Periprosthetic acetabular bone loss using a constrained acetabular component.

We describe two patients with a constrained acetabular component who required treatment for recurrent dislocation showing postoperative periprosthetic acetabular bone loss. These hips required revision surgery and demonstrated considerable bone loss caused by the migrated acetabular component. Impingement may have occurred with increased stress at the bone-prosthesis interface, and the sharp ends of screws with a metal shell may have gradually plowed up the acetabular bone. These failures illustrate the potential risk of using a constrained acetabular component.