Illustration of the ligaments of the knee, including the anterior and posterior cruciate ligaments

Cruciate ligaments (also cruciform ligaments) are pairs of ligaments arranged like a letter X.^[1] They occur in several joints of the body, such as the knee. In a fashion similar to the cords in a toy Jacob's ladder, the crossed ligaments stabilize the joint while allowing a very large range of motion.

Toy Jacob's ladder

[edit] Etymology

Look up cruciate or ligament in Wiktionary, the free dictionary.

The adjective cruciate is from the Latin crux, crucis, meaning "cross".

In Classical Latin, the verb cruciare means "to torture". By the time in the Late Latin period when Latin medical terminology was being established, this old meaning of cruciare seems to have fallen out of use in common speech, and the word was re-invented with the meaning "arrange in cross shape". Use of "cruciat-" to refer to torture is now obsolete in English, but this old usage is shown in the common English word excruciating, and in the "Cruciatus" curse in the Harry Potter fictional scenario.

[edit] Anatomy

Cruciate ligaments occur in the knee of humans and other bipedal animals and the corresponding stifle of quadripedal animals, and in the neck and foot.

[edit] Knee and stifle

The cruciate ligaments of the knee are the anterior cruciate ligament (ACL) and the posterior cruciate ligament (PCL). These ligaments are two strong, rounded bands that extend from the head of the tibia to the intercondyloid notch of the femur. The ACL is lateral and the PCL is medial. They cross each other like the limbs of an X. The ACL and PCL remain distinct throughout and each has its own partial synovial sheath. Relative to the femur, the ACL keeps the tibia from slipping backward and the PCL keeps the tibia from slipping forward.

The ACL is the most commonly injured ligament in the human knee^[2] and is commonly damaged by athletes. Anterior cruciate ligament injuries are diverse, often occurring together with tears of the medial meniscus, lateral meniscus, or both. Techniques of anterior cruciate ligament reconstruction use a wide range of replacement tissues and surgical approaches.

In the stifle joint of non-human quadrupeds, the corresponding ligaments are referred to as the cranial cruciate ligament (CrCL) and the caudal cruciate ligament (CaCL). Injuries and pathologies of the stifle joint are common in horses and dogs, and have a number of surgical treatments. In dogs, these include tibial tuberosity advancement, an orthopedic procedure to repair deficient cranial cruciate ligaments.

Medical diagnosis of cruciate ligament injuries in the human knee uses several tests, including the anterior drawer test, drawer test, and Lachman test. These are hands-on test involving manipulation of the knee. Other methods include magnetic resonance imaging (MRI) and exploratory surgery.

ACL injuries are more common in women than in men, and especially common in younger women. To prevent ACL injuries, training programs that emphasize plyometrics and strength rather than balance are more effective.^[3]

Knee replacement surgery generally involves sacrificing the ACL, but some types of knee prosthesis permit the PCL to be preserved.^[4]

Successful repair of both cruciate ligaments in a human knee was first reported in 1903. The patient, a miner who suffered a dislocated knee in an earthfall, regained near normal function of the knee.^[5]

[edit] Neck

Another structure of this type in human anatomy is the cruciate ligament of the dens of the atlas vertebra, also called "cruciform ligament of the atlas", a ligament in the neck forming part of the atlanto-axial joint.^[6]

[edit] Foot

The human foot has a cruciate crural ligament, also known as inferior extensor retinaculum of foot.

The equine foot has a pair of cruciate distal sesamoidean ligaments in the metacarpophalangeal joint. These ligaments can be seen using computed tomography.^[7]

[edit] References