Not Exactly Par for the Course

Woods's ACL Injury Seen As a Rarity in Pro Golfers

Experts on knee injuries were puzzled yesterday over the announcement that Tiger Woods suffered an injury -- rupture of an anterior cruciate ligament -- almost always associated with fast-paced, quick-cutting sports such as football, basketball and lacrosse, but almost never with golf.

They speculated that there is more to know about the events leading to Woods's decision to have the ligament surgically replaced, ending his season on the PGA Tour. However, they did not rule out that this was a rare consequence of Woods's play -- and one more example of the limit-breaking athleticism he has brought to his sport.

Woods's Web site, which announced the injury and the golfer's plans, said he ruptured his left ACL in 2007 "when he was running at his home in Orlando." At the time, he elected to forgo surgery "and instead attempted to play through the pain," according to the announcement.

"I don't know we have all these pieces of the puzzle," said Nicholas DiNubile, an orthopedic surgeon in the Philadelphia area and consultant to the Philadelphia 76ers. "You don't have to be tackled, but you do have to be moving pretty quickly to tear an ACL. It is not a wear-and-tear injury."

William N. Levine, an orthopedic surgeon and director of sports medicine at New York-Presbyterian Hospital, agreed.

"It is not usual in straight-ahead running or jogging to tear ACLs. Until we have more information from the surgeon or the athlete, it is going to be very difficult to understand," he said.

Woods has undergone three previous operations on his left knee, the last one in April to, as his Web site statement put it, "clean out cartilage damage." Two previous operations -- one in 1994 and another in 2002 -- were done to remove a benign tumor, and later to remove fluid inside and outside the anterior cruciate ligament and to remove benign cysts.

Whether those growths weakened the ligament is unknown, but one expert said yesterday that was possible.

"If you think about the torque that Tiger generates and the speed with which he swings, you don't have to go too far out on a limb to say that was the nature of the injury -- especially if the cyst may have compromised the integrity of the ligament somehow," Levine said. "Otherwise, it is hard to understand exactly how this occurred."

Whatever the exact cause of the injury, experts predicted that with the much-improved modern surgery for ACL ruptures, Woods probably will regain full function.

"This used to be a career-ending injury for athletes. Now we say it is a season-ending injury," DiNubile said.

The anterior cruciate ligament runs inside the knee joint in a diagonal direction, connecting the lower end of the thigh bone to the upper end of the main bone of the lower leg. It prevents the thigh bone from moving backward, and prevents the entire knee joint from straightening too much (also known as hyperextension).