Unstable Knee
Patients often come into my office with complaints of an “unstable knee”. As an orthopaedic surgeon, I have to decipher if the knee is actually unstable (meaning loss of ligamentous stability) vs. an injury that creates muscle weakness and imbalance creating the feeling of instability. These are very different things. I had a 65 year old patient this week whose chart read “unstable knee”. Before going into the room, I pulled up his x-rays and saw significant arthritis, which led me to the second option. Not truly an unstable knee and something that would require some work and retraining.
Ligament Damage
I can usually tell if it is a ligament issue based on a patient’s story. The classic anterior cruciate ligament (ACL) story is an athlete where their foot stayed planted and their body rotated away. Then, they hear the classic pop with swelling. The leg may “give out” after this because the ACL is not doing its job.
Muscle Weakness
This is often the case with minor injuries or more chronic (long term) knee pain. The classic patient here is an older patient with arthritic pain. They stop moving as much because of the pain, which leads to muscles weakening. Then they get the sensation of instability because the quads, glutes, hamstrings, and many other muscles have lost their function.
Final Thoughts
Which are you? Ideally the muscle weakness type because this is often easier to treat and doesn’t require surgery. There is typically no big injury or swelling with this category.
If you have a big injury or hear a pop and then feel unstable… see orthopaedics! Make sure your ligaments are all solid.
Sometimes it's both, which is why the history, physical exam, and imaging matter.
If you have the chronic long term feelings of instability, then you guessed it… probably time for some physical therapy!
Let me know which topics you’d like to hear more about in the comments.
Dr. Megan Lisset Jimenez
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