While I'm doing a little bit of a necropost, Chad is very correct about the McMurray's test. It can be pretty accurate, but you have to know that it can cause a lot of false positives and negatives. The test is actually easier to perform than to explain with words. I perform the McMurray's in a very similar way that Chad does. Basically I also cup the patient's foot and and heel so that I'm basically supporting the leg and then I make a "C" with my other hand and put the thumb and forefinger right along the joint line.
While extending and flexing the knee, you externally and internally rotate the tibia in the hope that you're going to cause the meniscus tear to kind of "pop up" and get caught between surfaces, thus causing the "click." I've also put a little varus and valgus pressure (nowhere near enough to test for MCL/LCL stability) on the joint to stress the specific meniscus I'm checking from time to time.
As to the false positives, sometimes the clicking you may feel is debris floating in the joint that happens to get caught, or it can be a plica that gets pinched a little bit. The test can also cause a false negative in that if the tear is NOT in a direction that won't normally result in the tear popping up or if the tear simply isn't big enough to get caught between articulating surfaces, you might not get the expected "click."
The varus/valgus force that I use to check for MCL/LCL laxity is much different that what I'd use in this test.
While I'm not an ATC, I missed becoming one simply because my supervising ATC dropped off the face of the earth right after I graduated... by moving away quite unexpectedly for me and for her. Life also got in the way preventing me from "redoing" the hours with another ATC. Otherwise, I'd be an ATC as well...
I miss the training room... but where I'm at now provides better health insurance and retirement.
Oh, and I start RN school this August.