Minimum five years outcomes of modular dual mobility in primary total hip arthroplasty: a systematic review.

backgroundModular dual mobility (MDM) cups are constituted by a cobalt-chromium (CoCr) liner inserted into a standard acetabular shell, allowing for intra-operative decision and supplementary screw fixation of the acetabular component. MDM could face mechanical issues and biological issues, with the associated risk of elevated blood metal ions levels and adverse local tissue reactions (ALTRs). MATERIALS AND

methodsA systematic review of the literature on minimum five years outcomes of modular dual mobility in primary total hip arthroplasty (THA) was performed on PubMed, Cochrane, and Google Scholar databases, in adherence with PRISMA guidelines. Risk of bias in each study was assessed through the JBI checklist for case series.

resultsA total of 381 primary THAs with MDM acetabular cup were performed. At minimum five years follow-up, mean revision rate was 2.3% and implant survivorship was 98.2%. No MDM acetabular construct was revised specifically due to liner mechanical failure, neck-rim impingement, or ALTRs. No intraprosthetic dislocation or iliopsoas tendinitis was observed. No cases of THA dislocation were reported. Mean serum metal ion levels were observed to be within laboratory reference ranges. Greater-than-normal values of serum Co were observed in 9.4% of cases, while greater-than-normal values of serum Cr were observed in 1.6% of patients.

conclusionsThe main finding of this systematic review is that modular dual mobility acetabular construct appears to be a safe and effective option for primary THA at minimum five years follow-up. Longer follow-up time is needed in order to investigate modular dual mobility long-term survivorship, revision and complication rates, clinical and radiological outcomes.