What is an ACL Tear?

The Anterior Cruciate Ligament (ACL) is located in the center of the knee. It runs in a diagonal orientation. It is attached to the bottom end of the thigh bone (femur) and the top end of the lower leg bone (tibia). It helps prevent the tibia from moving forward toward the front of the femur. The ACL also helps provides rotational stability to the knee. When an activity overloads the ligament, the ACL can tear. Often this injury occurs as a result of compromised body mechanics, such as falling back when landing a jump, suddenly changing direction, or a direct collision which places the knee in an awkward position. Athletes involved in high level cutting and pivoting sports such as skiing, soccer, football, and basketball are more prone to ACL tears. Female athletes sustain ACL tears more frequently than male athletes.

Dr. Cunningham is a knee specialist at Vail Summit Orthopaedics. He is an expert at diagnosing and treating ACL tears for patients in Vail, Summit County, Aspen, and Denver, CO.

How Do ACL Tears Happen?

Most often ACL tears occur during sports. These are usually non-contact injuries, where there is not a collision. The most commonly reported events involve:

  • Suddenly changing direction such as when cutting or pivoting
  • Coming to a sudden stop while running
  • Pivoting while the foot is firmly planted
  • Poor mechanics when landing a jump
  • An out-of-control, high energy action
  • A collision with another player

ACL tears occur because the ligament is stretched beyond its normal limits. Most ACL injuries are complete tears, although partial tears occasionally occur. Other structures in the knee may be damaged at the same time. For instance, the medial and/or lateral meniscus commonly tear when the ACL tears.

Factors that predispose one to have an ACL tear include:

  • Young, female athletes 
  • Participation in cutting and pivoting sports
  • Poor core strength
  • Imbalances in the strength between the muscles in the front and the back of the leg as well as poor hip muscle strength.
  • Improper equipment
  • Ill-fitting, or improper footwear
  • Playing on artificial surfaces or uneven ground

What Does a Torn ACL Feel Like?

A torn ACL typically causes immediate symptoms. If symptoms are not immediate, there is a notable change in a patient’s condition within the first 24 hours. Most commonly, symptoms include:

  • An initial popping sound, similar to a rubber band snapping
  • Swelling
  • Pain, usually intense and often coupled with a burning sensation
  • Progressive limitation in normal knee range of motion
  • Significant reduction in the weight bearing capacity of the knee
  • Developing tenderness to the touch
  • Sensation of looseness in the knee joint
  • Warm to the touch due to joint inflammation
  • Change in appearance of the knee as compared to healthy knee
  • Abnormal movement of tibia away from knee, when examined

Does an ACL Tear Cause Swelling?

Swelling is one of the main symptoms of an ACL tear. In addition to the initial period of pain and diminished function, blood and fluid fills the knee joint causing swelling. This typically begins within the first 2 – 3 hours. The body normally reacts to injury by flooding the injured area with healing and protective fluids, along with the bleeding that occurs from tearing the small blood vessels within the ACL. When fluid fills the knee joint capsule, the knee feels tight and stiff. The use of ice will help control the amount of swelling and lessen pain.

Can You Walk with a Torn ACL?

Most patients can put partial or even full weight on the leg and walk with varying degrees of difficulty. However, some patients require crutches. Patients may not trust the knee as it feels unstable. It is advisable to limit walking, so as to limit the swelling and resultant pain.

Following an orthopedic evaluation and when injuries such as a fracture to the knee are ruled out, your doctor will allow you to put as much weight as you tolerate on the knee. However, you should limit the amount of walking you do or you will increase swelling and pain. It is also important to avoid twisting on the knee or else the knee may give out again. Knee bracing often helps make the knee feel more stable. Week by week, the knee will feel better and better after an ACL tear. However, returning to high level activity with a torn ACL is not recommended as then the knee may forcefully give out again and cause more damage to the knee.

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Can an ACL Tear Heal on its Own?

Non-surgical management is most often successful in patients such as:

  • Middle aged or older adults who are sedentary and/or who are employed in light duty work
  • Partial tears without a patient feel unstable
  • Adults with complete tears who choose to give up cutting and pivoting sports and who do not feel unstable with everyday activities.

Physical therapy consisting of swelling reduction techniques, easy range of motion, and gentle strengthening is encouraged. Pain management, ice therapy, and alternate fitness practices not impacting the progress of the knee are used as necessary.

For younger patients or for patients who are unstable with the activities that they enjoy, ACL reconstruction surgery may be recommended. ACL surgery is one of the most common surgeries performed on the knee. Many patients report a full return to activities after ACL surgery. Dr. Cunningham is a knee specialist at Vail Summit Orthopaedics. He is an expert at diagnosing and treating ACL tears for patients in Vail, Summit County, Aspen, and Denver, CO. Contact him today.

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