Signs of a Torn ACL

Knee injuries can be particularly disabling; leg injuries can make it difficult to walk. If you’ve injured your knee badly, you may have torn your anterior cruciate ligament (ACL). It’s important to seek professional treatment right away so that you don’t damage it further. 

Our board-certified orthopedic surgeon and musculoskeletal and regenerative medicine specialist at Urgently Ortho, in Scottsdale, Arizona, are ready to provide the immediate medical treatment you need for an ACL tear. 

What is an ACL tear? 

Your anterior cruciate ligament has an important job. It joins the large bone in your thigh — your femur — to your shinbone, or tibia, creating the stability you need to walk, run, dance, and move in general. 

If your ACL is completely severed, you may need an operation. After nonsurgical treatment, usually involving physical therapy and recovery, if your knee is still unstable and buckles, your doctor may recommend surgery. You don’t want your knee to give out suddenly and cause a fall and further injury. 

ACL tears are unfortunately fairly common in athletes and weekend warriors; this injury has been called an epidemic. Female athletes are especially prone to injury. If you love sports and play frequently, you’re at increased risk of an ACL tear. Pivoting quickly, as in football, soccer, tennis, or basketball, can cause an ACL tear. The injury can also result from any significant trauma to the knee: a car accident, missing a stair step, or falling from a step stool, for instance. 

What are the symptoms of an ACL tear? 

An ACL tear is a major knee injury. Following are typical symptoms you’ve torn the ligament. 

Popping sound 

Many people who tear their ACLs say that they hear a sound similar to that of a piece of popcorn being popped. It’s actually the ligament tearing apart. 

Severe pain 

You’ll likely experience severe pain at first. In the days after you sustain the injury, the pain may become a strong, deep ache in the entire section of the leg around the knee. 


Your injured leg may look 50 percent bigger than the other one right away. It can take more than a week for swelling to subside. 

Inability to bear weight 

If your tear is severe, you may not be able to bear weight on the leg when first injured. 

Knee instability

As noted above, once the swelling subsides and you’ve received initial treatment, you may find that your knee is unstable. It may move from side to side when you walk or even give out when you’re moving, creating the danger of a fall. 

Incomplete range of motion

You may not be able to fully extend your knee. Your movement is restricted. 

ACL tear treatment 

Immediate medical treatment includes stabilizing the knee, applying ice to reduce swelling, administering pain medication, and ordering an X-ray to rule out broken bones. Your Urgently Ortho physician performs a gentle physical examination of the knee. She is usually able to diagnose a torn ACL from the physical examination and your movement limitations. However, a follow-up MRI is useful to provide pictures of the tissue and determine if you have also sustained cartilage damage, which usually occurs. 

Call or request an appointment with Urgently Ortho through our online portal for all of your musculoskeletal needs.

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