Pittsburgh Steelers safety Ryan Clark will not play in Pittsburgh's playoff game against Denver this weekend, head coach Mike Tomlin announced Tuesday. Clark carries the sickle cell trait, which becomes especially dangerous in high-altitude, low-oxygen conditions, which the Steelers will be experiencing Sunday afternoon in Denver.

The last time Clark played in Denver, it cost him his spleen, his gallbladder, 30 pounds and the rest of the season. Since that 2007 game, the Steelers have played in Denver twice, and Clark was held out of both of those games, too.

Here's Steelers head coach Mike Tomlin:

Admittedly, I'm an outsider who knows nothing about any of this, but holding Clark out of the game seems like the responsible decision to make. An easy one, too. If one game was that harmful to him, you don't let him put himself in that situation again. There's football, and there's life. Like Tomlin said, it's that simple.

A lot of people with sickle cell can lead perfectly normal lives with treatment. Clark is proof of that, having made himself a world-class athlete despite the condition. In a small number of patients, though, physical exertion at high altitudes can be really dangerous.

Sickle cell works by preventing red blood cells from traveling through the body, depriving vital organs of oxygen. At high altitudes, getting enough oxygen is hard enough. That's what happened to his spleen in the 2007 game. Oxygen deprivation damaged it to the point it had to be taken out with emergency surgery. Later, his gallbladder had to come out, too.

I'm sure it's tough for Clark to have to sit out a playoff game, but when you measure the pros and cons, it seems like no decision at all. Ryan Mundy will start in his absence.

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