Which test is most specific for an anterior cruciate ligament rupture?

Which test is most specific for an anterior cruciate ligament rupture?

• A. Anterior drawer test
• B. Lachman test
• C. Pivot shift test
• D. Thessaly test

Answer: (B)

Testing ACL integrity relies on isolating the ligament’s barrier to anterior tibial movement as much as possible. The Lachman test does this by placing the knee in about 20–30 degrees of flexion, stabilizing the femur, and translating the tibia forward. This position minimizes hamstring activation and reduces interference from other structures, so a clear, firm endpoint with little anterior translation strongly indicates an intact ACL, while increased laxity or a soft/absent endpoint suggests a rupture. This makes the Lachman test more specific for an ACL tear than the anterior drawer test, which can be influenced by hamstring guarding and other capsular structures. Although the pivot shift test is also highly specific, it is more technique-dependent and harder to perform consistently in routine exams. The Thessaly test targets the menisci, not the ACL. Therefore, when identifying an ACL rupture with a single best test, the Lachman test is the most specific choice.

Testing ACL integrity relies on isolating the ligament’s barrier to anterior tibial movement as much as possible. The Lachman test does this by placing the knee in about 20–30 degrees of flexion, stabilizing the femur, and translating the tibia forward. This position minimizes hamstring activation and reduces interference from other structures, so a clear, firm endpoint with little anterior translation strongly indicates an intact ACL, while increased laxity or a soft/absent endpoint suggests a rupture.

This makes the Lachman test more specific for an ACL tear than the anterior drawer test, which can be influenced by hamstring guarding and other capsular structures. Although the pivot shift test is also highly specific, it is more technique-dependent and harder to perform consistently in routine exams. The Thessaly test targets the menisci, not the ACL. Therefore, when identifying an ACL rupture with a single best test, the Lachman test is the most specific choice.