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Objective: The primary objective of this trial was to compare the parastomal hernia rates 1 year after the construction of an end colostomy by 3 surgical techniques: cruciate incision, circular incision in the fascia and using prophylactic mesh. Secondary objectives were evaluation of postoperative complications, readmissions/reoperations, and risk factors for parastomal hernia. Summary of Background Data: Colostomy construction techniques have been explored with the aim to improve function and reduce stoma complications, but parastomal herniation is frequent with an incidence of approximately 50%. Methods: A randomized, multicenter trial was performed in 3 hospitals in Sweden and Denmark; all patients scheduled to receive an end colostomy were asked to participate. Parastomal hernia within 12 months was determined by computed tomography of the abdomen in prone position and by clinical assessment. Complications, readmissions, reoperations, and risk factors were also assessed. Results: Two hundred nine patients were randomized to 1 of the 3 arms of the study. Patient demographics were similar in all 3 groups. Assessment of parastomal hernia was possible in 185 patients. The risk ratio (95% confidence interval) for parastomal hernia was 1.25 (0.83; 1.88), and 1.22 (0.81; 1.84) between cruciate versus circular and cruciate versus mesh groups, respectively. There were no statistically significant differences between the groups with regard to parastomal hernia rate. Age and body mass index were found to be associated with development of a parastomal hernia. Conclusion: We found no significant differences in the rates of parastomal hernia within 12 months of index surgery between the 3 surgical techniques of colostomy construction. [ABSTRACT FROM AUTHOR]

The vital microscopic chamber is an experimental implant of commercially pure titanium that admits in vivo and in situ observations of bone vascularity and bone remodeling. The bone growth chamber and the bone harvest chamber, in particular, are useful tools for quantifying bone regeneration under the most variable experimental conditions. [ABSTRACT FROM AUTHOR]

Bone induction and conduction by demineralized bone matrix (DBM) implantation can aid union in experimental bone defects of a poor healing capacity. In this study the effects of DBM in defects with highly favorable healing conditions were observed. A dividable titanium implant with a transverse bone ingrowth canal (Bone Harvest Chamber) was inserted in each rabbit tibia. Under normal conditions bone will invariably invade the bone ingrowth canal from both ends and fuse in the middle. In one chamber, a needle-like allogenous DBM implant was deposited in the canal, occupying less than 20% of its volume; another chamber in the contralateral extremity of the same animal served as control. After 14 days, the bone mass in the DBM-treated canal was diminished to 65% of that of the control, although the DBM itself was largely resorbed. This was in spite of the fact that the DBM used had inductive properties verified by its capacity to induce bone formation at an intramuscular site. The results suggest that DBM cannot be used to speed up bone healing under already favorable healing conditions, as is represented by the BHC model. [ABSTRACT FROM AUTHOR]

BACKGROUND: There is a clinical need for novel oral anticoagulants with predictable pharmacokinetics and pharmacodynamics. Rivaroxaban is an oral direct Factor Xa (FXa) inhibitor in clinical development for the prevention and treatment of thromboembolic disorders. This analysis was performed to characterize the population pharmacokinetics and pharmacodynamics of rivaroxaban in patients participating in two phase II, double-blind, randomized, active-comparator-controlled studies of twice-daily rivaroxaban for the prevention of venous thromboembolism after total hip- or knee-replacement surgery. METHODS: Sparse blood samples were taken from all patients participating in the studies (n = 1009). In addition, a subset of patients in the hip study (n = 36) underwent full profiling. Rivaroxaban plasma concentrations, FXa activity and the prothrombin time were determined. Nonlinear mixed-effects modelling was used to model the population pharmacokinetics and pharmacodynamics of rivaroxaban. RESULTS: An oral one-compartment model described the population pharmacokinetics of rivaroxaban well. On the first postoperative day only, categorization of patients as slow or fast absorbers as a tool to address variability in absorption improved the fit of the model. Clearance of rivaroxaban was lower and more variable on the first postoperative day, and so time was factored into the model. Overall, the only major difference between the models for the hip study and the knee study was that clearance was 26% lower in the knee study, resulting in approximately 30% higher exposure. Residual variability in the models was moderate (37% and 34% in the hip and knee studies, respectively). Plasma concentrations of rivaroxaban increased dose dependently. Pharmacokinetic parameters that were estimated using the models agreed closely with results from full-profile patients in the hip study, demonstrating that rivaroxaban pharmacokinetics are predictable. The pharmacokinetics of rivaroxaban were affected by expected covariates: age affected clearance in the hip study only, haematocrit (on the first postoperative day only) and gender affected clearance in the knee study only, and renal function affected clearance in both studies. Bodyweight affected the volume of distribution in both studies. However, the effects of covariates on the pharmacokinetics of rivaroxaban were generally small, and predictions of ‘extreme’ case scenarios suggested that fixed dosing of rivaroxaban was likely to be possible. FXa activity and the prothrombin time were both affected by surgery, probably because of perioperative bleeding and intravenous administration of fluids; therefore, time was included in the pharmacodynamic models. In both studies, FXa activity correlated with rivaroxaban plasma concentrations following a maximum effect model, whereas prothrombin time prolongation correlated following a linear model with intercept. The slope of the prothrombin time prolongation correlation was 3.2 seconds/(100 µg/L) in the hip study and 4.2 seconds/(100 µg/L) in the knee study. Both pharmacodynamic models in both studies demonstrated low residual variability of approximately 10%. CONCLUSION: This population analysis in patients undergoing major orthopaedic surgery demonstrated that rivaroxaban has predictable, dose-dependent pharmacokinetics that were well described by an oral one-compartment model and affected by expected covariates. Rivaroxaban exposure could be assessed using the prothrombin time, if necessary, but not the international normalized ratio. The findings suggested that fixed dosing of rivaroxaban may be possible in patients undergoing major orthopaedic surgery. [ABSTRACT FROM AUTHOR]