English version of the website of Dr. J.E.Perraudin, french orthopaedic surgeon in paris : : the content is intended for general information only and does not replace the need for personal advice from a qualified health professional.

Last updated Feb 12, 2017

Patella Dislocation or instability

Patellar apprehension test

Is a sign of an unstable kneecap. While the examiner places pressure on the kneecap, the patient may complain of the sensation that the knee cap is going to "pop out" of its groove.

Surgery for patella mal-alignment involves releasing tight structures on the lateral side (lateral release), reconstruction of the medial patellafemoral ligament and sometimes repositionning the tibial tubercule.

Lateral release is an operation to cut the overly tight lateral ligament of the patella (lateral retinaculum). It can be performed from the skin side ("open" lateral release) or from inside the knee in the arthroscopic technique. An isolated lateral release is rarely indicated.

Reconstruction of the medial patellafemoral ligament : this ligament is stretched or torn when the patella dislocates. I use a hamstring graft to reconstruct it. The difficulty is not to over-tighten it.

Repositioning of the tibial tubercule (on which the patella tendon is attached) :

  • either medially (towards the inside) : this diminishes the tendency of a patella to slide laterally (to the outside).
  • or towards the foot if the patella is too high
  • or both

To be continued...

Docteur Jean Etienne Perraudin, last updated 1 Sept 2012


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