RT Journal Article T1 Differences in foetal topographical anatomy between insertion sites of the iliopsoas and gluteus medius muscles into the proximal femur: a consideration of femoral torsion A1 Zhao, P. A1 Jin, Zhe Wu A1 Kim, Ji Hyun A1 Abe, Hiroshi A1 Murakami, Gen A1 Rodríguez Vázquez, José Francisco AB Background: Prenatal twisting of the femoral neck seems to result in an angle of anteversion or torsion, but the underlying process has not been elucidated.Materials and methods: This study analysed sagittal, frontal and horizontal sections of 34 embryo and foetal specimens of gestational age (GA) 6-16 weeks (crown-rump length 21-130 mm). At GA 6-7 weeks, the iliopsoas (IP) and gluteus medius (GME) muscles were inserted into the anterior and posterior aspects of the femur, respectively, allowing both insertions to be viewed in a single sagittal section.Results: At GA 8 weeks, the greater trochanter and the femoral neck angle became evident, and the GME tendon was inserted into the upper tip of the trochanter. At GA 9 weeks, the location of IP insertion was to the medial side of the GME insertion. After 9 weeks, the IP insertion consisted of a wavy, tendino- us part of the psoas muscle and another part of the iliacus muscle, with many fibres of the latter muscle attached to the joint capsule. After GA 12 weeks, the IP was inserted into the anteromedial side of the greater trochanter, while the aponeurotic insertion of the GME wrapped around the trochanter. At GA 15-16 weeks, a deep flexion at the hip joint caused an alteration in the relative heights of the lesser and greater trochanter, with the former migrating from the inferior to the slightly superior side.Conclusions: These findings indicate that twisting of the femoral neck started at GA 8-9 weeks. PB Via Medica SN 1644-3284 SN 0015-5659 YR 2019 FD 2019-05-28 LK https://hdl.handle.net/20.500.14352/109509 UL https://hdl.handle.net/20.500.14352/109509 LA eng NO Zhao P, Jin ZW, Kim JH, Abe H, Murakami G, Rodríguez-Vázquez JF. Differences in foetal topographical anatomy between insertion sites of the iliopsoas and gluteus medius muscles into the proximal femur: a consideration of femoral torsion. Folia Morphol (Warsz). 2019;78(2):408-418. doi: 10.5603/FM.a2018.0083 NO Ministerio de Educación, Cultura, Deportes, Ciencia y Tecnología (Japón) DS Docta Complutense RD 7 abr 2025