Knee ACL Injury

The ACL… What is it?

Knee ACL injury compared to a healthy knee

The anterior cruciate ligament (ACL) is one of the four major ligaments in the knee. A ligament connects one bone to another bone as in the illustration above. It is an important structure that provides stability to the knee. It is commonly injured when an impact or blow is sustained to the outer knee (that is one of the reasons “clipping” was banned in football). Sometimes the ACL is torn without getting hit.

What happens when you tear your ACL?

This is the most common scenario that I hear in the office. When a patient tell me this story, I have already made the diagnosis.

“DOC, I got hit. I went down. Everyone heard a LOUD pop. I couldn’t get back up. I was carried off of the field. I couldn’t go back in the game. I thought it was broken. I went to the ER and got an x-ray because I knew something was wrong.” The knee swells immediately and gets to “grapefruit” proportions.

Initial Treatment

  • “RICE” Rest. Ice. Compression (an ace wrap). Elevation. This is important to do right away.
  • X-rays should be done to make sure that there are no dislocated or broken bones.
  • An MRI can confirm the diagnosis.
  • Non-surgical treatment includes activity modification, physical therapy and a special brace.


Surgery is done to create a new ACL. Bone-Patella Tendon-Bone is the graft I use most often to reconstruct or recreate the ACL. A new ACL graft is carved out of the knee using bone from the front of the knee cap (patella) part of the patella tendon and bone from the top of the shin bone (tibia). This is carved out of the knee, shaped and sized to match your knee and slides inside the knee in the same direction and with the same attachment sites as the original ACL. Some surgeons use hamstring grafts, posterior tibialis tendon grafts or cadaver grafts (allografts). Your surgeon can spell out the options for you.

After Surgery

  • Hit the gym baby!
  • Physical therapy and post-op rehabilitation is the key to a successful result.

Post-operative goals should include:

A. Swelling control
B. Range of motion
C. Thigh muscle strengthening and retraining.

Most people return to contact sports with a brace at the 6th month!

Check out the AOSSM link to view a 3-D animated video of ACL surgery.

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Orthopedic Surgeon Modesto CA Dr. Eric Giang

Dr. Eric Giang, DO

Dr. Giang is a leading fellowship-trained shoulder surgeon in Modesto, CA. As a trusted orthopedic surgeon, he is serving the Modesto community with a commitment to enhancing the quality of life for every patient.

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