Direct anterior approach and dual mobility cup: the "head-first" reduction technique: a technical note and early case series.

Abstract

Less invasive direct anterior approach (DAA) and dual mobility cup (DMC) are increasingly adopted in practice over the last decade. Their use aims to reduce, as much as possible, soft tissue dissection and dislocation rate. This study aims to present a novel surgical technique to reduce a DMC prosthesis during a DAA easily. A mildly modified version of the direct anterior approach is proposed. When leg lengths, stability, impingement, and tension have been checked, the trial stem is disassembled in situ, dislocated, and removed, leaving the space to exchange the trial double mobility head with the definitive one. When the definitive stem is inserted, the surgeon guides and helps the assistant to match the trunnion in the double mobility head. As soon as the components are matched, the traction is released, and the unit is impacted by an alternation of axial traction and release. Of 164 patients who underwent primary total hip arthroplasty (December 2016-May 2017) by a single surgeon, a double mobility cup through DAA and the "head-first" technique was performed in 26 patients (15.8%). The mean operative time was 130min (85-220min; SD 34.28). No significant complications occurred during the mean follow-up of 23.6months. Specific difficulties can be anticipated when pairing dual mobility cup and direct anterior approach. The "head-first" technique is a useful technique in reducing the possible difficulties related to the reduction of double mobility cup through a less invasive direct anterior approach.