Bell: Many variables will determine Pierce's fate

An audible pop and a buckling of the knee. Paul Pierce's evident pain as he lay on the floor holding his leg in close as if to protect it. Teammates carrying their fallen captain from the floor to his hallway chariot, er, wheelchair. The look of agony on his face as Pierce was wheeled out of sight to be examined.

Any athlete who has suffered a major knee injury knows that a pop, a giving-way sensation, significant pain and an unwillingness or inability to bear weight are all familiar hallmarks that indicate something is seriously amiss. It is no surprise, then, that many watching the game thought they might have witnessed the early termination of Pierce's season. It all painted a picture of gloom and doom for the Celtics' All-Star guard and leader who, perhaps of everyone, deserved to enjoy this moment after surviving some of the leaner Celtics years of late.

But wait! Could it be? After just 1:45 had elapsed on the game clock, Pierce was making his way back to the court at TD Banknorth Garden. Not limping back, mind you, but moving lightly on his feet, practically skipping back to join his team. Sporting a dark sleeve on his right knee for support, Pierce not only re-entered the game but also provided the rejuvenating spark, nailing back-to-back 3-pointers that helped propel the Celtics to a Game 1 victory Thursday.

So what really happened to Pierce in the third quarter? What could look so devastating one minute and turn out to be not such a big deal just minutes later? More importantly, will Pierce be able to play, and play effectively, in the upcoming matchups? These are the key questions arising after Pierce's injury scare in this NBA Finals.

While it is perhaps unusual given his quick turnabout, it is not altogether unrealistic that Pierce, as he claims, could have thought his knee was seriously injured. In his postgame news conference, Pierce acknowledged that he "thought [he] tore something once [he] heard the pop." He added that when he "couldn't move it at first, [he] thought that was it."

A pop in the knee often suggests ligament damage and/or injury to the meniscus, a fibrocartilage disc (of which there are two, one medial and one lateral) in the knee that helps cushion the joint. The body has some natural self-protective mechanisms built in for the knee, including preventing an individual from putting full weight through the leg immediately after significant injury so as to prevent further damage to the joint structures. Certainly any trauma within the joint can provoke pain, which further contributes to the feeling of not being able to bear weight and to the anxiety of the injured athlete. Add to that the adrenaline coursing through the body at a rapid rate, all part of the high level of emotion present during not just any contest, but a championship matchup. It's no wonder that Pierce allowed himself to be carried and carted back to the exam area as he feared the worst.

Once Pierce was in a safe place, far removed from the main court, he was able to then try putting weight on the knee to see how it responded. Pierce saw that he could, in fact, bear weight and could even move side to side. A complete ligament blowout would have prevented him from being able to perform those maneuvers so immediately. Pierce could be reassured that he was not facing a worst-case scenario. With a sleeve to offer some support, a still-warm (and therefore not so stiff) knee and the aforementioned anxiety-producing adrenaline now serving to override the pain, Pierce could, and did, return to the game to finish it out effectively.

Pierce even wondered aloud during his news conference if it was the adrenaline itself that got him through the night. The fact that he could run, jump, turn and even fall to the floor again bode well for his injury being on the less serious side. As far as his actual diagnosis and prognosis, the team will only say that Pierce suffered a sprained knee, a generic term used to describe ligament injury. The fact that he was permitted to return to play suggests that the sprain is not severe, although it is difficult to extrapolate any further without additional details related to his physical exam.

In his postgame news conference, Pierce said, "The doctor said I have a strained meniscus. I'll see how it feels tomorrow, the next day and go from there." Pierce appeared to be pointing to the inside of his knee after his injury, which would suggest that either his medial meniscus or medial collateral ligament (MCL), or even both, were the potential culprits. He was injured when teammate Kendrick Perkins appeared to fall into the back of Pierce's knee, causing him to buckle forward, although it is not easy to visualize the exact collision on the video. For his part, Pierce said that when he saw the replay, "Perkins came down on my foot and at the same time I think I turned my leg while he was on it." Pierce's description would support the notion of an injury to the meniscus. Incidentally, Perkins ended up leaving the game later in the third quarter with a sprained ankle.

The concerns for Pierce going forward, no matter what tissue is injured specifically, are how much swelling he develops in the knee (especially overnight when the knee is immobile, a big reason he was wrapped in ice as he left the Garden) and how stiff and painful the knee is in the next two to three days (which will be influenced by the amount of swelling). If the swelling is significant, Pierce will have difficulty with the range of motion in his knee, and his ability to contract his quadriceps muscle -- the large muscle on the front of the thigh necessary for running and jumping -- will be impaired. If indeed he has injured the meniscus, it can catch or lock within the joint, not only becoming a source of irritation but also limiting his extremes of motion and hindering his ability to twist and pivot. Are these things he can play through? Yes, potentially, but the degree to which his game is affected will be dependent on the variables outlined above.

The medical staff will be working around the clock to help Pierce take any necessary steps to ready his knee for the remaining games, but the drama so evident in every historic Lakers-Celtics championship series has already shown itself in Game 1. Stay tuned, because there is no doubt that this situation will continue to develop.

Stephania Bell is an injury expert for ESPN.com. She is a physical therapist who is a Board Certified Orthopedic Clinical Specialist and a Certified Strength and Conditioning Specialist.