The central dorsal component of the dorsoradial ligament of the trapeziometacarpal joint: Cadaveric and sonographic validation.

Purpose: Osteoarthritis of the trapeziometacarpal joint is very common, especially in females, and is closely associated with ligamentous laxity and joint subluxation. The dorsoradial ligament (DRL) remains largely unexplored in ultrasound studies despite its clinical relevance. This study aimed to identify the central fascicle of the DRL anatomically and ultrasonographically and to establish a standardized ultrasound examination protocol.

Methods: This observational cross-sectional validation study was conducted in two phases. First, anatomical dissections were performed on five cadaveric specimens to define anatomical landmarks and guide the development of an ultrasound protocol. In the second phase, bilateral ultrasound examinations were performed on the thumbs of 26 healthy participants (n = 52) to assess ligament morphology and establish normative measurements.

Results: The DRL was successfully identified in all cases, and ultrasound imaging allowed for the reproducible visualization of its central fascicle. The mean joint distance was 0.36 ± 0.13 cm, and the mean ligament area was 0.20 ± 0.08 cm. Significant differences were observed between the sexes, with males having statistically higher distances (p < 0.05) than females from the tubercle of the trapezium to the skin and from the tubercle of the trapezium to the upper edge of the first metacarpal. However, no significant correlations were found with age, and no significant asymmetries were found between both sides.

Conclusion: The DRL can be reliably assessed by ultrasound and provides clinically relevant parameters to assess ligament morphology. The standardized protocol developed provides a valuable tool for detecting ligamentous insufficiency and capsuloligamentous changes. These findings contribute to understanding the anatomy and function of the DRL and provide a basis for future research into its role in joint stability and osteoarthritic progression.