The Overlooked Cause of Knee Instability

Last week I spoke with someone who’s been experiencing right knee pain.  

(To protect her privacy, I’ll call her Kim.)

“I just want a new perspective,” she admitted. 

“I had a Baker's cyst, and I've had my knee drained.”   

“And before I go back to the orthopedist again for another MRI and potentially cortisone shots, I'm just trying to understand what's going on.”

(Here are my thoughts on cortisone / steroid injections.)

Kim wants to be able to walk for long distances when she travels to Europe this fall.  

And her biggest concern is that her right knee feels “unstable.”

What is a Baker’s Cyst?

A Baker’s Cyst – also known as a popliteal cyst – is an accumulation of fluid found on the back side of a knee. (source)

Frequently, people have Baker’s Cysts without knowing it. (source)  

And when pain is present, it typically occurs among people who have intra-articular knee issues, like arthritis or meniscus tears. (source) 

Swelling is associated with these conditions.

And this larger volume of fluid causes an increase in pressure inside the knee.  

The fluid essentially inflates all the available spaces inside the knee.  

In some people, their anatomy is such that some of that fluid presses into a small area and becomes trapped.

Baker’s Cysts are continuous with the inside of the knee, but the fluid from the cyst can’t easily flow back into the main part of the knee.  

(There are two images of Baker’s Cysts on this webpage.)

What makes a Baker’s Cyst problematic?

Kim’s primary concern is instability – a feeling that her knee iss weak and might buckle when she walks too long or too far.  

Most of your knee stability comes from ligaments.  

Ligaments are the tough cords of connective tissue that secure bones together.  

In the case of your knees, ligaments tether your thigh bone (femur) and your shin bone (tibia) together. 

The most common cause of knee instability occurs when ligaments are injured.  

If your knee twists abruptly, for example, the force may stretch or tear one or more knee ligaments.  

But in Kim’s case, she hadn’t sustained an injury due to an abrupt force. 

And her previous MRI didn’t reveal any damage to her knee ligaments.  

Her MRI results, however, did indicate she had “effusion” or swelling inside her knee.  

Even a small amount of swelling – as little as an extra tablespoon of fluid – can cause the muscles to weaken. (source) 

Known as Arthrogenic Muscle Inhibition or AMI, this relative muscle weakness results in the instability Kim was complaining about. (source)

How are Baker’s Cysts treated?

Over 15 years ago, I remember surgery was commonly performed to remove Baker’s Cysts.  

In Kim’s case, she had her knee aspirated, which means the physician took a syringe and removed extra fluid from inside her knee.  

(This orthopedist removed 3 shot glasses of fluid from a patient’s knee.)

But both procedures don’t necessarily solve the problem because Baker’s Cysts often return. (source)

Why do Baker’s Cysts return?

Removing the fluid within a Baker’s Cyst, and removing the actual Baker’s Cyst, both are procedures that treat a symptom of the problem rather than the problem itself.  

I hope this never happens to you, but let’s say you step off a curb and twist your ankle.  

You’ll probably get ankle swelling.  

Swelling is a symptom of your ankle being too weak to withstand the forces applied to those tissues.

If you rest your ankle, the swelling will likely resolve.  

But if all you do is rest – even if the swelling goes away – if you abruptly turn your ankle while you’re hiking, for example, the swelling will probably come back. 

Because while the symptom (swelling) improved with rest, the root of the problem (ankle weakness) hasn’t changed.  

The swelling in a Baker’s Cyst occurs because the surfaces (the cartilage) inside the knee are weak. (source)

In both the case of knee arthritis and meniscus tears, the inside surfaces of the knee are too weak to withstand the forces from particular movements. 

These offending movements are typically repetitive forces (like jumping, running, hiking, or climbing stairs) rather than a trauma (like what happens during a sudden movement or sprain).  

Over time, these forces accumulate and result in the symptom of swelling. 

Removing the swelling with a syringe, or even resting long enough that the swelling goes away, may make your knees feel temporarily better.  

But the swelling and instability will likely return when the activities occur again because the weakness is still present inside your knees.  

A successful solution requires strengthening the surfaces inside your knees.

The Solution to Knee Instability

Kim has two choices.  

She could decrease the likelihood of her knee swelling and instability by being cautious and limiting how often and how far she walks.  

Or she can strengthen the inside of her knees, allowing her to travel and walk distances without causing knee problems.  

(Learn more about strengthening the inside of your knees here.)

For Inside Out Knee Health,

here's a guide to get started:

You can access it here. 

For personalized guidance to build Better Knees:

Schedule a free 20-minute Strategy Session.  (Find your best time here.)

Disclaimer: The information in this blog post is for educational and informational purposes only and is not intended as medical advice. It should not be used to diagnose, treat, or prevent any health issue or disease without consulting with a qualified healthcare professional. The author of this blog and the website do not bear any responsibility for any actions taken based on the information provided in this blog.