Morphological Characteristics of the Distal Iliopsoas Tendon and Its Relationship to Adjacent Osseous Structures

Background The iliopsoas muscle influences lumbo-pelvic posture and gait stability, with its distal portions contributing to common anterior hip pathologies, including iliopsoas bursitis, impingement, and tendinopathy. Despite its role in such pathologies, the anatomical variation of the iliopsoas musculotendinous morphology is poorly described. This project, therefore, evaluated distal iliopsoas tendon morphology and its relationship to pelvic osseous structures. Methods Data on the iliopsoas tendon and osseous morphology were collected from 49 body donors. Linear measurements were collected between the anterior superior iliac spine (ASIS), lesser trochanter (LT), pubic tubercle (PT), and medial and lateral femoral epicondyles (ME, LE). Angles between landmarks were calculated trigonometrically. Correlation analyses were performed to determine whether correlations existed among variables, and independent t-tests and Chi-squared tests were used to assess differences among sexes and tendon morphotype categories.  Results Tendons were classified into three morphotypes: notched (53%), fan-shaped (25%), and narrow (22%), with narrow tendons being more common in males (25.8% versus 16.7%) and fan-shaped tendons in females (33.3% versus 19.4%). Fan-shaped tendons had a higher mean LT angle, but no variables differed significantly between tendon types. Females had significantly higher LT angle (p = 0.007) and psoas minor presence (60% versus 32.4%) versus males. Highly significant correlations were identified between ASIS angle and length from PT to LT (r = 0.659; p < 0.001), LT angle and length from ASIS to PT (r = 0.581; p < 0.001), and PT angle and distance between ASIS and LT (r = 0.474, p = 0.001). Overall, there was a significant relationship between sex and several linear and angular measurements. Conclusion The identification of distinct tendon morphotypes and relationships between the musculotendinous complex and osseous landmarks provides novel insight into anterior hip morphology. Findings may assist in the identification of persons at risk of anterior hip pathology.