A CT study of the femoral and sciatic nerve periacetabular moving in different hip positions

BACKGROUND: Femoral and sciatic nerves could be damaged during various stages of the periacetabular osteotomy. Changing the position of the hip could be the most effective way of preventing nerve injuries. The purpose of the present study was to investigate the distances of the nerves to various bony landmarks with different hip positions in computerized pelvic scanograms of healthy adults. MATERIALS AND METHODS: Fifteen healthy male adults (30 hips) (age 30 ± 6) were included. Scans were performed at three different hip positions measured by goniometer (neutral “N,” flexion (30–45°) + abduction (30–45°) + external rotation (20°) “F” and neutral+ abduction (30–45°) + external rotation (20°) (N(abext)) at three different levels (sourcil “1,” the middle of the femoral head “2,” and lower border of triradiate cartilage “3.” RESULTS: At the sourcil level, the femoral nerve was found to be the furthest distance from the anterior acetabulum in the neutral position compared to flexion or neutral plus abduction, external rotation (p < 0.001). For the sciatic nerve, at level 2, hip flexion resulted in a greater distance than in the neutral position (p = 0.001). For level 3, hip flexion caused a decrease in the distance of the sciatic nerve to the acetabulum compared to both neutral positions (N or N(abex)) (p = 0.001). CONCLUSIONS: During a pubic cut of the osteotomy, the femoral nerve moves closer to the anterior acetabulum wall with hip flexion or abduction plus external rotation. During an ischial cut, the sciatic nerve gets closer to the ischium with hip flexion while it moves away from the bone during retroacetabular cut. Level-III Study