Background: Recognition that total laminectomy may perpetuate or cause segmental instability heralded the introduction of less invasive techniques of decompression in lumbar spinal stenosis surgery. Aim : It was our aim to compare formal laminectomy and minimally invasive decompressive procedures in terms of safety and clinical outcome, specifically in respect to the development of postoperative spinal instability. Methods: A retrospective analysis of medical records for 73 patients operated on for lumbar spinal stenosis (22 patients after laminectomy and 51 patients after minimally invasive decompression), with available follow-up data was performed. Basic variables were analyzed in respect to clinical outcome and in regard to development of radiological instability. Results: Radiologic instability was present in 27,3% of patients after laminectomy, as compared to only 2,0% after laminotomy (p<0,001). Regression analysis identified presence of preoperative slip (p=0,0056) and type of surgery (p=0,0204) as sole predictors of instability after surgery. Clinical outcome analysis (laminectomy vs. laminotomy) revealed favorable outcome in both treatment groups, although significantly in favor of the laminotomy group (VAS p= 0,013 and RM p=0,031). Finally, difference in outcome was affected by weather radiologic instability was present or not (p=0,04 and p=0,09 for difference in outcome graded by VAS and RM values respectively) Conclusion: Our results suggest that laminectomy is associated with prohibitively high incidence of postoperative radiologic instability when compared to minimally invasive decompression techniques. Furthermore, radiological instability translates to worse clinical outcome. Finally, patients undergoing laminectomy experience less favorable clinical outcome when compared to those undergoing minimally invasive decompression surgeries.

O objetivo do estudo foi avaliar o efeito do enxerto osseo corticoesponjoso na osteogenese em falha cortical ulnar de galinhas domesticas. Foram utilizadas 18 galinhas, com aproximadamente 70 semanas de idade e peso corporeo medio de 2,5kg. Criou-se uma falha ossea na porcao diafisaria media da ulna em ambas as asas, sendo a direita utilizada como grupo-controle (grupo I) e a esquerda como grupo-tratado (grupo II). As aves foram subdivididas aleatoriamente em quatro subgrupos de acordo com o periodo de observacao (14, 35, 60 e 90 dias). No grupo II, dois fragmentos osseos da carena do esterno foram retirados, seccionados e implantados na falha ossea. Ao termino do periodo de observacao de cada subgrupo, as aves foram abatidas com tiopental sodico para realizacao dos exames histopatologico e radiografico post-mortem, com classificacao dos resultados em escala semiquantitativa (escore). O grupo II demonstrou osteogenese mais evidente aos 35 e 90 dias de pos-cirurgico (P<0,05). Ao comparar os grupos I e II, sem levar-se em consideracao o tempo de observacao, foi possivel observar que houve diferenca estatistica significativa (P<0,05). Conclui-se que o enxerto osseo corticoesponjoso demonstra potencial osteogenico satisfatorio na especie estudada, entretanto retarda o tempo de remodelacao ossea quando aplicado sobre falhas estaveis pequenas.

Due to its simplicity, the Becker-Kistiakowsky-Wilson (BKW) equation of state has been used in many thermochemical codes in the calculation of detonation properties. Much work has been done in the calibration of the BKW EOS parameters to achieve agreement with experimental detonation velocities and pressures thus resulting in many different sets of BKW constants (α, β, κ and θ) and covolumes of detonation products, with varying levels of accuracy over broad density limits, i.e. broad pressure limits. The covolumes of the product gases in BKW EOS may be regarded as measures of intermolecular interactions, and their values should affect the predicted detonation properties, particularly at higher explosives densities. This work aims to study the effect of covolumes on calculated values of detonation parameters. Several sets of covolumes available from literature and derived by different methods (matching experimental Hugoniots of individual products, by stochastic optimization, and calculated from van der Waals radii), were studied. In addition, the covolumes of the product gases were also calculated by ab initio methods. The effect of covolumes is studied comparing detonation properties calculated using different sets of covolumes, and experimental data for a series of standard CHNO explosives. It was found that it is possible to reproduce experimental detonation velocities and pressures within reasonable accuracy (root mean square error of less than 5 % for all tested sets) using different set of covolumes, and simultaneously optimizing constants in BKW EOS. However, different values of covolumes strongly affect the composition of detonation products at the Chapman-Jouguet state. It particularly applies to oxygen-deficient explosives and at higher densities, where formic acid appears to be an important detonation product.