Terms used for the potential options allowed by the NCAA for players with incapacitating injuries are sometimes confused. There are different choices based on the injury's severity.
MEDICAL HARDSHIP (A.K.A. MEDICAL REDSHIRT)
A student-athlete can apply for a medical hardship waiver, which allows for an extra year of eligibility, if he or she suffers an injury or illness that prevents them from finishing the current season. The injury must occur during the first half of the season, and the player can't have participated in more than three games (or 30 percent of the scheduled games, whichever is greater). The Big 12 Conference determines whether to grant the waiver, but it can be appealed to the NCAA if denied. The medical hardship is sometimes called a “medical redshirt,” but can be used to gain a sixth year if an injury occurs when the player has already used his or her regular redshirt season.
Examples of OU football medical hardship waivers: Jason White (1999, 2002, suffered a back injury as a freshman and then had ACL tears in back-to-back seasons, allowing him to return for a sixth year, one season after winning the Heisman Trophy); Dusty Dvoracek (2005, was dismissed after allegations of violent, off-the-field behavior as a senior in 2004, had a hardship waiver denied by the Big 12 before a successful appeal to the NCAA, which allowed it on the basis of alcohol addiction).
A medical exemption can be given to an athlete who suffers an injury or illness that ends their career. It ensures that, for their remaining eligibility, they receive all the financial aid they would have received before the medical problem. A medical exemption does not count against the program's scholarship limit (for football, it is 85), but is still paid for from the program's budget. If the injury occurs during a season, that player still does count against the scholarship limit. Once the season ends, they can be moved to medical exemption and another scholarship is freed up.
Examples of OU football medical exemptions: Dylan Dismuke (2012, knee injury); Laith Harlow (2012, back injury suffered while still in high school, but committed to OU); Corey Wilson (2009, car accident left him paralyzed).