Geographical Differences in Wound Complication Rates Following the Sinus Tarsi Approach in Displaced Intra-articular Calcaneal Fractures: A Systematic Review of the Literature

Background

The sinus tarsi approach (STA) has gained popularity for the treatment of displaced intra-articular calcaneal fractures. No large studies comparing wound complications worldwide after STA surgery are available. The aim of this systematic review was to compare postoperative wound complication (POWC) and postoperative wound infection (POWI) rates following STA surgery between continents and countries and their differences in climate.

Methods

A literature search was performed using the databases of PubMed, Embase, and the Cochrane Library. Studies published before January 1, 2000, including < 10 patients and written in a language other than English were excluded.

Results

In total, 86 studies containing 4,392 surgeries via STA from 20 different countries were included. The mean POWC was 5.9% and the mean POWI was 4.4%. The highest median POWC rate was in North America (8.5%) and the lowest in South America (2.0%). No significant differences were found in the POWC and POWI rates between countries (p = 0.178 and p = 0.570, respectively), but significant differences were found between the POWC and POWI rates between continents (p = 0.011 and p = 0.036, respectively). The number of surgeries per year and climate differences, as represented by mean local temperature, were not correlated with both the POWC/POWI rates and functional outcome scores.

Conclusions

Significant differences between the POWC and POWI rates were found between continents but not between individual countries. With a mean POWC of 5.9% and a mean POWI rate of 4.4%, STA has an intrinsic low risk for complications given the minimally invasive nature of the approach and is inevitably becoming the gold standard for calcaneal surgery.

Acoustical gas-leak detection in the presence of multiple reflections, dispersion, and uncorrelated noise using optimized residual complexity

Precise acoustical leak detection calls for robust time-delay estimates, which minimize the probability of false alarms in the face of dispersive propagation, multiple reflections, and uncorrelated background noise. Providing evidence that higher order modes and multi-reflected signals behave like sets of correlated noise, this work uses a regression model to optimize residual complexity in the presence of both correlated and uncorrelated noise. This optimized residual complexity (ORC) is highly robust since it takes into account both the level and complexity of noise. The lower complexity of the dispersive modes and multiple reflections, compared to the complexity of the plane mode, points to the robustness of ORC against multiple reflections and dispersion. Experimental investigations using recorded sounds of gas leaking from a pipe confirm the robustness of ORC against multiple reflections. Numerical simulations also show robustness against dispersive modes, even when they disturb the linearity of the cross-spectrum phase. Comparisons with other methods-mutual information, cross correlation, and residual complexity-underline the general advantages of ORC in terms of robustness in the presence of reflection and dispersion, against both correlated and uncorrelated noise, and to short signals.

Application of direct search optimization for pharmacokinetic parameter estimation

PURPOSE

For simple pharmacokinetic compartmental models, analytical solution to the governing differential equations along with common graphical methods provide a mean to evaluate the associated rate constants. These graphical methods, however, can not be used for the more complex multi-compartment models. Furthermore, parameter estimation using slope and intercept values from the graphical methods is often accompanied with error. In this study a numerical solution is applied for the solution of the governing differential equations and a simple direct search optimization procedure utilizing random numbers is used for pharmacokinetic parameter estimation.

METHOD

The methodology is demonstrated with reference to experimental literature data for ciprofloxacin and ofloxacin whose pharmacokinetic behavior has been reported in terms of a two-compartment model.

RESULTS

Examination of the predicted drug concentrations from the graphical method and the optimization methodology indicate that both methods have comparable accuracy in predicting the drug concentrations. The graphical method, however, only shows good accuracy in the early stages both after i.v. and oral drug administration whereas the optimization procedure, due to the nature of the objective function formulation, provides good accuracy over the entire range of times after drug administration.

CONCLUSIONS

The methodology is simple, provides optimized parameters which accurately predict drug concentrations, and is flexible to include more weight on the early-time data or be extended to multi-compartment models.