AANP Official Practice Test 2025 - Free Nurse Practitioner Practice Questions and Study Guide

The Lachman test is specifically designed to assess the integrity of the anterior cruciate ligament (ACL) in the knee. It involves the examiner stabilizing the femur with one hand while pulling the tibia forward with the other hand. This movement creates a shearing force that allows for the assessment of any anterior instability in the knee, which is characteristic of ACL injuries. A positive Lachman test, indicated by increased anterior movement of the tibia relative to the femur compared to the unaffected knee, suggests a possible ACL tear.

While other tests such as the McMurray's test, Lockman's test, and posterior drawer test are also utilized for evaluating knee injuries, they target different components of knee stability and structures. The McMurray's test is mainly used for meniscal tears, Lockman’s test is a specific variant often compared to the Lachman test, and the posterior drawer test focuses on injury to the posterior cruciate ligament (PCL). Thus, the Lachman test is considered one of the most reliable and sensitive methods for assessing ACL integrity in knee injuries.