Which exam finding is most indicative of a PCL injury?

Which exam finding is most indicative of a PCL injury?

• A. Decreased ROM
• B. Swelling
• C. Positive posterior sag sign
• D. Positive posterior drawer test with soft end feel or increased posterior tibial translation

Answer: (D)

The key concept is posterior stability of the knee, specifically how much the tibia can move backward relative to the femur when the PCL is stressed. The posterior drawer test performed with the knee flexed to about 90 degrees directly assesses this posterior translation. If the tibia moves back more than the other knee and there is a soft or diminished end feel, that indicates PCL laxity or rupture. This finding directly reflects the PCL’s role in preventing posterior tibial translation, making it the most specific and informative sign of a PCL injury. In contrast, swelling or decreased range of motion are nonspecific and can accompany many knee problems, and while a posterior sag sign can hint at PCL injury, it’s less precise than an objective posterior drawer test result.

The key concept is posterior stability of the knee, specifically how much the tibia can move backward relative to the femur when the PCL is stressed. The posterior drawer test performed with the knee flexed to about 90 degrees directly assesses this posterior translation. If the tibia moves back more than the other knee and there is a soft or diminished end feel, that indicates PCL laxity or rupture. This finding directly reflects the PCL’s role in preventing posterior tibial translation, making it the most specific and informative sign of a PCL injury. In contrast, swelling or decreased range of motion are nonspecific and can accompany many knee problems, and while a posterior sag sign can hint at PCL injury, it’s less precise than an objective posterior drawer test result.