A NEW CLASSIFICATION OF LUNATE NECROSIS

The classifications of lunate necrosis used by Decoulxet al. (1957)³ and Lichtmanet al. (1977)⁷ and Lichtman and Degnan (1993),⁶ respectively, do not refer to early changes in MRI nor to changes to the carpal architecture, but do attribute the onset of the disease to the presence of a fracture. A recent publication of Lichtman and Ross (1994)⁸ did not solve the problem of a precise description of the disease. This necessitates a new, reliable classification based on the true natural course of the disease.

In a prospective study of 49 patients and in a retrospective analysis of 125 lunate necrosis, the findings obtained prove the regular natural course of the disease. It starts with normal x-ray appearance but the intensity of the signal in T1-weighted MRI is decreased; a fracture line is part of the latter course and not the beginning. It precedes the collapse of the lunate, followed by the collapse of the carpus and the arthritis of the wrist.