Influence of MC3T3-E1 preosteoblast culture on the corrosion of a T6-treated AZ91 alloy.

This study investigated the corrosion of artificially aged T6 heat-treated Mg-9%Al-1%Zn (AZ91) for biomedical applications. Corrosion tests and surface analysis were completed both with and without a monolayer of mouse preosteoblast MC3T3-E1 cells cultured on the sample. Electrochemical impedance spectroscopy (EIS) and inductively coupled plasma mass spectroscopy (ICPMS) were used to explore the corrosion processes after either 3 or 21 days of AZ91 incubation in cell culture medium (CCM). The EIS showed both the inner layer resistance (Rin ) and outer layer resistance (Rout ) were lower for samples without cells cultured on the surface at 3 days (Rin = 2.64 e4 Ω/cm(2) , Rout = 140 Ω/cm(2) ) compared to 21 days (Rin = 3.60 e4 Ω/cm(2) , Rout = 287 Ω/cm(2) ) due to precipitation of magnesium and calcium phosphates over time. Samples with preosteoblasts cultured on the surface had a slower initial corrosion (3 day, Rin = 1.88 e5 Ω/cm(2) , Rout = 1060 Ω/cm(2) ) which was observed to increase over time (21 day, Rin = 2.99 e4 Ω/cm(2) , Rout = 287 Ω/cm(2) ). Changes in the corrosion processes were thought to be related to changes in the coverage provided by the cell layer. Our results reveal that the presence of cells and biological processes are able to significantly influence the corrosion rate of AZ91.

Femoral nerve block for diaphyseal and distal femoral fractures in the emergency department. Surgical technique.

BACKGROUND: Diaphyseal and distal femoral fractures are painful injuries that are frequently seen in patients requiring a trauma work-up in the hospital emergency department prior to definitive management. The purpose of this study was to determine whether a femoral nerve block administered in the emergency department could provide better pain relief for patients with femoral fractures than currently used pain management practices. METHODS: Patients who presented with an acute diaphyseal or distal femoral fracture were identified as potential candidates for this study. Eligible patients were randomized by medical record number to receive either (a) the femoral nerve block (20 mL of 0.5% bupivacaine) along with standard pain management or (b) standard pain management alone (typically intravenous narcotics). The pain was assessed with use of a visual analog scale at the initial evaluation and at five, fifteen, thirty, sixty, and ninety minutes following the initial evaluation. Fifty-four patients were enrolled in the study from April 2005 to May 2006. Thirty-one patients received a femoral nerve block, and twenty-three patients received standard pain management alone. RESULTS: Baseline scores on the visual analog pain scale did not differ between the groups at the initial evaluation. The patients who received a femoral nerve block (along with standard pain management) had significantly lower pain scores at five, fifteen, thirty, sixty, and ninety minutes following the block than did the patients who received standard pain management alone (p < 0.001). The score on the visual analog pain scale across these time points was an average of 3.6 points less (on a 10-point scale) for those who received the block. There were no infections, paresthesias, or other complications related to the femoral nerve block. CONCLUSIONS: The acute pain of a diaphyseal or distal femoral fracture can be significantly decreased through the use of a femoral nerve block, which can be administered safely in the hospital emergency department.

Femoral nerve block for diaphyseal and distal femoral fractures in the emergency department.

BACKGROUND: Diaphyseal and distal femoral fractures are painful injuries that are frequently seen in patients requiring a trauma work-up in the hospital emergency department prior to definitive management. The purpose of this study was to determine whether a femoral nerve block administered in the emergency department could provide better pain relief for patients with femoral fractures than currently used pain management practices. METHODS: Patients who presented with an acute diaphyseal or distal femoral fracture were identified as potential candidates for this study. Eligible patients were randomized by medical record number to receive either (a) the femoral nerve block (20 mL of 0.5% bupivacaine) along with standard pain management or (b) standard pain management alone (typically intravenous narcotics). The pain was assessed with use of a visual analog scale at the initial evaluation and at five, fifteen, thirty, sixty, and ninety minutes following the initial evaluation. Fifty-four patients were enrolled in the study from April 2005 to May 2006. Thirty-one patients received a femoral nerve block, and twenty-three patients received standard pain management alone. RESULTS: Baseline scores on the visual analog pain scale did not differ between the groups at the initial evaluation. The patients who received a femoral nerve block (along with standard pain management) had significantly lower pain scores at five, fifteen, thirty, sixty, and ninety minutes following the block than did the patients who received standard pain management alone (p < 0.001). The score on the visual analog pain scale across these time-points was an average of 3.6 points less (on a 10-point scale) for those who received the block. There were no infections, paresthesias, or other complications related to the femoral nerve block. CONCLUSIONS: The acute pain of a diaphyseal or distal femoral fracture can be significantly decreased through the use of a femoral nerve block which can be administered safely in the hospital emergency department.