Photo courtesy of Dr. Christopher Kaeding
Anyone who follows sports, from children’s intramural teams up to the professional level, has certainly heard of the anterior cruciate ligament (ACL) – and the injuries it can sustain.
The ligament, located in the knee, is prone to tears for those who engage in certain types of athletic activity. Dr. Christopher Kaeding, executive director of sports medicine at The Ohio State University Wexner Medical Center and head team physician in the department of athletics, discusses the causes and prevention of and recovery from ACL injuries.
What activities and types of motion most put the ACL at risk?
Most ACL injuries occur in competitive cutting sports such as soccer, football, basketball, rugby and lacrosse. The common denominator is that the athlete is making a sudden, violent deceleration move – a sudden stop or a sudden change of direction. With a violent quadriceps contraction, you put an increased load on the ligament, and the ACL can snap or pop.
What are the signs that an ACL may be weakened or prone to injury?
Poor control of the hip girdle; letting the leg fall into what’s called the condition – that means the knee kind of falls inward and goes into a knock-kneed position; landing from a jump with your hips and knees more extended as opposed to landing deeper and softer; and not learning to land and co-contract your hamstrings and your quadriceps can all increase risk of injury. At OSU Sports Medicine, we have the world’s expert on the biomechanics and risk factors, Dr. Timothy Hewett. In his lab, he can identify risks by putting patients through screening tests to determine who might be at a high risk of tearing the ACL if they play a contact sport.
What are the indications that the ACL has been injured?
In the typical ACL injury, about 70 percent of people will hear a pop or shift in their knee. They’ll fall to the ground and they’re unable to continue playing, and within two hours, there’s swelling in the knee. But because it’s often a non-contact injury, some people will underestimate the seriousness of the damage and will continue playing.
What other factors might make someone more likely to tear his or her ACL?
ACL injuries often have a genetic component; they tend to run in families. There’s a high incidence between twins; if one has an ACL injury, there’s a greater chance the other twin will have one. And if you tear an ACL in one knee, you have more risk of tearing the ACL in the other knee.
Can an ACL injury lead to problems later in life?
The potential problems with tearing your ACL are threefold. The first problem is a trick knee – that’s a knee you can’t trust for those running-jumping-leaping types of activities. The second problem is a torn meniscus. The third problem is it puts you at greater risk for arthritis later in life. The younger you are, the more all three of those issues are a problem.
What factors determine the best route to recovery from an ACL injury?
Age is the biggest determinant. The younger you are, the more likely you are to have problems with the knees if you try to live your life without an ACL. Conversely, the older you are, the more likely you are to do OK without the ACL. Obviously, there are always exceptions, but as a general rule, most knee specialists would say if you’re healthy and under the age of 30, you’re better off going through life with a stable knee than with an unstable knee, so we recommend reconstruction.
What is the surgical solution for a torn ACL?
You need to find something with which to build the new ACL. Now, that can be an allograft from a donor, it could be a hamstring graft from your own body or it could be a patella tendon graft from your own body. There are some new, experimental techniques being used to repair the ACL, but for all practical purposes, 99 percent of ACL injuries are reconstructed, not repaired.
What does nonsurgical recovery entail?
The physical therapy treatment really entails neuromuscular training, which means strength, balance and protective reflexes. The second part of nonsurgical recovery is modifying your activities by avoiding those that make the knee sore, swollen, buckle or give way.
What can one do to reduce one’s chances of suffering an ACL injury?
The No. 1 thing to do if you want to avoid an ACL tear is avoid playing cutting competitive sports. If you do play those sports, you should undergo an ACL prevention program, which involves neuromuscular training. They work on how you land and cut to decrease the risk. They won’t eliminate the risk, but they can reduce the risk of an ACL injury.
Are ACL tears becoming more common? Why?
I think they are more common. We have more people playing more cutting sports at a higher level year-round, so we’re seeing more injuries.
Studies have shown women are decidedly more likely to injure their ACLs than are men. What explains the difference?
It’s multi-factorial. For a given exposure, women will tear their ACL anywhere from double to five times the rate that men will, and most of it has to do with how they land and control the forces across the hip and knee. Studies have asked questions: Are the ligaments smaller? Is elasticity a factor? Do the sizes and shapes of the bones play a role? But really, I think it’s how they land and how they control their knees. For example, when a man lands from jumping off a box, his legs and knees bend more, and he keeps his knees aligned directly over his feet, whereas women land upright and the knees tend to turn inward and go into that knock-kneed position. Researchers are trying to develop a way to screen some of these women without having to put them through this $1 million lab and identify the techniques for how they land from an 18-inch jump or drop. If the knee seems to collapse inward, they’re at risk and would benefit from some neuromuscular training.
EXPERT
Christopher C. Kaeding, MD, is executive director of The Ohio State University sports medicine department, head team physician for the OSU athletic department and a professor in the OSU department of orthopedics.
Kaeding received his bachelor of science degree and his medical doctorate from Northwestern University in 1979 and 1983, respectively. He completed a general surgery internship at Northwestern in 1984, an orthopedic surgery residency at Northwestern in 1988 and a sports medicine fellowship with the Cleveland Clinic Foundation in 1989.
He has been at OSU since 1991 and helped establish the OSU Sports Medicine Center. He was interim chairman of the department of orthopedics from 2006 to 2009.
