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Background Use of dual mobility (DM) in total hip arthroplasty has gained popularity due to the ability to reduce dislocation through increased jumping distance and impingement-free arc of movement. Recently, modular dual mobility (modDM) systems were introduced to give the possibility to use DM with standard metal-backed shells, however few has been studied to date regarding how jumping distance and the center of rotation change with modDM. The objective of this study was to evaluate, through analytical simulation, how jumping distance, center of rotation and arc of movement change between DM and standard cups with modDM or fixed bearings (FB). Methods 3D-models of DM and standard press-fit cups with modDM or FB liners were used to simulate DM, modDM and FB implant configurations, matched for same cup size, according to same cup position and different femoral head diameters. Jumping distance was calculated and center of rotation lateralization and oscillation angles were measured for each size of these three implant configurations. Results Jumping distance with modDM was reduced by -3.9 mm to -8.6 mm in comparison with DM, from 48 to 64 mm size, but resulted comparable to polyethylene 36 mm FB and increased by + 1.1 mm and + 1.4 mm than ceramic 36 and 40 mm FBs for sizes > 54 mm. ModDM lateralized the center of rotation up to + 2.5 mm and + 4.0 mm in comparison with DM and FBs, respectively. Oscillation angle with modDM resulted higher than + 16°, + 23°, + 17° and + 14° in comparison to DM, 28 mm, 32 mm and 36 mm FB cups, respectively, for 56 mm cup size. Conclusions According to its specific design, modDM might change hip stability parameters in comparison to DM, worsening jumping distance and center of rotation position, but increasing arc of movement. As not restoring stability parameters in the same fashion, modDM implants should be properly used when DM cups are not feasible.

Euclid is a European Space Agency medium-class mission selected for launch in 2020 within the cosmic vision 2015–2025 program. The main goal of Euclid is to understand the origin of the accelerated expansion of the universe. Euclid will explore the expansion history of the universe and the evolution of cosmic structures by measuring shapes and red-shifts of galaxies as well as the distribution of clusters of galaxies over a large fraction of the sky. Although the main driver for Euclid is the nature of dark energy, Euclid science covers a vast range of topics, from cosmology to galaxy evolution to planetary research. In this review we focus on cosmology and fundamental physics, with a strong emphasis on science beyond the current standard models. We discuss five broad topics: dark energy and modified gravity, dark matter, initial conditions, basic assumptions and questions of methodology in the data analysis. This review has been planned and carried out within Euclid’s Theory Working Group and is meant to provide a guide to the scientific themes that will underlie the activity of the group during the preparation of the Euclid mission.

This review is a pedagogical introduction to models of gravity and how they are constrained through cosmological observations. We focus on the Horndeski scalar-tensor theory and on the quantities that can be measured with a minimum of assumptions. Alternatives or extensions of general relativity have been proposed ever since its early years. Because of the Lovelock theorem, modifying gravity in four dimensions typically means adding new degrees of freedom. The simplest way is to include a scalar field coupled to the curvature tensor terms. The most general way of doing so without incurring in the Ostrogradski instability is the Horndeski Lagrangian and its extensions. Testing gravity means therefore, in its simplest term, testing the Horndeski Lagrangian. Since local gravity experiments can always be evaded by assuming some screening mechanism or that baryons are decoupled, or even that the effects of modified gravity are visible only at early times, we need to test gravity with cosmological observations in the late universe (large-scale structure) and in the early universe (cosmic microwave background). In this work, we review the basic tools to test gravity at cosmological scales, focusing on model-independent measurements.

Purpose The use of dual mobility cups in total hip arthroplasty has gained popularity in light of the fact it enables to reduce dislocation through increased jumping distance (JD) and impingement-free arc of movement. Modular Dual Mobility Cup (modular DMC) systems have been recently introduced to enable the use of dual mobility cups with standard metal-backed shells. The objective of this study was twofold: calculate the JD for each modular DMC system and conduct a systematic literature review to report clinical outcomes and reasons for failure of this construct. Methods The JD was calculated using the Sariali formula: JD = 2 R sin [( π /2 − Ψ − arcsin (offset/ R ))/2]. A qualitative systematic literature review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. A comprehensive search for English and French articles between January 2000 and July 2020 was run on PubMed, EMBASE, Google Scholar, and Scopus with the primary objective of finding articles about modular DMC systems. Results We identified eight 8 different manufacturers of modular DMC systems and 327 publications on the subject. After screening for duplicates and eligibility, we identified 229 publications: 206 articles were excluded because they contained no reports on modular DMC systems, whereas other three were not included because they focused on biomechanical aspects. Among the 11 included articles, 2 were prospective case series, 9 were retrospective case series. True dislocation occurred in 25 cases (0.9%), and six of them were solved by closed reduction without necessity of revision, while all 5 intraprosthetic dislocations were operated. Conclusions Modular DMCs are a valid method to deal with complex THA instability, with good clinical and patient-reported outcomes, low complication rates, and low revision rates at early follow-up. We would advise cautious optimism on the role of modular DMC implants, as it seems safer to use ceramic instead of metallic heads whenever possible to avoid the increase cobalt and chromium trace ion serum levels.

Three-dimensional (3D)-printed anatomical models of the bones play a key role in complex surgical procedures. These subject-specific physical models are valuable in pre-operative planning and may also offer assistance during surgery by improving the visibility of inaccessible anatomical structures, particularly in spine surgery. Starting from medical imaging, virtual 3D bone models are reconstructed, and these can also be used for quantifying original, planned, and achieved bone-to-bone alignments. The purpose of this study is to report on an original exploitation of these techniques on a patient with a severe cervical deformity to undergo corrective and stabilizing surgery. A virtual anatomical model of the cervical spine before surgery was obtained from computer tomography to assess the original deformity and for surgical planning. The corresponding 3D model was printed in acrylonitrile-butadiene-styrene and used to simulate the surgery by performing bone cuts, implanting the screws, and placing and shaping the fixation elements. During surgery, this physical 3D-printed model was used as a reference for each surgical action. The comparisons between pre- and post-operative virtual models confirmed that the planned correction was achieved. Virtual and 3D-printed anatomical models of the cervical spine offer advantages in the planning and execution of personalized complex surgeries, in addition to improving surgical safety.

The detection of the accelerated expansion of the Universe has been one of the major breakthroughs in modern cosmology. Several cosmological probes (Cosmic Microwave Background, Supernovae Type Ia, Baryon Acoustic Oscillations) have been studied in depth to better understand the nature of the mechanism driving this acceleration, and they are being currently pushed to their limits, obtaining remarkable constraints that allowed us to shape the standard cosmological model. In parallel to that, however, the percent precision achieved has recently revealed apparent tensions between measurements obtained from different methods. These are either indicating some unaccounted systematic effects, or are pointing toward new physics. Following the development of CMB, SNe, and BAO cosmology, it is critical to extend our selection of cosmological probes. Novel probes can be exploited to validate results, control or mitigate systematic effects, and, most importantly, to increase the accuracy and robustness of our results. This review is meant to provide a state-of-art benchmark of the latest advances in emerging “beyond-standard” cosmological probes. We present how several different methods can become a key resource for observational cosmology. In particular, we review cosmic chronometers, quasars, gamma-ray bursts, standard sirens, lensing time-delay with galaxies and clusters, cosmic voids, neutral hydrogen intensity mapping, surface brightness fluctuations, stellar ages of the oldest objects, secular redshift drift, and clustering of standard candles. The review describes the method, systematics, and results of each probe in a homogeneous way, giving the reader a clear picture of the available innovative methods that have been introduced in recent years and how to apply them. The review also discusses the potential synergies and complementarities between the various probes, exploring how they will contribute to the future of modern cosmology.

Purpose The purpose of the study was to investigate the outcome of dual-mobility cup (DM) compared with a standard cup (SC) in primary total hip arthroplasty (THA) in the long-term follow-up based on a regional Italian joint registry (RIPO). Methods The Registry of Prosthetic Orthopaedic Implant (RIPO) was consulted, looking for all primary THAs implanted from 2000 to 2019. Three thousand seven hundred ten were dual-mobility cup (DM) total hip arthroplasties (THA) and 85.816 were standard cup (SC) THAs, on a total of 89.526 primary THA. Demographics, survival rates and causes of revision were evaluated and compared between the two groups. Results The use of DM progressively increased from 0.4% in 2000 to 7.5% in 2018 of all primary THAs. Revision rate was 3.5% (128 on 3710) for DMC and 4.7% (4061 on 85,816) for SC. DM presented lower dislocation rate if compared to SC with 22–28-mm femoral head diameter. However, DM showed a higher risk of revision for any causes than SC with 32-mm femoral head diameter in long-term follow-up. Nevertheless, no significant difference was measured in terms of demographics and surgical approach for dislocation rate. Conclusions The DM cup represents a valid implant solution and has a lower dislocation rate than 22–28-mm SC. A slight increase in the use of DM implants over time was observed in the RIPO. However, a larger population and a longer follow-up are needed to further monitor the survival rate of new-generation DM implants.

The morbidity of surgical procedures for spine tumors can be expected to be worse than for other conditions. This is particularly true of en bloc resections, the most technically demanding procedures. A retrospective review of prospective data from a large series of en bloc resections may help to identify risk factors, and therefore to reduce the rate of complications and to improve outcome. A retrospective study of 1,035 patients affected by spine tumors—treated from 1990 to 2007 by the same team—identified 134 patients (53.0% males, age 44 ± 18 years) who had undergone en bloc resection for primary tumors (90) and bone metastases (44). All clinical, histological and radiological data were recorded from the beginning of the period in a specifically built database. The study was set up to correlate diagnosis, staging and treatment with the outcome. Oncological and functional results were recorded for all patients at periodic, diagnosis-related controls, until death or the latest follow-up examination (from 0 to 211 months, median 47 months, 25th–75th percentile 22–85 months). Forty-seven on the 134 patients (34.3%) suffered a total of 70 complications (0.86 events per 100 patient-years); 32 patients (68.1%) had one complication, while the rest had 2 or more. There were 41 major and 29 minor complications. Three patients (2.2%) died from complications. Of the 35 patients with a recurrent or contaminated tumor, 16 (45.7%) suffered at least one complication; by contrast, complications arose in 31 (31.3%) of the 99 patients who had had no previous treatment and who underwent the whole of their treatment in the same center ( P  = 0.125). The risk of major complications was seen to be more than twice as high in contaminated patients than in non-contaminated ones (OR = 2.52, 95%CI 1.01–6.30, P  = 0.048). Factors significantly affecting the morbidity are multisegmental resections and operations including double contemporary approaches. A local recurrence was recorded in 21 cases (15.7%). The rate of deep infection was higher in patients who had previously undergone radiation therapy (RT), but the global incidence of complications was lower. Re-operations were mostly due to tumor recurrences, but also to hardware failures, wound dehiscence, hematomas and aortic dissection. En bloc resection is able to improve the prognosis of aggressive benign and low-grade malignant tumors in the spine; however, complications are not rare and possibly fatal. The rate of complication is higher in multisegmental resections and when double combined approach is performed, as it can be expected in more complex procedures. Re-operations display greater morbidity owing to dissection through scar/fibrosis from previous operations and possibly from RT. The treatment of recurrent cases and planned transgression to reduce surgical aggressiveness are associated with a higher rate of local recurrence, which can be considered the most severe complication. In terms of survival and quality of life, late results are worse in recurrent cases than in complicated cases. Careful treatment planning and, in the event of uncertainty, referral to a specialty center must be stressed.

Introduction Eosinophilic granuloma (EG) is a benign bone tumor that rarely occurs in adults. It is usually found occurring in flat and long bones, but spine is often affected too. EG is of unknown aetiology, and the course of the disease is unpredictable. Materials and methods Two cases of EG of the adult lumbar spine are reported, representing a difficult challenge for diagnosis and treatment. Conclusion CT scan guided trocar biopsy allowed to achieve a definitive diagnosis, and CT scan guided intralesional infiltrations of corticosteroids were the successful treatment.

Revision of large-diameter, monoblock acetabular components for both hip resurfacing arthroplasty and metal-on-metal (MoM) total hip arthroplasty (THA) is correlated to a high amount of complications. For this reason, performing a limited revision by conversion to a dual mobility (DM) without acetabular component exchange has been proposed in order to limit these complications. Although DM bearing offers an easy solution avoiding the intraoperative and time-associated complications, concern about polyethylene wear and stability remains due to the difference regarding the design, the coverage angle and the clearance of the two implants. In order to evaluate the performance of this new solution with the new material to prevent the possibility of failure it is essential to conduct a review of the literature A qualitative systematic review of the literature has been conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. A comprehensive search of PubMed, EMBASE, Google Scholar, and Scopus for English and French articles between January 2000 and October 2019 was performed, with the primary objective of finding articles about dual mobility bearing coupling with large metal-on-metal cup in the case of hip revision procedure. Various combinations of the key words were used in the search strategy. Thirteen articles with DM bearing mated with MoM cup were analyzed. Of the 130 hip revisions selected, with a follow-up from 6 to 53 months, there were a total of 14 with complications (10.77%): four true dislocations (3.08%); six intra-prosthetic dislocations (IPD, 4.6%), two of which presented plastic deformation and polyethylene wear; four other complications (3.08%), included a cup osteolysis, a clicking noise, a superficial infection and a periprosthetic fracture. All the mentioned true dislocations occurred during the first month while IPDs appeared during the first two years from the index revision. In conclusion, according to the literature analyzed, we can stress that the concerns and doubts about mating a DM bearing with large MoM cup cannot be dissolved. It has been pointed out that a DM bearing is not designed for a MoM cup; it is not mechanically tested on MoM cups, which presents different clearance and coverage angles. Predictable complications may occur, such as IPD, polyethylene wear and true dislocation. These complications have been reported at an even higher rate than they were in the eighties, when the first generation of DM implants were of a lower quality of polyethylene and the characteristic of the design was less optimal than modern ones.