Gender Differences in the Morphology of the Finger Flexor Pulley System: An Ultrasound-Based Assessment of Recreational Rock Climbers

Abstract

Background Many rock climbing techniques place tremendous stress on the finger flexor pulley system of the hand and may cause a pulley rupture. A pulley injury can be assessed with ultrasound by measuring an elevated tendon liftoff from the bone during flexion, referred to as the tendon-to-bone distance (TBD). The purpose of this study was to assess gender-specific and experience-related differences in TBD, tendon dimensions, and grip strength among asymptomatic recreational rock climbers to better understand potential anatomical adaptations and injury risks. Methodology We conducted a prospective, cross-sectional study at a single indoor climbing facility in San Bernardino County, California, over several days. A total of 65 adult recreational climbers (36 men, 29 women) completed a health and climbing experience survey. A portable ultrasound probe was used to measure TBD, tendon depth, and tendon width at rest and during maximal isometric flexion. Grip strength was measured using a handheld dynamometer. Sex-based differences were analyzed using independent one-tailed t-tests, with significance set at p-values <0.05. Results The mean age of the participants was 29.3 ± 7.8 years. On average, women reported a maximum climbing grade of V4, while men reported V6. Men had significantly higher grip strength and tendon cross-sectional area (p < 0.001). The average unflexed TBD was 0.20 cm in women and 0.24 cm in men. During flexion, TBD increased by 0.03 cm in women and 0.05 cm in men, with no significant difference (p = 0.07). Conclusions In this study, women exhibited significantly smaller tendon cross-sectional area and lower grip strength compared to men. These anatomical differences warrant further research to explore implications for climbing performance and injury risk.