The ACL ligament, which is the anterior cruciate ligament in the knee, holds the tibia in place and keeps it from sliding and moving in front of the femur. This ligament can be torn as a result of hyperextension, pivoting and twisting, which are all movements in many sports. As a result, many athletes have unfortunately torn or damaged one or both of their ACLs. This knee injury is also common in women. An ACL tear will make a partial tear or stretch intensely painful.

Popping Sound

One common symptom of a tear of the ACL ligament is a popping sound in the middle of your knee at the time of the injury. This is your anterior cruciate ligament breaking in two, or in the case of a partial tear, ripping a little bit. This sound is also linked with the feeling of a rubber band snapping. In some cases, you may snap your posterior and your medial collateral ligaments in the same injury.

ACL tear


Immediately after the injury, you will typically feel sudden and extreme pain. Athletes that experience an ACL tear say it's a burning or a searing pain that can be extremely intense, indicating the severity of the injury. Even if you think you know what's happened, a doctor still needs to perform an X-ray to confirm the tear.

pain ACL tear


Within a few hours of the time if injury, you can expect to see and feel some swelling in the area. Swelling around the ACL tear is brought on by fluids, including blood from the tear, flowing into and around the injury. In most cases, there is no open wound through which this blood could be released, so it builds up behind the skin around the torn ligament. Apply ice to your injury as soon as possible to reduce the swelling.

swelling ACL tear

Warm to the Touch

Your ACL injury is likely to be warm to touch under the swelling. This is a sign of the inflammation resulting from the accumulation of fluid and blood around the tear. The longer the swelling goes untreated, the more likely inflammation is likely to occur.

warm to the touch ACL tear

Restricted Movement

If you have torn your ACL, you won't be able to straighten the knee to its full extension. If you stand on the knee when the ACL is sprained, but not torn, you will still feel as if it might give way at any moment, and walking will be extremely difficult, and painful. Your ordinary movements will be heavily restricted, and you are likely to require some form of help to get around.

movement ACL tear

Difficulty Bearing Weight

Once you have torn your anterior cruciate ligament, you'll find it extremely hard to walk, since the ACL is one of the four main ligaments that surround and support the knee. Any weight will cause your knee to give way completely and cause much pain. If you can't put any weight on your knee, it is a sure fire sign that you have torn something important. Surgery is available to repair the ligament, but you may also heal without surgery by taking on physical therapy and rehabilitation.

bearing wight ACL tear

Tenderness in the Joint

Any injury to a joint subsequently leads to tenderness after the initial pain has subsided. Even if the pain lasts for weeks, a knee joint that has experienced an ACL tear will continue to be tender to the touch. Swelling may be reduced, and the injured knee may look just like the other one, but the pain is still there. A simple joint line tenderness test, which is often used to diagnose meniscal tears, can help determine how severe the injury is.

joint ACL tear

Loose Joint

Particularly in the case of a partial tear, where you are still able to walk and put some pressure on the knee, the knee joint tends to feel loose. This is understandable, as the strings that hold it together have partially torn away, much like a marionette puppet without one string attached. Even with a brace to help the knee stay aligned and in place, the interior feeling of a loose joint can stay with you throughout the healing process.

joints ACL tear


Deformity in the knee when a complete tear occurs is seen soon after the initial injury happens. These deformities include swelling, bruising, asymmetry compared to the other leg, and other physical differences between the healthy knee and the knee with an ACL tear. When the ACL has been overstretched or had a partial tear, these small deformities can come on gradually if the ligament doesn't heal properly.

deformity ACL tear

Separable Bones

The shinbone should not move away from the knee at any time. If you have an ACL tear, the Lachman test can determine whether the ligament is still attached. When lying down, a doctor or therapist places the injured knee at a 30-40 degree angle. Holding the femur with one hand, they take hold of the lower leg at the top of the calf muscle and pull slightly up and away from the knee. If the ACL is torn, there will be a sloppy movement of the bone coming away from the knee. If not, there should not be much movement at all within the knee joint. Please do not perform this test on someone who has freshly injured their ACL.

bones ACL tear


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