Knee

Anterior cruciate ligament injury

Mechanism

Usually a non-contact injury: landing or cutting with the knee in valgus and the tibia in external rotation, while the quadriceps contracts strongly with the knee near extension.

Recognition

An audible pop, inability to continue playing, and swelling within two hours. The Lachman test is the most reliable in the acute phase; the pivot shift is often not feasible in an awake patient.

Course

Swelling within two hours means blood in the joint, and then there is a cruciate rupture in roughly seven out of ten cases. In about half there is concomitant meniscal or cartilage damage.

Structures

• Anterior cruciate ligament (ACL)
• Medial meniscus of the knee (Body, anterior horn, posterior horn)
• Lateral meniscus of the knee (Body, anterior horn, posterior horn)

Joints involved

• Knee joint

Clinical tests

• Lachman test
• Anterior drawer test
• Pivot shift test
• Fluctuation test for effusion

Sources

• Magee DJ, Manske RC. Orthopedic Physical Assessment, 7e editie. Elsevier. 2021