Often referred to as “water on the knee,” knee swelling, can be a debilitating and painful condition. It occurs when excess water builds in and around the knee joint and is most often caused by overuse, underlying condition or because of an injury.
The knee is one of the largest and most complex joints in the body. It connects the shinbone (tibia) and the thighbone (femur) and includes the kneecap and the smaller leg bone (fibula) as well. Tendons connect the leg muscles and knee bones, while the bones are joined together by ligaments:
- The anterior cruciate ligament (ACL) the tibia from sliding forward on the femur.
- The posterior cruciate ligament (PCL) prevents tibia from sliding backwards on the femur.
- The medial and lateral collateral ligaments make sure the femur does not slide from side to side
The medial and lateral menisci (C-shaped cartilages) are the shock absorbers that lie between the tibia and femur.
3 Common Causes of Knee Swelling
- Knee Osteoarthritis: When the knee joints begin to degenerate, there is an over accumulation of joint fluid and this essentially causes the knee to swell. This type of swelling is usually accompanied by pain in the area and a feeling of the knee “catching” or “locking”. It will be difficult to fully straighten or bend the knee
- Bursitis: Bursae are tiny, fluid-filled sacs surrounding the joints in the body. They serve to protect the joints from friction. If the bursa is inflamed, then it will fill with joint fluid and cause swelling. This type of swelling is not usually accompanied by pain, but the knee and swollen area will feely “squishy.” This is referred to as nonseptic bursitis.
Septic bursitis occurs when a small microorganism finds its way into the bursa, causing the area to become inflamed and fill with pus. In this case, the knee may appear red and warm to the touch.
- Knee Injury: Finally, and probably the most common cause of knee swelling is trauma to the bones, joints, bursae, ligaments, tendons, menisci, or cartilage. A more serious injury can open the area for blood to flow into the joint, which leads to extreme stiffness, swelling, warmth, and bruising. Most knee injuries occur as a result of a direct trauma, such as the knee hitting another object or being overextended in any direction.
It is important to have your knee evaluated at the first sign of swelling or injury so that a proper treatment protocol can be established. At OUCH, our orthopedic specialists can diagnose and treat injuries to the knee and utilize on-site MRI and X-ray to determine the underlying cause of knee swelling. Most importantly, no appointment is needed and you can walk into any of our orthopedic urgent care locations in Toms River and Wall, NJ to be seen by an orthopedic specialist.