Posterior Cruciate Ligament Wheeless

Description: function and natural history:
- provides 95% of total restraining force to straight posterior translation of the tibia relative to femur;
- secondary restraints to posterior displacement of the tibia include posterolateral capsule, popliteus, & MCL;
- secondary action includes resistance to varus, valgus, and external rotation;
- PCL is more verticle in extension and more horizontal in flexion;
- hyperflexion mechanism: most common mechanism for an isolated PCL injury:
- hyperflexion causes the large anterolateral component to fail but spares the posteromedial band (which is loose in flexion);
- this type injury does not involve the secondary restraints and does well with non operative treatment;
- dashboard injury (from MVA): may result in severe combined injuries;
- left untreated PCL ruptures may lead to chronic patello femoral as well as medial compartment arthrosis;
Wheeless' Textbook of Orthopaedics