The current study was conducted to establish normal values of Distal radioulnar joint (DRUJ) translation using ultrasound imaging (USI). Repeatability of quantifying DRUJ translation of the forearm in various positions using USI was additionally investigated. Lastly the data collected was compared to previously documented values established in the literature using Computerised Tomography (CT) imaging. It is fundamental to further clinical research in this area to ascertain the validity of using USI to quantify DRUJ translation in a normal population.

A cross-sectional reliability study was conducted with 23 normal participants. Ultrasound examination was conducted bilaterally on two separate occasions, using the Phillips iU22 diagnostic ultrasound machine. Static transverse images of maximal supination, neutral and maximal pronation, were taken three times. This process was repeated with the participant gripping a 1kg weight for the supination and pronation positions. Using the Sketchbook Express software programme, lines were drawn to assess the relative distance of known bony landmarks. This method is consistent with the rheumatoid arthritis subluxation ratio (RASR) described by Henmi et al. (2007). Statistical analyses of repeatability included a hierarchical mixed model method, analysis of variance (ANOVA) and Cronbach’s alpha. Validity was also assessed comparing data to previously documented values in CT literature.

Translation was found to occur in both non gripping supination and pronation compared with neutral (p<0.001). There was statistically significantly more translation found with pronation (mean=1.69mm). Ulna radial translation in supination was found to occur to a lesser extent and in a volar direction compared with neutral (mean=0.67mm). Gripping pronation did not produce statistically significant changes compared to non gripping pronation. However, gripping supination was significantly higher (p<0.01) in comparison to non gripping supination. Cronbach’s alpha measurement for internal consistency was very high (0.9). Other than forearm position, there was no statistically significant difference between hand, left versus right, state or session. The RASR values in the current study demonstrated consistent measurements when compared to previously documented values.

This study demonstrated that USI can reliably detect translatory movement of the DRUJ in healthy participants. It supports the role of USI in future musculoskeletal applications and research. Alternative methods to accurately record translation may provide a less expensive and more accessible diagnostic tool in assessing DRUJ instability. This would reduce the dependence on CT or magnetic resonance imaging (MRI) scans to diagnose DRUJ instability in patients after trauma, inflammatory joint diseases or developmental disorders.