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Patella Luxations

What is it? What can be done about it?

Anatomy of the Stifle:

The quadriceps combine into the patellar ligament, which inserts on the tibial crest. The patella itself lies in the trochlear groove of the femur.

Components that Contribute to Patellar stability:

  • Depth of the Trochlear groove
  • Tibial crest alignment
  • Strength of the quadriceps muscle

Any of these components, either alone or in some combination, can effect the stability of the patella


  • Depth of the Trochlear groove
  • Can be too shallow, allowing for the patella to easily slip out
  • Tibial crest alignment
  • Tibial crest may not be completely aligned with the trochlear groove of the femur

"There are 4 types of patella luxations.

  • Grade 1 - The patella is positioned normally but can be luxated with slight manual pressure.
  • Grade 2 - Spontaneous luxation occurs; however, it can reduced spontaneously or can be replaced manually.
  • Grade 3 - The patella is luxated most of the time; however it can be replaced manually.
  • Grade 4 - The patella cannot be reduced manually."

Of these, grades 3 and 4 require surgical correction. Up til now, grades 1 and 2, we merely "watched."

Quad = Four
Four heads

  • Vastus Medialis
  • Vastus Intermedius
  • Vastus Lateralis
  • Rectus Femoris

The four heads of the quadriceps insert into the patellar ligament.

How the Quadriceps Affect the Patella

  • When a dog has a medial patella luxation, the patella is "popping out" of the trochlear groove to the medial side (or "inside") of the joint. To help prevent the frequency, strengthen the Vastus LATERALIS.
  • When a dog has a lateral patella luxation, the patella is "popping out" of the trochlear groove to the lateral side (or "outside") of the joint. To help prevent the frequency, strengthen the Vastus MEDIALIS.

But how do we strengthen individual heads of the quads?



Using therabands, we can isolate individual heads of the quadriceps to strengthen the appropriate one via contractions. Strengthening the appropriate head will help increase patellar stability.

  • By teaching owners simple exercises to help strengthen the appropriate heads of the quadriceps, we can help to DECREASE the frequency of the patella luxations.
  • This is not a CURE but a means of slowing the development of problems associated with this, such as arthritis.
  • We can also do this in the hopes to avoid having a Grade 1 or 2 BECOME a Grade 3 or 4 and eventually require surgery.

Why bother?

  • Left alone, a continuously luxating patella will wear the ridges of the trochlear groove, making it even shallower.
  • Arthritis will prematurely effect that joint because of the constant rubbing of the patella on the bone, causing pain and decreasing mobility.

If your pet has been diagnosed with a patella luxation, call Valley Animal Hospital, EXT 320 for the Rehab Office, to set up your Rehab Informational Consult to learn these exercises that you can do at home for your pet.


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