The cause of water on the knee is most often knee arthritis. When patients have arthritis, fluid accumulation within the joint is a common finding. Patients often find relief when the fluid is removed from the joint, but the fluid will likely return eventually.
Traumatic injuries can also cause accumulation of either fluid or blood within the joint. For example, meniscus tears and ligament injuries can cause fluid to collect. Furthermore, tearing of small blood vessels can cause blood to accumulate within the joint, this is commonly seen in patients with an ACL tear.
Excess fluid around the joint can accumulate in the bursa, a condition called prepatellar bursitis. While the fluid is not actually within the knee joint itself, prepatellar bursitis also causes swelling, or water on the knee.
Treatment of Knee SwellingTreatment of water on the knee depends on the underlying problem.
In cases of knee arthritis, the fluid may be drained from the knee. Patients are usually given anti-inflammatory medications or perhaps a cortisone injection. Patients with severe arthritis may eventually require knee replacement surgery.
Cartilage tears and ligament injuries that cause fluid or blood accumulation may also require surgical treatment. Often these conditions can be treated with arthroscopic surgery. In the case of meniscus tears, the treatment may consist of removing part of the meniscus or repairing the meniscus. Ligament injuries may be treated with reconstruction of the torn ligament.