Association of the Interfacet Angle and the Lunate Facet Inclination Angle With Kienböck Disease

Purpose The etiology of Kienbock disease remains unclear, although mechanical, vascular, and metabolic risk factors have been suggested. We aimed to investigate the association of the angle between the curvatures of the distal radius and the development of Kienbock disease. Methods The lunate facet inclination (LFI), scaphoid facet inclination, and interfacet angle (IFA) values were measured using posteroanterior plain radiographs of 82 patients diagnosed with Kienbock disease. The results were compared with normative angular reference values published based on an analysis of 400 wrists of Caucasian patients aged between 20 and 45 years. The posteroanterior radiographs were divided into 3 categories: negative, neutral, and positive based on ulnar variance, and the relationship between ulnar variance and facet angles was evaluated. Results The IFA value was significantly higher than the normative angular reference value in the patients with Kienbock disease. Conversely, the LFI values were significantly lower in the Kienbock patient group. There were no statistically significant differences in the IFA and LFI values among the ulnar variance groups. Conclusions Measuring IFA and LFI allows the evaluation of the bifacet curvature of the distal radius articular surface in the coronal plane. Steep IFA and shallow LFI are associated with Kienbock disease. Increased IFA may lead to abnormal load transmission to the intermediate column, which might eventually lead to increased stress on the lunate. Copyright (C) 2022 by the American Society for Surgery of the Hand. All rights reserved.