In the field, which finding suggests a suspected ACL tear?

In the field, which finding suggests a suspected ACL tear?

• A. No swelling
• B. Pain only during rest
• C. A history of a pop and instability
• D. Absence of instability

Answer: (C)

A sudden pop at the moment of injury with the knee feeling unstable or giving way is the strongest clue for an ACL tear. The ACL’s job is to stabilize the knee by preventing the tibia from moving forward and by resisting rotational forces. When it tears, the knee often feels unstable, especially during twisting or pivoting movements, and many patients remember an audible pop. Swelling can occur, but the combination of a pop and instability is the most telling field sign. Signs like no swelling, pain only at rest, or no instability don’t fit the typical ACL injury pattern, since instability is a key feature of an ACL tear.

A sudden pop at the moment of injury with the knee feeling unstable or giving way is the strongest clue for an ACL tear. The ACL’s job is to stabilize the knee by preventing the tibia from moving forward and by resisting rotational forces. When it tears, the knee often feels unstable, especially during twisting or pivoting movements, and many patients remember an audible pop. Swelling can occur, but the combination of a pop and instability is the most telling field sign. Signs like no swelling, pain only at rest, or no instability don’t fit the typical ACL injury pattern, since instability is a key feature of an ACL tear.