Evaluation of the sigmoid notch with computed tomography following intra-articular distal radius fracture

A classification system for disruption patterns of the sigmoid notch of the radius associated with distal radius fractures has not been established. U sing plain x-rays and corresponding computed tomography (CT) scans we chara cterized and quantified the types of sigmoid notch involvement in 20 consec utive distal radius fractures with radiocarpal joint extension. Plain radio graphs revealed fracture extension into the sigmoid notch in only 7 cases ( 35%) and the CT scans demonstrated fracture extension into the sigmoid notc h in 13 cases (65%). Of the 13 fractures with sigmoid notch involvement, 9 (69%) were displaced and 4 (31%) were nondisplaced. Sigmoid notch articular step-off (n = 7) and gapping (n = 9) were detectable on the CT scans but n ot on the x-rays. Plain x-rays appear to underestimate sigmoid notch involv ement following distal radius fractures. In addition, CT appears to be a su perior diagnostic modality for quantifying sigmoid notch fracture step-oft and articular gapping. (J Hand Surg 2001;26A:244-251. Copyright (C) 2001 by the American Society for Surgery of the Hand.).