What does ACL reconstruction surgery involve?
McCulloch: The surgery itself is done on an outpatient basis. We can't repair that ACL so we just make a new one. ... We'll take a tendon -- either from somewhere else on the patient's knee or from a donor ... it's fixed to the femur and fixed to the tibia.
Mishra: It typically is a much bigger deal than just a knee arthroscopy [the type of surgery Woods had in April]. You've got to reconstruct the ligament, which is a bigger challenge than doing just a meniscus surgery. It takes an hour and a half or two hours of time, depending on how they do it.
When is ACL reconstruction surgery needed?
McCulloch: The decision whether or not to reconstruct the ACL ligament is based on several factors, the most important of which is the patient's desired activity level and type of activities they engage in.
If someone has a low demand on their knee and they tend to participate in linear sports such as jogging or running or swimming, they may do fine without having the ACL reconstructed. And in fact, Tiger went on to win five of his next six or seven tournaments after he had rehabilitated from the torn ACL itself.
However, one concern is that when the knee has an abnormal motion to it, if you do engage in cutting-and-pivoting sports, the knee can continue to give way, and this can cause further damage in the knee.
There's a high rotational torque to the knee in the forward leg during a golf swing, and this is Tiger's left knee, which is his forward leg. With an ACL-deficient knee, you do run the risk of developing further tears in the meniscus over time.
Mishra: It's amazing he won the U.S. Open, given the fact he didn't have an ACL reconstruction [earlier]. To be able to compete at that level with that sort of disability is flat-out astounding.
He tore his ACL in 2007. According to what his agent released, he planned on trying to compete as much of the season as possible, especially through Torrey Pines [the U.S. Open]. He might have planned this and said, 'Let's see how far I can go.'