When we get injured, we tend to rest, and we usually get the fear that if we practice “too soon” we might hurt our self again or more severely, or we will not be able to perform.
It is important to rest after an injury, for the amount of time doctors prescribe. It is also important to get back to activity and move our body again, even the injured part, cautiously and mindfully.
Simon Borg Olivie in his interview about natural movement says: "if you never use something, if you never move it, then it’s going to be very stiff. It’s like saying you got a sore ankle, let’s put a bandage on it, let’s keep the bandage on for the rest of your life. It doesn’t make sense. To lock the ankle with a bandage while it’s heeling is fine. But generally you take the bandage off the ankle."  

So remember that and when you next going to practice after injury, slow down, listen to your body, remember to move the area that is injured – so it won’t become stiff, move it cautiously, but don’t be afraid to move.

 Here are some tips for practicing after injury:

*  Gradually come back to activity
So, as we said it is important to move! Gradually come back to the practice, maybe it will be shorter practice time, less days, less intense practice. Maybe you will have to get back to basic even if you already were advanced. Bend knees, hold the posture shorter, do variations of the pose. Don’t let your ego hurt your body :) it is all for your health. With time you will get back to were you stopped before the injury.
 

*  Bend knees & use accessories
This is an important one in the world of yoga. Our knees connected to the ego, and it is connected to what I said in the first paragraph. Don’t let your ego prevent you from heeling.
Bend the knees almost in all the poses with this variation, it will help you reach further while taking less toll on the legs. It helps to deepen the poses without stress of straight legs, this flexibility will come with time, but the alignment of bent knees prevent other or more injuries.        Another thing that can help prevent injuries, help you reach further in some postures and take less toll from areas tend to be stress – accessories. Blocks, chairs, wall, folded blankets, books, bolsters. Everything can use you as accessories during the practice.
 

*  Move from the core, keep Bandhas  
Our natural movement start from the core, not our legs, hands or shoulders. Keep that in mind during all the practice. In every posture, move from the core. Here I explain about the bandhas https://goo.gl/OQRng5 which are locks we can use to our benefits in the practice. There are also locks to major joints; wrists, shoulders, hips, knees, ankles. So this is all part of moving cautiously and preventing more injuries.

When you feel you can come back fully to practice, the injury is healed and your doctor certify! don’t hesitate to speed up your pace and get back to your normal.

Good luck, don’t stress it ;)