His knee was injured in a basketball practice, untraumaticly.
What Tanner looks like when they're putting in the i.v.
He was annoyed I took his picture.
A normal knee. Shows the upper and lower leg bones, and the "padding," or meniscus that cushions the bones.
That huge blob is the tear, or shred. That's the portion that was cut away, as shown in the lower portion of the picture.