Biomechanical Investigation of a Novel Revision Device in an Osteoporotic Model: Pullout Strength of Pedicle Screw Anchor Versus Larger Screw Diameter.

STUDY DESIGN: In vitro cadaveric biomechanical study. OBJECTIVE: To assess revision pullout strength of novel anchored screws (AS) versus conventional larger diameter traditional pedicle screws (TPS) in an osteoporotic model. SUMMARY OF BACKGROUND DATA: Pedicle screws are the most ubiquitous method of treating spinal pathologies requiring lumbar fusion. Although these screws are effective in providing 3-column stabilization of the spine, revision surgeries are occasionally necessary, particularly for geriatric and osteoporotic populations. Innovative technologies should be tested to ensure continued improvement in revision techniques. METHODS: For 4 specimens at L2-L5 (T-score=-3.6±0.54), 6.5-mm-diameter TPS were inserted into left and right pedicles and were pulled out; revision screws were then inserted. Polyether-ether-ketone anchors, designed to expand around a 6.5-mm screw, were inserted into all left pedicles. On the contralateral side, 7.5-mm-diameter TPS were inserted at L2-L3, and 8.5-mm-diameter TPS at L4-L5. Pullout testing was performed at 10 mm/min. The maximum pullout strength and insertion forces were recorded. RESULTS: The initial average pullout force (6.5-mm screw) was 837 N (±329 N) and 642 N (±318 N) in L2-L3 and L4-L5 left pedicles, and 705 N (±451 N) and 779 N (±378 N) in L2-L3 and L4-L5 right pedicles, respectively. Comparison of revision pullout forces versus initial pullout forces revealed the following: 87% and 63% for AS in L2-L3 and L4-L5 left pedicles, respectively; 56% for 7.5-mm and 93% for 8.5-mm TPS in L2-L3 and L4-L5 right pedicles, respectively. CONCLUSIONS: Anchor sleeves with 6.5-mm-diameter pedicle screws provided markedly higher resistance to screw pullout than 7.5-mm-diameter revision screws and fixation statistically equivalent to 8.5-mm-diameter screws, possibly because of medial-lateral expansion within the vertebral space and/or convex filling of the pedicle. AS results had the lowest SD, indicating minimal variability in bone-screw purchase.

The effect of craniectomy size on mortality, outcome, and complications after decompressive craniectomy at a rural trauma center.

INTRODUCTION: Decompressive craniectomy (DC) has increasing support with current studies suggesting an improvement in both survival rates and outcomes with this intervention. However, questions surround this procedure; specifically, no evidence has indicated the optimal craniectomy size. Larger craniectomy is thought to better decrease intracranial pressure, but with a possible increase in complication rates. Our hypothesis is that a larger craniectomy may improve mortality and outcome, but may increase complication rates. MATERIALS AND METHODS: A retrospective observational therapeutic study was undertaken to determine if craniectomy size is related to complication rates, mortality, or outcome. Our institution's Trauma Registry was searched for patients undergoing DC. Craniectomy size was measured by antero-posterior (AP) diameter. Mortality, outcome (through admission and discharge Glasgow Coma Score and Glasgow Outcome Scale), and complications (such as re-bleeding, re-operation, hygroma, hydrocephalus, infection, and syndrome of the trephined) were noted. Complications, mortality, and outcome were then compared to craniectomy size, to determine if any relation existed to support our hypothesis. RESULTS: 20 patients met criteria for inclusion in this study. Craniectomy size as measured by AP diameter was correlated with a statistically significant improvement in mortality within the group. All patients with a craniectomy size less than 10 cm died. However, outcome was not significantly related to craniectomy size in the group. Similarly, complication rates did not differ significantly compared to craniectomy size. DISCUSSION: This study provides Level 3 evidence that craniectomy size may be significantly related to improved mortality within our group, supporting our initial hypothesis; however, no significant improvement in outcome was seen. Similarly, in contrast to our hypothesis, complication rates did not significantly correlate with craniectomy size.

Fibrilación auricular en la estenosis mitral / Atrial fibrillation in mitral stenosis

Con el objetivo de analizar la relación entre una fibrilación auricular y el tamaño de las auriculas se estudiaron 50 pacientes con estenosis mitral, 19 de ellos con la arritmia. A cada paciente se le realizó un ecocardiograma bidimensional y Doppler, y se midió el diámetro útil de la válvula y el diamétro mayor de la auricula izquierda a partir de estas medidas se calculó la circunferencia y el tiempo teórico necesario para que la onda de activación completara su circuito. La presencia de fibrilación auricular se relacionó con el tamaño de la aurícula. El tiempo calculado para la duración del circuito auricular fue menor que el valor mínimo aceptado para el período refractario efectivo auricular. Los resultados descartan la posibilidad del circuito único como mecanismo de la fibrilación, pero no permiten establecer si ésta es debida a circuitos múltiples variables o a la formación de ondas fraccionarias

Intoxicación por animales marinos / Sea animals intoxications

Describe las diferentes formas de intoxicación por animales marinos-contaminación, degradación y contenido tóxico-; distingue tres tipos de intoxicación, por enterotoxina estafilococica, por peces escombroides y por contenido tóxico; identifica los inhibidores y activadores químicos de los canales de sodio, y aborda la ciguatera y el envenenamiento por tortugas marinas presentando características clínicas y tratamiento

Síndrome de preexcitación: incidencia en el Hospital Dr. Salvador B. Gautier / Pre-stimulus syndrome: occurrence in Hospital Dr. Salvador B. Gautier

Se reportan 15 trazados, electrocardiográficos con síndrome de preexcitación en un estudio de 1,000 pacientes