Fibular collateral ligament

The LCL measures some 5 cm in length. Because of this, the LCL is more flexible than its medial counterpart, and is therefore less susceptible to injury. Relations 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. == Function ==

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 stability in the mediolateral axis. == Clinical significance ==

Causes of injury 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. An LCL injury usually occurs simultaneously as the other ligaments of the knee are injured. Multiple knee ligament tears and stresses can result from a significant trauma that includes direct blunt force to the knee, such as an automobile crash. Symptoms Symptoms of a sprain or tear of the LCL includes pain to the lateral aspect of the knee, instability of the knee when walking, swelling and ecchymosis (bruising) at the site of trauma. Direct trauma to the medial aspect of the knee may also affect the peroneal nerve, which could result in a foot drop or paresthesias below the knee which could present itself as a tingling sensation. ==Treatment==

An isolated LCL tear or sprain rarely requires surgery. If the injury is a Grade 1 or Grade II, microscopic or partial macroscopic tearing respectively, ==Additional images==

File:Gray352.png|Capsule of right knee-joint (distended). Posterior aspect. File:Slide2CAC.JPG|Anterior view of knee. == See also ==