Risk of injury to the femoral blood vessels based on the extent of acetabular dysplasia in total hip arthroplasty.

We evaluated the course of the femoral blood vessels of patients with acetabular dysplasia. Patients were divided into five groups: those with Crowe type I, II, III, and IV dysplastic hips and those with normal hips. A computed tomography-based hip navigation software was used to measure the distance between the femoral blood vessels and the anterior pelvic wall in four axial planes located 10-40 mm proximal to the pelvic teardrop. In Crowe Groups I through IV, the distance was shortest at a point 20 mm proximal to the pelvic teardrop. Furthermore, the distance decreased as the Crowe classification grade increased. Because the femoral blood vessels pass close to the pelvis in many patients in Crowe III and IV hips, caution is required during surgery in these patients.