One day before training camp was set to open, the Sixers announced Monday they would shut down their new franchise All-Star for three weeks as a precaution after he received knee treatment in Germany.
Bynum was grounded before his first practice in the No. 33 jersey.
"I'm going to do everything in my power to get back," Bynum said.
Bynum had injections of plasma-rich platelets that supposedly stimulate healing in arthritis-affected areas in both of his knees. The Sixers said last week he was cleared to play in camp. Bynum felt some discomfort late last week and, after meeting with doctors in New York and Philadelphia, the Sixers made the call to bench him. The Sixers wanted to give him enough time to have the treatments take hold in the knee.
The team said Bynum also had a bone bruise on his right knee. Bynum said the bone bruise was unrelated to the knee treatments.
Bynum came to Philadelphia with an oversized warning label on his achy knees. He's been plagued by problems in the past, one reason he sought out the same treatment - called Orthokine - in Germany used by former Los Angeles teammate Kobe Bryant and New York Yankees third baseman Alex Rodriguez.
Bynum said this current knee ailment isn't as bad as the issues that have dogged him in the past. He reported no swelling in his knees.
"I feel a lot better," he said. "The Orthokine is definitely working."
Bynum, 7-foot and 285 pounds, said doctors advised he have the knee treatment closer to the season for maximum effectiveness. Bynum said he had the injections during the third week in September. He will continue to participate in low-impact conditioning drills.
The Sixers open the regular season Oct. 31. Bynum would have about a week between his scheduled return and the opener.
"At this point, I just need to go out and work on my craft," Bynum said. "I should still be able to do that, even with being shut down."
The injury throws an unwanted wrinkle into the start of coach Doug Collins' third season. Collins led the Sixers to the playoffs each of the last two seasons and was rewarded Monday when the team picked up the option on his contract for the 2013-14 season.
Collins said he wants to remain with the organization in some capacity when his coaching career is over.
He said Bynum was "incredibly down" about not being able to play.
"He is so champing at the bit to come in here and live up to all the expectations that have been placed on his shoulders," Collins said. "He knows what's at stake."
Collins doesn't want to end his coaching career without winning a championship, something the Sixers believe they're closer to because of Bynum. The Sixers acquired Bynum from the Lakers in a four-team deal that saw them ship Andre Iguodala to Denver. He is set to make $16.1 million this season in the final year of his contract.
The news spoiled the early part of the day for a Sixers team with real expectations to reach the Eastern Conference finals. Bynum is one of several new additions, joining Jason Richardson, Kwame Brown, Dorell Wright and Nick Young, who are counting on using training camp to adapt to Collins' system and build some chemistry. Brown, Lavoy Allen and Spencer Hawes will all play at power forward and center.
"I don't think it'll be an issue," 76ers guard Jrue Holiday said. "But I think we'll be a lot better once Andrew comes back."
Bynum was expected to soon help the Sixers win their first championship since 1983. Only 24, the New Jersey native won two championships with the Lakers.
Bynum is coming off his best NBA season after averaging career highs with 18.7 points and 11.8 rebounds while making his first All-Star team, starting for the West. He was the NBA's third-leading rebounder and 20th-leading scorer, while also ranking sixth in the league with 1.93 blocked shots per game.
Bynum also avoided the injuries that have dogged him throughout a seven-year career since the Lakers made him the youngest player ever drafted in 2005. Bynum played in 60 of the Lakers' 66 regular-season games, missing four due to suspension.
He was ready to embrace becoming the face of the franchise.
"I'm looking forward to the opportunity to kind of cement yourself and take the next step in your career," he said.
The Sixers had a packed offseason that saw them land Bynum and name Tony DiLeo general manager. The latter is a firm believer in analytics and wants the Sixers to use the Moneyball-type of thinking popularized in baseball. Sixers owner Josh Harris is a believer, as well. He said the team was close to hiring experts in statistics and analytics that would report to DiLeo.
"We're inching closer," Harris said. "It's likely to be more than one person, but there will be one person that's in charge of it. We haven't finalized the specifics around the exact title. But, by and large, it's going to be a pretty significant effort."