For-if patient has mechanical symptoms.

Against-if complaint is only pain, and all other conservative measures have not been exhausted.

The problem is most likely an arthritic knee.  The knee system is deranged.  

Try to improve the knee system-diet, weight modification, alignment, muscle function-(regionally strength; systemically vita D??), improve bone health/homeostasis.

If that meniscal issue is associated to osteoarthritis, then the artrhoscopy has Insufficient evidence that it is useful. (Nelson AE et al, Seminars in Arthritis and Rheumatism 43 (2014) 701–712).

If the patient has no osteoarthritis, then a traumatism could be the cause of meniscal tear. In this case, a classification of severity of the meniscal tear should be taken in account: mild to severe, even bucket handle tear. This might be outweight against the physical demands of the patient. Arthroscopy might be helpful in moderate cases affecting the mobility/walking of patients after other several non surgical measures incluiding exercise, protective measures did not help or the patient is still having effusion.

For severe cases, as bucket handle tear, arthroscopy should be considered as soon as posible, because conservative measures will not help and disability, loss of function and pain usually deteriorate the quality of life of patients.

I send my patients for arthroscopic surgery when there is painful locking and catching despite adequate physical therapy measures. It is helpful to address weight issues and joint mechanics prior to surgery. 

There are a couple of high quality randomized controlled trials of arthroscopic knee surgery for meniscal pathology in particular that have not shown any significant benefit. 

To answer your question though, I first ask if they have severe enough arthritis to send for joint replacement. If so, forget about arthroscopy; they should go for arthroplasty. If they don't have arthritis, and they have failed all other conservative measures, I send them to the surgeon for arthroscopy. Will it work?

I have two answers:

1. The best evidence does not really support it, but these studies have their limitations, and it is considered the standard of care in many places regardless of the evidence. 

2. The surgeon is the best judge of that question, so I let the surgeon decide on the answer to that question. In my experience reputable surgeons will turn patients away if they don't think that the surgery will help.

I provide links to 2 studies: One in those with meniscal tears and OA and one in those with meniscal tears without OA. These studies have their limitations, and there are definitely some patients to whom they do not apply:

http://www.nejm.org/doi/full/10.1056/NEJMoa1305189

http://www.nejm.org/doi/full/10.1056/NEJMoa1301408

I have been doing arthroscopic surgery during the last thirty five years. In spite of being now 61 years old, I still practice contact sports at least twice a week without any sign of OA in my knees. If I had a torn meniscus by now, I would ask a surgeon friend to do an arthroscopic procedure.  There are cases and cases. Hope this report will be of some help.

The arbitrary distinction of 50 years is precisely arbitrary and irrelevant.  If there are signs of degenerative disease (OA) then there are lots of evidence that arthroscopic treatment is not indicated (see recent Finnish article in NEJM)

If, however, the meniscal tear is in an otherwise healthy knee, the condition should be treated as it is in younger individuals, i.e. by arthroscopy.

Remember that most people that die, do so with healthy knees, that is without OA.

Arthroscopic management is generally useful and effective in the well-selected patients over 50 years. The main problems in these patients are degenerative meniscal tear or chondral damage (chondromalacia.). We can treat degenerative meniscal tear and grade II-III chondromalacia effectively.

However,only arthroscopic treatment is inadequate for chronic meniscal root tear with degeneration and III-IV chondromalacia. Especially, meniscal root tear is at high risk of retear due to low healing potential after arthroscopic fixation regardless of the method.  Accordingly, we perform HTO after arthroscopic debridment  in active patients with chronic meniscal root tear accompanied by grade III-IV chondromalacia, and think that this method is very effective. 

I have practice with good results with conservative treatment with LLLT, of knee by patient with meniscus degeneration and chondromalacia too. 

LLLt is effective if the meniscus has not been ruptured.  

I have had good results with physical therapy management. Also, there are some papers related to this issue. Furthermore, arthroscopic meniscectomy had same results compared to sham. 

Kind regards

http://www.ncbi.nlm.nih.gov/pubmed/23506518

http://www.ncbi.nlm.nih.gov/pubmed/24369076