Dual Stent Application on Congenital Tracheobronchial Stenosis / 대한흉부외과학회지

We report successful application of dual tracheobronchial stent to the diffuse tracheal stenosis. An one-month-old boy was transferred to the emergency room due to tachypnea and respiratory difficulty with CO2 retention. Preoperative computed tomography revealed pulmonary artery sling with diffuse tracheal stenosis. We found that the diameter of the both main bronchus was less than 3mm and the trachea was a complete ring. We divided the left pulmonary artery and implanted it to the main pulmonary artery under cardiopulmonary bypass. After that, tracheoplasty was performed with autologous pericardium. However, after the initial measures, CO2 retention and respiratory difficulty persisted due to the granulation tissue and dynamic obstruction of the airway ensued by the overlying pericardial flap. Therefore, we decided to apply a single tracheal stent. After the insertion of tracheal stent, residual stenosis of the both main bronchus opening continued to cause respiratory difficulty. Finally we applied dual tracheobronchial stent and resolved the airway obstruction.

A Biomechanical Analysis of Surgical Procedures for Osteonecrosis of the Femoral Head using Three-Dimensional Finite Element Method: A Parametrical Analysis by Varying Physiological Loading Conditions / 대한정형외과연구학회지

Many operative procedures for osteonecrosis of the femoral head(ONFH) have been proposed, but their clinical results remain controversial to many clinicians. Recently, a new surgical procedure that incorporates cementation with polymethylmethacrylate(PMMA) after core drilling has been tried clinically. In this study, a finite element method (FEM) was employed to analyze and compare various surgical procedures of ONFH to provide a biomechanical insight by varying physiological loading conditions. Our finite element models were constructed for this purpose they included normal, necrotic, core decompressed, fibular bone grafted, and cementation models. The extent of necrotic region was determined based upon the average CT-scan data from 10 patients. The physiological load directions and magnitudes during the gait cycle were selected at the stage of heel-strike, toe-off, and average stance. The von Mises stresses were calculated and volumetric percentages of the necrotic region under different levels of stresses were analyzed for each model. Our results indicated that there were substantial increase of the necrotic region subjected to the high stress level (beyond 11 MPa) and decrease in the low stress level (below 5 MPa) with the core decompression model, an indication of a malignant stress transfer pattern. On the other hand, the exact opposite pattern of stress transfer was noted with the fibular bone graft and cementation methods suggesting that they could provide structural integrity within the necrotic region.