Let us say you say "injuries to the knee" Or "injuries of the knee" injuries of the knee makes it sound like it could have happened 6 years ago - a 100 years ago. When you say injuries to the knee it makes it sound like it has happened recently, and your narration is in the recent past, so you don't want to make it vaguely sound like it could have happened a long time ago, so you use the better preposition. The preposition you want to choose is to.
New words, one handy idiom, and a 2-minute quiz — delivered to your inbox to keep your streak alive.