Morphology and anatomical relations of iliac and femoral bony landmarks, gluteal muscles and the sciatic nerve: Sex differences and clinical implications

The objective of this study was to determine sex differences in the anatomical relations between clinically relevant and palpable bony landmarks (anterior superior iliac spine, or ASIS), posterior superior iliac spine (PSIS), iliac tubercle and greater trochanter, and with the gluteal muscles and sciatic nerve. After dissection, distances along the iliac crest, angles and distances between bony landmarks, muscle thicknesses of gluteus maximus and gluteus medius, the fibre angles of gluteus maximus, and anatomical relations between the sciatic nerve and bony landmarks, were measured. In 23 cadavers (11 males; 12 females), iliac crest total length, distances between the greater trochanter, ASIS and iliac tubercle, and between the sciatic nerve and iliac crest, but only the angle at the PSIS between the iliac tubercle and greater trochanter, were significantly larger in males. Distances and angles reflecting horizontal measures, iliac crest proportions, and gluteus maximus fibres angles were not different between sexes. Gluteus maximus muscle fibre angles differed significantly along the sagittal plane and from medial to lateral. In conclusion, while males have a larger ilium and taller pelvis, there was no sex difference in pelvic width. Therefore, the female pelvis is shorter and relatively wider with respect to pelvic height, but is not absolutely wider than the male pelvis. This puts females at a greater risk of sciatic nerve injury with a dorsogluteal site injection. The angles of the gluteus maximus muscle fibres varied along their length and were not consistently 45o as commonly described.