It can be worrisome to see one knee swell while the other one stays the same. When both knees swell, it usually means that you have a systemic condition, such arthritis. When one knee expands, it’s usually a sign of a condition that is only in that area. If you know what caused your knee to swell, you can decide if you need to see a doctor.
1. Injury or trauma
The most common cause of swelling in just one knee is trauma or overuse. If you hurt yourself doing the same thing over and over again, you might not even remember when it happened. Here are several difficulties that could happen:
Tearing or straining the ACL or MCL ligament
Tear in the meniscus
Patella that has come out of place
A broken bone or a bruise
In these cases, swelling normally appears within a few hours and may be accompanied by pain, stiffness, or a feeling that the joint is unstable.
2. Bursitis
Bursae are little fluid-filled sacs that keep the knee safe. If you feel frustrated because of pressure, trauma, or kneeling for a long time, you could have prepatellar bursitis, sometimes known as “housemaid’s knee.” This usually only happens to one knee, and it makes the front of it swell.
3. Infection
Septic arthritis, also called a joint infection, is an extremely serious illness that can quickly cause one knee to swell, turn red, feel hot, and pain a lot. This usually starts with a fever or chills, and you should see a doctor straight away. You might need to undergo a joint aspiration to get rid of the fluid that is contaminated.
4. Gout or “pseudogout”
Uric acid crystals cause gout, which is a type of arthritis. Gout could be the cause of the edema if it happens swiftly and hurts a lot. Pseudogout, which has calcium crystals in it, can cause the same symptoms. These issues normally only affect one joint at a time, and they may come back from time to time.
5.Localized OA
Osteoarthritis normally affects both knees over time, although it may start in just one knee, especially if that knee has been damaged earlier or needs to carry more weight. The swelling could be mild to moderate and get worse when you move about.
6. Baker’s Cyst
A Baker’s cyst is a lump that arises behind the knee and is filled with fluid. Some typical causes are arthritis or damaged cartilage. One knee may feel tight or swollen, especially when you bend or straighten the leg.
7. A blood clot or an issue with blood flow
Deep vein thrombosis, or a blood clot in the leg, can cause the knee area to expand, especially if it is also accompanied by calf edema, warmth, or pain. Because it’s a medical emergency, it needs to be treated straight now.
When to See a Doctor
You should see a doctor if you have any of the following:
The swelling came on all of a sudden, is particularly bad, or occurs accompanying a fever.
When you touch the knee, it aches, feels hot, or is red.
You can’t bend your knee or walk.
After a few days, the swelling doesn’t go down.
In the End
It’s not a reason to panic if one knee swells, but you should definitely pay attention to it. There are a lot of possible causes, from little injuries to more serious joint diseases or infections. Getting the appropriate diagnosis is the first step toward getting better and keeping your knees healthy for a long time.