Don’t forget to pay attention on the knee position of your young goalkeeper (or handball player) while doing jumps!!!! The example in this video clearly shows incorrect knees position in landing after the jump.

Knee injury prevention – knee position in landing after the jump from Handball Goalkeeper's Coaching on Vimeo.

 
This is very important because we know that the most serious knee injuries occur during landings and in situations that require fast changes of direction (such as feint).

The knees should not fall inward!

If you have a goalie (or player) with this problem, you should know that s/he has bigger risk to get a serious knee injury.
They need additional training with balance exercises and awareness of knees position during different training situations.

Stay safe!