Ryan Clark thought that Saturday might be different. Even though he sat out the Pittsburgh Steelers' last two games at Denver -- after suffering a severe medical condition when he played there in 2007 -- Clark thought he might have a shot this week because it's a playoff game.

But Steelers coach Mike Tomlin has decided otherwise. He doesn't want to risk another incident like the last one, when Clark became violently ill and had his spleen and gall bladder removed as a result of sickling after playing in Denver's high elevation.

"Everybody knows I want to play and I would have played," Clark told ESPN. "I talked to my doctors and we actually had a plan in place for me to play. All things pointed to me going until (Tomlin) told me I can't. He said he wouldn't have let his son play, and so I'm not playing either."

Clark, who leads the Steelers with 100 tackles this season, has sickle-cell trait, which can lead to organ damage after exertion at high altitude. His case is the latest in a line of incidents dating back to 1974, when University of Colorado defensive back Polie Poitier collapsed during a workout and died as a result of SCT.

Just this week, the Oklahoma Medical Examiner's Office said that a former University of Tulsa football player who died in September after an unsanctioned boxing match suffered from sudden exertion due to SCT complications.

Sickle-cell anemia can cause chronic problems, with intense pain, life-threatening infections and organ damage. People with SCT carry only one copy of the gene (opposed to two) and are generally healthy. But SCT trait has been a controversial subject in athletics since Rice cornerback Dale Lloyd II died after a workout in 2006. His parents filed a lawsuit, and the NCAA instituted mandatory screening for sickle cell in August 2010.

The testing raised fear of discrimination, since the trait is much more prevalent in blacks. The Sickle Cell Anemia Association of America and a federal panel that advises the Department of Health and Human Services raised objections. A study released last month said that the program alone isn't enough to save athletes from sudden death related to overexertion and exhaustion, also noting that not every case involves SCT.

Tomlin said that the decision to keep Clark out of Saturday's game against the Denver Broncos was easy. "We came to the determination that he is at more risk than the other men on the field," he told reporters. "So we're not going to play him. It's just that simple."

That was the right call. Just like making sure that athletes, trainers and medical staff are aware of SCT.

Being informed beats being ignorant.

Like The Root on Facebook. Follow us on Twitter.