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.

Instability continues to be a troublesome complication after THA and has been reported to be the main indication for revision in the United States, accounting for 22.5% of revisions. Risk factors associated with dislocation include: age of 75 years or older, body mass index (BMI) of 30 kg/m2 or greater, alcohol abuse, and neuro-degenerative diseases such as multiple sclerosis or Parkinson's disease. Dual-mobility articulations have become an increasingly popular option for these “at risk” primary THAs. Few studies have assessed their use in this complex patient population. The purpose of this study was to assess dislocation rate, radiographic outcomes and complications of the dual-mobility articulation in the setting of primary THA for patients at high risk for dislocation at a minimum follow up of 2 years. We retrospectively reviewed 151 dual mobility acetabular components, that had been performed using a single design (ADM Stryker, Mahwah, NJ) between 2010 and 2014 at a single institution by a single surgeon. The mean age at time of index surgery was 82 years (range, 73–95), 114 patients were female, and mean BMI was 26.2 kg/m2 (range, 16.1–60.9). Dislocation rate and complications associated with dual mobility cups were reviewed, along with the radiographic outcomes after an average follow-up period of 3.6 years (range, 1.9–6.1 years). The indication for hip replacement was osteoarthritis in all cases. We had one traumatic dislocation which required component revision after intraprosthetic dislocation following an attempt of closed reduction. There were no further dislocations in this cohort. No progressive radiolucencies or component positional changes were seen on radiographic assessment. At short-term follow-up dual mobility provides a stable reconstruction in patients at high risk of dislocation with excellent radiographic results. Longer follow-up is needed to confirm the durability of these reconstructions

Introduction. Dual-mobility (DM) articulations may be useful for patients at increased risk for instability in primary and revision THA. While DM articulations are becoming increasingly popular, its routine use in primary THA is more uncertain. Even less is known about femoral head penetration in DM designs manufactured with highly cross-linked polyethylene infused with Vitamin E (E-HXLPE). The purpose of this study was to evaluate the early clinical results and femoral head penetration rates of primary THA implanted with DM E-HXLPE. Methods. Between 2012 and 2017, 105 primary DM THAs were performed using a one-piece acetabular shell, 28mm ceramic head, coupled with an E-HXLPE outer bearing via a standard posterior approach. Three patients refused follow-up after six months. 102 hips (92 patients) were available for review. The diagnosis was 99% OA. Average age was 65.7 years (33–90 years). 56% of patients were female. The most common femoral head size was 50mm (range, 44–60mm). The average thickness of the E-HXLPE outer bearing was 22.7mm (range, 16–32mm). Patients were followed at two months (baseline radiograph), six months, one, three, five, and seven years. Harris hip scores (HHS), UCLA activity score, and femoral head penetration (Martell method) were obtained at each visit beyond two months. Follow-up averaged 3 years (range, 1–7 years). Results. Average HHS improved from 43 to 95 points (50–100) at final follow-up. Similarly, average Harris pain scores improved from 10 to 42 points (20–44) with 78% of patients pain free and one patient, each, reporting groin and thigh pain (1%). Average UCLA activity scores was 8.1 (range, 5–10). There were no dislocations, revisions, or loose cups. The average femoral head penetration (including bedding-in) was 0.25mm/yr (s.d. 0.2mm/yr) at seven years. Discussion/Conclusion. The theoretical benefits of DM designs in diminishing wear include a smaller inner head, lower frictional torque with motion, less micro-separation, and less wear with impingement. The early clinical results of primary DM THA are promising. Although the early femoral head penetration using DM E-HXLPE appears to be less than other DM designs, it was greater than that of conventional THA using HXLPE and E-HXLPE inserts. The additional outer bearing surface, while affording additional stability, may actually enhance polyethylene creep and wear. For any tables or figures, please contact the authors directly

Aims

Instability is a common cause of failure after total hip arthroplasty. A novel reverse total hip has been developed, with a femoral cup and acetabular ball, creating enhanced mechanical stability. The purpose of this study was to assess the implant fixation using radiostereometric analysis (RSA), and the clinical safety and efficacy of this novel design.

Aims

Custom triflange acetabular components (CTACs) play an important role in reconstructive orthopaedic surgery, particularly in revision total hip arthroplasty (rTHA) and pelvic tumour resection procedures. Accurate CTAC positioning is essential to successful surgical outcomes. While prior studies have explored CTAC positioning in rTHA, research focusing on tumour cases and implant flange positioning precision remains limited. Additionally, the impact of intraoperative navigation on positioning accuracy warrants further investigation. This study assesses CTAC positioning accuracy in tumour resection and rTHA cases, focusing on the differences between preoperative planning and postoperative implant positions.

Aims

In metal-on-metal (MoM) hip arthroplasties and resurfacings, mechanically induced corrosion can lead to elevated serum metal ions, a local inflammatory response, and formation of pseudotumours, ultimately requiring revision. The size and diametral clearance of anatomical (ADM) and modular (MDM) dual-mobility polyethylene bearings match those of Birmingham hip MoM components. If the acetabular component is satisfactorily positioned, well integrated into the bone, and has no surface damage, this presents the opportunity for revision with exchange of the metal head for ADM/MDM polyethylene bearings without removal of the acetabular component.