Influence of head size on the development of metallic wear and on the characteristics of carbon layers in metal-on-metal hip joints

Background and purpose Particles originating from the articulating surfaces of hip endoprostheses often induce an inflammatory response, which can be related to implant failure. We therefore analyzed the metal content in capsular tissue from 44 McKee-Farrar metal-on-metal hip prostheses (with 3 different head sizes) and we also analyzed the morphological structure of layers located on articulating surfaces

Pathways of SME Internationalization: a bibliometric and systematic review

Business is dynamic and rapidly changing. Global markets were previously the playing field of multinational corporations (MNCs), while small and medium enterprises (SMEs) were local; however, the removal of imposed barriers, and recent technological advances in manufacturing, transportation and communications have indorsed SMEs and international entrepreneurs (IE) global access. SMEs and IEs are increasingly fueling economic growth and innovation and these trends are presenting both opportunities and challenges to both MNCs and SMEs in the global arena. This review systematically examines comparative SME and IE research, analyzing (after fine tuning) 762 articles published in leading journals from 1992 to September 2018. Our bibliometric and systematic review classifies SME and IE research findings into three echelons: (i) subjects; (ii) theories; and (iii) methods

Swimming simulation: a new tool for swimming research and practical applications

Swimming is one of the major athletic sports and many efforts are being made to establish new records in all events. To swim faster, thrust should be maximized and drag should be minimized. These aims are difficult to achieve because swimmers surge, heave, roll and pitch during every stroke cycle. In addition, measurements of human forces and mechanical power are difficult due to the restrictions of measuring devices and the specificity of aquatic environment

Effects of screw eccentricity on the initial stability of the acetabular cup

One of the major failure modes of cementless acetabular components is the loosening of the acetabular cup, which is mostly attributable to insufficient initial stability. A hemispherical cup with a porous coating which is inserted with press-fit fixation and secured with several screws is one of the most widely used approaches. Many studies have found that bone screws are very helpful aids for cup fixation, but the optimal surgical technique for inserting screws has not been clearly reported. In this study, hemispherical cups were fixed into blocks of foam bone with zero to three screws. The effects of three types of screw eccentricity (a 1-mm offset and angular eccentricities of 15° and 25°) on the initial stability of the acetabular cup were evaluated. The experimental results indicate that increasing the number of screws enhances the cup stability in the case of ideal screwing (i.e., with no eccentricity). An angular eccentricity of 15° did not affect the cup stability for fixation with one or two screws. However, the presence of 25° of angular eccentricity significantly reduced the stability of the cup, while 1 mm of offset eccentricity produced an even greater impact