Intraprosthetic Dislocation of Dual-Mobility Total Hip Arthroplasty: The Unforeseen Complication

Abstract

Total hip arthroplasty (THA) is one of the most successful and widely accepted orthopedic procedures. Instability after THA is one of the most significant postoperative complications. Dual-mobility THA components were introduced in 1974 to overcome the risk of instability by increasing the jump distance. Dual-mobility bearings couple two articulations, namely, one between a 22-28 mm prosthetic head and polyethylene liner and another larger articulation between the polyethylene liner and the metal cup. Dislocation of the polyethylene liner and the consequent direct articulation between the prosthetic head and metal cup is recognized as intraprosthetic dislocation (IPD). This mode of THA failure is specific to dual-mobility implants. Despite the reduced incidence of IPD in modern dual-mobility implants compared to the early designs, iatrogenic IPD can occur during closed reduction of dislocated polyethylene liner-metal cup articulation. IPD requires timely diagnosis and early surgical intervention to minimize the necessity of major revision surgeries. This study presents a comprehensive review for dual-mobility-bearing THA, including the history and biomechanics, and focuses on the pathomechanics, diagnosis, and management of IPD.

Intraprosthetic Dislocation of a Modular Dual-Mobility Total Hip Arthroplasty With Posterior Migration of the Polyethylene Liner

“…reported a 71% incidence of IPD following closed reduction of a dislocated DM hip [ 11 ]. Delayed recognition can lead to increased damage to the cup with potentially significant soft-tissue metallosis and elevated levels of cobalt and chromium [ 12 , 13 ].…”

A Missed Diagnosis of Intraprosthetic Dislocation in a Dual-Mobility Bearing Following Closed Reduction

“…IPD warrants open reduction as retrieval and replacement of the dislodged liner are required. Operative treatment begins with an open exploration to locate and revise the polyethylene component [ 17 ]. If not located in the hip joint, intrapelvic migration of the liner should be suspected and identified with a postoperative CT scan.…”

Intraprosthetic dislocation of dual-mobility total hip arthroplasty implant

“…Adjusting windows/levels on CT is critical for visualizing the different components and limiting metal artifacts. CT imaging can demonstrate the position of the dislocated polyethylene component and provide information for surgical planning [9] . The polyethylene head can migrate into the soft tissues, as seen in our patient, or deeper into the pelvis [10] .…”

“…Though IPD of dual-mobility implants is uncommon, this type of hardware failure is vital to identify on imaging as they can cause further issues. We have identified only one other case in the literature illustrating IPD on radiographs and CT [9] .…”