I've recently learned how to spot a torn ACL from a normal one on an MRI.  Fun party trick huh?  I'm no expert though so don't send me your MRI images :)

A couple normal ACLs:

If you look at the arrows you can see the black band which represents the ACL.  It's supposed to be solid and undisturbed/uninterrupted.

A couple torn ACLs:

 
This ACL is completely messed up.  Probably a full tear.   You can't see really any black band at all.

 
Partial tear?  I'm no expert.  The ligament is bowed which is also bad I guess.

Jessica's Knee:

My ACL is definitely interrupted (sort of like the movie Girl, Interrupted? I'm working on the sequel: ACL, Interrupted).  Some could argue it's still attached if you look close enough.  It's also not bowed which means it's not very lax?  Hmm.  The MRI reader called my ACL a high-grade partial tear which means at least 50% of the ACL is disrupted. Also, I think because there is black on both ends of the ACL, that is what they mean by "fibers still intact".  I'm no expert but I don't see 50% interrupted.  One of my docs thinks the MRI was "over-read".  Either way, it's a moot point really.  A partial tear, no matter how partial will require surgery if the knee is not stable or the ACL does not heal.  Only time will tell...

Jessica