Knee Swelling…What does it mean?
First we have to explain the different types of swelling that can occur. The soft tissues (i.e. muscles, skin & fat) around the knee can retain fluid and swell. This usually occurs with a direct contact injury that typically can cause a contusion. With contusions, bruising may be associate with the swelling.
The next type of swelling around the knee joint is inflammation of a bursa known as bursitis. Most people of heard of bursitis but often confuse it with arthritis. There are bursa sacks throughout the body. The most common one around the knee is directly on top of the kneecap known technically as the pre-patellar bursa. Normally the bursa is a thin fluid filled sack that you can’t even feel. However, when it is injured it enlarges as it fills with fluid and/or blood. This can happen when you are hit directly in the front of the knee or fall on the knee. Pre-patellar bursitis is also seen frequently in people who work down on their knees such as carpet layers and those that clean their kitchen floors by hand. That is the reason this condition used to be referred to as “housemaid’s knee”.
The final type of swelling is actually fluid or blood within the knee joint. If the swelling occurs suddenly after an injury then it often means that some structure inside of the joint has torn (this is known as an acute injury). If the swelling occurs gradually over time without a specific injury then you could still have something torn but it is usually as a result of wear and tear or overuse (i.e. chronic condition).
The most common acute knee injuries are fractures, torn ligaments, and torn cartilage. They can cause pain, stiffness, swelling, catching, locking, giving way and weakness.
If untreated any of the above conditions can become chronic. Other causes for chronic swelling would be arthritis and chrondromalacia. This last condition is where the normal cartilage that covers the bone within the knee joint begins to wear down. Once the cartilage is worn down to bone or in multiple different areas then it is known as arthritis.
Regardless of the type of swelling, most conditions can initially be treated with rest, ice, compression and elevation (R.I.C.E). You can also take over-the-counter pain relievers or anti-inflammatories. If there is severe pain that cannot be controlled, deformity, loss of feeling or movement then you should see a doctor more urgently.
In the coming weeks we will discuss many of these conditions in more detail. If you have questions or comments please feel free to post them.
Vic Goradia, MD
Sports Medicine Specialist