[Knee pain: choosing the right imaging]

Gonalgia is a frequent reason for consultation of a primary care physician. The road leading to diagnosis is mainly clinical. A detailed medical history and physical examination are capital for establishing diagnostic hypotheses and choosing the most appropriate imaging test. Initially, a simple X-ray of the knee joint is the most common exam, even though it is not always needed, especially after a minor trauma. MRI and CT-scan allow a more detailed examination of the structures; however, they should only be ordered to answer a specific question. Most of the time, echography is reserved to extra-articular pathologies and for guiding an articular tap.