Final answer:
An MRI is the most sensitive test for detecting a combined ACL/MCL tear, often diagnosed after physical knee injury with symptoms consistent with a 'terrible triad' pattern of damage.
Step-by-step explanation:
The most sensitive test for a combined ACL/MCL tear is typically a thorough clinical examination followed by imaging tests like magnetic resonance imaging (MRI). Specifically, MRI has a high sensitivity for detecting ligamentous injuries within the knee. A powerful blow to the lateral side of an extended knee can lead to a 'terrible triad' injury involving sequential damage to the tibial collateral ligament medial meniscus and anterior cruciate ligament.
Arthroscopic surgery is often used for treatment harnessing an arthroscope and other specialized instruments to repair or reconstruct the damaged ligaments and menisci.