Ultrasound Diagnosis of A2 Pulley Injuries: Landmark-Specific Tendon-Bone Distance and Flexor Tendon Curvature in a...

BackgroundA2 pulley ruptures are common in rock climbers, yet diagnosing partial ruptures remains challenging due to variability in tendon-bone distance (TBD) measurements in ultrasound assessments.ObjectiveThis study evaluated TBD at multiple anatomic landmarks to differentiate intact, partial, and complete A2 pulley ruptures; compared landmarks for optimal ultrasound diagnosis; and investigated flexor tendon curvature as an additional indicator.MethodsForty-two fingers from 14 fresh-frozen cadaveric arms were examined using high-frequency ultrasound. Fingers were assigned to 5 simulated groups: intact; low-grade partial (5 mm), medium-grade partial (10 mm), and high-grade partial (15 mm) ruptures; and complete ruptures (≥20 mm). TBD was measured at 4 anatomic landmarks: distal edge of A2 pulley (point A), 5 mm proximal to point A (point B), 10 mm proximal to point A (point C), and the midpoint of the proximal phalanx (MPP point). Analysis of variance and Bonferroni correction were used for statistical analysis.ResultsTBD significantly differed between intact, partial, and complete ruptures at most landmarks. Point C reliably differentiated high-grade partial ruptures from complete ruptures (P<0.05), whereas point A was most responsive to low-grade partial ruptures. The flexor tendon curvature correlated with increasing rupture severity, supporting its use in ultrasound diagnosis.ConclusionTBD provides an indirect, objective, and reproducible ultrasonographic sign for assessing A2 pulley injuries, whereas tendon curvature serves as a complementary direct sign. Using both improves diagnostic accuracy, refines injury classification, and supports clinical decision making. These findings may guide management and rehabilitation strategies for climbers and other athletes with finger pulley injuries.