As the Doctor watched Scotsman after Scotsman fall over the castle walls to their deaths on the small screen, he failed to suppress a wince. The so-called Kamikaze Scotsmen sketch that Jo and Captain Yates were finding so amusing had hit a little too close to home for him...
There had been a hearts-stopping moment when Jamie's battle-cry turned into a shocked and fearful scream that abruptly broke off too soon. In the boy's eagerness to catch his opponent, he had chased and then followed the creature over the edge of the city walls. Had the young piper not miraculously been caught on a decorative carving halfway down, he would've been just as dead as his enemy who lay broken on the ground below.
It took nearly an hour to carefully haul the young boy up, and when he'd been brought in, it had been revealed that he had two broken ribs, some internal damage, and his spleen had needed to be replaced. Since knowledge regarding surgical techniques that were used on humans was theoretical on his part and non-existent on his hosts' part, he had spent a good deal of the operation worrying about whether Jamie would make it off the table or not.
After the surgery, the boy had promised to stay away from the edges of high walls in the future, but not two weeks later subjective time, he was being hauled back into the TARDIS with a broken leg.