Bryant, 35, injured his left knee in the third quarter of the Lakers' game Tuesday against Memphis. He played the fourth quarter, however. The injury was diagnosed as a fracture of the lateral tibial plateau.
The Lakers said Bryant will miss about six weeks.
"You hate it for Kobe," Lakers Coach Mike D'Antoni said. "He's worked so hard to get back."
The start of Bryant's season was delayed 19 games as he recovered from a torn Achilles tendon, suffered in a game last April. He averaged 13.8 points and 4.3 rebounds a game in the six games he has appeared in this season.
Those figures are well off Bryant's career averages of 25.5 points and 5.3 rebounds a game. Bryant has scored 31,700 points over his NBA career, which began in 1996-97. That point total is No. 4 in NBA history.