Is your meniscus weaker after part of it has been removed and easier to tear?

Probably: Partial meniscal removal gets rid of the obviously injured part, but often the meniscus has other "micro tears " and or degenerative changes that while not visible at the time of surgery can be a problem in the future. Re-tear requiring further meniscectomy is relatively rare. Often we see re-tears in patients years after their meniscectomy at the time of a total knee replacement.

Not always.: The goal of arthroscopy for treating a meniscus tear is to remove the portion that is causing the symptoms (pain, swelling, & catching). The remaining meniscus is usually stable & less likely to retear because the unstable portion has been removed. A good analogy is trimming a hangnail to avoid propagation of the tear and prevention of further injury (except arthroscopy is performed under water).