Wrists aren't flexible - affecting exercise

When I was in kindergarten, I broke my right wrist. I feel as though perhaps when I was younger following that, I favored it, and thus my left wrist also suffered and wasn't used much. I was in gymnastics as well, and couldn't do a front walk-over, and didn't know why, and have come to figure it out. The problem is, my wrists don't bend back at 90 degree angles. I'd even say they barely go at a 45 degree angle (for front/back walk-overs, you pivet on your wrists/hands, so you'd have to bend then at 90 degree angles to do it without straining them). This is a problem now, because when I go to exercise now, doing regular work outs or yoga, any position that requires me to hold up my body with my hands [push up position, etc.] feels strained because I can't properly bend my wrists [for example, my shoulders aren't directly above my hands when I do push ups, because I can't bend my wrists upright]. I suppose what I am wondering is if there is any way to train or ease my wrists into bending more and more into a right angle (such as, how you can obviously train into being able to do the splits). Is this possible? Or has my childhood injury, and my being careful with it, caused my wrists to forever be less than flexible?