Dislocation post THA confers a higher risk of re-dislocation (Kotwal et al, 2009). The dual mobility (DM) cup design (1974) was aimed at improving the stability by increasing the femoral head to neck ratio (Cuthbert et al., 2019) combining the ideas of low friction arthroplasty with increased jump distance associated with a big head arthroplasty. Understand the dislocation rates, rates of aseptic loosening, infection rate and revision rates between the 2 types of constructs to provide current and up-to date evidence. Medline, pubmed, embase and Cochrane databases were used based on PRISMA guidelines. RevMan software was used for the meta-analysis. Studies (English literature) which used DM construct with atleast 6 months follow-up used as intervention and non DM construct as control were included. 2 independent reviewers conducted the review with a third reviewer in case of difference in opinion regarding eligibility. Primary outcome was dislocation rate and secondary outcome was rate of revision. 564 articles identified out of which 44 articles were screened for full texts and eventually 4 systematic review articles found eligible for the study. Thus, study became a review of systematic reviews. From the 4 systematic reviews, another 35 studies were identified for data extraction and 13 papers were used for meta-analysis. Systematic reviews evaluated, projected an average follow up of 6-8 years with significantly lower dislocation rates for DM cups. The total number of patients undergoing DM cup primary THA were 30,559 with an average age 71 years while the control group consisted of 218,834 patients with an average age of 69 years. DM group had lower rate of dislocation (p < 0.00001), total lower rate of cup revision (p < 0.00001, higher incidence of fracture (p>0.05). DM THA is a viable alternative for conventional THA. The long-term results of DM cups in primary THA need to be further evaluated using high quality prospective studies and RCTs

Abstract. Introduction. Dislocation post THA confers a higher risk of re-dislocation (Kotwal et al, 2009). The dual mobility (DM) cup design (1974) was aimed at improving the stability by increasing the femoral head to neck ratio (Cuthbert et al., 2019) combining the ideas of low friction arthroplasty with increased jump distance associated with a big head arthroplasty. Aims. Understand the dislocation rates, rates of aseptic loosening, infection rate and revision rates between the 2 types of constructs to provide current and up-to date evidence. Methods. Medline, pubmed, embase and Cochrane databases were used based on PRISMA guidelines. RevMan software was used for the meta-analysis. Studies (English literature) which used DM construct with atleast 6 months follow-up used as intervention and non DM construct as control were included. 2 independent reviewers conducted the review with a third reviewer in case of difference in opinion regarding eligibility. Primary outcome was dislocation rate and secondary outcome was rate of revision. Results. 564 articles identified out of which 44 articles were screened for full texts and eventually 4 systematic review articles found eligible for the study. Thus, study became a review of systematic reviews. From the 4 systematic reviews, another 35 studies were identified for data extraction and 13 papers were used for meta-analysis. Systematic reviews evaluated, projected an average follow up of 6–8 years with significantly lower dislocation rates for DM cups. The total number of patients undergoing DM cup primary THA were 30,559 with an average age 71 years while the control group consisted of 218,834 patients with an average age of 69 years. DM group had lower rate of dislocation (p < 0.00001), total lower rate of cup revision (p < 0.00001, higher incidence of fracture (p>0.05). Conclusion. DM THA is a viable alternative for conventional THA. The long-term results of DM cups in primary THA need to be further evaluated using high quality prospective studies and RCTs. Declaration of Interest. (b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project

Pelvic tilt can vary over time due to aging and the possible appearance of sagittal spine disorders. Cup position in total hip arthroplasty (THA) can be influenced due to these changes. We assessed the evolution of pelvic tilt and cup position after THA and the possible appearance of complications for a minimum follow-up of ten years. 343 patients received a THA between 2006 and 2009. All were diagnosed with primary osteoarthritis and their mean age was 63.3 years (range, 56 to 80). 168 were women and 175 men. 250 had no significant lumbar pathology, 76 had significant lumbar pathology and 16 had lumbar fusion. Radiological analysis included sacro-femoral-pubic (SFP), acetabular abduction (AA) and anteversion cup (AV) angles. Measurements were done pre-operatively and at 6 weeks, and at five and ten years post-operatively. Three measurements were recorded and the mean obtained at all intervals. All radiographs were evaluated by the same author, who was not involved in the surgery. There were nine dislocations: six were solved with closed reduction, and three required cup revision. All the mean angles changed over time; the SFP angle from 59.2º to 60º (p=0.249), the AA angle from 44.5º to 46.8º (p=0.218), and the AV angle from 14.7º to 16.2º (p=0.002). The SFP angle was lower in older patients at all intervals (p<0.001). The SFP angle changed from 63.8 to 60.4º in women and from 59.4º to 59.3º in men, from 58.6º to 59.6º (p=0.012). The SFP angle changed from 62.7º to 60.9º in patients without lumbar pathology, from 58.6º to 57.4º in patients with lumbar pathology, and from 57.0º to 56.4º in patients with a lumbar fusion (p=0.919). The SFP cup angle was higher in patients without lumbar pathology than in the other groups (p<0.001), however, it changed more than in patients with lumbar pathology or fusion at ten years after THA (p=0.04). Posterior pelvic tilt changed with aging, influencing the cup position in patients after a THA. Changes due to lumbar pathology could influence the appearance of complications long-term

Summary Statement. We analysed impaction bone grafting used together with cemented or uncemented fixation in acetabular revision surgery. The overall risk for re-revision did not differ between the cemented and uncemented group. However, aseptic loosening was more common in the cemented group. Background. Several surgical techniques address bone defects in cup revision surgery. Bone impaction grafting, introduced more than thirty years ago, is a biologically and mechanically appealing method. The primary aim of this study was to evaluate the effect of bone impaction grafting when used with uncemented and cemented fixation in cup revision surgery. Uncemented cups resting on more than 50% host bone were used as controls. Patient and Methods. Cup fixation was studied in ninety hips (eighty-two patients), revised due to loosening between 1993 and 1997. There were fifty-three isolated cup and thirty-seven total revisions. Patients were followed for thirteen years using conventional radiography, radiostereometry (RSA), Harris Hip score and a pain questionnaire. Peroperatively the surgeon assessed the acetabular bone bed vitality. In hips where the cup was judged to rest on > 50% vital bone (group I, n=43), an uncemented cup was used. If the cup was resting on ≤ 50% living bone, uncemented (group IIa, n=21,) or cemented (group IIb, n=26) technique was chosen, according to the surgeon's preference. The mean age of patients at index revision was 61±12 years, 56% were females. The most common index diagnosis was primary osteoarthritis (n=45) followed by rheumatoid arthritis (n=10). Results. At thirteen years, acetabular component failure had necessitated a second revision in 6/7/8 hips in Groups I/IIa/IIb respectively. These re-revisions were performed 1–10 (mean 7.1) years after index revision. Moreover four cup / liner revisions were performed in hips with femoral loosening, not allowing further RSA measurements. These twenty-five hips were followed until re-revision. Deceased patients (n=21) and patients with deteriorating medical condition, not able to attend the follow-up (n=7), were censored in the survival statistics. Aseptic loosening was the most common reason of re-revision. However, in the uncemented groups (I/IIa), four cups were re-revised due to liner wear, osteolysis or instability. In the total study population, and up to two years, the median proximal migration was lowest in Group I followed by Group IIa and Group IIb (p≤0,006). At thirteen years the mean proximal migration was highest in Group IIb 1.29 mm (SD 1.23) followed by Group I 0.30 mm (SD 0.40) and Group IIa 0.22 mm (SD 0.22), p = 0.05. In cases subsequently re-revised because of loosening or with radiographically loose cups at the last follow-up, a higher proximal migration was observed compared to the non-revised and radiographically well-fixed group (up to seven years: p < 0.001; thirteen years: p=0.04). Discussion/Conclusion. We found an increased risk for rerevision in cases with less than 50% host bone-implant contact. These cups showed high early proximal migration, measured by RSA, indicating poor initial fixation. Rate of re-revision due to any reason did not differ between cemented and uncemented cups. The cemented group (IIb) had a higher risk of being re-revised due to aseptic loosening. Poor bone stock, use of small bone chips, inferior impaction technique, and no or restricted contact with living bone are probable reasons for failures when extensive bone grafting is needed