Ultrasound assessment of vertebral ligaments: development and validation of a landmark-based scanning protocol with potential applicability in spondyloarthritis.

OBJECTIVES

To provide a comprehensive description of a standardised, landmark-based ultrasound (US) technique for evaluating the lateral costotransverse (LCTL), supraspinous (SSL) and iliolumbar (ILL) ligaments of the thoracolumbar spine and to assess its reliability, feasibility and its potential applicability in spondyloarthritis (SpA).

METHODS

LCTL, SSL and ILL were examined using US in specimens, followed by dissection to confirm structure location and validate US findings using a standardised anatomic-based and sonoanatomic-based landmark approach. The US technique was subsequently applied in 20 healthy controls (HC), in whom feasibility and inter-rater and intra-rater reliability among four operators with different expertise were assessed. Ligament visualisation was scored as: 0, not visualised; 1, incompletely visualised; 2, perfectly visualised. The technique was tested in three patients with SpA to evaluate its applicability.

RESULTS

Anatomical study confirmed location and landmarks for all three ligaments. 120 ligaments were assessed in two rounds in HC. Visualisation scores ranged from 1 to 2 in 100% LCTL, 99.1% SSL and 85.9% ILL, with score 2 obtained in 69.6% of 960 assessments. Mean examination time decreased from 12'17″ to 10'56″ between rounds, with no significant differences between operators. Intra-rater and inter-rater agreement ranged from moderate to high. In patients with SpA, US detected both inflammatory and structural lesions in the three ligament entheses.

CONCLUSION

The proposed standardised US approach allows reliable assessment of LCTL, SSL and ILL. This technique provides a robust and reproducible method for evaluating the ligaments of the thoracolumbar spine and opens a new approach to the US assessment of patients with spinal inflammatory diseases, including SpA.