Morphological analysis of the retrotalar pulley and its role in flexor hallucis longus impingement: Insights from a CT-based study

The Flexor Hallucis Longus (FHL) is a muscle that can be subject to multiple conflicts. The most common conflict is due to inflammation of the tendon at the retrotalar pulley. The constraints exerted on the FHL are responsible for a pathology called functional Hallux Limitus. The purpose of this anatomical study is to describe morphologic finding about retrotalar pulley, which may account the impingement between FHL and the hindfoot. Using a retrospective approach at a single center, a detailed analysis was conducted on a cohort of 350 patients. Precise measurements were taken to document the angles, areas, and distances that define the relationship between the Flexor Hallucis Longus (FHL) tendon and its surrounding anatomical structures. The angle between the retrotalar pulley and the sustentaculum tali exhibited a range of 124 to 170 degrees in profile and 113.3 to 178 degrees in frontal view. The dimensions of the retrotalar pulley varied from 1.1 to 54 mm², while the posterolateral and posteromedial tubercles displayed dimensions ranging from 3.4 to 77.9 mm² and 2.6 to 35.2 mm², respectively. Distances between posterior tubercles further underscored the anatomical diversity, ranging from 4.3 to 17 cm proximally and 10.5 to 18.4 cm distally. In unraveling the morphological complexities surrounding FHL impingement, this study provides valuable insights into the biomechanical intricacies of the foot. These findings not only deepen our understanding of musculoskeletal anatomy but also pave the way for future investigations into the dynamic interplay between structure and function in the lower extremities.