He is reported to have a "high ankle sprain", from this piece it seems like it can be more serious then a normal sprain:
All About High Ankle Sprains
Jim Brown June 26, 2009
Overview
Just the term “high ankle sprain” is enough to grab the attention of, if not frighten, the toughest athletes. Even if you're not exactly sure what's involved, you probably know that it's an injury that could keep you out of action for months. And you're right. High ankle sprains are much less common than the garden variety low ankle sprain, which can be serious enough, but they're hard to treat and can cause long-term problems.
“In a high ankle sprain, the ligaments that connect the two lower leg bones together are injured,” explains M. Ramin Modabber, MD, of the Santa Monica Orthopaedic and Sports Medicine Group.
“The location is higher up the leg, it is usually associated with a higher degree of injury, and requires a longer time to recover and return to sport. The forces on these ligaments are greater and they need to be healed before athletes can tolerate running, jumping, and cutting—another reason for the longer time to return to sport."
While you can often return from standard ankle sprains in days or weeks, Dr. Modabber says high ankle sprains can take weeks to months.
■A grade 1 sprain is the mildest form of injury and consists of a stretch to the ligaments.
■A grade 2 sprain is a partial tear of the ligaments.
■A grade 3 sprain is a complete tear.
In spite of increased awareness, the mechanism of high ankle sprains is still not completely understood, and there is an ongoing debate about the best ways to diagnose and manage the injury
add on: I saw his interview on talkin ball and he said he heard/felt something "pop", that is often something tearing