Normal values for the lunocapitate angle measured on standard lateral wrist radiographs.

Abstract

The lunocapitate angle is a radiological parameter that can be used to identify midcarpal malalignment. This study aimed to determine the reproducibility of a measurement method for the lunocapitate angle on plain lateral wrist radiographs and to determine the normal values. The lunocapitate angle was measured in a standardized manner by three observers. Inter- and intra-observer variabilities were first tested on 18 radiographs. The lunocapitate angle was measured on lateral wrist radiographs of 172 patients with a mean age of 30 years (range, 20-40). Forty-nine percent of the patients were men and in 56% the left wrist was involved. The interobserver variability was good with an intraclass correlation coefficient (ICC) of 0.89. The intraobserver reliability was excellent for all three investigators, with ICCs of 0.93, 0.93 and 0.91, respectively. The mean lunocapitate angle was 15° (SD 10; range, -18 to 43°) 95% CI -3 to 34°. The mean lunocapitate angle was 17° in women and 13° in men (<i>p</i> = 0.005). In this study, a reproducible method is presented to measure the lunocapitate angle on plain radiographs and normal values were established that can be used as a reference. IV.