The anatomical course of the sciatic nerve in relation to different approaches in total hip arthroplasty.

Purpose: Although sciatic nerve (SN) injury is relatively rare, it is a devastating complication after primary and revision total hip arthroplasty (THA). Therefore, precise localization of the SN is essential for arthroplasty surgeons.

Methods: We dissected 50 hemipelves from formalin-fixed cadavers. The course and location of the sciatic nerve were investigated in relation to different approaches for THA with the help of anatomical landmarks like the greater trochanter (GT), the iliac tubercle, the ischial tuberosity (IschT), the infrapiriform foramen, and the suprapiriform foramen.

Results: We found and exposed the sciatic nerve in all 50 specimens with no sex-specific differences. No SN was encountered up to 22 mm posterior from the GT. The zone affording the highest probability of finding the nerve was posterior to the GT between 32 and 55 mm in 39 (78%) cases, thus defining a danger zone for different approaches for the THA.

Conclusion: Special care should be taken with posterior and deep instrument placement between the GT and IschT during THA. Moreover, manipulations in the proximal third of the posterior approach reaching deep and posteriorly should be performed with the utmost care.