The mechanical performance and the stress shielding effects of the Howmedica Spherolock MKII implant were evaluated. Three types of stable proximal femoral fractures were created in composite femurs and fixed with the nail-plate. The femurs were loaded to failure, and the yield strength, stiffness, and failure modes were noted. Additional intact composite femurs were fitted proximally with strain gauges, and the strain was examined under load. The femurs then underwent intertrochanteric fracture, plating, and re-testing. Comparative analysis showed that while the Spherolock system is less strong and stiff than other commonly used implants, it provides excellent and uniform load transfer across the fracture site. Varus rotation of the femoral head under load tended to open the fracture gap and localize the resultant load medially. Stress shielding of the calcar was less than 25% of the applied load even in the worst case. This very low stress shielding behavior was attributed mainly to the implant's low stiffness. 相似文献
Thromboembolism constitutes one of the most dangerous complications during the immediate postoperative period of prosthetic
surgery. Pharmacological prophylaxis and mechanical vascular compression are not always sufficient to protect from this surgical
complication. In patients at greatest risk for thromboembolism, often with a positive history for pulmonary embolism, temporary
vena cava filters may be used to reduce the incidence of vascular and pulmonary complications. However useful, these filters
cannot be routinely used in orthopedic surgery. We present our results with the use of Filcard RFO2 vena cava filters in an
open, randomized study of 30 patients.
Received: 5 November 2001/Accepted: 30 November 2001 相似文献
Here we present the results of a study performed on 59 patients affected by Waardenburg syndrome (WS), 30 with the I variant, 21 having the type II, and 8 of them being isolated cases without telecanthus. These patients belong to 37 families; the main contributions and conclusions are based on the detailed study of 25 of these families, examined using standard procedures. All patients were examined as to the presence of eight cardinal signs important for the diagnosis of the condition; from each patient, from many of his/her normal relatives, and from a control sample of 300 normal individuals stratified by age and sex, 23 different craniofacial measurements were obtained. We also estimated, using our own data as well those collected from the literature, the frequencies of the cardinal signs, based on a total sample of 461 affected individuals with WSI and 121 with WSII. In order to originate discriminant functions to separate individuals affected by one of the two variants, both metric (from craniofacial measurements) as well as categoric data (based on the frequencies of the cardinal signs or symptoms) were used. Discriminant analysis based on the frequency of the eight cardinal signs can improve the separation of WSI patients without telecanthus from those presenting the variant II. We present also a Table with the conditional probabilities favoring the diagnosis of WSI for suspect subjects without telecanthus and any combination of the other seven signs/symptoms. The discriminant function based on the four ocular measurements (inner and outer intercanthal, interpupillary, and inferior lacrymal distances), on the other side, perfectly classifies patients affected by one of the variants of WS, the same taking place when the average values of the W index of all affected individuals per family are used. The discriminant function based solely in the individual W index values of patients correctly classifies 93% of WSII subjects, but only 60% of the patients with the I variant of WS. 相似文献
The tropical endogeic earthworm Pontoscolex corethrurus, a non-standard species used in ecotoxicity, has been found in crude oil-contaminated habitats. We estimated the removal of total hydrocarbons from heavy crude “Maya” oil on an artificially contaminated soil with a median lethal concentration of P. corethrurus and an addition of oil palm bagasse. P. corethrurus had a high survival rate, and the addition of oil palm bagasse led to a greater growth and an increase in abundance of bacteria and fungi. The activity of P. corethrurus and the nutritional quality of oil palm bagasse had a significant impact on the removal of a larger amount of petroleum hydrocarbons from contaminated soil. We concluded that the endogeic earthworm P. corethrurus and oil palm bagasse acted synergistically to achieve a more effective removal of total petroleum hydrocarbons from soil. These results show the potential for using P. corethrurus to remove, either directly or indirectly, crude oil from soil.
Recent studies suggest that nitric oxide (NO) may partly be responsible for the beneficial effect of hydroxyurea (HU) in sickle cell disease (SCD) patients. NO stimulates cyclic guanosine monophosphate (cGMP) production, which mediates vasodilatation. We investigated the association between NO, cGMP and fetal haemoglobin (HbF) levels after HU administration. Our data showed that chronic HU significantly increased NO, cGMP, and HbF levels in SCD. Recently it was shown that HbF production was stimulated by cGMP-dependent protein kinase. Our results suggest that NO stimulates cGMP production, which then activates a protein kinase and increases the production of HbF. 相似文献