Долгосрочные результаты эндопротезирования тазобедренного сустава у пациентов с опухолевым поражением проксимального отдела бедренной кости

Relevance. The development of the modern principles of combined tumor treatment has significantly improved the survival of the patients. For these patients, the organ-preserving surgerybecomes now the mainstream tactics. For the restoration of the lower limb support ability and the hip function, the hip arthroplasty is now the most used type of surgery. Purpose of the study. The purpose of this work was to evaluate the long-term results of hip arthroplasty in the patients with extensive proximal femur defects caused by tumors and tumor-like lesions. Materials and Methods. The data on 126 patients with proximal femur tumors, undergone the surgical treatment in 2000–2013, were collected and summarized. The average age of the patients was 53.8 years (26–74), 94 women (74.6%), and 32 men (25.4%). There were 16 primary malignant bone tumors (12.7%), 10 benign aggressive (7.9%); 92 metastatic (73%), and 8 tumor-like lesions (6.4%). The average follow-up after the surgery was 72.6 months. The complications classification and analysis were performed according to the criteria of the International Society of Limb Salvage 2014 (ISOLS 2014). For the assessment of the functional result, patients were divided into 4 groups. In this context, the following indicators were taken into account: whether the acetabular component or the bipolar head were used, and the method of the soft tissues fixation to the femoral component of the endoprosthesis. Functional outcome was evaluated using the international Musculoskeletal Tumor Society (MSTS) scoring system at 3, 6, and 12 months. Results. The total number of complications, identified during the observation period from 2000 to 2018, was 26 (20.6%). The oncological complications, represented by local recurrence, were detected on average after 11.5 months. The total number of local recurrences is 6 (4.7%) which amounted to 23% in the structure of all complications. Dislocations of the endoprosthesis became the most frequent complication — 13 (10.3%) observations, 50% in the structure of all complications. Only one patient with aseptic instability of the femoral component was identified over the entire follow-up period. There were 4 (3.1%) patients with complications due to the destruction of metal constructions. All of them had an endoprosthesis stem fracture. The average period of onset of these complications was 122.5 months. Prosthetic joint infection was observed in 2 (1.6%) patients (7.2% of all complications), on the 14th and 31st days. The patient with the latter onset of infection underwent a twostaged revision arthroplasty. Functional result by the MSTS scale: 3 months — 74.8%, 6 months — 79%, 12 months 81.8%. In the patients under investigation, 5-, 10-, and 15-year survival for aggressive benign tumors and tumorlike lesions was 95%, 84%, 62%; for malignant primary tumors — 88%, 65%, 24%; for secondary bone lesions 55%, 43%, 12%, respectively. Conclusion. The use of a bipolar head made it possible to reduce the likelihood of an endoprosthesis dislocation. The fixation of the preserved muscle elements with a polymer mesh made it possible to obtain the best functional result already in the early postoperative period.Актуальность. Развитие современных принципов комбинированного лечения опухолевого поражения позволило значительно улучшить выживаемость пациентов, для которых теперь органосохраняющая хирургическая тактика является основной. С целью восстановления опороспособности нижней конечности и функции тазобедренного сустава наиболее широко применяется эндопротезирование тазобедренного сустава. Цель исследования — оценить долгосрочные результаты эндопротезирования тазобедренного сустава у пациентов с обширными дефектами проксимального отдела бедренной кости при опухолевом и опухолеподобных поражениях. Материал и методы. Выполнен сбор и обобщение данных о 126 пациентах, прооперированных по поводу опухолевого поражения проксимального отдела бедренной кости в 2000–2013 гг. Средний возраст составил 53,8 лет (26–74); пациентов женского пола было 94 (74,6%), мужского — 32 (25,4%). Первичные злокачественные опухоли кости — 16 (12,7%); доброкачественные агрессивные — 10 (7,9%); метастатическое поражение — 92 (73%); опухолеподобные заболевания — 8 (6,4%). Средний период наблюдения за пациентами после проведенного оперативного лечения составил 72,6 мес. Классификация и анализ осложнений производились согласно критериям International Society of Limb Salvage (ISOLS 2014). Для проведения оценки функционального результата пациенты были разделены на 4 группы с учетом того, использовался вертлужный компонент либо биполярная головка, и способа фиксации мягких тканей к бедренному компоненту эндопротеза. Функциональный результат оценивался с помощью международной системы Musculoskeletal Tumor Society (MSTS) в сроки 3, 6 и 12 мес. Результаты. Общее число осложнений, выявленных за период наблюдения с 2000 по 2018 г., составило 26 (20,6%). Онкологические осложнения, представленные локальным рецидивом, были выявлены в среднем через 11,5 мес. Общее количество локальных рецидивов — 6 (4,7%), что в структуре всех осложнений составило 23%. Самым частым осложнением стали вывихи эндопротеза — 13 (10,3%) наблюдений, что в структуре всех осложнений составило 50%. За весь период наблюдений выявлен только один пациент с асептической нестабильностью бедренного компонента. В группе пациентов с осложнениями, связанными с разрушением металлоконструкции, было выявлено 4 (3,1%) пациента. У всех был выявлен перелом ножки, средний срок наступления этого типа осложнений составил 122,5 мес. Перипротезная инфекция наблюдалась у двоих (1,6%) пациентов (7,2% от всех осложнений); срок развития осложнений составил 14 и 31 день соответственно. Пациенту с инфекционными осложнениями, наступившими на более поздних сроках, было выполнено двухэтапное ревизионное вмешательство. Функциональный результат по шкале MSTS: 3 мес. — 74,8%, 6 мес. — 79%, 12 мес. — 81,8%. В исследуемой нами группе пациентов 5-, 10-, и 15-летняя выживаемость для агрессивных доброкачественных опухолей и опухолеподобных заболеваний составила 95%, 84%, 62%; для злокачественных первичных опухолей — 88%, 65%, 24%; для вторичного поражения кости — 55%, 43%, 12% соответственно. Заключение. Применение биполярной головки позволило снизить вероятность вывиха эндопротеза, а фиксация сохраняемых элементов мышечного аппарата при помощи полимерной сетки позволила уже в раннем послеоперационном периоде получить лучший функциональный результат

Finite sum of gluon ladders and high energy cross sections

A model for the Pomeron at $t=0$ is suggested. It is based on the idea of a finite sum of ladder diagrams in QCD. Accordingly, the number of $s$-channel gluon rungs and correspondingly the powers of logarithms in the forward scattering amplitude depends on the phase space (energy) available, i.e. as energy increases, progressively new prongs with additional gluon rungs in the $s$-channel open. Explicit expressions for the total cross section involving two and three rungs or, alternatively, three and four prongs (with $\ln^2(s)$ and $\ln^3(s)$ as highest terms, respectively) are fitted to the proton-proton and proton-antiproton total cross section data in the accelerator region. Both QCD calculation and fits to the data indicate fast convergence of the series. In the fit, two terms (a constant and a logarithmically rising one) almost saturate the whole series, the $\ln^2(s)$ term being small and the next one, $\ln^3(s)$, negligible. Theoretical predictions for the photon-photon total cross section are also given.Comment: 18 pages, LaTeX, 2 EPS figures, uses axodraw.st

Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in √s = 7 TeV pp collisions with the ATLAS detector

A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fb−1 of proton–proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results

Jet size dependence of single jet suppression in lead-lead collisions at sqrt(s(NN)) = 2.76 TeV with the ATLAS detector at the LHC

Measurements of inclusive jet suppression in heavy ion collisions at the LHC provide direct sensitivity to the physics of jet quenching. In a sample of lead-lead collisions at sqrt(s) = 2.76 TeV corresponding to an integrated luminosity of approximately 7 inverse microbarns, ATLAS has measured jets with a calorimeter over the pseudorapidity interval |eta| < 2.1 and over the transverse momentum range 38 < pT < 210 GeV. Jets were reconstructed using the anti-kt algorithm with values for the distance parameter that determines the nominal jet radius of R = 0.2, 0.3, 0.4 and 0.5. The centrality dependence of the jet yield is characterized by the jet "central-to-peripheral ratio," Rcp. Jet production is found to be suppressed by approximately a factor of two in the 10% most central collisions relative to peripheral collisions. Rcp varies smoothly with centrality as characterized by the number of participating nucleons. The observed suppression is only weakly dependent on jet radius and transverse momentum. These results provide the first direct measurement of inclusive jet suppression in heavy ion collisions and complement previous measurements of dijet transverse energy imbalance at the LHC.Comment: 15 pages plus author list (30 pages total), 8 figures, 2 tables, submitted to Physics Letters B. All figures including auxiliary figures are available at http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HION-2011-02

Measurement of the polarisation of W bosons produced with large transverse momentum in pp collisions at sqrt(s) = 7 TeV with the ATLAS experiment

This paper describes an analysis of the angular distribution of W->enu and W->munu decays, using data from pp collisions at sqrt(s) = 7 TeV recorded with the ATLAS detector at the LHC in 2010, corresponding to an integrated luminosity of about 35 pb^-1. Using the decay lepton transverse momentum and the missing transverse energy, the W decay angular distribution projected onto the transverse plane is obtained and analysed in terms of helicity fractions f0, fL and fR over two ranges of W transverse momentum (ptw): 35 < ptw < 50 GeV and ptw > 50 GeV. Good agreement is found with theoretical predictions. For ptw > 50 GeV, the values of f0 and fL-fR, averaged over charge and lepton flavour, are measured to be : f0 = 0.127 +/- 0.030 +/- 0.108 and fL-fR = 0.252 +/- 0.017 +/- 0.030, where the first uncertainties are statistical, and the second include all systematic effects.Comment: 19 pages plus author list (34 pages total), 9 figures, 11 tables, revised author list, matches European Journal of Physics C versio

Observation of a new chi_b state in radiative transitions to Upsilon(1S) and Upsilon(2S) at ATLAS

The chi_b(nP) quarkonium states are produced in proton-proton collisions at the Large Hadron Collider (LHC) at sqrt(s) = 7 TeV and recorded by the ATLAS detector. Using a data sample corresponding to an integrated luminosity of 4.4 fb^-1, these states are reconstructed through their radiative decays to Upsilon(1S,2S) with Upsilon->mu+mu-. In addition to the mass peaks corresponding to the decay modes chi_b(1P,2P)->Upsilon(1S)gamma, a new structure centered at a mass of 10.530+/-0.005 (stat.)+/-0.009 (syst.) GeV is also observed, in both the Upsilon(1S)gamma and Upsilon(2S)gamma decay modes. This is interpreted as the chi_b(3P) system.Comment: 5 pages plus author list (18 pages total), 2 figures, 1 table, corrected author list, matches final version in Physical Review Letter

Search for displaced vertices arising from decays of new heavy particles in 7 TeV pp collisions at ATLAS

We present the results of a search for new, heavy particles that decay at a significant distance from their production point into a final state containing charged hadrons in association with a high-momentum muon. The search is conducted in a pp-collision data sample with a center-of-mass energy of 7 TeV and an integrated luminosity of 33 pb^-1 collected in 2010 by the ATLAS detector operating at the Large Hadron Collider. Production of such particles is expected in various scenarios of physics beyond the standard model. We observe no signal and place limits on the production cross-section of supersymmetric particles in an R-parity-violating scenario as a function of the neutralino lifetime. Limits are presented for different squark and neutralino masses, enabling extension of the limits to a variety of other models.Comment: 8 pages plus author list (20 pages total), 8 figures, 1 table, final version to appear in Physics Letters

Measurement of the inclusive isolated prompt photon cross-section in pp collisions at sqrt(s)= 7 TeV using 35 pb-1 of ATLAS data

A measurement of the differential cross-section for the inclusive production of isolated prompt photons in pp collisions at a center-of-mass energy sqrt(s) = 7 TeV is presented. The measurement covers the pseudorapidity ranges |eta|<1.37 and 1.52<=|eta|<2.37 in the transverse energy range 45<=E_T<400GeV. The results are based on an integrated luminosity of 35 pb-1, collected with the ATLAS detector at the LHC. The yields of the signal photons are measured using a data-driven technique, based on the observed distribution of the hadronic energy in a narrow cone around the photon candidate and the photon selection criteria. The results are compared with next-to-leading order perturbative QCD calculations and found to be in good agreement over four orders of magnitude in cross-section.Comment: 7 pages plus author list (18 pages total), 2 figures, 4 tables, final version published in Physics Letters

Measurement of D*+/- meson production in jets from pp collisions at sqrt(s) = 7 TeV with the ATLAS detector

This paper reports a measurement of D*+/- meson production in jets from proton-proton collisions at a center-of-mass energy of sqrt(s) = 7 TeV at the CERN Large Hadron Collider. The measurement is based on a data sample recorded with the ATLAS detector with an integrated luminosity of 0.30 pb^-1 for jets with transverse momentum between 25 and 70 GeV in the pseudorapidity range |eta| < 2.5. D*+/- mesons found in jets are fully reconstructed in the decay chain: D*+ -> D0pi+, D0 -> K-pi+, and its charge conjugate. The production rate is found to be N(D*+/-)/N(jet) = 0.025 +/- 0.001(stat.) +/- 0.004(syst.) for D*+/- mesons that carry a fraction z of the jet momentum in the range 0.3 < z < 1. Monte Carlo predictions fail to describe the data at small values of z, and this is most marked at low jet transverse momentum.Comment: 10 pages plus author list (22 pages total), 5 figures, 1 table, matches published version in Physical Review

Search for scalar top quark pair production in natural gauge mediated supersymmetry models with the ATLAS detector in pp collisions at sqrt(s) = 7 TeV

The results of a search for pair production of the lighter scalar partners of top quarks in 2.05 fb-1 of pp collisions at sqrt(s) =7 TeV using the ATLAS experiment at the LHC are reported. Scalar top quarks are searched for in events with two same flavour opposite-sign leptons (electrons or muons) with invariant mass consistent with the Z boson mass, large missing transverse momentum and jets in the final state. At least one of the jets is identified as originating from a b-quark. No excess over Standard Model expectations is found. The results are interpreted in the framework of R-parity conserving, gauge mediated Supersymmetry breaking `natural' scenarios, where the neutralino is the next-to-lightest supersymmetric particle. Scalar top quark masses up to 310 GeV are excluded for the lightest neutralino mass between 115 GeV and 230 GeV at 95% confidence level, reaching an exclusion of the scalar top quark mass of 330 GeV for the lightest neutralino mass of 190 GeV. Scalar top quark masses below 240 GeV are excluded for all values of the lightest neutralino mass above the Z boson mass.Comment: 7 pages plus author list (20 pages total), 4 figures, 1 table, matches published PLB versio