There's been some questions in the comments about the exact nature of Lee's injury, so I've done a little poking around. Here's what I've found regard fractures of the distal radius (Distal, by the way, is apparently a reference to a geographical region of the radius bone, namely the end furthest from the body), culled from this site, which I was led to by a search on WebMD:

A distal radius fracture is one of the most common kinds of fractures (a break in a bone) that can happen to the wrist. It is most commonly caused by falling on an extended hand and usually occurs in children and older adults.

The radius is a bone in your forearm. The distal radius is the end of the forearm bone that is at the wrist. When a person falls on an outstretched hand, the hand suddenly becomes rigid, and the momentum from the fall will cause both a twisting force and a compressing force on your forearm. The kind of injury these forces are likely to cause depends on the age of the person who is injured. In children, and in older adults, such a fall is likely to result in a fracture of the radius.

That gives us an idea of the force involved in the collision with Furcal. If this is an injury usually suffered by falling oldsters with fragile bones and falling youngsters whose bones are still growing, I'd imagine there would have to be quite a bit of energy displaced when such an injury occurs to a grown, very healthy man. They say speed kills, and you have to figure in this instance, Furcal's speed was a contributor to the injury's severity.

In any case, here's some additional information from the American Academy of Orthopaedic Surgeons website:

When someone falls on their outstretched hand, they sometimes get a "broken wrist." The bone that is usually broken is called the radius. It is the larger bone on the upper side of the photograph above [see link provided]. The end toward the wrist is called the distal end. The medical term for "broken bone" is fracture. Therefore, the medical term for the most common type of "broken wrist" is a distal radius fracture (that is, the larger forearm bone is broken near the wrist).

This kind of fracture is very common. In fact, the radius is the most commonly broken bone in the arm. The break usually happens when you fall and land on your outstretched hands. It can also happen in a car accident, a bike accident, a skiing accident, and similar situations. Sometimes, the other forearm bone (the ulna) is also broken. When this happens, it is called a distal ulna fracture.

Again with the high impact, high force situations. That Lee's ulna was also involved gives us another data point about how violent the collision was. Semantically speaking, it's also notable that what's breaking here are technically bones in Lee's arm. I don't know if there's any difference beyond the semantics, but I'm just enough of a nerd to find the possibility interesting.

Anyway, that's what I've gleaned from cursory surfing. Anything to add, plug away in the comments.