Knee special tests are at their most useful when they confirm or refute a hypothesis you already formed from the history and observation - mechanism of injury, swelling pattern, locking, and giving way tell you which cluster to run. This guide gathers the tests that actually change management, grouped by suspected structure, with how to perform each one and how to interpret a positive or negative result.
Choose the ligament cluster the mechanism suggests - a valgus contact injury points to the MCL and ACL; hyperextension or a dashboard blow points to the PCL.
No single meniscal test is reliable alone - combine joint-line tenderness with a provocation test and interpret as a cluster.
The Lachman test is the most accurate clinical test for ACL integrity, with high sensitivity and specificity. It is performed at 20–30° of flexion, where hamstring guarding is reduced, making it more reliable acutely than the anterior drawer test.
No single test is conclusive. Combine joint-line tenderness with a provocation test such as McMurray or the weight-bearing Thessaly test, and interpret them as a cluster alongside the history of locking, catching, or giving way.
Both assess the ACL. The Lachman is performed at 20–30° of flexion and is more reliable acutely; the anterior drawer is performed at 90°, where effusion and hamstring spasm reduce its sensitivity in the early stages after injury.
Accuracy varies by test and by how acute the injury is. Diagnostic value rises substantially when tests are clustered for a single hypothesis and interpreted alongside the mechanism of injury, swelling pattern, and functional testing.