I take it an orthopedist presents a similar problem.
BTW, here is a cool page with the common knee tests.
http://www.sportsdoc.umn.edu/Clinica...m/lachmans.htm
It step by step with pictures plus vids with normal and symptomatic results. If you were to study them with your wife you could probably do them. And if you look up the individual tests and what they indicate it may help a bit.
Also check this post for some other test plus more info:
http://www.bodybuilding.net/17151-25-post.html
There are a couple other articles in here as well.