Steinberg told AP that Williams' would be in a sling for four to six weeks and is he's looking at a rehabilitation time of about five months.
The next move will be for the Dolphins, who have not commented on the severity of the injury, to put Williams on injured reserve and officially end his season.
After being injured, Williams refused medical attention on the sideline and actually returned to action when the Dolphins got the ball again. But he took himself out after being tackled following a 3-yard gain.
Williams, who entered the game on a third down on the Dolphins' second possession, finished with 15 yards. He did rush for 5 yards on his first carry to give the Dolphins a first down.
In addition to Williams, running back Jesse Chatman also was injured against the Steelers. He came into the game with a slightly injured ankle and left in the third quarter after what appeared to be a helmet-to-helmet hit from safety Anthony Smith.
The injury was said to be to Chatman's neck and he didn't return.
With Williams and Chatman both injured, the Dolphins turned to Patrick Cobbs, who likely would get the start Sunday against the Jets if Chatman is unable to play.