Water on the Knee? What is THAT!? Five Strategies to Eliminate Swelling

Hey Team,

Knee effusion, or effusion in general, is swelling inside a joint capsule. A deciding factor between effusion and swelling is where the swelling occurs. When woven together, each joint is encapsulated by multiple tight ligaments, creating the "capsule" of the joint. Fluid usually circulates inside the capsule to provide nutrients to the joint, aid in lubrication, and assist in joint health. The fluid inside the joint has a constant inflow-to-outflow regulation process keeping the same amount of fluid in the knee at all times. As the body uses the fluid for nutrients… the capsule circulates in new nutrient-dense fluid, thus keeping the joint healthy. Knee effusion occurs when the knee is traumatized, and capsule fluid becomes excessive. The fluid is trapped and cannot travel to other body parts. 

WHY DOES MY KNEE HURT SO MUCH?

Knee effusion is painful due to the enlargement occurring to the joint capsule. Picture your joint capsule as a balloon filling up with fluid. The capsule is very thick and does not stretch much; therefore, adding more fluid will push against the joint capsule and attempt to extend the capsule. This pressure in the joint creates pain! A lot of pain! The distention of the capsule is the root of your pain overall. Joint effusion occurs due to any irritation to the joint capsule or within the knee. This swelling is a protective mechanism but is NOT an indicator of the severity of the damage. Effusion can occur from slight irritation to significant ligament damage. Therefore, inferring the severity would be improper. 

MY DOCTOR WON'T DRAIN MY KNEE! WHY NOT?

Knee effusion is a fluid regulation issue. The inflow to outflow process within the joint capsule disrupts; therefore, more influx occurs than outflow. Naturally, the joint will slowly distend as a consequence. Many patients are confused about why their doctor will not drain the fluid. Some doctors will drain this fluid if the distention becomes too great. The challenge is the fluid will return, and each poke of the needle increases the chance of infection in the patient. Therefore, aspiration (draining) of the joint is not usually favored unless the pain becomes too great. Please note, however, this is a bandaid and not a long-term strategy. Knee inflammation and irritation will continue to disrupt the inflow/outflow of fluid to the joint capsule. 

HOW DO YOU KNOW IT'S NOT SOMETHING ELSE?

One strategy to determine if your knee swelling is effusion is to observe while the knee rests in a straight position. Take a look at the patella (knee cap). Directly to the left and right of the patella should be a dimple on each side. Is it there? Can you see the dimples? If you cannot see a dimple… effusion is present. If the dimples are equal to the other non-injured knee, then swelling is absent. 

One other area to observe when effusion appears to be present is to move the fluid. Take your hand and push the side tissue where the dimple should be. Does this feel squishy, and does the fluid move to the other side of the joint? If so… this is effusion.

What is not effusion? Effusion is not swelling behind the knee. Many patients ask me why they have swelling behind the knee but nowhere else. They report it is annoying when they squat or feel behind the knee, but it is not painful. Usually, this is a Bakers Cyst. A Baker's Cyst is not effusion because this is fluid accumulating outside of the joint capsule (not inside). Please note this is not the same as effusion, and I will explain Baker's Cyst another day. 

5 STRATEGIES TO ELIMINATE EFFUSION TO THE KNEE

#1. Rest: Knee effusion stays in the joint for as long as the body continues to have inflammation or irritation. The more the joint remains inflamed…, the longer effusion will be present. Resting the joint is essential to reduce inflammation and return to a prior activity level. 

#2. Avoidance: The complementary factor to rest in reducing irritation is avoiding the exacerbating factors. Part of the process of lowering knee effusion is to avoid painful activities. Typical activities to avoid: ascending/descending stairs, deep squatting, long-standing with non-supportive shoes, and increased walking more than usual. These activities will increase pressure on the joints, thus reducing healing timeframes. 

#3. Knee sleeve: A knee sleeve will not remove the effusion from the joint, as the swelling is encapsulated and has nowhere to go, but it can help with the pain. A knee sleeve will assist in creating compression to the knee and allow you to feel more stable and secure with regular daily activities. 

#4. Light reciprocal exercise: Light non-weight bearing reciprocal activity has demonstrated effectiveness in assisting tissue healing, thus reducing effusion. Reciprocal exercises would consist of a stationary bicycle. A recumbent bike is preferred and helps create a non-painful, non-exacerbating mode of activity with constant knee flexion/extension. Movements in a non-weight bearing position will create a "flushing" effect in the knee and assist in an overall reduction in effusion. 

#5. Light quad activation exercises: Once the effusion starts to reduce and pain continues to decrease, an excellent way to return to full function is to start light quadriceps activation exercises. These exercises are beneficial in allowing the quad muscle to regain proper activation. More than a few small amounts of fluid will begin to reflexively limit quad activation as a protective mechanism after the knee swells. The quadriceps are the first muscle to atrophy (shrink); therefore, we will need to begin engaging the quads with safe non-painful activity. 

OK TEAM. I enjoyed this write-up today as I have multiple questions regarding knee effusion, how to get rid of it, and ways to improve once effusion is present. Please note knee effusion is a common occurrence for people as we use the knee in a weight-bearing fashion daily. Consistent weight-bearing or a change to knee activity will create effusion at times. I sure hope these strategies are helpful to you in your path to better knee health. Feel free to email me a response if you have more questions or have a future topic you would like for me to discuss. 

• The author, Rob Sumner, is a Doctor of Physical Therapy and owner of Sumner Specialized Physical Therapy. He's happy to answer any questions about this article, wellness, fitness, or physical therapy overall by phone at (509) 684-5621 or by email at Rob@SumnerPT.com