The Anatomic Position of the Sciatic Nerve During Percutaneous Retrograde Posterior Column Fixation Is Determined by Hip Position.

OBJECTIVES: There are multiple established patient positions for placement of a percutaneous retrograde posterior column screw for fixation of acetabulum fractures. The sciatic nerve is at risk of injury during this procedure because it lies adjacent to the start point at the ischial tuberosity. The purpose of this study was to define how the position of the sciatic nerve, relative to the ischial tuberosity, changes regarding the patient's hip position. METHODS: In a cohort of 11 healthy volunteers, ultrasound was used to measure the absolute distance between the ischial tuberosity and the sciatic nerve. Measurements were made with the hip and knee flexed to 90 degrees to simulate supine and lateral positioning and with the hip extended to simulate prone positioning. In both positions, the hip was kept in neutral abduction and neutral rotation. RESULTS: The distance from the lateral border of the ischial tuberosity to the medial border of the sciatic nerve was greater in all subjects in the hip-flexed position versus the extended position. The mean distance was 17 mm (range, 14-27 mm) in the hip-extended position and 39 mm (range, 26-56 mm) in the hip-flexed position ( P < 0.001). CONCLUSIONS: The sciatic nerve demonstrates marked excursion away from the ischial tuberosity when the hip is flexed compared with when it is extended. The safest patient position for percutaneous placement of a retrograde posterior column screw is lateral or supine with the hip flexed to 90 degrees.

A 7-year perspective on femoral neck fracture management in New York State-Do Level 1 trauma centers provide better care?

INTRODUCTION: Patients with femoral neck fractures are at a substantial risk for medical complications and all-cause mortality. Given this trend, our study aims to evaluate postoperative outcomes and the economic profile associated with femoral neck fractures managed at level-1 (L1TC) and non-level-1-trauma centers (nL1TC). METHODS: The SPARCS database was queried for all geriatric patients sustaining atraumatic femoral neck fractures within New York State between 2011 and 2017. Patients were then divided into two cohorts depending on the treating facility's trauma center designation: L1TC versus nL1TC. Patient samples were evaluated for trends and relationships using descriptive analysis, Student's t-tests, and Chi-squared. Multivariable linear-regressions were utilized to assess the effect of trauma center designation and potential confounders on patient mortality and inpatient healthcare expenses. RESULTS: In total, 44,085 femoral neck fractures operatively managed at 161 medical centers throughout New York during a 7-year period. 4,974 fractures were managed at L1TC while 39,111 were treated at nL1TC. Following multivariate regression analysis, management at L1TC was the most significant cost driver, resulting in an average increased cost of $6,330.74 per fracture. CONCLUSION: Our results suggest that femoral neck fractures treated at L1TC have more comorbidities, higher in-hospital mortality, longer LOS, and greater hospital costs.

Warm lidocaine/tetracaine patch versus placebo before pediatric intravenous cannulation: a randomized controlled trial.

STUDY OBJECTIVE: We compare the pain of intravenous (IV) cannulation in pediatric emergency department (ED) patients after applying a topical lidocaine/tetracaine patch versus placebo. We hypothesized that application of the active patch would reduce the pain of IV cannulation by at least 15 mm. METHODS: We conducted a randomized, double-blind, placebo-controlled trial in a suburban academic ED. Patients aged 3 to 17 years who required nonemergency IV cannulation were eligible for enrollment. At triage, a nurse placed a commercially available topical lidocaine/tetracaine patch or an identical-looking placebo patch over the antecubital or hand vein in patients for whom an IV catheter was anticipated. After IV cannulation by the treating nurse, the pain of cannulation was measured on a validated 100-mm visual analogue scale or Wong Baker scale. Outcomes were compared between groups with Mann-Whitney U, Student t, and chi(2) tests. A sample of 40 patients had 80% power to detect a 13-mm difference in pain scores. RESULTS: Forty-five patients were randomized to lidocaine/tetracaine patch (22) or placebo (23), and IV cannulation was attempted in 40 of these patients. Mean age was 10 years (SD=4.3), 35% were female patients. The median pain of IV cannulation in the active treatment group (18 mm [interquartile range (IQR) 1 to 40 mm]) was significantly lower than in the placebo group (35 mm [IQR 20 to 59 mm]; P=.04). Adequate pain relief was more common in the active treatment group (75% [95% confidence interval (CI) 53% to 89%] versus 35% [95% CI 18% to 57%]; difference 40% [95% CI 6% to 64%]). The number of successful IV cannulations after the first attempt was similar in both the lidocaine/tetracaine and the placebo groups (90% [95% CI 70% to 97%] versus 85% [95% CI 64% to 95%]; difference 5% (95% CI -21% to 30%). CONCLUSION: Application of a topical lidocaine/tetracaine patch resulted in a modest reduction in the pain of IV cannulation in pediatric ED patients and did not alter the rate of successful cannulations.

Fewer active motors per vesicle may explain slowed vesicle transport in chick motoneurons after three days in vitro.

Vesicle transport in cultured chick motoneurons was studied over a period of 3 days using motion-enhanced differential interference contrast (MEDIC) microscopy, an improved version of video-enhanced DIC. After 3 days in vitro (DIV), the average vesicle velocity was about 30% less than after 1 DIV. In observations at 1, 2 and 3 DIV, larger vesicles moved more slowly than small vesicles, and retrograde vesicles were larger than anterograde vesicles. The number of retrograde vesicles increased relative to anterograde vesicles after 3 DIV, but this fact alone could not explain the decrease in velocity, since the slowing of vesicle transport in maturing motoneurons was observed independently for both anterograde and retrograde vesicles. In order to better understand the slowing trend, the distance vs. time trajectories of individual vesicles were examined at a frame rate of 8.3/s. Qualitatively, these trajectories consisted of short (1-2 s) segments of constant velocity, and the changes in velocity between segments were abrupt (<0.2 s). The trajectories were therefore fit to a series of connected straight lines. Surprisingly, the slopes of theses lines, i.e. the vesicle velocities, were often found to be multiples of ~0.6 mum/s. The velocity histogram showed multiple peaks, which, when fit with Gaussians using a least squares minimization, yielded an average spacing of 0.57 mum/s (taken as the slope of a fit to peak position vs. peak number, R(2)=0.994). We propose that the abrupt velocity changes occur when 1 or 2 motors suddenly begin or cease actively participating in vesicle transport. Under this hypothesis, the decrease in average vesicle velocity observed for maturing motoneurons is due to a decrease in the average number of active motors per vesicle.

Speckled microtubules improve tracking in motor-protein gliding assays.

Gliding assays of motor proteins such as kinesin, dynein and myosin are commonly carried out with fluorescently labeled microtubules or filamentous actin. In this paper, we show that speckled microtubules (MTs), prepared by copolymerizing 98% unlabeled tubulin with 2% rhodamine-labeled tubulin, can be localized to +/-7.4 nm (24 measurements) in images acquired every 125 ms. If the speckled MTs move at about 800 nm s(-1), ten images are sufficient to determine their velocity to a precision of +/-6.8 nm s(-1) (6 microtubules, 24 measurements). This velocity precision is four-fold better than manual methods for measuring the gliding velocity of uniformly labeled MTs by end-point localization. The improved velocity precision will permit the determination of velocity-force curves when one, two and three kinesin motors pull a single load in vitro.