Cruciate Ligament Tears

Anterior medial ? flexion
Posterior lateral ? extension

Mechanism

Sudden deceleration
Hyperextension and internal rotation of tibia on femur

Sudden posterior displacement of tibia when knee is flexed or hyperextended (dashboard MVA injury)

History

Audible “pop”
Immediate swelling
Knee “giving way”
Inability to continue activity

Audible “pop”
Immediate swelling
Pain with push off
Can’t descend stairs

Physical

Effusion (hemarthrosis)
Posterolateral joint line
tenderness
Positive anterior drawer
Positive Lachmann
Pivot shift
Test for MCL, meniscal injuries

Effusion (hemarthrosis)
Anteromedial joint line tenderness
Positive posterior drawer
Posterior sag
Reverse pivot shift
Other ligamentous, bony injuries

Treatment

Stable knee with minimal
functional impairment:
immobilization 2-4 weeks with
early ROM and strengthening
Unstable knee or young
person/high-demand lifestyle:
ligament reconstruction

Stable knee with minimal functional impairment:
immobilization 2-4 weeks with early
ROM and strengthening
Unstable knee or young person/high-demand lifestyle:
ligament reconstruction

O’Donahue’s unhappy triad: ACL, MCL, medial meniscal tears commonly occur simultaneously so if you see one, look for the other two