Every year, millions of athletes across the country undergo routine preparticipation physical exams for sports. Some stand in long lines in crowded gyms. Others visit their regular doctor. But most of them grudgingly undergo the exam, because by rule, they cannot play without one. If anyone wonders why we enforce this rule, I ask you to consider Boston Celtics forward Jeff Green.

Green was preparing to start his first full season for the Celtics, who obtained him in a midseason trade last year for Kendrick Perkins and Nate Robinson. Fans were frustrated with the former Georgetown swingman, who was the fifth pick in the 2007 draft, as he struggled to find a role with the team. He averaged 9.8 points and 3.3 rebounds, but he was expected to improve and be a major contributor this season. The team recently signed him to a one year, $9 million contract.

Days after the contract was finalized and training camp started, observers noticed that Green was not much more than a spectator. He was seen shooting but was never involved in any of the team's full-contract drills. The reason? He did not pass his physical.

Head coach Doc Rivers expressed his concern to the media at that point. "Usually you pass your physical by now. Listen, I'll give you guys more tomorrow for sure. But I've been around long enough to know that if you haven't passed your physical yet, then there's something going on. I just haven't found out, but I've been around long enough to know there's something going on."

On Saturday, the Celtics announced that Green has an aortic aneurysm, which was detected during his physical. Green then consulted with cardiac specialists at The Cleveland Clinic, who reportedly advised him that he needs surgery. Green is expected to miss the entire season. According to the Celtics' news release, the operation "should completely repair Green's condition and that he can expect to resume his NBA career next season"

"An aortic aneurysm happens when the aorta, the large blood vessel that comes off the heart and delivers blood to the entire body, dilates to a size greater than 50 percent over what is normal," says John Ikonomidis, M.D., Ph. D., Chief of Cardiothoracic Surgery at The Medical University of South Carolina and Director of the Thoracic Aortic Surgery program there. "As the aorta expands, the pressure on its wall increases, increasing the risk of rupture."

Green was prepared to start his fifth season in the NBA, and he has played numerous years of basketball at various levels with no mention of symptoms. He surely has undergone a number of preparticipation physical exams in his young career, so I was somewhat surprised that an aortic aneurysm wasn't detected earlier, with Green now 25.

"Usually these aneurysms grow slowly over a long time, and most people with them are asymptomatic," Dr. Ikonomidis states. They often do not even know they have them and are at risk for rupture. A physician might detect a heart murmur if the aneurysm causes the aortic valve to become incompetent, but these murmurs do not always exist. "Often patients go to the doctor for a cold or some other illness, and an aneurysm is detected on a chest X-ray performed for that purpose," he points out.

Green will undergo surgery soon at The Cleveland Clinic. Dr. Ikonomidis explains the typical surgery for a thoracic aortic aneurysm. "The surgeon will place the patient on bypass and arrest the heart. He will cut out the diseased portion of the aorta and replace it with a synthetic graft made out of Dacron." If the surgery and recovery go well, patients get back to running in a few months and ultimately return to all prior activities.

Green tweeted a message to fans expressing his thanks and determination to return to basketball Saturday. "Thank u everyone for ur thoughts and prayers…much appreciated love u all..and I'll be back soon stronger and better than ever I promise."

As an NBA fan and a sports medicine physician, I was shocked by the news, knowing the serious nature of the condition and the surgery. I completely agree with the Celtics head coach, who even before the team's announcement, suggested that there are more important things in life than basketball. "It's life, you know. So let's just hope he's good."

Dr. Geier is Director of MUSC Sports Medicine and an orthopaedic surgeon.

For more information about basketball injuries and other sports medicine topics, please go to Dr. Geier's blog at drdavidgeier.com.