Lister's tubercle revisited: Anatomical variants and tendon relationships on wrist MRI

Lister's tubercle (LT) is a palpable bony prominence on the distal radius and is in close proximity to the extensor pollicis longus (EPL) tendon. Despite its clinical relevance, detailed knowledge regarding its morphological variations, anatomical relationships, and developmental aspects remains limited. This study aims to evaluate the morphological variants of LT and its anatomical relationships with EPL using wrist magnetic resonance imaging (MRI), and to propose a novel classification system with potential clinical implications.

A total of 302 wrist MRI scans (138 males, 164 females; age range 18-44 years) were retrospectively analyzed. Morphometric measurements were recorded, and a five-type classification system with subtypes based on peak prominence and shape was developed. Statistical analyses evaluated morphometric differences by gender, side, and variant type.

Five main LT types were identified: Type 1 (48.34 %) with a dominant radial peak, Type 2 (23.18 %) with a dominant ulnar peak, Type 3 (4.30 %) with only a ulnar peak, Type 4 (20.86 %) with only a radial peak, and Type 5 (3.31 %) with no crest formation. Significant gender-based differences were found in several morphometric parameters, with generally larger measurements in males (p < 0.001). Strong correlations were noted between LT peak heights and EPL positioning, with the groove's depth and EPL alignment largely determined by the relative height of radial and ulnar peaks.

This study highlights previously underappreciated morphological diversity of LT and proposes a clinically relevant classification. These anatomical variations may influence the risk of EPL injury, especially during distal radius fracture management and surgical interventions. Preoperative imaging evaluation of LT type may improve surgical planning and outcomes.