A knee that gives way without pain during resisted activities is most consistent with which diagnosis?

A knee that gives way without pain during resisted activities is most consistent with which diagnosis?

• A. Loose body
• B. ACL instability
• C. True locking
• D. Meniscus tear

Answer: (B)

Think about what “giving way” signals in the knee. The ACL normally resists anterior tibial translation and rotatory loads when the knee is loaded, especially as the quadriceps fire during resisted movements. If the ACL is torn or lax, those restraints are lost, so during activities that load the tibia forward or require quick directional changes, the knee can buckle or give way—even without pain. This pattern points to ACL instability rather than other issues. A loose body tends to cause catching or locking with pain, true locking is a mechanical block to motion, and a meniscal tear often brings joint line pain, swelling, or locking rather than painless buckling during resisted activity.

Think about what “giving way” signals in the knee. The ACL normally resists anterior tibial translation and rotatory loads when the knee is loaded, especially as the quadriceps fire during resisted movements. If the ACL is torn or lax, those restraints are lost, so during activities that load the tibia forward or require quick directional changes, the knee can buckle or give way—even without pain. This pattern points to ACL instability rather than other issues. A loose body tends to cause catching or locking with pain, true locking is a mechanical block to motion, and a meniscal tear often brings joint line pain, swelling, or locking rather than painless buckling during resisted activity.