PCL injuries are often diagnosed with which imaging feature?

PCL injuries are often diagnosed with which imaging feature?

• A. Anterior tibial sag on imaging
• B. Posterior tibial sag on imaging; confirmation with MRI
• C. Lateral collateral laxity
• D. Osteophyte formation

Answer: (B)

PCL injuries are suggested on imaging by a posterior sag of the tibia—the tibia sits further back relative to the femur on knee imaging. The PCL normally resists posterior translation of the tibia, so tearing it allows gravity to pull the tibia into a more posterior position, which is seen as a posterior sag on lateral knee views. MRI is then used to confirm the tear and to assess associated injuries, such as meniscal or other ligament damage. The other signs listed don’t fit PCL injury: an anterior sag would indicate ACL involvement, collateral laxity points to collateral ligament injuries, and osteophytes reflect degenerative changes rather than an acute PCL rupture.

PCL injuries are suggested on imaging by a posterior sag of the tibia—the tibia sits further back relative to the femur on knee imaging. The PCL normally resists posterior translation of the tibia, so tearing it allows gravity to pull the tibia into a more posterior position, which is seen as a posterior sag on lateral knee views. MRI is then used to confirm the tear and to assess associated injuries, such as meniscal or other ligament damage. The other signs listed don’t fit PCL injury: an anterior sag would indicate ACL involvement, collateral laxity points to collateral ligament injuries, and osteophytes reflect degenerative changes rather than an acute PCL rupture.