I had a handful of the usual stuff- Osgood Schlatters, shin splints, sprained ankle, broken hand, but there was also a big ordeal with the unusual. I developed a condition called Paget von Schroetter, a deep vein thrombosis in the subclavian vein. I was just shy of my 13th birthday and extraordinarily young for the condition. It took a few days to diagnose but when the doctors finally figured it out I was told to go immediately to the hospital and the first procedure was done shortly after arrival. For the first procedure I was awake, just had the arm numbed, and had a tube inserted into my right arm to deliver blood thinners. My arm was taped to a board and I had to lie flat on my back. The next day the tube was removed, only to have the clot return. I then had to have the same procedure done again, this time with angioplasty- basically a balloon was inserted into my vein and blown up where the clot was. The vein was still not opened so I had surgery (they actually put me asleep for this one thank goodness!) to remove my right top rib to allow more room. I spent 13 days in the hospital (they only let me out then because it was my birthday and I cried), half of that in the ICU, and then spent 3 more months on blood thinners. I wasn't supposed to go back to gymnastics, but I gave it a shot for 2 more years.
The condition, at least in my case, was caused by too much upper body muscle mass and not enough space for it. The doctors just said that my body was not built to withstand gymnastics.
Fortunately for the parents and gymnasts out there, the condition is really rare, and I was told much more common among construction workers and body builders. I was the youngest person they had seen with the condition.