The 35-year-old, who spent almost eight months on the sidelines with a torn left Achilles' tendon before making his comeback on December 8, hyper-extended his left knee during Tuesday's 96-92 win against the Grizzlies in Memphis.Bryant, a 15-times All-Star and five-time NBA champion, had an MRI exam on Thursday and was also examined by a team physician."Results of the MRI show that Bryant has a fracture of the lateral tibial plateau of his knee," the Lakers said. "He is expected to be out approximately six weeks."Bryant's latest injury comes as a major blow for the Lakers, who only last month signed the league veteran to a two-year, $48.5 million contract extension."That's too bad, you hate it for Kobe," Lakers coach Mike D'Antoni said after the team practiced at their El Segundo training facility."He's worked so hard to get back. But he'll be back. He'll be back in six weeks. He's got to weather the storm to get back. We're going to play hard. We have enough guys and enough talent. We'll be fine."Xavier Henry will take over as starting point guard in Bryant's absence, the Lakers said.Bryant, who injured his left knee with 3:25 left in the third quarter of Tuesday's game against Memphis before returning to the court to finish with a total 21 points, posted a brief comment on Twitter on Thursday."#BrokenNotBeaten," he tweeted.Asked on Tuesday to explain what happened during the decisive play when he fell after backing Tony Allen down into the post, Bryant told reporters: "I just hyper-extended it. I tend to hyper-extend my knees every now and then."Bryant's widely anticipated return from his Achilles' tendon injury gave the team a significant boost, though they have struggled to a win-loss record of 2-4 since then.Making matters worse for the Lakers is that all three of their point guards have been sidelined by injury - Steve Nash (nerve damage in back), Steve Blake (torn ligament in right elbow) and Jordan Farmar (torn hamstring).Bryant has averaged 13.8 points, 4.3 rebounds and 6.3 assists in six games this season for the Lakers (12-13) who sit 11th in the 15-team Western Conference.(uk.eurosport.yahoo.com)ANN.Az