What is the ACL?
The anterior cruciate ligament, or ACL, exists from the front of the medial femoral condyle and passes through the middle of the knee between the tibia plateaus. The ACL’s main job is to prevent the thighbone, or your femur, from sliding backwards on your tibia and preventing the tibia from sliding forward under the femur. It also stabilizes your knee from rotating when the foot is planted and the leg pivots. Without it, the knee becomes unstable and buckles if you plant your leg or you try to turn too quickly.
How do ACL tears happen?
Most of the time, an ACL injury happens during some sort of sport or fitness activity. Soccer, basketball, football, and gymnastics players often get ACL tears because the sport often involves quick change in direction, which causes stress on the ligament. When the ligament gets stretched when your foot is planted firmly and your knee locks or twists, it can cause a tear. A tear can also happen when the tibia is pushed forward toward the femur, which can happen when skiing, from a direct blow to the front of the knee, or even in a car accident.
What are symptoms and signs of a torn ACL?
How do you know you have a tear in your ACL? Many people report hearing a loud pop at the time of injury, followed by intense pain in their knee. Walking or bearing any weight on the knee can be difficult too. The joint will begin to swell within a few hours of the injury, but to know for sure if you’ve caused any damage, you’ll probably go through a few tests.
The doctor usually starts with understanding how the injury happened. They will want to know, in detail, the sequence of events, the position of the body and the leg, the circumstances that led up to the injury and more. It helps them determine what the next steps should be and if they should look for more damage.
Next is the physical examination. The doctors look for any bruising, swelling or deformity in the joint. They note any areas of tenderness and if there is evidence of effusion (knee joint fluid). Most importantly, they will assess the stability. There are four main ligaments in the knee that are at risk for injury. They may try to test and see which ones could potentially be damaged.
If the physical examination and other tests don’t conclusively identify the injury, the doctor may order an MRI (Magnetic resonance imaging) of the knee. The MRI can definitively determine if the ACL is torn and help the doctor decide the best course of treatment.
Treatment of an ACL Tear
There are both surgical and non-surgical treatment options for an ACL tear. Both the patient and the doctor will need to discuss what is the best option, because every patient is different.
Nonsurgical treatment may be the best approach for patients that may be less active than others and don’t participate in activities that require running, jumping, or pivoting. Physical therapy and exercise rehabilitation can help return strength and range of motion to the knee. Surgical repairs often happen in young athletes. An orthopedic surgeon can repair the ACL using arthroscopic surgery and is often followed by weeks of physical therapy and rehabilitation.
Anterior Cruciate Ligament: ACL Tears 101