Fluid inside Knee
Fluid in knee or also can be say as water on knee is a condition in which fluid collects in your knee joint or is a general term for excess fluid accumulation in or around your knee joint. This fluid in knee also called as an effusion (uh-FU-zhun) in knee joint. Fluid in knee occurs when there is an accumulation of synovial fluid, blood or pus. The watery fluid secreted by this lining is called synovial fluid which acts as a lubricant during knee movement In medical terms this condition is called knee effusion.
Fluid on the knee joint may be the result of trauma, overuse injuries, or an underlying disease or condition. To determine the cause of water on the knee, your doctor may need to obtain a sample of the fluid to test for infection, disease or injury.
Removing some of the fluid also helps reduce the pain and stiffness associated with water on the knee. Once your doctor determines the underlying cause of your water on the knee, appropriate treatment can begin.
Type of Fluid
There are two types of fluid in Knee
Blood in the Knee
Two conditions commonly cause the accumulation of blood within the knee; these are an ACL tear and a fracture of the bone and cartilage of the knee. These injuries allow blood to enter the joint and will create a large, swollen knee. When bleeding is the cause of knee swelling, the onset is rapid, and the swelling can be intense. Fluid usually accumulates within minutes of the injury.
Non-Blood Fluid in Knee
Acute injuries that cause the accumulation of non-blood fluid within the knee include meniscus tears and ligament sprains. The knee swelling seen with these injuries is acute in onset, but less rapid than blood accumulation. Typically patients with these injuries will notice fluid accumulation hours to days after the injury (rather than within minutes as seen with bleeding into the knee). The amount of fluid can be significant, but it is not typically as tense as seen with blood accumulation.
Various Causes Of Fluid In Knee
One of the common causes of fluid in knee symptoms is injuries. Any damage to the different related structures of your knee can lead to fluid buildup which is very painful. Examples of sustained injuries that can cause fluid buildup in your knees are as follows:
- Ligament tear
- Broken bones
- Meniscus tear
- Overuse injuries
How the knee works
To understand how injuries happen, it helps to know how the knee works. The knee is the largest joint in the body; it provides stability and allows the legs to bend, swivel, and straighten.
The knee joint is at the ends of the femur (thighbone) and the tibia (shinbone); it is protected by the patella (kneecap). The ends of the femur and tibia and the back of the patella are covered in articular cartilage, which acts as a cushion to keep the femur, patella, and tibia from grinding against each other. On the top of the tibia, extra pads of cartilage called menisci help absorb the body's weight. Each knee has two menisci — the inside (medial) meniscus and the outside (lateral) meniscus.
The muscles around the knee include the quadriceps, a large muscle at the front of the thigh, and the hamstring, located at the back of the thigh. The quadriceps help straighten the leg and the hamstring helps bend the knee.
Several tendons — cables of strong tissue that connect muscles to bones — work together to help move the knee. The tendons in the knee are the quadriceps tendon, the patellar tendon, and the hamstring tendons. All work together to allow the leg to extend. Ligaments are cables of strong tissue that connect bones to bones. The four main ligaments in the knee that help connect the femur to the tibia and keep the knees stable are: