Write a football blog for a few years and you will learn, in a very amateur way, a lot about high ankle sprains.
You will learn how to quickly and effectively explain the difference between a "high" ankle sprain and an ankle sprain.
Why is a high ankle sprain worse than a typical ankle sprain? One can figure it out pretty intuitively, actually. A regular ankle sprain involves an ankle overextending medially. The ankle is designed for some medial movement. That means it can twist and turn from a straight position towards the middle of one's body. That motions is called pronation. It does not move well laterally. That motion is called supination. A lateral, common ankle sprain involves movement of the foot medially. The sprain occurs to the ligaments being stretched rather than the ligaments being compacted. When someone suffers a high ankle sprain, it is because the ankle is over supinated. It has moved too far laterally and strained the ligaments on the medial side.
You will learn that they can haunt some players and be a bad moment in an otherwise healthy career for others. In the above article, both Sean Locklear and Josh Wilson had been diagnosed with high ankle sprains. Locklear has been haunted by the injury and it's possible he lost some of his talent along the way. Wilson has suffered no recurrence that I know of. (You also learn that it's recurrence and not reoccurence like I used to write. Stupid me.)
You will learn hopeful anecdotes, like this from the Seattle Times:
Nov. 9, 1997: Jones missed Seattle's game at San Diego because of a sprained ankle. It was the fourth game he missed because of injury his rookie year, and the last game he missed because of injury until after he suffered a knee injury on Nov. 27, 2008 at Dallas.
That's right, Walter Jones, megastud and everything and more we hope for Russell Okung to become, suffered two separate sprained ankles his rookie season and missed four games. Jones missed time with both a right ankle sprain and a left ankle sprain and his left ankle was "so sore that Jones [couldn't] put any weight on it." Neither injury was classified as a high ankle sprain, but that might just point to the evolving nature of jargon.
Mostly what you learn though is that it sucks when a talented young player is injured, but that there is no way to know exactly what that means to his career or his potential. I find it somewhat heartening that both of Okung's injuries were suffered at the hands of a teammate, not because I get off on that sort of thing, but because it makes the injury seem more "freak" i.e. more like a chance run of bad luck and not evidence of a player that is vulnerable to injury or prone to injury or, blech, whose body is actively breaking down.
Which is to say, in long form, Okung's injury is serious, serious enough for concern and caution, and we're all bummed that such a talented kid has been slowed in his fated journey of domination and exploitation of the NFL, but he may follow this disheartening start with ten consecutive seasons of pristine health. We have no way of knowing.