Comparison of two different Radiostereometric analysis (RSA) systems with markerless elementary geometrical shape modeling for the measurement of stem migration.

UNLABELLED: Radiostereometric analysis (RSA) is the gold standard of measurement for in vivo 3D implants migration. BACKGROUND: The aim of this study was to evaluate the in vivo precision of 2 RSA marker-based systems compared with that of marker-free, elementary geometrical shape modeling RSA. METHODS: Stem migration was measured in 50 patients recruited from an on-going Randomized Controlled Trial. We performed marker-based analysis with the Um RSA and RSAcore systems and compared these results with those of the elementary geometrical shape RSA. FINDINGS: The precision for subsidence was 0.118 mm for Um RSA, 0.141 mm for RSAcore, and 0.136 mm for elementary geometrical shape RSA. The precision for retroversion was 1.3° for elementary geometrical shape RSA, approximately 2-fold greater than that for the other methods. The intraclass correlation coefficient between the marker-based systems and elementary geometrical shape RSA was approximately 0.5 for retroversion. All 3 methods yielded ICCs for subsidence and varus-valgus rotation above 0.9. DISCUSSION: We found an excellent correlation between marker-based RSA and elementary geometrical shape RSA for subsidence and varus-valgus rotation, independent of the system used. The precisions for out-of-plane migration were inferior for elementary geometrical shape RSA. Therefore, as a mechanism of failure, retroversion may be more difficult to detect early. This is to our knowledge the first study to compare different RSA systems with or without markers on the implant. INTERPRETATION: Marker-based RSA has high precision in all planes, independent of the system used. Elementary geometrical shape RSA is inferior in out-of-plane migration.

Coating of titanium with hydroxyapatite leads to decreased bone formation: A study in rabbits.

OBJECTIVES: An experimental rabbit model was used to test the null hypothesis, that there is no difference in new bone formation around uncoated titanium discs compared with coated titanium discs when implanted into the muscles of rabbits. METHODS: A total of three titanium discs with different surface and coating (1, porous coating; 2, porous coating + Bonemaster (Biomet); and 3, porous coating + plasma-sprayed hydroxyapatite) were implanted in 12 female rabbits. Six animals were killed after six weeks and the remaining six were killed after 12 weeks. The implants with surrounding tissues were embedded in methyl methacrylate and grinded sections were stained with Masson-Goldners trichrome and examined by light microscopy of coded sections. RESULTS: Small amounts of bone were observed scattered along the surface of five of the 12 implants coated with porous titanium, and around one out of 12 porous coated surfaces with Bonemaster. No bone formation could be detected around porous coated implants with plasma-sprayed hydroxyapatite. CONCLUSION: Porous titanium coating is to some degree osteoinductive in muscles.

Norwegian monitoring programme on the inorganic and organic contaminants in fish caught in the Barents Sea, Norwegian Sea and North Sea, 1994-2001.

The results from part of a monitoring programme of contaminant levels in fish and other seafood products initiated by the Directorate of Fisheries in Norway in 1994 are presented. Concentrations of 22 elements (four are presented here: As, Cd, Hg and Pb) and HCB, HCH, PCB 28, 52, 101, 105, 118, 138, 153, 156, 180, pp-DDD, p-DDE, p-DDT, sum DDT and (137)Cs were determined in 17 species of fish caught in three sampling locations: the Barents Sea, the Norwegian Sea and the North Sea. The fish species analysed in the survey were limited to species of commercial importance for Norway with catching volumes of at least 10,000 metric tons year(-1). The survey started in 1994 and is expected to continue beyond 2010. The analyses were carried out on 25 individual fish from each species and each sampling location, and the locations were representative of commercial fishing grounds for the species in question. The concentrations of contaminants found were considerably lower than the maximum levels permissible in fish set by CODEX and the European Union for contaminants in seafood products.

A confirmatory factor analysis on the DSM-IV ADHD and ODD symptoms: what is the best model for the organization of these symptoms?

Confirmatory factor analysis (CFA) was used to evaluate five different models for the organization of the DSM-IV ADHD and oppositional defiant disorder (ODD) symptoms (Model 1: a single factor model; Model 2: an ADHD and ODD two factor model; Model 3a: an inattention (INA), hyperactivity/impulsivity (HYP/IMP), and ODD three factor model; Model 3b: an INA, HYP/IMP, and ODD three factor model where the three IMP symptoms cross-load on the ODD factor; Model 4: an INA, HYP, IMP, and ODD four factor model). To evaluate these models, maternal ratings of ADHD and ODD symptoms were obtained at outpatient pediatric clinics on 742 children not in treatment and 91 children in treatment for ADHD. Model 3a resulted in a good fit as well as a significantly better fit than Model 2. Model 3a was also equivalent across treatment status, gender, and age groupings for the most part. Though Models 3b and 4 provided a statistically better fit than Model 3a, the improvement in fit was small and other model selection criteria argued against these more complex models.

The advantages of early operation with splenorrhaphy versus nonoperative management for the blunt splenic trauma patient.

The importance of splenic preservation in reducing the risk of overwhelming post-splenectomy sepsis as well as the heightened awareness of transfusion-related infections have led to changing concepts in the management of blunt splenic trauma. A 10-year retrospective review (1980-1989) of blunt splenic trauma at a Level I trauma center is presented. One hundred eighty five blunt splenic injuries were treated, with a mortality rate of 7 per cent. Splenorrhaphy was performed in 7 per cent of patients in the first 5-year period (48% underwent splenectomy, and 45% were managed nonoperatively). The rate of splenorrhaphy increased to 22 per cent during the second 5-year period, with a subsequent decrease in both splenectomy (39%) and nonoperative management (39%). During the last year of review, 65 per cent of bluntly injured spleens were able to be salvaged (35% managed by splenorrhaphy and 30% by observation). Blood usage averaged 1.1 units/patient in the nonoperative group, 3.3 units/patient in the splenorrhaphy group, and 7.9 units/patient in those undergoing splenectomy. Nonoperative management of blunt splenic trauma can clearly be successful. However, patients chosen for this method should be completely hemodynamically stable to avoid requiring blood transfusions. A combination of early operation and splenorrhaphy with the use of autotransfusion devices, remains a better alternative in the less stable patient with multiple injuries. This method provides for a high rate of splenic salvage while decreasing the need for homologous blood transfusions.

Fatty acid patterns in the classification of some representatives of the families Enterobacteriaceae and Vibrionaceae.

Twenty-three strains representing the families Enterobacteriaceae and Vibrionaceae were analysed for fatty acid composition of whole cells by means of glass capillary column gas chromatography. Among the several alternatives tested, cluster analysis based on data normalized to hexadecanoate and logarithmically transformed provided good separations of species, genera and families. Strains from the genera Salmonella, Escherichia, Proteus, Enterobacter, Klebsiella, Vibrio and Aeromonas were studied.