Sorry to burst your bubble, but the matter of a fact is – if you haven’t injured your knee while training BJJ so far, there’s a high chance that you’ll injure it sometime down the line. And when you do injure it, it’s really important to know how to handle it.
Therefore, here’s a simple step-by-step guide for you to follow. There’re a lot of details that will make your recovery different from other people’s; but these pieces of advice will serve you well no matter what.

TAKE THE PAUSE

The first thing you should do after sustaining an injury is to rest. After you’ve heard that pop or snap, you won’t continue rolling immediately. Instead, you’ll pause for a bit, sit out a round or two, and see what’s going on.
Sure, perhaps it’s nothing to worry about. But more likely than not, it is something to be concerned with; and the absolute worst thing you can do is to train through an injury. This only maximizes the chances of your injury becoming a serious one.

SEE A DOCTOR

You wouldn’t imagine the number of Jiujiteiros who sustain a knee injury and refuse to see a doctor. The most common reasoning behind is: „The doctor isn’t going to suggest anything else other than a surgery or rest. And I already know that it’s going to be one or the other, so what difference does it make?“

It makes a whole lot of difference. A BJJ practitioner may be hesitant to have that surgery because of fears that it’ll keep them sidelined for a long time… But if they don’t get that surgery, there’s a really high probability that they’ll get sidelined even longer; because they haven’t had their surgery and because the problem only became worse with time.

DO YOUR KNEE REHAB

After you see your doctor and physiotherapist, get to doing your rehab. Once again, it’s remarkable just how many Jiujiteiros skip this very important (if not the most important) part of the recovery equation. They excuse it with „just being lazy“ or by making an argument that „it will solve itself on its own“.

Well, yeah it may solve itself on its own – your injury will heal. But what won’t solve itself is the range of motion of your knee. Plus, you will be much more susceptible to additional injuries down the road.
The point is, do what you know you should be doing. Don’t ignore it, don’t be lazy about it. Your Jiu Jitsu longevity and quality depends on it.

WAIT A BIT BEFORE RETURNING TO THE MATS

Then, don’t be too quick to return to the mats. Let your body heal; if you’re too stubborn and don’t provide it with enough time, you’re setting yourself up for further injuries, much more serious and long-lasting ones.
So, do what you can instead. Go to the gym, lift some weights. Swim. Watch instructionals and Youtube videos. All of this will aid your progress!

BE TACTICAL WHEN YOU RETURN

Finally, once you’re back on the mats, make sure to be tactical in the beginning. This means rolling with people you can trust (evade beginners at all costs), staying clear from standing and kneeling positions (as they leave your knee prone to getting twisted and bent and re-injured) and doing more Half Guard instead.
It means doing more positional rolling and slowly picking up speed in your drills and rolls as the time flies by.

All of this will make sure that your knee heals properly and that you are good to go in the shortest amount of time possible.