What clinical signs and symptoms should I assess to confirm a suspected ACL injury in a patient?

To confirm a suspected anterior cruciate ligament (ACL) injury, assess for a history of a sudden twisting injury to the knee often accompanied by an audible 'pop' and immediate swelling within hours, which are key clinical symptoms. Patients typically report instability or a feeling of the knee 'giving way' during weight-bearing activities. On examination, look for joint effusion and tenderness along the joint line. Perform specific clinical tests such as the Lachman test, which is the most sensitive for detecting ACL rupture, showing increased anterior tibial translation compared to the uninjured side. The anterior drawer test and pivot shift test can also be used to assess ACL integrity, with the pivot shift test being more specific but less sensitive. Assess for a positive pivot shift sign indicating rotational instability. Additionally, evaluate for associated injuries such as meniscal tears, which may present with joint line tenderness or locking symptoms. These clinical signs and symptoms combined provide a strong basis for diagnosing ACL injury in primary care before referral for imaging or specialist assessment ¹ (Benjaminse et al., 2006; Huang et al., 2016; LÍŠka and ZelnÍk, 2020).