injuries and poisoning
Knee Sprains and Related Injuries
Introduction
Knee sprains occur when the ligaments that attach the thighbone (femur) to the shinbone (tibia) are torn. The cartilage pads (menisci), which act as shock absorbers in the knee, may also be injured. Knee sprains are often caused by bending or twisting the knee when the foot is planted on the ground. The knee is usually painful and swollen. The diagnosis is usually based on results of the physical examination. Resting and keeping the knee immobile are often the only treatment needed, but sometimes severe injuries must be repaired surgically. (See also Overview of Sprains and Other Soft-Tissue Injuries .) Several ligaments help hold the knee in place: Collateral ligaments:These ligaments, located on either side of the knee prevent the knee from moving from side to side too much. The medial collateral ligament is located on the inside of the leg, and the lateral collateral ligament is located on the outside of the leg. Cruciate ligaments:These ligaments prevent the knee from moving forward or backward too much. The anterior cruciate ligament (ACL) crosses in front of the posterior cruciate ligament (PCL) to form an X. Cartilage pads (menisci) fill in the space between the thighbone (femur) and shinbone (tibia). They help stabilize and cushion the knee joint. Two ligaments, one on either side of the knee, prevent the knee from moving from side to side too much: Medial collateral ligament, which is on the inside of the leg Lateral collateral ligament, which is on the outside of the leg Two ligaments inside the joint (cruciate ligaments) prevent the knee from moving forward or backward too much: Anterior cruciate ligament (ACL) Posterior cruciate ligament (PCL) The ACL crosses in front of the PCL, forming an X. The menisci are pads of cartilage that act as cushions between the thighbone (femur) and larger lower leg bone (tibia), which form part of the knee joint. Themost commonly injured structuresin the knee are The medial collateral ligament The anterior cruciate ligament Which structures are torn depends on the direction of the force against the knee: Medial collateral and anterior cruciate ligaments:One or both of these ligaments can be torn if the knee is hit from the side while weight on one foot that is firmly planted on the ground, as occurs during a football tackle. Damage is more likely if the knee also twists. Lateral collateral and anterior cruciate ligaments:These ligaments can be damaged when force against the knee is directed outward. This type of injury can occur when the leg is pushed from the inside. Anterior and posterior cruciate ligaments:These ligaments can be damaged when the knee is forcefully straightened. Menisci:The menisci can be damaged when people have their weight on a foot and their knee twists as it is injured. 