Anatomical features of the iliocapsularis muscle: a dissection study

PURPOSE: Iliocapsularis (IC) overlies the anteromedial hip capsule and is an important landmark in anterior approaches to hip arthroplasty. Previously believed to be part of iliacus, few publications describe the prevalence, attachments, fibre direction, blood supply, innervation, and size of IC. This study was aimed to determine these anatomical features using embalmed bodies and whether they vary between sides, sex, and age. METHODS: Thirty-eight formalin-fixed adult bodies were dissected and the prevalence, presence of a connective tissue raphe, attachments, fibre direction, blood supply, and innervation, were documented. Length and width were measured, and significant differences were investigated with t tests. RESULTS: Iliocapsularis was present in all bodies examined, originating from the inferior border of the anterior inferior iliac spine, and inserting 20 mm distal to the lesser trochanter in 54 muscles (71%). Iliocapsularis was supplied by a thin branch from the femoral nerve and by branches of the lateral circumflex femoral and deep femoral arteries and veins. Muscle fibre direction was from superolateral to inferomedial. Mean length was 116.8 ± 11.2 mm and width was 12.8 ± 3.1 mm, with no significant differences between sides, sex, and age. CONCLUSION: This was the first study to document the venous drainage and compare the dimensions with sides, sex, and age, using adult bodies. However, the true function of IC is still unknown. Iliocapsularis is a constant muscle, distinct from iliacus, which is relevant to orthopaedic surgeons and physical rehabilitation specialists, particularly for postoperative patient care. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s00276-022-02905-y.