by Rob Mitchum and Matt Wood

When superstar Derrick Rose crumpled to the ground late in the Chicago Bulls game Saturday, the playoff hopes of Chicago basketball fans followed suit. Experienced sports fans saw the point guard grabbing at the front of his left knee and thought immediately of three dreaded letters: A, C, and L. Sure enough a subsequent MRI confirmed that Rose had torn his anterior cruciate ligament, an injury that would knock him out of this year’s NBA playoffs, the Olympics, and a significant chunk of the next season.

Despite the long rehabilitation time, an ACL tear is a common injury for athletes playing sports that involve frequent cutting and pivoting. J. Martin Leland, assistant professor of surgery at the University of Chicago Medicine, performs 75 to 100 ACL reconstructions each year on recreational athletes who injured themselves during basketball, soccer, lacrosse, or skiing activities. On Monday, after repairing the ACL of a cricket player, Leland sat down with ScienceLife to discuss how ACLs are torn, how they are repaired, and “the perfect storm” of factors that may have led to Rose’s injury.

Q: First of all, what is the ACL?

The ACL is one of four major ligaments in the knee that stabilize the knee. You have one ligament on the inside of the knee called the MCL or medial collateral ligament, one ligament on the outside of the knee called the LCL, or lateral collateral ligament, then two ligaments in the center of the knee: the ACL, which is right in front of the PCL, or posterior cruciate ligament.

The ACL is most important for rotational stability of the knee, so if someone has an ACL rupture, once the knee comes down and the swelling goes away, they’ll find they can walk, jog, go up stairs, no problem. Then, if they get an MRI showing an ACL tear they’re very confused: “How can I possibly have an ACL tear if I can walk without difficulty with no pain?” But the ACL is not important for walking, it’s important for rotational stability.

Q: What happens to a person’s knee right after they tear the ligament? Are they in pain?

The ACL has an artery that runs right up the center of it. So the first thing that happens is the knee typically swells up like a balloon in a matter of an hour to two hours. Normally people have difficulty putting weight on it because it just feels weird. Some people will describe a pop, other people won’t, but you’ll feel like a sharp shooting pain in the knee, and then it will be gone, and it won’t really hurt. But the knee typically tends to get very swollen within 1 to 2 hours usually, and will stay swollen for up to a week, so people tend to say they have trouble putting weight on it for anywhere between immediately after the injury and four or five days. After that they can put weight on it, but the knee is very stiff, and it takes anywhere between a week and three weeks for that swelling to go down and the stiffness to go away so that you can get range of motion again.

Q: With Rose’s injury, Bulls trainers were doing knee exams right on the court after he collapsed. Can a doctor diagnose an ACL injury that quickly?

The Lachman exam is the name of the test that’s typically done to test the ACL. It’s done with the knee at 30 degrees of flexion. Basically, you stabilize the femur, and with your hand on the tibia, you just kind of pull up. If you feel increased laxity, or the tibia pulls forward on the femur more than what’s normal, you know right off the bat that they tore their ACL.

When I watched the video, I could tell that he had ruptured his ACL without even examining him. The sportscasters couldn’t tell the instant when he injured it, they said he jumped up and was complaining of pain, so maybe it was the jump. But it was when he planted, immediately before jumping. If you watch the clip very carefully, you can see he comes in, plants, and his left knee bows in, so that the knee comes towards the right knee as well as rotates, and then he comes out of that and jumps up. That’s why he dishes the ball off, because the second the knee went in that position, he felt it pop, and felt the pain, and you can see for a split second the classic valgus instability where the one knee moves towards the other knee and ruptures the ACL.

Q: Was it unusual that Rose injured his knee without being struck by another player or running into an object?

The most common way of tearing your ACL is non contact. It was the perfect storm for Derrick Rose to rupture his ACL. He’s missed much of the season because of his prior four injuries, and he’s only been back playing for three weeks, and it was in the last minute and a half of the game. He can’t possibly be at full strength because he missed so much time, so his muscles are more weak.

He went to make that sudden stop, and normally, if he was a little bit stronger, his muscles would have fired and kept his knee still. But his muscles were fatigued and they just gave out, and once they gave out, his knee started going into that position. Basically, he was coming in and stopped with such force that normally his muscles would have kicked in and stabilized his leg, but because his muscles were weak, his knee just kept going, and then ruptured the ACL. So it was really the fact that he wasn’t at 100 percent strength, and the fact that he was fatigued at the end of a game.

When you hear about skiers rupturing the ACL, it’s almost always in the afternoon, because someone like myself who is a recreational skier is not used to 8 hours of sports participation because we work all day. In the afternoon, my muscles are tired and fatigued, and that’s when my knee gets in that bad position.

Q: Is the ACL the most fragile knee ligament, or do sports fans just hear about those injuries more often?

The most commonly injured ligament in the knee is the MCL. But the MCL when injured in isolation, it heals very well non-operatively. So some people will be in a knee brace for six weeks and then get right back out there. Professional football, if it’s a mild injury, they might not even miss a game. People are injuring their MCLs all the time but we never hear about them, because it’s not nine months until you come back, it’s anywhere between two and six weeks.

Q: Is basketball one of the worst sports for causing ACL injuries? Who’s at highest risk for the injury?

There are some studies that have been done, and it’s been shown that women who play soccer and basketball have a much higher likelihood of developing ACL ruptures, versus men or women who play other sports. It hasn’t been shown in men’s sports that basketball is any more dangerous than say football or soccer.

It’s sometimes shown that women have an even higher risk of rupturing their ACL than men. There’s a 2 to 4 times higher rupture risk in women that play soccer or basketball in comparison to male counterparts, because of different reasons. Hormones tend to stretch out ligaments and estrogen can cause increase rupture of ligaments when there’s stretching at certain times of the menstrual cycle. Women also have proportionally smaller ACLs, even accounting for the fact that women are slightly smaller than men. But there haven’t been any research to show that men who play basketball are at a higher likelihood of injury than men who, say, play soccer.

Q: When the ACL is torn, is the treatment always surgical?

Assuming the ACL is completely ruptured, generally speaking with a cutting and pivoting athlete, especially a high level athlete, the treatment is always surgical. In patients that have a partial ACL tear where the cell fibers have been stretched but not completely torn and it’s just a little bit loose, they can usually be treated with rehab and then getting them back to sports. But if the fibers are completely torn, you usually recommend reconstruction because you can’t repair the ACL. If you try to put stitches in the ACL, they’ll just pull right through. You’ve got to actually pull that torn tissue out and put other tissue in its place, either from the patient’s patellar tendon or from their hamstrings. Occasionally, people will use a quadriceps tendon or tissue from someone who died, which is called an allograft or cadaveric tissue.

The reason why we recommend surgery is because 90-plus percent of people who have an ACL tear will continue to have instability, and if they try to get back into sports without having reconstruction, it’ll pivot out of place again. Every time the knee pivots out of place, you risk doing damage to the cartilage or the meniscus, and sometimes you can actually do damage that can’t be repaired. If you allowed Rose to continue playing, he probably wouldn’t be able to play, because every time he’d pivot on his knee, his knee would buckle, it would swell up, and he’d be done for the game. Then it will buckle again as soon as he went back on the court, and he might do more permanent damage that can’t be repaired and could lead up to shortening his playing days.

Q: How serious is the surgical procedure?

It’s outpatient surgery, the patients come in and go home the same day. Sometimes they wear a brace post-operatively for anywhere between two and six weeks depending on the surgeon’s preference. Within six weeks they’re walking around doing fine, usually very good range of motion in the knee, but it’s still quite some time until that ACL can be healed in, and quite some time until they get their strength back.

Q: What is a reasonable amount of time to expect Rose to be sidelined?

With recreational athletes we tend to let people get back to sports at about six months, because it takes about six months for the graft to heal in and for them to get some of their strength back. However, professional athletes obviously have to be at a much higher level of function, and need to be much stronger than your recreational athlete. In order to get that recreational strength, usually professional athletes will say anywhere between 9 months and a year.

When I was working with the Philadelphia Eagles, Donovan McNabb tore his ACL and had it reconstructed. Nine months into his recovery he was telling reporters he was about 75 percent back, because he understood in order to get back on the field, he had to be literally 100 percent, the best shape he’d ever been in in his life, or else he would get crushed by someone on the defense. Recreational athletes tend to get back a little sooner because you don’t need that same level of strength. But for professional athletes it’s usually 9 to 12 months, which means not only will Derrick miss the entire playoffs, no matter how long they go for the Bulls, he’ll miss the Olympics, and probably miss anywhere between the beginning and the entire first half of this next season.

Q: Over those nine months, what is happening? Is it all rehabbing to get the strength back in the new ligament

For the first 2 to 4 weeks, you’re trying to decrease swelling, make the patient more comfortable, get the swelling out of the knee so the quads can function. When the knee has a big swelling in it, the quads actually shut down, they go to sleep. So you’re getting the swelling out of the knee, getting the range of motion back, and making the patients feel comfortable.

In months 1 through 3, post-operatively, you tend to slowly start working on a little bit of strengthening but not pushing things too hard because you’re still really allowing that ACL to be healing in. Months 4 through 6 you’re really starting to work on strengthening, you’re getting more confident that the ACL is either healed in or mostly healing in, and really starting to work on strength. And then months 6 to 9 to 12, you’re really working on getting that 100 percent strength back so you can get back on the field.

Q: What are the chances of re-injuring the knee after an ACL reconstruction? Will Derrick Rose ever be the same player again?

The treatment has changed a lot, it’s constantly changing. The way in which we do ACL reconstructions is very different, especially with where we put the ACL, from what we did even five years ago. However, it’s been a very successful surgery for quite some time. We frequently will tell patients that 90 to 95 percent of people will get back to complete activity with no problems from where they were pre-operatively. But what we’re finding now from the long-term literature is that with procedures from 10 to 20 years ago, maybe only 50 percent of people truly got back to that elite level of activity. But techniques are constantly changing, it’s been a very successful surgery for quite some time. I would even venture to say that when we look back 15 years from now, we’ll have even better results than what we had 10 years ago.

For Derrick Rose, who is only 23 years old, this is not going to be a career ending injury for him, he will get back.

Q: Are there any common myths you often hear from patients about ACL injuries or reconstruction?

One myth would be that not every person needs to have their ACL reconstructed. I would say that every athlete needs to have their ACL reconstructed; if you tore your ACL playing a sport, you probably need to have it reconstructed if you ever want to play that sport again. But if you have a 60-year-old patient who missed a couple stairs and ruptured their ACL, they could do very well non-operatively, just as long as they don’t play any cutting or pivoting sports, or any aggressive cutting or pivoting maneuvers. If you imagine the average 65-year-old patient, they’re not really doing very much cutting and pivoting, and they might do well without surgery.

Ed. note, February 2015: Since this article was published, Dr. Leland has moved on to become the medical director of sports medicine at University Hospitals Geauga Medical Center in Cleveland, Ohio. Science Life thanks him for his many contributions to this blog.

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