Evaluation of radiological instability signs in the distal radioulnar joint in children and adolescents with arthroscopically-verified TFCC tears

Introduction Recent reports in the adult literature reported the use of standardized radiographic measurement techniques to determine distal radioulnar joint (DRUJ) instability. The aim of this study was to evaluate the efficacy and accuracy of (1) the MRI-based modified radioulnar ratio technique and (2) the pisoscaphoid (PiSca) and radioulnar (RaUl) distances in true lateral radiographs in children and adolescents with arthroscopically-verified TFCC tears. Materials and methods We retrospectively assessed lateral wrist radiographs and axial MRI sequences of 18 adolescent patients (22 wrists) who had arthroscopically-confirmed TFCC tears and compared them to similar imaging of a control group of 28 healthy patients (28 wrists). Three raters assessed the images twice in a 2-week interval. Intraclass correlation coefficients (ICCs), unifactorial ANOVA, and ROC analysis were performed with regards to the different radiographic variables. Results The interrater ICCs were almost perfect for all measurements except RaUl1, which showed a substantial agreement (0.751) among the three observers. The intrarater ICCs were almost perfect when measuring PiSca and MRI, and substantial to almost perfect for RaUl. Pearson‘s correlation showed a moderate, positive correlation between PiSca and RaUl distances ( r = 0.608; p < 0.001), and a moderate, negative correlation between RaUl distance and MRI shift ( r = − 0.486; p = 0.010). When the three core groups (peripheral, central tear, controls) were compared to each other regarding the radiographic instability parameters, only the MRI shift revealed a statistically significant difference ( p = 0.003). Comparisons revealed significant differences between patients and controls ( p = 0.004) and peripheral tears vs. controls ( p = 0.001 and p = 0.010). The ROC analysis revealed a significant AUC only for the MRI (AuC 0.787 and p = 0.002). Conclusions Children and adolescents with peripheral TFCC tears showed significantly increased instability parameters in MRI compared to controls. These measurement techniques are no replacement for a thorough clinical examination but may be helpful for indicating diagnostic wrist arthroscopy in ambiguous cases. Level of evidence Level III; Diagnostic.