When I was in the process of destroying my ACL through series of partial tears and when I finally tore it, that's what it felt like for a while - like it was loose. It was, I had torn it and stretched it and now it's gone. The only way to compensate for that other than getting a new one, is to tone up the muscles that surround the knee to tighten it all up and take up the slack with the stretched ACL.

Obviously something has happened to your ACL and although it's hard to see how that would happen with cycling, someone needs to analyze why this happened to you and what motions your knee is going through when you are cycling (if that's how it happened). This is the domain of the PT's in conjunction with sports medicine MD and maybe a sports physiologist. You need to get to the bottom of this conclusively.

It's worthy to note, that to help get to the bottom of my problem, a friend is a PhD Physiology at a world famous medical facility who gave me some good advice and helped figure out what the problem was. He said this is relatively common difficulty because X-rays don't show the soft tissue and the MRI's don't show the non soft tissue well, so it can be hard to put together what is happening when the two interact and you have a problem.

Get to the best knee guys you can find and get to the root cause - specific knee specialists as PT, MD and who are acquainted with range of motion issues. It's going to be a major hassle and it's going to take some time, but you need to do this. Would absolutely be best if they were looking at this as a team so that you get all perspectives argued through and they come to a consensus and know how to test for it.

Obviously, I'm not a doc and I am probably wrong about this, but I've been dealing with ACL issues for 30 years and have spent a lot of time investigating this whole thing vis a vis my issue. What you describe, I've never heard of and it sounds a lot like someone reaching for an explanation on a mechanism of injury they don't understand as well as the injury itself.

J