Effusion, right knee

This code signifies the presence of excess fluid within the right knee joint capsule. This accumulation, often referred to as "water on the knee," can result from various underlying inflammatory, traumatic, or degenerative conditions.

Apply this code when documentation explicitly states effusion of the right knee. This is commonly seen in cases of arthritis, meniscal tears, ligamentous injuries, or infection affecting the right knee. Supporting documentation should include physician notes detailing the physical exam findings (e.g., swelling, ballotable patella) or imaging reports confirming intra-articular fluid.

• Ensure laterality is clearly documented (right vs. left vs. bilateral).
• Always code the underlying cause of the effusion if known and documented.
• Do not confuse with hemarthrosis (blood in the joint), which has a separate code.