Modular dual mobility cups with multihole metal back in total hip arthroplasty revision: a systematic review.

Dislocation after hip revision is a frequent complication; amongst the strategies to prevent dislocation dual mobility (DM) implants are gaining popularity. We want to evaluate the reliability of non cemented DM cups with multihole metal back and chrome-cobalt liner called Modular Dual Mobility (MDM). We performed a systematic review and selected 5 studies with a total of 285 hips who underwent revision surgery with MDM implants. The mean survivorship rate of the 5 studies was 92.46% (range 90-96%). 267 prosthesis (93.6%) were still implanted at the last follow-up; the mean weighted follow up was 38.7% (range 24-48). We found 13 mechanical complications in 285 hips (4.5%). Five of them were treated conservatively; the other 8 were treated with re-revision. Nine of these complications were dislocation and recurrent instability; 2 of them were associated to metallosis and adverse local tissue reaction. There was 1 patient that had episodes of subluxation; 2 cases of impingement and 1 case of metallosis. Zero intraprosthetic dislocations (IPD) occurred in 285 hips. A 93.6% survivorship is a good result for MDM implants, considering that most of patients had important bone loss and went through multiple revisions. The rate of dislocation is very low compared to the mean rate of dislocation in revision hip surgery. In our review, fretting is a rare complication but it can lead to ALTR and metallosis. For this reason, MDM implants have to be used in selected cases at high risk of dislocation. In conclusion MDM is a great option for decreasing dislocation rate in hip revision, but a longer follow-up and a greater number of cases is needed to assess its reliability.