What causes fluid buildup behind surgery incision at knee?

Fluid buildup behind a surgery incision at the knee, known as seroma or hematoma, can be caused by several factors, including surgical trauma, inflammation, or inadequate drainage of surgical wounds. The body's natural response to surgery involves increased blood flow and fluid accumulation to the area, which can lead to excess fluid collecting in the tissue. Additionally, infection or complications during the healing process may exacerbate fluid accumulation. Proper post-operative care and monitoring can help minimize this risk.