Postoperative dislocation is a challenging complication after total hip arthroplasty (THA) that affects patient outcome worldwide. Instability is one of the main complications with rates exceeding 20% in some series. Currently, alternative acetabular components are available with dual mobility (DMTHA) bearing surfaces and larger femoral head size that may reduce the risk of dislocation, yet provide the functional benefit of standard single mobility (STHA) bearing surface THA. However, whether STHA, big femoral head (BTHA) and DMTHA should be used is still controversial. This systematic review and meta-analysis aim to compare postoperative dislocation and revision (aseptic loosening and infection) of BTHA, STHA and DMTHA in primary or revision THA. These clinical outcomes consist of postoperative dislocation and revision (aseptic loosening and infection). This systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Relevant studies were identified from Medline and Scopus from inception to June 8, 2017, that reported postoperative dislocation and revision (aseptic loosening and infection) of either implant THA. Eleven of 677 studies (nine comparative studies and two RCTs) (N = 4084 patients) were eligible; all 11 studies were included in pooling. Intervention included dual mobility THA (N = 1068 patients), standard THA (N = 2568 patients), big head THA (N = 378 patients) and constrain THA (N = 70 patients). A network meta-analysis showed that risk of revision and dislocation of DMTHA was significantly lower with RR of 2.19 (1.36, 3.53) and 4.19 (2.04, 8.62) when compared to STHA. While there was no statistically significant risk of having revision and dislocation of DMTHA when compared to BTHA and CTHA. The SUCRA probability of DM and BTHA was in the first and second rank with 46.5 and 44.8% in the risk of revision and 46.7 and 45.1% in the risk of dislocations. In short-term outcomes (5 years or less, with follow-up of 0-5 years), the best implant of choice that has lowest risk of revision and dislocation after THA is DMTHA follow by BTHA. We recommend using dual mobility and big head as an implant for safety in THA. However, there were only two studies that reported long-term survivorship (more than 5 years, with follow-up of 5-15 years). Further research that assesses long-term survivorship is necessary to further evaluate which implants are the best for THA.

In all, 117 of 493 studies were eligible and 32 studies (2,013 shoulders) and 11 studies (1,498 shoulders) were evaluated with MRA and MRI. The summary sensitivity, specificity, likelihood ratio (positive and negative) and AUROC were 0.87 (95 % confidence interval, CI: 0.82, 0.91), 0.92 (95 %CI: 0.85, 0.95), 10.28 (95 %CI: 5.84, 18.08), 0.14 (95 %CI: 0.10, 0.20) and 0.94 (95 %CI: 0.92, 0.96) respectively for MRA, and 0.76 (95 %CI: 0.61, 0.86), 0.87 (95 %CI: 0.71, 0.95), 5.89 (95 %CI: 2.5, 13.86), 0.28 (95 %CI: 0.17, 0.47) and 0.94 (95 %CI: 0.92, 0.96) respectively for MRI. The diagnostic performance of MRA was superior to MRI by both direct and indirect comparisons for the detection of SLAP lesions.

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