Measurement of specific shoulder joint distances with handheld and conventional ultrasound: a reliability and...

Ultrasonography is a widely accepted imaging method for evaluating anatomical structures around the shoulder joint. However, the consistency of measurements across different devices and operators remains a critical issue for clinical and research validity. The aim of this study is to assess the inter-device and intra-operator reliability of ultrasound-based measurements of four key anatomical shoulder distances and to establish normative reference values in a healthy population.

A total of 195 healthy volunteers (390 shoulders) underwent ultrasonographic evaluation of the acromioclavicular distance (AC), coracoclavicular distance (CC), acromiohumeral distance (AH), and coracohumeral distance (CH). Two physicians, TC (radiologist) and GB (sports medicine), performed the measurements independently using two different ultrasound machines: Siemens S3000 and C10X, respectively. To assess intra-rater temporal reliability, all measurements were repeated on the same participants after two weeks. Stratified sex-matched randomization was applied during participant recruitment.

AC, AH, and CH ultrasound measurements showed intra- and inter-rater reliability with minimal bias and acceptable limits of agreement, indicating good consistency and interchangeability. In contrast, CC measurements exhibited significant inter-rater differences (p = 0.034 and p = 0.023) and wide limits of agreement, reflecting greater variability and limited interchangeability.

Given their consistent performance across statistical methods, AC, AH, and CH measurements may be used interchangeably across different raters or sessions, particularly in clinical or research settings where reliable reproducibility is essential. However, due to its high inter-rater variability and broad limits of agreement, CC measurements are not recommended for interchangeable use between evaluators or devices.