[Comparison of functional outcomes in angle-stable osteosynthesis of comminuted fractures of the proximal humerus with those in percutaneous Kirschner-wire fixation. A prospective study of mid-term results]. / Porovnání funkcních výsledku úhlove stabilních osteosyntéz víceúlomkových zlomenin proximálního humeru a perkutánní fixace Kirschnerovými dráty ve strednedobém horizontu: prospektivní studie.

PURPOSE OF THE STUDY: To evaluate the mid-term results in a group of patients with displaced comminuted (three- and four-fragment) fractures of the proximal humerus treated by angle-stable plate osteosynthesis and compare them with the results in the patients in whom the method of percutaneous Kirschner-wire (K-wire) fixation was used. MATERIAL AND METHODS: The group treated with angle-stable implants (ASI group) consisted of 55 patients, 13 men and 42 women. A Targon Ph nail was used in 32 and a Philos plate in 23 patients. These patients were compared with a group of nine patients, one man and eight women, treated by percutaneous K-wire fixation (K-wire group). At a follow-up of 12 months at least, final Constant (CS) and DASH scores were assessed. The CS was related to the values for the unaffected limb, and an individual relative CS was calculated and expressed in percent. The mean follow-up was 30 (range, 13-55) months in the ASI group and 58 (range, 39-76) months in the K-wire group. The following seven characteristics were evaluated : fracture type, surgical technique, dominance of the affected limb, patient age, injury-surgery interval, and individual relative CS and DASH scores. The results were statistically analysed with a 5% level of statistical significance set for all tests. RESULTS: The average age in the ASI group was 62.1 years, with 64.7 (range, 29-95) years for women and 35.5 (range, 26-76) years for men. In the K-wire group the average age was 66.1 (range, 53-84) years. The functional outcomes in four-fragment fractures were significantly worse than in three-fragment fractures (mean relative CS and DASH scores of 56 and 21 versus 72 and 32). The K-wire group showed a significantly worse functional outcomes than the ASI group in both the mean relative CS score (p<0.001) and the mean DASH score (p=0.003). No significant relationship was found in any other pair of variables. The patient's age had no effect on functional outcome, as assessed by CS (p=0.412) and DASH (p=0.076) and the injury-surgery interval had no influence, either (CS, p=0.220; DASH, p=0.118). There was no relation between the patient's age and choice of the surgical method (p=0.467), between the patient's age and a fracture type (p=0.356) and between the patient's age and injury to either a dominant or a non-dominant limb (p=0.659). Dominance or non-dominance of the affected limb had no effect on CS or DASH scores (p=0.662 and p=0.302, respectively) or on a type of fracture (p=0.183). DISCUSSION: Several surgical techniques used for the treatment of proximal humerus fractures suggest the absence of consensus in therapy. Novel angle-stable implants show better biochemical properties and meet criteria required in minimally invasive techniques. Some authors prefer intramedullary nailing for three-fragment fractures and the use of an angle-stable plate for four-fragment fractures. These indication criteria were also confirmed by the results of our study. CONCLUSIONS: The analysis of functional outcomes showed that the therapeutic effect of K-wire transfixation was significantly worse than the effect of the angle-stable plate technique, and therefore the authors stopped using this method. At present intramedullary nailing is indicated in two- and three-fragment fractures and in some less displaced four-fragment fractures. An angle-stable plate is used in severely displaced four-fragment fractures. If the head is broken or dislocated, older patients are primarily indicated for hemiarthroplasty and younger ones for humeral head reconstruction.

Quantification of the regional carbon cycle of the biosphere: policy, science and land-use decisions.

This paper addresses some issues related to the carbon cycle and its utilization by society. Traditional uses for agriculture, forestry, as a source of fuel and other products, and for pastoral farming, among others, have recently been supplemented by identifying its potential for mitigating the increasing concentration of greenhouse gases in the atmosphere. Through the Kyoto Protocol, carbon has become a commodity and the CO(2)-absorbing capability of the vegetation and soils an economically valuable asset. The multi-facetted roles of the C cycle and its sensitivity to human activities present a demand for techniques that permit accurate, timely and affordable characterization of the various components of this cycle, especially on land where most human activities take place. Such techniques must satisfy a range of demands in terms of purpose, clients for the information, and biosphere properties. However, if successful, they offer the potential to support monitoring, reporting, policy setting, and management of terrestrial biospheric resources. The context for these requirements and possibilities is illustrated with reference to the China Carbon Sequestration Project and its findings.

Comparison of dentine-resin interface in total-etch and self-etching adhesives using electron microscopy.

The important condition for the adhesive bond between dentine and composite filling is the change of dentine property from hydrophilic to hydrophobic. Substances able to accomplish this change, dentinal adhesives, have undergone complex development. Recently, the so-called self-etching adhesives have been formulated. The aim of the present paper was to compare the structural pattern of dentin/resin interface after the application of dentinal adhesives used in total- and self-etching technique. Dentinal adhesives Single bond, Prime bond, Prompt-L-pop Adper, and Xeno III were used. The former two belong to the total etch technique, the latter two to the self-etching technique. The dentin/resin interface was studied in transmission (TEM) and scanning (SEM) electron microscope. In TEM sixteen teeth were investigated, each adhesive was applied in four teeth. Under SEM forty teeth were studied, each adhesive was applied in ten teeth. The obtained results demonstrated that all the dentine adhesives studied were able to penetrate into dentinal tubules and to form a hybrid layer with the demineralized intertubular and peritubular dentine. There was no substantial difference in morphology of the dentine/resin interface between the techniques studied. Our results suggest that the hybrid layer function of all four adhesives might be of the same quality.

Remotely sensed habitat diversity predicts butterfly species richness and community similarity in Canada.

Although there is no shortage of potential explanations for the large-scale patterns of biological diversity, the hypothesis that energy-related factors are the primary determinants is perhaps most extensively supported, especially in cold-temperate regions. By using unusually high-resolution biodiversity and environmental data that have not previously been available, we demonstrate that habitat heterogeneity, as measured by remotely sensed land cover variation, explains Canadian butterfly richness better than any energy-related variable we measured across spatial scales. Although species-richness predictability declines with progressively smaller quadrat sizes, as expected, we demonstrate that most variability (>90%) in butterfly richness may be explained by habitat heterogeneity with secondary contributions from climatic energy. We also find that patterns of community similarity across Canada are strongly related to patterns of habitat composition but not to differences in energy-related factors. Energy should still be considered significant but its main role may be through its effects on within-habitat diversity and perhaps, indirectly, on the sorts of habitats that may be found in a region. Effects of sampling intensity and spatial autocorrelation do not alter our findings.

Injection moulded hydroxyapatite ceramics.

The injection moulding of hydroxyapatite (HA) and properties (relative density, shrinkage, microstructure, thermal strength and phase composition) of HA ceramics sintered at temperatures of 1373-1773 K were studied. Particles of oval shape and size of 0.5 microns were most suitable for injection moulding. Polymer/HA mixture contained 63 vol% of the HA powder. Maximum relative density (98.7%) and shrinkage (16%) of HA ceramics were obtained at a sintering temperature of 1523 K. Maximum flexural strength (60 MPa) of HA ceramics occurred at a sintering temperature of 1473 K. The strength of these ceramics decreased at sintering temperatures higher than 1473 K. Loss in strength was owing to the grain growth and decomposition of HA ceramics. The relationship between grain size and strength is described by the equation: sigma = 53.3d1/2. The calculated activation energy of grain growth obtained was 215kJ mol-1 K-1. The decomposition of HA to alpha-tricalcium phosphate was important at temperatures greater than 1573 K.

Plant canopy gap-size analysis theory for improving optical measurements of leaf-area index.

Optical instruments currently available for measuring the leaf-area index (LAI) of a plant canopy all utilize only the canopy gap-fraction information. These instruments include the Li-Cor LAI-2000 Plant Canopy Analyzer, Decagon, and Demon. The advantages of utilizing both the canopy gap-fraction and gap-size information are shown. For the purpose of measuring the canopy gap size, a prototype sunfleck-LAI instrument named Tracing Radiation and Architecture of Canopies (TRAC), has been developed and tested in two pure conifer plantations, red pine (Pinus resinosa Ait.) and jack pine (Pinus banksiana Lamb). A new gap-size-analysis theory is presented to quantify the effect of canopy architecture on optical measurements of LAI based on the gap-fraction principle. The theory is an improvement on that of Lang and Xiang [Agric. For. Meteorol. 37, 229 (1986)]. In principle, this theory can be used for any heterogeneous canopies.