Fibular collateral ligament

Fibular collateral ligament
Left knee-joint, posterior aspect, showing interior ligaments. (Fibular collateral ligament labeled at center left.)
Details
From	Lateral epicondyle of the femur
To	Head of the fibula
Identifiers
Latin	Ligamentum collaterale fibulare, ligamentum collaterale laterale
Dorlands /Elsevier	l_09/12491936
TA	A03.6.08.011
FMA	9660
Anatomical terminology []

The fibular collateral ligament (long external lateral ligament or lateral collateral ligament, LCL) is a ligament located on the lateral (outer) side of the knee, and thus belongs to the extrinsic knee ligaments and posterolateral corner of the knee.

Rounded, more narrow and less broad than the medial collateral ligament, the fibular collateral ligament stretches obliquely downward and backward from the lateral epicondyle of the femur above, to the head of the fibula below. In contrast to the medial collateral ligament, it is fused with neither the capsular ligament nor the lateral meniscus. Because of this, the lateral collateral ligament is more flexible than its medial counterpart, and is therefore less susceptible to injury.

Both collateral ligaments are taut when the knee joint is in extension. With the knee in flexion, the radius of curvatures of the condyles is decreased and the origin and insertions of the ligaments are brought closer together which make them lax. The pair of ligaments thus stabilize the knee joint in the coronal plane. Therefore damage and rupture of these ligaments can be diagnosed by examining the knee's mediolateral (side) stability.

Immediately below its origin is the groove for the tendon of the popliteus.

The greater part of its lateral surface is covered by the tendon of the biceps femoris; the tendon, however, divides at its insertion into two parts, which are separated by the ligament.

Deep to the ligament are the tendon of the popliteus, and the inferior lateral genicular vessels and nerve.

The LCL is usually injured as a result of varus force across the knee, which is a force pushing the knee from the medial (inner) side of the joint, causing stress on the outside. An example of this would be a direct blow to the inside of the knee. The LCL can also be injured by a noncontact injury, such as a hyperextension stress, again causing varus force across the knee.