Imaging

Abstract

Since the first report by Robert Kienböck himself, the diagnosis of Kienböck’s disease has usually been made on plain radiographs. Radiographs show different lunate findings as the disease progresses. In early lesions, the lunate shows a normal architecture and bone density, whereas as the disease progresses, it shows osteosclerosis, fragmentation of the lunate, and abnormal carpal arrangement. Radiographs are also important in determining the associated anatomic and mechanical properties of the involved wrist, such as ulnar variance, radial inclination, carpal height, radioscaphoid angle, and lunate size or shape.

Magnetic resonance imaging (MRI) is helpful early in the disease when plain radiographs may not reveal any abnormalities. On T1-weighted images, the lunate demonstrates diffuse low signal intensity as a result of decreased vascularity. T2-weighted images may reveal high or low signal intensity, depending on the extent of the disease process. It is critical to consider that this diffuse signal change within the entirety of the lunate is necessary to establish the diagnosis of Kienböck disease.

Computed tomography (CT), especially sagittal reconstruction views, is helpful in assessing the extent of articular surface collapse and the presence of fractures. CT sagittal views are also helpful in detecting the presence of carpal instability as well as early osteoarthritis of the radiocarpal and midcarpal joints.

Staging of Kienböck disease depends primarily on the radiographic findings. Staging is an important step for planning the treatment by the stage of disease. The classification system described by Lichtman et al. is used most commonly.