First, who this section is and is not about. Meniscal tears come in two broad kinds. A traumatic tear happens to a specific knee at a specific moment, usually a younger one, usually with a twist and a pop. A degenerative tear is wear: the meniscus frays over years, and it is extremely common in middle-aged and older knees, including knees that do not hurt at all. This section is about the second kind only. It does not apply to traumatic tears, to meniscal repairs, to younger patients, or to a knee that is genuinely locking or blocked — those are different situations with different answers.
The finding this page is built on For degenerative meniscal tears, arthroscopic surgery was compared against a SHAM operation — patients taken to theatre and given a simulated procedure. Both groups improved substantially, and the difference between them was not significant: knee scores rose 21.7 points after real surgery and 23.3 points after the sham.
That is the New England Journal of Medicine in 2013, in patients who had a symptomatic degenerative tear but no established knee osteoarthritis. Five years on, the same trial found the surgical group had a slightly higher risk of developing radiographic osteoarthritis with no accompanying benefit on symptoms or function. And a separate randomised trial of 321 people, mean age 58, found exercise-based physiotherapy still noninferior to surgery at five years — its authors conclude physiotherapy should be the preferred treatment.
Source: Arthroscopic partial meniscectomy versus sham surgery for a degenerative meniscal tear, New England Journal of Medicine (2013), PMID 24369076
The most important part of that result is the part people skip. Both groups got substantially better. This is not a finding that people with degenerative tears do not recover — they do, and by a lot. It is a finding that in these trials the improvement did not depend on the trimming. If you have already had this operation and your knee is better, nothing here says otherwise, and there is no reason to read it as a verdict on your own care.
If you have not had it yet, this is a reasonable and specific thing to raise: is my tear degenerative or traumatic, and would a course of physiotherapy be a sensible first step in my case? Sometimes the answer will be no for a good reason — a true mechanical block, a bucket-handle tear, a knee that will not straighten. Your surgeon has your imaging and your examination; a webpage has neither. But it is a question the strongest evidence in this field supports asking, and the trials above are what you would be asking about.