This very useful test can be performed with the patient standing or in lateral recumbency (affected leg up), awake or sedated. The stifle is held in slight flexion. The index finger of one hand is placed over the tibial crest. The other hand flexes & extends the hock. The beauty of the tibial compression test is that it mimics the loading that causes cranial tibial thrust when the dog walks. If the ACL is torn, the tibial tuberosity will move cranially, ever so slightly, as the hock is in the flexed position. The reason for this displacement is that hock flexion causes tension of the gastrocnemius muscle, which in turn displaces the tibia cranially. This is called tibial compression or cranial tibial thrust. The beauty of the tibial compression test is that it mimics the loading that causes cranial tibial thrust when the dog walks. This is very different than the cranial drawer sign, which is a motion that doesn’t exist in real life. Think of it this way: The cranial drawer sign is “iatrogenic” whereas the cranial tibial thrust is generated by the patient when walking (or running). <HOME> Phil Zeltzman, DVM, Dipl. ACVS, is a small-animal board-certified surgeon at Valley Central Veterinary Referral Center in Whitehall, Pa. His website is DrPhilZeltzman.com.
