The Bernese periacetabular osteotomy (PAO) is a widely used procedure to reorient a dysplastic acetabulum resulting from developmental dysplasia of the hip, retroversion, protrusio, or some deformities with a traumatic etiology. Throughout the execution, the lateral femoral cutaneous nerve (LFCN) as well as the obturator, femoral, and sciatic nerves can be injured. Injury to 1 of the 3 major nerves is a devastating event for the patient followed by an ill-defined period of hope for nerve recovery and fear of lifelong disability. Surgical experience is an essential factor in reducing the prevalence of nerve injury, whereas proof of the value of intraoperative fluoroscopy and nerve monitoring still must be established. Although it is known that, for example, the ischial cuts of the complex osteotomy place the sciatic nerve at risk, the action causing the nerve injury is rarely clear in the individual situation. The literature has been mostly limited to reports of incidence and offers little analytic information.
Through the use of cadaveric dissections, we visualized the possible impacts of the different steps of the procedure on the nerves in their anatomic vicinity, and the present report demonstrates how nerves can be protected with retractor positioning and how lower-limb positioning can lead to nerve relaxation, an important means to avoid mechanical injury. While the frequent injuries of the LFCN are exclusively related to the approach, sciatic nerve injuries are mainly the result of the ischial osteotomy steps and femoral nerve injuries are seen nearly exclusively with the correction of the acetabular fragment. The authors implemented the demonstrated measures for 9 years, during which approximately 800 periacetabular osteotomies resulted in a total of 2 femoral and 2 sciatic nerve lesions—or a nerve injury rate of 0.5%. The nerves injuries resolved within 6 to 9 months in 3 hips, and 1 patient had a definitive foot drop requiring a splint at the time of writing.