Because the arthroscope and surgical instruments are thin, your surgeon can use very small incisions, rather than the larger incision needed for open surgery. This results in less pain for patients, less joint stiffness, and often shortens the time it takes to recover and return to favorite activities. During arthroscopy, your surgeon can see the structures of your knee in great detail on a video monitor.
For a function of three variables, a level set is a surface in three-dimensional space that we will call a level surface. For a constant value $c$ in the range of $f(x,y,z)$, the level surface of $f$ is the implicit surface given by the graph of $c=f(x,y,z)$.
vb (mainly tr) , sets, setting or set. 1. to put or place in position or into a specified state or condition: to set a book on the table; to set someone free. 2. (also intr; foll by to or on) to put or be put (to); apply or be applied: he set fire to the house; they set the dogs on the scent.