A source told Newsday that "If they don't get the joint to move again, [surgery] is probably going to be the only option."
Snee dealt with a similar injury in his other hip for several years, but the pain was manageable and he had surgery to repair it this offseason. This injury isn't allowing him full function of his hip, however, and the Giants started James Brewer this week as Snee was unable to travel.
Having to undergo hip surgery would likely mean Snee would miss the remainder of the season given the nature of said injury. As noted by Hanzuz, Snee considered retirement this season so the surgery could signify the end of his career if he elects to go in that direction.