Robert Kienböck described radiographic changes associated with idiopathic lunate osteonecrosis in 1910. The radiographic progression of this eponymous condition has been well-described to progress from normal radiographs, to lunate sclerosis, lunate collapse, proximal capitate migration, scaphoid flexion, and pancarpal arthritis. Diagnosing early stages of the disease without radiographic changes presented a challenge. As imaging modalities have evolved, diagnosis has become possible with MRI. Although numerous classification systems exist, the Lichtman classification and the Bain arthroscopic grading system have become widely used. This article outlines the available classification systems and aims to highlight when each may be useful in patient management.