What Does a Torn ACL Feel Like
The anterior cruciate ligament, or ACL, is one of the main ligaments stabilizing the knee. It plays a key role in balance and movement, especially during pivoting, jumping, or sudden stops.
ACL injuries are common among athletes but can also happen during everyday activities like slipping or awkward landings. According to the American Academy of Orthopaedic Surgeons (AAOS), an estimated 100,000 to 200,000 ACL injuries occur each year in the U.S., many requiring surgery for proper recovery.
This article explains what a torn ACL feels like, how to recognize the symptoms, and what to expect during diagnosis and treatment, helping you stay informed and confident in your next steps.
What Is a Torn ACL?
Understanding the ACL
The anterior cruciate ligament (ACL) is one of four major ligaments in the knee that connect the thigh bone (femur) to the shin bone (tibia), along with the posterior cruciate ligament (PCL), medial collateral ligament (MCL), and lateral collateral ligament (LCL).
Together, these ligaments stabilize the joint and support knee movement. Located in the center of the knee, the ACL plays a crucial role in stabilizing the joint, especially during movements that involve sudden stops, pivots, or changes in direction.
When the ACL is torn—either partially or completely—it can lead to pain, swelling, and a feeling that the knee is unstable or may “give out” during activity.
How ACL Tears Occur
ACL tears often happen suddenly and are usually the result of quick, forceful movements that put stress on the knee joint. Some of the most common causes and risk factors include:
- Sports injuries – High-impact sports like basketball, soccer, and skiing often involve quick turns and jumps that can strain the ACL.
- Sudden stops or pivots – Abrupt changes in direction or speed can put excessive pressure on the knee.
- Awkward landings – Landing off-balance after a jump can twist the knee and damage the ligament.
Torn ACL Symptoms
Common Symptoms of a Torn ACL
Recognizing the symptoms of a torn ACL is key to getting the right treatment early. Many people notice the injury right away because of the sudden impact it has on the knee. Common signs include:
- A popping sound or sensation – Many people report hearing or feeling a “pop” at the moment of injury.
- Immediate swelling – The knee often begins to swell quickly within the first few hours.
- Loss of range of motion – Bending or straightening the knee may become difficult and painful.
- Instability or a “giving out” feeling – The knee may feel loose or unstable, especially when trying to stand or walk.
Symptoms of a Torn ACL vs. Other Knee Injuries
A torn ACL often causes a sudden pop, quick swelling, and knee instability, while other injuries like meniscus tears or MCL sprains may feel different.
Meniscus tears can cause the knee to catch or lock, and MCL injuries usually cause pain along the inner knee. Because symptoms can overlap, medical imaging—especially an MRI—is important for an accurate diagnosis and proper treatment.
What Does a Torn ACL Feel Like?
A torn ACL is often felt immediately. Many people describe hearing or feeling a sudden “pop” in the knee at the moment of injury, followed by sharp pain and an inability to bear weight.
As the swelling sets in, daily movements become difficult. The knee may feel unstable, especially when walking, turning, or going down stairs. Twisting motions can cause discomfort or a sense that the knee might give out.
Without treatment, symptoms often persist. Many experience ongoing looseness, weakness, or chronic pain and swelling, especially during physical activity.
Can You Walk With a Torn ACL?
Short-Term Mobility After Injury
In the short term, some people can still walk after tearing their ACL, especially if swelling goes down or the tear is partial. However, this can be misleading, as the knee may still be unstable and prone to giving out during movement.
Long-Term Implications
Walking on a torn ACL without treatment can worsen the injury over time. Ongoing instability may lead to additional damage to the cartilage or meniscus, increasing the risk of long-term joint problems and arthritis.
How Is a Torn ACL Diagnosed?
Physical Exams and Initial Assessment
Diagnosis often begins with a physical exam. Tests like the Lachman test and pivot shift test help assess the stability of the knee. Doctors also observe for swelling and check the knee’s range of motion to evaluate the extent of the injury.
Imaging and Tests
An MRI is commonly used to confirm an ACL tear by showing damage to other knee ligaments and any related injuries. X-rays may also be done to rule out fractures, especially after trauma or impact.
Imaging tests like MRI not only confirm an ACL tear but can also help identify damage to surrounding structures, such as the medial collateral ligament, meniscus, or posterior cruciate ligament.
Torn ACL Recovery and Rehabilitation
Treatment Options
Treatment depends on the severity of the tear and the individual’s lifestyle. Non-surgical options, such as physical therapy and the use of a knee brace, can help manage ACL tear symptoms and provide support for those with partial tears or lower physical demands.
In contrast, surgical reconstruction is often recommended for athletes or active individuals with complete tears who want to return to high-level activity.
Torn ACL Recovery Time
Recovery varies based on the treatment approach. Without surgery, patients may regain function in 3 to 6 months through consistent physical therapy. With surgery, full recovery typically takes 6 to 12 months, depending on healing and rehabilitation progress.
Before and After Torn ACL Surgery
- Pre-Surgery (Prehab & Evaluation): Focus on reducing swelling, regaining basic movement, and completing imaging tests like MRI to prepare for surgery.
- Swelling Control (Weeks 1–2): Ice, elevation, and rest help manage swelling and pain after surgery.
- Range of Motion (Weeks 2–6): Gentle exercises restore knee flexibility and prevent stiffness.
- Strength Building (Months 2–6): Gradual strengthening of the leg muscles supports knee stability and function.
- Return to Sport (Months 6–12): Functional training and testing guide a safe return to athletic activity.
Torn ACL Recovery Time Without Surgery
For individuals with partial tears or lower activity levels, physical therapy alone can help manage a torn ACL. Strengthening muscles and improving stability may restore function.
It’s most effective for those not involved in high-impact sports. While the ligament won’t fully heal, rehab can lead to a stable, usable knee.
When to Seek Medical Help
Red Flags Not to Ignore
If you experience swelling that doesn’t go down, knee instability, or a sensation of the joint locking or giving out, it’s important not to ignore these signs. Recurrent pain, especially with movement, can also signal a more serious injury that needs attention.
Getting a Professional Evaluation
A timely orthopedic consultation helps confirm the diagnosis and rule out related damage. Early evaluation leads to better treatment outcomes and can prevent long-term joint issues, especially if surgery or rehab is needed.
FAQs About Torn ACL
Can You Walk on a Torn ACL?
Yes, many people can still walk on a torn ACL, especially if the swelling goes down and the knee regains some strength. However, walking on it without proper treatment can lead to instability and increase the risk of further damage to the knee joint.
What Does a Torn ACL Look Like on an MRI?
On an MRI, a torn ACL may appear as a disrupted or absent ligament where it normally connects the femur and tibia. Radiologists often look for signs like swelling, bone bruising, and irregular fibers where the ACL should be intact.
How Long Does It Take for a Torn ACL to Heal?
The healing time for a torn ACL depends on the severity of the injury and the chosen treatment. With surgery, recovery usually takes 6 to 12 months. Without surgery, some people may regain function in 3 to 6 months with a physical therapist, though the ligament itself will not fully heal.
What Are the Signs of a Torn ACL vs. a Sprain?
A torn ACL often causes a loud popping sound, sudden swelling, and a feeling of the knee “giving out.” In contrast, a knee sprain may cause milder discomfort and less joint instability. Recovery from an ACL sprain is usually faster and less complex than recovery from a torn ACL.
Can an ACL Tear Heal Without Surgery?
A completely torn ACL does not heal on its own because it lacks the blood supply needed for natural repair. However, with physical therapy and muscle strengthening, some people can regain stability and function without surgery, especially if they’re not involved in high-demand activities.
Conclusion
If you’re experiencing knee pain, swelling, or instability, don’t wait to get the care you need. Early diagnosis and the right treatment plan can make a big difference in your recovery and long-term joint health.
The orthopedic specialists at OPA Ortho are here to help with expert evaluations, advanced imaging, and personalized treatment options tailored to your lifestyle. Book a consultation today to take the first step toward healing and getting back to the activities you love.