Inter- and intra-observer reproducibility of ultrasound analysis of the long head of the biceps

Introduction: Ultrasound assessment of the long head of the biceps (LHB) is difficult. The aim of the present study was to analyze the inter- and intra-observer reproducibility of 2 ultrasound cross-sections not previously assessed: humeral head apex (image 1) and bicipital groove entrance (image 2).

Hypothesis: These ultrasound cross-sectional images allow reliable and reproducible analysis of the intra-articular LHB.

Material and methods: A single-center prospective study was conducted. Inter-observer reproducibility was assessed between 2 radiologists in 20 healthy shoulders (asymptomatic group) and 35 painful shoulders (symptomatic group); intra-observer reproducibility was assessed for 1 observer in 10 healthy shoulders. Quantitative parameters comprised short and long axes and transverse area, and qualitative parameters comprise echogenicity and LHB position.

Results: On images 1 and 2, inter-observer agreement on the 3 quantitative parameters was good to excellent in both subject groups (p<0.05), and more precise and highly reproducible for image 1. Agreement on the 2 qualitative parameters was excellent (p<0.001). Intra-observer reproducibility results were non-significant on all parameters.

Discussion: The 2 intra-articular LHB cross-sections proved reliable and reproducible in painful and in healthy shoulders. A standardized ultrasound protocol could thus enhance the precision of LHB assessment and treatment. The difficulties of LHB measurement, often related to shoulder pathology, may, however, hinder interpretation.

Level of evidence: III, prospective intra- and inter-observer study.