Triple-Plane Dissection of Combined Forehead and Scalp Flaps for Large Posttraumatic Forehead Defects

Introduction Reconstruction of large (>20 cm2) posttraumatic forehead defects, with esthetically pleasing results and without distorting the surrounding anatomical landmarks like eyebrow and hairline, is a significant surgical challenge. This study was aimed to determine the effectiveness of a triple-plane dissection technique of significantly-sized flaps, combining forehead, and scalp to cover large forehead defects. Materials and Methods A retrospective review from January 2009 to December 2019 revealed that 12 patients with large defects over the forehead were operated on. Significantly-sized rotation and advancement flaps, combining both the forehead and scalp tissues, were performed. Triple-plane dissection and careful galeal scoring recruited more tissues and increased the reach of these flaps while maintaining adequate flap vascularity. Results Large forehead posttraumatic defects in all 12 patients were covered in a single surgery with this combined flap. Eight patients were men and four were women (mean age, 58 years). Size of the defects ranged from 21 to 40 cm2 (mean, 27 cm2). Complications included deep marginal necrosis in one patient (8%), superficial necrosis in one patient (8%), and mild venous stasis in four patients (33%). Superficial necrosis and venous stasis resolved by itself. Good color and contour match, minimal alopecia, maintained positions of eyebrow, and hairline positions were found in most patients. Six months postoperatively, patient satisfaction measured on a visual analogue scale ranged between 3 and 9 out of 10 (mean, 7). Conclusion Primary forehead reconstruction with significant-sized flaps combining forehead and scalp tissues, with triple-plane dissection and galeal scoring, appears to be an effective option for covering large forehead defects.

FREE VIBRATION ANALYSIS OF TRIPLY COUPLED PRE-TWISTED ROTOR BLADES BY THE DIFFERENTIAL QUADRATURE METHOD

Key parameters on the dynamic characteristics of triply coupled pretwisted rotor blades are investigated. The issues of concern include the combined flap-wise bending, chord-wise bending, and torsion vibrations of the pretwisted rotor blade, considering the centrifugal force and Coriolis effects. The governing differential equations of motion presented by Houbolt and Brooks for the rotor blade are used as the basis of study, which contain many factors previously ignored. The differential quadrature method is adopted as the method of solution for its ease in implementation, accuracy, and fast convergence. The dynamic responses of the rotor blade are obtained for different cases of coupling and geometries, which agree well with existing results. The dynamic responses of the rotor blades are plotted against parameters such as angular velocity, pretwisting angle, and hub radius in proper curves and discussed in details.