Can you explain a knee scope for a meniscus tear?

Easy. Arthroscopy is minimally invasive procedure that entails making access points to the affected joints (holes) through which inspection is carried out. Then instruments are introduced in the joint cavity and whatever arthritis is seen is "cleaned up" and the torn meniscus/ligaments are sewn.
Knee arthroscopy. If a meniscus is not ammenable to repair, the torn portion is removed.