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 $c=f(x,y,z)$.
The amount or percentage of weight reduced at each step is also one aspect of the method with much variety. A wide drop set method is one in which a large percentage (usually 30% or more) of the starting weight is shed with each weight reduction. A tight drop set would remove anywhere from 10% to 25%. These definitions are somewhat arbitrary, of course, and not everyone will agree on the exact definitions.