In 1965, he fell and broke a leg after his horse collapsed beneath him. In 1974, he had 16 screws removed from his leg after one nasty fall, and promptly fell again, breaking his collarbone. In 1976, he sustained his most serious injuries after being trampled in a race by several other horses. He suffered seven broken ribs, several fractured vertebrae, a broken wrist and thigh, and a major concussion, and was in a coma for two days. After recovering, he announced, at the age of 57, that he planned to race yet again. Race organizers wisely revoked his license "for his own safety."
Incredibly, over the course of his painful career, the duke managed to finish only one race (in last place, while wearing a plaster cast). His ineptitude was so apparent even in 1963 that when he entered the Grand National that year, bookies placed odds of 66-1 -- against him even finishing the race atop his horse!
[Though the Iron Duke never won a Grand National title, he did break another record: he sustained more fractures than any other jockey in history.]