Below are answers to the most frequently asked questions about anterior cruciate ligament reconstruction (ACLR) surgery. These are based on two decades of MOON Knee Group research following patients for ten years starting before surgery. This information is provided for you to discuss with your surgeon about how it might apply to your body and injuries.
The ACL is one of four strong fibrous tissue bands called ligaments that hold together and support the knee. The ACL runs diagonally inside your knee between your thigh (femur) and shin (tibia) bones. Your ACL primarily keeps your knee stable when you turn, cut, twist and pivot. Unfortunately, it is the knee ligament most often injured. An ACL tear is one of the most common and devastating sports injuries.
In addition to the anterior cruciate ligament, the other three knee ligaments are:
Unfortunately, your body can move in ways your knee ligaments can’t support. When that happens, the fibrous ligament tissues stretch or tear, as you can see in the image on the right. An ACL tear usually happens when jumping, turning or moving suddenly while running. Most of the time, the injury happens without contact. An ACL tear (also called a rupture) is the most common knee injury. More than 90 percent of the time, it tears completely.
When your ACL tears:
ACL tears can be confirmed only through medical evaluation or magnetic resonance imaging (MRI). If you experience symptoms of a torn ACL, you should get a medical professional’s diagnosis as soon as possible to begin your recovery. A skilled musculoskeletal specialist can usually diagnose a tear by physical examination. An MRI confirms the tear and any other injuries in the knee. If your ACL is torn, you’ll be referred to an orthopedic physician and physical therapist specializing in knee injuries.
After an ACL tear is diagnosed, your knee will benefit from prehabilitation exercises. Research shows improved results—including for return to sport—when the following are true before ACL reconstruction surgery:
This is the first of many times where you’ll be rewarded for being patient. You’ll benefit from getting your body ready before surgery, even if it takes a few weeks. There is no standard duration for prehabilitation as injuries and strength vary.
Completing a full step-by-step rehabilitation program improves your final result and reduces your retear risk.
Immediately after suffering a full ACL tear, walking will be uncomfortable at best. You will likely feel unstable. This is result of several factors:
Choosing to not having surgery? Eventually, you should be able to walk without pain after physical therapy. Note that deciding to not reconstruct your torn ACL usually means you have to permanently avoid aggressive cutting and pivoting.
Following reconstruction surgery and with full completion of rehabilitation and return-to-sport training, you can recover greater than 90 percent of your preinjury functionality as measured by commonly used sports outcome scores. However, this depends on your body, injury, graft choice and commitment to prehabilitation and rehabilitation. As you go through rehabilitation, continue to be evaluated and discuss your progress with your physical therapist and athletic trainer.
Yes. Even the best reconstruction surgery cannot eliminate the possibility of a retear. See the reinjury risk section and calculators to see how graft choice for your ACL reconstruction affects your retear possibility. You can reduce your retear risk by completing full pre-surgery (prehab) and post-surgery rehabilitation programs plus specific return-to-sport training.
Yes. Studies have shown females are two to seven times more likely to tear an ACL than males competing in the same sports. Theories for this difference between sexes range from hormonal and anatomical differences to lower biomechanic and neuromuscular control. This difference goes away after ACL reconstruction surgery: retear risk is the same regardless of sex.
Less than 10 percent of ACL tears are partial. The extent of an ACL tear can only be confirmed through medical evaluation. If you do suffer a partially torn ACL, you might be able to recover without surgery. This could leave you at higher risk for full tear, particularly if you return to a sport involving jumping, cutting and pivoting.
When you tear your ACL, other parts of your knee can also be hurt.
A medical evaluation that includes an MRI will detect any other injuries. Most can be treated at the same time as your ACL. Your physician can discuss in more detail your injuries and treatments.
There is no research on maintaining your reconstructed ACL over a lifetime. However, common sense and nearly all medical and training professionals advise maintaining strength, range of motion and fitness with non-impact aerobic exercise.
Tearing your ACL, along with any other knee trauma, increases your chances of developing arthritis in your knee. This is likely to occur at a much earlier age than without the ACL tear.
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