Postoperative scaphoid alignment, smoking, and avascular necrosis mostly influence union rate after scaphoid reconstruction: Results from a retrospective single center study involving 370 patients.

Current literature does not definitely demonstrate the superiority of any particular scaphoid reconstruction method. The primary goal of this retrospective single center study was to evaluate the influence of reconstruction techniques and other factors on the union rate after reconstruction of scaphoid nonunions. In the study, 370 patients with nonunions classified as stable (Mayo 1) or unstable (Mayo 2) depending on carpal alignment were included. Minimal radiological follow-up was 3 months. Bone healing after scaphoid reconstruction was evaluated using computer tomography scans in 294 and radiograms in 76 patients. Univariate and multivariate logistic regressions were applied in the analysis. Eight statistically significant factors that influenced the union rate were fixation method, type of previous operations, number of all operations, number of reconstructions, smoking, postoperative pathological lateral intrascaphoid angle (LISA>45°), avascular necrosis (AVN), and stability of nonunion. Smoking and postoperative LISA>45° significantly reduced the probability of bone fusion by approximately 4.4 and 9.5 times, respectively. Patients with reduced vascularity in the nonunion site had a 5.2 times lower chance of bone fusion. Our multivariate logistic regression model can explain 32% of failures after scaphoid reconstruction, including postoperative LISA>45°, patients' present record of smoking, and reduced vascularity in the nonunion site. However, bone graft type does not impact the union rate in general; however, in case of AVN, the tendency toward higher union rates was observed for medial femoral condyle free flaps when compared to other types of graft (non-vascularized and pedicled bone grafts considered as one group, p = 0.09).

Electron theory of fast and ultrafast dissipative magnetization dynamics.

For metallic magnets we review the experimental and electron-theoretical investigations of fast magnetization dynamics (on a timescale of ns to 100 ps) and of laser-pulse-induced ultrafast dynamics (few hundred fs). It is argued that for both situations the dominant contributions to the dissipative part of the dynamics arise from the excitation of electron-hole pairs and from the subsequent relaxation of these pairs by spin-dependent scattering processes, which transfer angular momentum to the lattice. By effective field theories (generalized breathing and bubbling Fermi-surface models) it is shown that the Gilbert equation of motion, which is often used to describe the fast dissipative magnetization dynamics, must be extended in several aspects. The basic assumptions of the Elliott-Yafet theory, which is often used to describe the ultrafast spin relaxation after laser-pulse irradiation, are discussed very critically. However, it is shown that for Ni this theory probably yields a value for the spin-relaxation time T(1) in good agreement with the experimental value. A relation between the quantity α characterizing the damping of the fast dynamics in simple situations and the time T(1) is derived.