Anterior Cruciate Ligament Tear (Torn ACL)
Benjamin Wedro, MD, FACEP, FAAEM
Dr. Ben Wedro practices emergency medicine at Gundersen Clinic, a regional trauma center in La Crosse, Wisconsin. His background includes undergraduate and medical studies at the University of Alberta, a Family Practice internship at Queen's University in Kingston, Ontario and residency training in Emergency Medicine at the University of Oklahoma Health Sciences Center.
William C. Shiel Jr., MD, FACP, FACR
Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.
- What is the function of the knee joint?
- What is a torn anterior cruciate ligament (ACL)?
- What causes a torn ACL?
- What are symptoms and signs of a torn ACL?
- How is a torn ACL diagnosed?
- What is the treatment for a torn ACL?
- How long does it take to recover from a torn ACL?
- Can ACL tears be prevented?
- Torn Anterior Cruciate Ligament (ACL) At A Glance
- Patient Comments: Torn ACL - Causes
- Find a local Doctor in your town
What is the function of the knee joint?
The purpose of the knee joint is to bend and straighten (flex and extend), allowing the body to change positions. The ability to bend at the knee makes activities like walking and running or standing and sitting much easier and more efficient.
The thighbone (femur) and the shinbone (tibia) meet the kneecap (patella) to form the knee joint. The rounded ends of the femur or condyles line up with the flat tops of the tibia called the plateaus. There are a variety of structures that hold the knee joint stable to allow the condyles and plateaus to maintain their anatomic relationship so that the knee can glide easily through its range of motion.
There are four thick bands of tissue, called ligaments, that stabilize the knee:
- The medial collateral ligament (MCL) and the lateral collateral ligament (LCL) stabilize the sides of the knee.
- The anterior cruciate ligament (ACL) and the posterior cruciate ligament (PCL) form an X on the inside of the knee joint and prevent the top and bottom of the knee from sliding back and forth.
The major muscles of the thigh also act as stabilizers: the quadriceps in the front of the leg and the hamstrings in the back.
A sprain occurs when a ligament is injured and the fibers are either stretched or torn.
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