As doctors removed bone spurs from Stiefel's knees, they found that the dancer's tendons were less damaged than expected, ABT spokesperson Kelly Ryan told the Times.
Stiefel's recovery is still expected to take four to six months, the same recovery period cited by ABT before the surgery took place. He plans to dance with ABT in its fall season at New York City Center in October.
Because of his knee problems and the surgery, Stiefel will not be appearing in the company's spring season at the Metropolitan Opera House, which begins on May 22.
Stiefel also recently resigned his post as artistic director of Southern California's Ballet Pacifica, but he and other company officials said that his departure was a result of the cancellation of the 2006-07 season, not his health problems.
According to the Times, Stiefel also had knee surgery in March 2005, for a unrelated problem.