Andrew Bynum is considering arthroscopic knee surgery that would end any chance of him playing this season for the Philadelphia 76ers, general manager Tony DiLeo said.Meanwhile, the organization has yet to decide whether to sign the one-time All-Star center when he becomes a free agent after this season.“He is Plan A,” DiLeo said. It was his first public comments about Bynum since the 7-footer on Friday announced a setback in his rehab from what could be career-threatening knee injuries.The 76ers gave up young prospects in Nikola Vucevic and Moe Harkless, along with former All-Star Andre Iguodala, in the four-team deal that moved Dwight Howard to the Los Angeles Lakers last summer. They built their entire team around Bynum as the building block. He has not played a minute because of knee troubles.Should Bynum get healthy and sign somewhere else, it would be a colossal blunder for the Sixers. Bynum experienced knee soreness over the summer, then injured his other knee bowling.The Sixers might still be able to get something for Bynum if they don’t re-sign him, in the event of a sign-and-trade, but that would require a team with cap space to absorb him and return assets. Bynum has previously said he’s interested in playing for Houston, which has the assets, but would the Rockets want to take on the risk of Bynum, given his health?Bynum is not worried about getting the deal he wants, nor should he. It’s a weak free-agency class, and he’s a top-quality center in a terrible time for centers.But for everyone else, the risk is severe and complicated. We’ll keep you updated on whether Bynum goes in for surgery.