Correlations between the Inclination of the Distal Radius and Carpal Alignment on Plain Radiographs

Abstract Radiographic parameters of the distal radius, such as radial inclination and palmar tilt, are crucial for wrist assessment, yet correlations with carpal alignment in radiographically normal-appearing adult wrists remain underexplored. This retrospective study aimed to analyze associations between distal radius morphology and carpal alignment. One hundred posteroanterior and lateral wrist radiographs from radiographically normal-appearing adults (mean age 47 years; 43 males, 57 females) were analyzed. Measurements included radial inclination, palmar tilt, Chamay and Bouman ulnar translation indices, Pagliei indices, and Capitate-to-Axis-of-Radius Distance (CARD). Correlations were assessed with Pearson or Spearman coefficients. No significant correlations were found in the coronal plane between radial inclination and the Chamay (Pearson r = 0.018, 95% CI −0.18 to 0.21, p = 0.858) or Bouman indices (Pearson r = − 0.097, 95% CI −0.29 to 0.10, p = 0.336). In the sagittal plane, palmar tilt showed significant negative correlations with both Pagliei indices (proximal D3/D1: Spearman ρ = − 0.372, 95% CI −0.53 to −0.19, p = 0.0001; distal D2/D1: Pearson r = − 0.575, 95% CI −0.69 to −0.43, p < 0.0001). No significant correlation was observed with CARD (Spearman ρ = − 0.103, 95% CI −0.29 to 0.10, p = 0.308). Moderate negative associations were observed between palmar tilt and the Pagliei indices on plain radiographs. However, these associations may partly reflect shared-reference artifacts inherent to two-dimensional imaging rather than a true biological relationship. The findings should be considered hypothesis-generating. Future three-dimensional studies are required to clarify whether a genuine anatomical relationship exists between distal radius inclination and sagittal carpal alignment.