Bone cement with reduced proportion of monomer in total hip arthroplasty: Preclinical evaluation and randomized study of 47 cases with 5 years' follow-up

Bone cement with reduced amount of monomer and low curing temperature may improve implant fixation due to reduced toxicity. We analyzed the mechanical, chemical and thermal properties of such a cement (Cemex Rx) using Palacos R as control. The in vivo performance of the 2 cements was also evaluated in a prospective randomized study of 47 hips, where either of the cement types was used to fixate Lubinus SP2 prostheses with the stem made of titanium alloy. Cemex Rx had a reduced tensile strength, probably because this cement was manually mixed, as recommended by the manufacturer. A standardized laboratory test showed lower curing temperature for Cemex, but measurements at 37° and with prechilled Palacos R and Cemex Rx, as in clinical work, showed no difference. In the clinical study radiostereometric measurements of cup and stem migration showed similar values in the 2 groups up to 5 years after the operation. The cement mantle was stable in both groups, but the stems migrated similarly inside the cement mantle regardless of the type of cement used. Proximal wear was low (0.04-0.05 mm/year) and tended to be lower in the Cemex group (p = 0.02). Aluminum and vanadium levels in serum increased 5 years after the operation, but no difference was noted between the 2 groups. Collagen markers (PICP, ICTP) showed similar increases in bone turnover 6 weeks and 6 months after operation in both groups.     

Carotid Artery Occlusion: Acute Symptoms and Long-term Prognosis

Abstract

Fifty-nine patients with carotid artery occlusion diagnosed during 1968-1977 were studied. The presenting symptoms were ipsilateral TIA in 12 patients, stroke in 41, 9 of whom died in the acute phase, and TIA or stroke from other vascular territory in 6 patients. Thirty-nine percent of the patients had preceding TIA. At the time of follow up (mean 48 months), only 2 cases with TIA and 2 with stroke on the occluded side were found. Seven patients had recurrent symptoms from other vascular regions. Twelve patients died during follow up because of diseases unrelated to stroke. Thus the annual incidence of ipsilateral stroke (～1 %) and TIA (～1 %) was low. Anticoagulant treatment of 20 of the patients might have contributed to the low recurrence rate.     

How facial expressions in a Rett syndrome population are recognised and interpreted by those around them as conveying emotions

Rett syndrome (RTT) is a neurodevelopmental disorder, including autonomic nervous system dysfunctions and severe communication impairment with an extremely limited ability to use verbal language. These individuals are therefore dependent on the capacity of caregivers to observe and interpret communicative signals, including emotional expressions. People in general, including therapists tend to focus on changes in facial expressions to interpret a person's emotional state or choices, but with this population it is difficult to know if the interpretations are correct. The aims of this study were to investigate if the Facial Action Coding System (FACS) could be used to identify facial expressions, and differentiate between those that expressed emotions and those that were elicited by abnormal brainstem activation in RTT. The sample comprised 29 participants with RTT and 11 children with a normal developmental pattern, exposed to six different musical stimuli during non-invasive registration of autonomic brainstem functions. The results indicate that FACS makes it possible both to identify facial expressions and to differentiate between those that stem from emotions and those caused by abnormal brainstem activation. This knowledge may be a great help to an uninitiated observer, who otherwise might incorrectly interpret the latter as an expression of emotion.     

A beam source model for scanned proton beams

A beam source model, i.e. a model for the initial phase space of the beam, for scanned proton beams has been developed. The beam source model is based on parameterized particle sources with characteristics found by fitting towards measured data per individual beam line. A specific aim for this beam source model is to make it applicable to the majority of the various proton beam systems currently available or under development, with the overall purpose to drive dose calculations in proton beam treatment planning. The proton beam phase space is characterized by an energy spectrum, radial and angular distributions and deflections for the non-modulated elementary pencil beam. The beam propagation through the scanning magnets is modelled by applying experimentally determined focal points for each scanning dimension. The radial and angular distribution parameters are deduced from measured two-dimensional fluence distributions of the elementary beam in air. The energy spectrum is extracted from a depth dose distribution for a fixed broad beam scan pattern measured in water. The impact of a multi-slab range shifter for energy modulation is calculated with an own Monte Carlo code taking multiple scattering, energy loss and straggling, non-elastic and elastic nuclear interactions in the slab assembly into account. Measurements for characterization and verification have been performed with the scanning proton beam system at The Svedberg Laboratory in Uppsala. Both in-air fluence patterns and dose points located in a water phantom were used. For verification, dose-in-water was calculated with the Monte Carlo code GEANT 3.21 instead of using a clinical dose engine with approximations of its own. For a set of four individual pencil beams, both with the full energy and range shifted, 96.5% (99.8%) of the tested dose points satisfied the 1%/1 mm (2%/2 mm) gamma criterion.