The hip injury Bo Jackson sustained playing football in January could end his careers rather than simply delay his baseball training.

The San Diego Tribune reported Friday Jackson may have avascular necrosis, a loss of blood circulation to the bone which causes the bone to die.The newspaper cited a source close to Los Angeles-based medical personnel who know of Jackson's condition, which has prevented him from taking part in the Kansas City Royals' training camp.

Dr. Gary Losse, the San Diego Chargers team physician, had no direct knowledge of Jackson's case but told the Tribune that a person can be born with the condition or it can be brought on by an injury - such as the one Jackson sustained Jan. 13 during an AFC playoff game for the Los Angeles Raiders.

"Usually it is brought on by a trauma," said Losse. "The injury hinders the blood supply to that part of the bone."

The Tribune said its source reported that the injury was at the top of the femur bone where it joins the hip.

"If that is the case, that is not a good place," Losse said.

The condition is not considered life-threatening but could require a hip replacement.

The Royals and Raiders have not acknowledged Jackson has the condition. Jackson arrived in Royals camp more than two weeks ago and has been told to remain on crutches.

Royals General Manager Herk Robinson told the Tribune he was not familiar with the term "avascular necrosis," but that Jackson was scheduled for a bone scan and Magnetic Resonance Imaging in Kansas City, Mo., Friday. Those results were to be sent to Dr. Jim Andrews, a prominent orthopedic surgeon, in Birmingham, Ala., for further tests Monday.

"By Tuesday we should have a better idea," Robinson said from Haines City, Fla., where the Royals train. "Dr. (Steven) Joyce (the Royals team doctor) said it was best to put him on crutches to take the weight off of the joint so there would be a better chance of healing."