Interview with Dr. Sally Harris about ACL Injuries

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The Anterior Cruciate Ligament (the ACL) is one of the four ligaments that stabilize the knee joint. Without the ACL, many people feel as though their knee is "giving way" and they cannot walk comfortably.

In this interview, Dr. Sally Harris of the PAMF Sport Medicine Department talks about treatment options for ACL injuries.

How does this injury happen?
Dr. Harris: This injury is specific to sports that involve starting, stopping, pivoting and turning with some speed -- particularly in sports like basketball, soccer, volleyball, football, field hockey, skiing and lacrosse. There are two ways the injury happens:

• Landing on an overly straight (hyper-extended) knee.


• Pivoting the leg inward (internal rotation) with a foot planted, without the foot pivoting as well. This can happen in contact and noncontact injuries.

How is this injury usually diagnosed?
Dr. Harris: Usually there is significant swelling, and there are only a few injuries with this amount of swelling. There is an exam maneuver done to test for looseness of the ligament (if it is firm it is not torn, and if it is loose, it is likely torn), and an MRI is usually done to confirm the diagnosis.

How is this injury typically treated?
Dr. Harris: If the injury is in an adolescent who intends to go back to sports that involve pivoting, s/he will need surgery. If the injury is in an older person, the injury may not need to be repaired.

What is the recovery like if this injury is treated with surgery?
Dr. Harris: The patient will need to be on crutches for about one week, and have physical therapy twice a week for a month. Then they can start biking, jogging, and swimming, but need to wait approximately four months before going back to the sport that requires any pivoting or turning. This is because the surgery includes adding some new ligament, which will get weaker before it gets stronger and takes this long to heal.

How can teens prevent an ACL injury?
Dr. Harris: This is really a hot topic because ACL tears are much more common in female than male athletes. There has been a lot of research done about why this is the case, and the results suggest that it is not because of the physiology or hormones of the female body. Instead it is more likely to be:

• Muscle imbalance in the thigh. The quadriceps muscles overpower the hamstring muscles, which need to work together to straighten (extend) and bend (flex) the leg.


• The way female athletes move during their sport, remaining more upright with their knees less bent than their male counterparts. This puts the ACL in a vulnerable position.

Prevention programs include 15 minutes several times a week training to learn how to:

• Stop and start keeping the knee straight over the foot. This avoids the knock-knee position that makes the ACL vulnerable.


• Keep the knee straight over the foot while standing on a block and jumping.
  Strengthen the hamstring muscles.

Read more about Sports Injuries on the PAMF We're Talking Teen Health Web site.