I already touched on the subject in the injuries discussion, but have since found out a handful of practitioners in Finland who train grappling or martial arts without an ACL (complete tear) with relatively little issues.

Curious if we have members here doing the same?

I found last year that I have no ACL anymore in my knee. Looking back to my injury history (this was the first time getting an MRI of the leg) I concluded that it was snapped in a competition match about 4 years ago. I have since, for example, had close to 60 comp matches, and only in one of them the knee gave in.

I have one training partner who also has torn his ACL years ago, and trains both grappling & stand-up arts without an operation, with practically no issues, only mild irritation after kicking.

My issue is basically only that the knee/kneecap can dislocate in certain circumstances, but this has much to do with my peculiar anatomy (bowlegs & kneecap higher than it should be) as well as the lack of ACL. The dislocations have happened approx. once a year since the original trauma, and from all of them (except one) I've been back to sparring fit within a week, with full range of motion in the joint. No special rehab needed. According to the MRI the dislocations have not damaged my meniscus. (The worse downside is the psychological effect: the feeling of kneecap dislocating is very unpleasant and haunts me in training for a while until I learn to trust the leg again.)

The last time the knee popped, I'm quite sure it would've torn the ACL if I had one. :D I'm not looking forward to reconstruction surgery and the following long rehab period, so for now settling to strengthen the legs and keep on training without an operation, like I have been doing for the past 4 years.