The knees are the most complex joints in the body. Even small losses of knee function can impact everyday activities, such as walking or climbing stairs. Three bones — the femur (thigh bone), the tibia (shin bone) and patella (knee cap) — come together to form the knee joint.
The femur and tibia are connected by ligaments, which provide stability to keep the bones aligned. The surfaces where these bones touch are covered with a smooth material called articular cartilage that helps cushion the bones. The knee is divided into three compartments: medial (inside), lateral (outside), and patellofemoral (between the kneecap and thigh bone). Since pain and arthritis can be localized to just one of these compartments, or can involve all three, replacement can be tailored to which compartment(s) are affected.
Anterior Cruciate Ligaments
The anterior cruciate ligament (ACL) is a main ligament of the knee that lies along the sides and back of the knee to keep the bones of the knee joint in place. Injuries to the ACL most often occur when the ligament is suddenly twisted or subject to a direct impact. It may not cause pain, but the leg may buckle when you try to stand up. An MRI can diagnose complete ligament tears and arthroscopy may be needed to diagnose partial tears.
Minor cruciate ligament injuries may respond to conservative treatment; however, most cruciate ligament injuries require surgery. A number of surgical options exist. The ligament may be replaced with one of your own tendons, such as the Achilles tendon, or a donor tendon. Sometimes a biological fixative device, such as absorbable screws, can be inserted to reattach the tendon to the bone, or sometimes synthetic materials can be used to "grout" the ligament.
Arthritis and joint injuries damage the cartilage between the bones that compose the knee. This can cause the knee to become painful and stiff, making everyday activities difficult. Some patients with only one affected compartment may be candidates for unicompartmental, or partial, knee replacements. Others, with more extensive damage, require total, or full, knee replacement. With advances in technology, many patients can have minimally invasive surgeries. Surgeons can now perform both of these replacements using incisions as small as three inches as opposed to 8 to 12 inches.
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