Drain cannulas are used in arthroscopic surgery to remove excess fluids, such as irrigation fluids, blood, or serous fluid, from the surgical site or joint cavity. These drain cannulas are designed specifically for arthroscopic procedures, where minimally invasive access to joints is essential. Drain cannulas help maintain a clear field of vision, facilitate joint irrigation, and prevent the buildup of excess fluids that can interfere with the surgeon's ability to visualize and operate on the joint.