Dual Mobility in Total Hip Arthroplasty: Biomechanics, Indications and Complications-Current Concepts

Abstract

Dual-mobility (DM) articulations are increasingly utilized to prevent or manage hip instability after total hip arthroplasty (THA). DM cups offer enhanced stability due to the dual articulation resulting in larger jump distance and greater range of motion before impingement. Improvement in design features and biomaterials has contributed to increased interest in dual-mobility articulations due to lower risk of complications compared to their historic rates. The incidence of implant-specific complications like intra-prosthetic dislocation (IPD) and wear has reduced with newer-generation implants. DM THAs are used in primary THA in patients with high risk for dislocation, e.g. neuromuscular disorder, femoral neck fracture, spinopelvic deformity, etc. They offer an attractive alternative option to constrained liner for treatment of hip instability in revision THA. The medium- to short-term results with DM THA have been encouraging in primary and revision THA. However, there are concerns of fretting, corrosion and long-term survivorship with DM THA. Hence, longer-term studies and surveillance are required for the safe use of DM THA in clinical practice.

Keywords: Complications; Dual-mobility; Instability; Total hip arthroplasty.

Fig. 1

Stryker dual mobility implant A MDM and B anatomic (ADM)

Fig. 2

Zimmer Biomet dual-mobility system (cup, metal liner, Vit E mobile poly and head)

Fig. 3

Biomechanics: A primary between the prosthetic femoral head and mobile polyethylene and B secondary articulation between outer surface of mobile bearing and the metallic acetabular cup

Fig. 4

Intraoperative photograph of cemented dual-mobility liner in revision THA

Fig. 5

Radiograph of dislocated DM THA

Fig. 6

Radiograph of intra-prosthetic dislocation following closed reduction of DM THA. Note the eccentric position of the head in the cup