Posterior Cruciate Ligament (PCL) Tear

Diagnosis Definition

• PCL tears are most commonly due to sports-related trauma and impaction of a flexed knee on a dashboard in motor vehicle accidents
• The PCL acts as the primary restraint to posterior tibial translation
• Up to 70% of PCL tears are associated with other ligamentous injuries with posterolateral corner injuries being the most common
• The PCL consists of anterolateral and posteromedial bundles

Imaging Findings

• The PCL is normally seen on MR as a well defined continuous band of low signal intensity
• Partial thickness tears appear as ligament thickening and intrasubstance increased signal
• Complete tears are seen as ligamentous disruption and have an abnormal contour
• An anteroposterior PCL measurement of 7mm (vertical portion) on T2 weighted imaging is strongly suggestive of a PCL tear
• May be associated with tibial avulsion fracture at the PCL insertion site, posterolateral corner injuries and microtrabecular injury to the anterior tibial plateau and posterior femoral condyle

KEY IMAGES

Pearls

• Hyperextension injuries are commonly associated with avulsion at the tibial attachment
• The presence of associated ligamentous and/or meniscal injuries is usually an indication for surgical rather than conservative management

References

1. Sonin AH, Fitzgerald SW, Hoff FL et al. MR imaging of the posterior cruciate ligament: normal, abnormal, and associated injury patterns. Radiographics 1995; 15(3):551-61
2. Fanelli GC, Edson CJ. Posterior cruciate ligament injuries in trauma patients: part II. Arthroscopy 1995; 11:526-529
3. Rodriguez W Jr, Vinson EN, Helms CA, Toth AP. MRI appearance of posterior cruciate ligament tears. AJR Am J Roentgenol 2008 191;4:155-159
4. Sonin AH, et al. Posterior cruciate ligament injury: MR imaging diagnosis and patterns of injury. Radiology 1994;190:455-458