Sciatic nerve course in adult patients with unilateral developmental dysplasia of the hip: implications for hip surgery

Sciatic nerve injury is a disastrous adverse complication of surgery and can cause debilitating pain, functional impairment and poor quality of life. Patients with developmental dysplasia of the hip (DDH) have a high incidence of sciatic nerve injury after total hip arthroplasty (THA). A better understanding of the course of the sciatic nerve in patients with DDH may help minimise the risk of sciatic nerve injury after THA. A total of 35 adult patients with unilateral DDH were enrolled in this retrospective study. We reviewed the patients' computed tomography (CT) scans, which included the area from the iliac crest to below the lesser trochanter. The distance between the sciatic nerve and regional anatomic landmarks in four different sections on CT scans was measured to identify the course of the sciatic nerve. The distance from the sciatic nerve to the spine's midline was shorter on the affected side than on the healthy side (p < 0.05); the same difference was also detected in the distance to the ilium/ischium outside the true pelvis (p < 0.05). The distance to the greater trochanter was longer on the affected side (p < 0.05). However, the two sides showed no significant difference in the distance from the sciatic nerve to the lesser trochanter (p > 0.05). For patients with unilateral DDH, the sciatic nerve was located near the ischium and ilium but relatively far from the femur of the affected hip joint, compared to its location on the healthy side. These findings reveal that sciatic nerve becomes shorter in the affected low-limb and is relatively unlikely to be directly injuried using the posterolateral approach in patients with unilateral DDH.