Which orthopedic test is pathognomonic for a ruptured CrCL?

Which orthopedic test is pathognomonic for a ruptured CrCL?

• A. Tibial compression test
• B. Meniscal test
• C. Cranial drawer test
• D. Patellar grind test

Answer: (C)

Crucial idea: the ligament prevents the tibia from sliding forward under the femur. When it’s ruptured, the tibia can move forward (cranially) relative to the femur, creating unmistakable instability. The cranial drawer test directly assesses that instability. With the knee flexed about 90 degrees, you apply a gentle cranial (forward) force to the tibia. A positive finding is a definite cranial translation of the tibia with a soft or absent end feel, sometimes described as a “drawer” movement. This anterior movement is a direct consequence of a CrCL rupture, so a positive cranial drawer is highly specific for that injury and is commonly considered pathognomonic. Other tests evaluate different structures or signs of knee disease. The tibial compression test can be positive in CrCL rupture but is not as specific. Tests aimed at the meniscus or patellofemoral joint assess separate structures and pain patterns, not the instability caused by CrCL rupture.

Crucial idea: the ligament prevents the tibia from sliding forward under the femur. When it’s ruptured, the tibia can move forward (cranially) relative to the femur, creating unmistakable instability.

The cranial drawer test directly assesses that instability. With the knee flexed about 90 degrees, you apply a gentle cranial (forward) force to the tibia. A positive finding is a definite cranial translation of the tibia with a soft or absent end feel, sometimes described as a “drawer” movement. This anterior movement is a direct consequence of a CrCL rupture, so a positive cranial drawer is highly specific for that injury and is commonly considered pathognomonic.

Other tests evaluate different structures or signs of knee disease. The tibial compression test can be positive in CrCL rupture but is not as specific. Tests aimed at the meniscus or patellofemoral joint assess separate structures and pain patterns, not the instability caused by CrCL rupture.