The initial assessment of injury to the lateral collateral ligament and posterolateral corner is often challenging, particularly in the context of a multiligamentous injury. Although advanced imaging techniques have enhanced the evaluation of knee injuries, the significant, and often unique, contribution of clinical examination should not be overlooked. Clinical examination starts with a thorough history, which is instrumental in elucidating not only the patient's symptomatology but also the mechanism of injury. Differentiating between acute and chronic injury and teasing out the patient's functional limitations are instructive in defining the appropriate treatment plan. The treating physician needs patience, vigilance, and a variety of diagnostic tools to reach a precise diagnosis. Each injury should be approached in a methodical and systematic manner to ensure an accurate initial assessment. This review provides a step-wise approach to the clinical assessment of the lateral collateral ligament and posterolateral corner injured knee. Adjunctive imaging modalities and investigations are also discussed.