Could I join the military if I have had knee surgery?

I'm fourteen and have wanted to join the military since I Was 10, but I had an athletic injury where I tore my ACL, LCL and meniscus. I rehabbed it vigorously and it now feels better than my other knee. I still do exercises to keep it strong,and I am not hampered by it, but the doctor recommended I wear a knee brace for athletics but this is just a precaution and the doctor says the knee is better than ever. I really want this and would be heart broken to learn I didn't have a chance of getting in. Also, if there's anything I could do that would increase my chances of enlisting that would be greatly appreciated. Thank you.