can provoke pain.

How do we diagnose displaced patella?

The displaced patella can easily be diagnosed as it is visible when it has a different position than the centerline of the femur.

What surgical procedure can we heal the displaced patella?

The treatment of the kneecap cartilage is not a simple task since the space is narrow for the proven cartilage protection process and the bone thickness below the cartilage is very thin (the patella is about 2 cm thick).

The lateral release is a commonly used method during which the band supporting the kneecap is cut from the outside, thus ceasing the outward pulling force suppressing the kneecap. The bone can move freely and the pressure on the surface of the cartilage is also reduced. This results in easier, more seamless complaint knee movement.

The surgery can be performed by open excavation and arthroscopies. Full transection of the band’s fiber has a great importance. The surgery has no significant complications.