We studied 16 femora retrieved at post-mortem from symptomless patients who had a satisfactory cemented total hip arthroplasty from two weeks to 17 years earlier, with the aim of delineating the initial mechanisms involved in loosening. Only one specimen showed radiographic evidence of loosening; the other 15 were stable to mechanical testing at 17.0 Nm of torque. In all 16 specimens, the cemen...

Phragmatopoma californica is a marine polychaete that builds protective tubes by joining bits of shell and sand grains with a secreted proteinaceous cement. The cement forms a solid foam (closed cells) via covalent crosslinking, as revealed by electron and laser scanning confocal microscopy. The cement contains extractable calcium and magnesium, and non-extractable phosphorus. Amino acid analys...

It is commonly believed that women are more likely to seek advice than men; for example, on aspects of health or asking for directions when lost. This paper investigates whether women’s relatively greater propensity for advice seeking extends to important business decisions, specifically those involving corporate takeovers. Consistent with the evidence from other contexts, we show that the pres...

In this paper we describe the perfect solving of rectangular empty Domineering boards. Perfect solving is defined as solving without any search. This is done solely based on the number of various move types in the initial position. For this purpose we first characterize several such move types. Next we define 12 knowledge rules, of increasing complexity. Of these rules, 6 can be used to show th...

Numerical studies were performed to investigate bone cement polymerization, temperature history and thermal osteonecrosis in cemented hip replacements with finite element methods. In this paper, the effects of pre-cooling and pre-heating of the prosthesis and/or the cement prior to implantation were simulated. It was found that the cement polymerization initiated near the bone-cement interface ...

An understanding of how the cementing technique influences cement penetration is important for surgeons to plan and conduct hip resurfacing procedures. Therefore the aim of this study is to determine the influence of the following parameters on cement penetration: use of pulse lavage, type of cement, and the standing period of the cement. Nine fresh frozen paired whole cadaver femora were used ...

PURPOSE The objective of this study was to evaluate the influence of various cement types on the stress distribution in monolithic zirconia crowns under maximum bite force using the finite element analysis. MATERIALS AND METHODS The models of the prepared #46 crown (deep chamfer margin) were scanned and solid models composed of the monolithic zirconia crown, cement layer, and prepared tooth w...

BACKGROUND AND PURPOSE Despite the longstanding use of micromotion as a measure of implant stability, direct measurement of the micromechanics of implant/bone interfaces from en bloc human retrievals has not been performed. The purpose of this study was to determine the stem-cement and cement-bone micromechanics of functionally loaded, en-bloc retrieved, cemented femoral hip components. METHO...

The aim of this review paper is to define the fixation of the cemented stem. Polymethyl methacrylate, otherwise known as "bone cement", has been used in the fixation of hip implants since the early 1960s. Sir John Charnley, the pioneer of modern hip replacement, incorporated the use of cement in the development of low frictional torque hip arthroplasty. In this paper, the concepts of femoral st...

BACKGROUND AND PURPOSE Many clinical reports have indicated that polished hip stems show better clinical results than rough stems of the same geometry. It is still unknown, however, what the mechanical effects are of different surface finishes on the cement at the cement-bone interface. We compared mechanical effects in an in vitro cemented hip arthroplasty model. METHODS Two sizes of double-...