I do remember a serious injury at a playground. It was when I was in 2nd grade, back in 1966. One of my classmates had the wooden seat break in the swings at school, he fell out backwards and broke both arms.
Of course, in 1966 his parents did NOT sue the school.
Swingset seats were changed to the strap kind within a month, however.
Same thing happened to my brother back in 1959, broke both arms after jumping out of the swing set backwards. Never occured to my parents to sue the school.