More rest will help Tiger's knee both short term and long term

Tiger Woods surprised just about everyone when he announced he had quietly undergone an arthroscopic surgical procedure on his left knee in April. Just days after finishing second in the Masters, making his bid for the Grand Slam in 2008 a moot point, he went under the knife. As it turns out, this procedure was the third on Woods' left knee in 14 years, and it has many asking the inevitable questions.

So what does this mean for the future of the world's No. 1 ranked player? How will his knee hold up when he makes his likely return for this June's U.S. Open as he continues to place the demands of professional golf on his body?

Before looking ahead to the future of Tiger and his knee, it is important to understand what exactly he has endured to date. According to reports on Woods' official Web site, the first two surgeries were of the less common variety. Dr. Thomas Rosenberg of Park City, Utah, who also performed Woods' most recent surgery, operated on him in 2002 to remove cysts and to drain fluid from around his anterior cruciate ligament (ACL).

In 1994, Woods had a benign tumor removed from the same knee. Although neither of these procedures is an everyday occurrence, both are also relatively minor and are not necessarily predictive of any long-term consequences.

Woods obviously went on to play successfully after each incident. In fact, after his December 2002 surgery, Woods returned to his first PGA Tour event the following February, the Buick Invitational, and won it. Where was that event held? Torrey Pines, site of this year's U.S. Open.

So make no mistake, Woods has established a precedent for returning with a bang after an extended layoff.

Woods' latest procedure, according to his official Web site, was an arthroscopic surgery (often referred to as a "scope") to address pain Woods had been experiencing in his left knee since the middle of 2007. Mark Steinberg, Woods' agent, told the Web site that "cartilage damage was found during the procedure, which Dr. Rosenberg was able to correct."

The description suggests there was some flaking or fraying of cartilage present, which can certainly occur in a knee joint as a result of wear and tear, and that a debridement, or clean-up type of procedure was performed to smooth out the rough edges.

So what are the concerns for Woods going forward? Clearly his left knee has suffered some cartilage damage, the extent of which is not fully known to anyone but perhaps Woods and his surgeon. Although these arthroscopic procedures can certainly lessen joint pain, it is important to note that damage to cartilage, the shiny smooth substance that protects the ends of bones and allows joints to glide friction-free, is not reversible.

As the cartilage wears down through its various layers, the end result is bone rubbing against bone. This "bone-on-bone" situation in any weight-bearing joint is extremely painful and the cartilage loss also results in the joint becoming stiffer. Eventually, if the wear and tear on the joint surfaces is extensive enough, a joint replacement may be warranted.

Fellow golfer Peter Jacobsen can attest to the effect of metal joints on the golf game, having undergone a right knee replacement in March and a left hip replacement in 2006. So far the replacements have not kept Jacobsen from golf but instead have allowed him to continue to play. He was 50 years old before he needed that degree of intervention.

Woods, on the other hand, is a mere 32 years young. This is not to say that Woods is anywhere near requiring such a replacement, nor to suggest that he will ever need one at all, but rather to point out that the end result of extensive cartilage damage within a joint can lead to that conclusion.

There are certain elements of golf, both general and specific to Tiger's game, which will impact the overall health of his knee. First, it might come as a surprise to consider how much mileage a golfer puts on the knees over the course of a tournament season.

Walking, while certainly not as stressful on the joints as running, still takes its toll as each step places roughly three times the individual's body weight through the knee (via a combination of muscle activation around the knee and reaction forces produced by the ground when the heel strikes it).

Consider this. The average golf course runs about 7,200 yards. During an "event" week, a golfer will walk the course roughly six times, totaling 43,200 yards, or for those of us that are mathematically challenged, about 24.5 miles. If Woods continues his pace of playing in approximately 17 events per year (his average over the past four years), he will add nearly 416.5 miles on his body for every year that he continues to play.

That translates to a force of three times his body weight through the knee (or roughly 555 pounds), for every step, for more than 400 miles. Now that does not include all of his practice days between tournaments, or his offseason preparation, and it certainly doesn't account for any recreational walking he might toss in there as well. Although there is no definitive marker for how much mileage one can place on a knee before it fails, it is worth considering the amount of force the knee has to endure, simply from walking the course!

In addition to the stress of walking, there is the stress of driving, and we're not talking about the kind where you get behind the wheel. It is no secret in the golf world that Tiger drives the ball hard. Known for having one of the most powerful swings in the business and for being able to drive the ball at speeds well over 100 mph, Woods regularly subjects his knee to significant strain.

Woods' left knee, the one on which he had surgery, is the front knee when he drives, meaning he has to transfer his body weight through to that leg as he swings. Video of Woods as he moves through his swing shows that left knee undergoing a great deal of torsion, or twisting force, as Woods completes his follow-through. The end result is a combined rotation and extension, which significantly increases the compressive force through the knee joint, particularly on the medial (inner) aspect.

While Woods finds the fairway nearly 60 percent of the time he tees it up on the PGA Tour, that leaves about a 40 percent chance that he ends up in the rough. Woods is well known for his strength and being able to hit out of the longer grass. But those swings take an additional toll on the body -- especially the lead leg -- as even more force is required to move the ball forward. The more Woods stays in the fairway and out of the rough, the better his knee will likely feel in the long term.

Woods has even sought to improve his swing with coach Hank Haney. Results of this undertaking may have included taking some of the stress off Woods' body by decreasing the amount of torque and by making his swing more efficient. Although it is hard to imagine there is much to critique when it comes to Woods' game, if there is anything that will contribute to his ability to remain competitive for a longer period of time, it is a sure bet that he will be the first to seek it out.

Beyond the aspects of his golf game itself, there are the elements of Tiger Woods' lifestyle that will serve to enhance his longevity. First and foremost, he maintains incredible physical fitness. It is a physical therapist's dream to have patients who subscribe to the notion of physical conditioning by challenging their cardiovascular endurance, strengthening their core musculature and promoting overall wellness in the way that Woods does.

Woods trains his body beyond his sport, something that will serve him well not only in terms of enhancing his golf career, but in his overall physical health beyond golf. He is also sensible about his schedule. Woods has always been judicious about his game, generally choosing not to play the week before a major tournament and often skipping the week afterward as well.

Woods need only look at Ben Hogan's 1953 season where he played in six tournaments (but won five!) to find confirmation that being selective can still be productive. Woods' latest decision to skip the Memorial, although no doubt a difficult personal one because of his allegiance to the tournament, is a smart one for him physically in that it gives his knee an additional two weeks before it will be submitted to the stress of a major event.

As for his next tournament appearance, Woods is lining up well for his comeback at the U.S. Open in mid-June. Torrey Pines is a course that appears to favor him and he has had much success there, winning six times as professional. Despite the noted difficulty of the U.S. Open venue, Woods' time frame for recovery from his recent surgery, his physical training, his familiarity and fondness for Torrey Pines and his mental fortitude will all have him positioned well to win there. The knee surgery may have been a bump in the road, but it will not be a barrier to Woods' ability to continue to succeed in his sport for many years to come.

Stephania Bell is the injury expert for ESPN.com fantasy.