The knee is the largest joint in the body and is frequently injured, particularly when the knee is bent. An ACL rupture (tear) is one of the most common sports injuries. Of all the knee ligaments, the ACL is more often torn because of the lack of muscular support for movements that involve twisting and rotation of the knee. An ACL tear is a serious injury that can potentially cause long-term dysfunction, arthritis and interfere with your quality of life.
Who is at risk for an ACL tear?
Active people who participate in physically demanding sports that require a high level of strength and fitness are the most frequent victims of an ACL tear. Female athletes who participate in competitive sports that place substantial demand on the ACL including downhill skiing, soccer, basketball, softball, lacrosse, or rugby are up to five times more likely than men to suffer an ACL tear. The exact reason females are more susceptible is not entirely clear, but research has shown that it may be due to specific differences in their anatomy, hormones or ligament composition.
What is the ACL?
Three bones that form the knee: the thighbone (femur), the shinbone (tibia) and the kneecap (patella). There are two ligaments in the center of the knee, the anterior cruciate ligament (ACL) and the posterior cruciate ligament (PCL). The purpose of the ACL is to stabilize the knee by holding the thighbone and shin bone together and prevent the tibia from sliding anterior and out of position, as well as helping control rotation of the knee.
There are also collateral ligaments on each side of the knee that control sideways knee movements and are frequently injured when the ACL is injured.
What causes an ACL tear?
Most ACL tears occur from a sharp twisting of the knee, a sudden stopping, sudden deceleration, cutting, pivoting and sidestepping movements, or a difficult landing from a jump. Additionally, a fall, trauma like an auto accident or direct hit on the knee, like a tackle, can tear the ACL.
What are the symptoms of an ACL tear?
A popping sound at the time of the injury is a predominant sign of an ACL tear, followed by immediate knee instability, intense pain, swelling, and knee buckling. Knee instability, a loss of range of motion, tenderness at the joint line (indicative of a meniscus tear) and difficulty walking may remain after the pain and swelling resolve. Use of the injured knee can cause additional damage.
How is an ACL tear diagnosed?
During your consultation with Dr. Cooper, he will talk with you about what how you injured your knee and discuss your symptoms. He will review your medical history and conduct a physical examination to check all knee structures, test your range of motion, and knee stability. Dr. Cooper will order x-rays to look for broken bones, and MRI imaging to view soft tissues including the ACL. Because more than half of all ACL injuries involve injuries to other parts of the knee including the articular cartilage, the menisci or other knee ligaments, imaging studies are important to reveal all the damage.
What is the treatment for an ACL tear?
Treatment depends on the activity level and age of the patient, as well as the location of the tear. Occasionally, even a complete ACL tear can be treated without surgery. Every patient has slightly differently shaped knees, and some knees are more able to tolerate not having a functioning ACL. An ACL is critical for cutting and pivoting sports, in lower demand patients that do not require turning or pivoting, a functioning ACL is not always required. For the majority of patients, an ACL tear requires surgery in order to continue to perform at the same level of activity as they are used to. Surgery for an ACL tear is generally an ACL reconstruction. In rare occurrences, an ACL repair may also be possible.
ACL reconstruction surgery
ACL reconstruction is the gold standard treatment for a complete tear. The goal of this surgery it to restore knee stability and function. It involves replacement of the damaged ligament with a graft, created from the patient’s tendon, called an autograft; or from a donor, called an allograft. ACL reconstruction surgery is typically performed with knee arthroscopy, a minimally invasive procedure used to view, diagnose and treat an ACL rupture. Recovery after surgery requires full rehabilitation for 6-9 months, to restore function and prevent subsequent injuries.