Anterior ankle arthroscopy, distraction or dorsiflexion?

Anterior ankle arthroscopy can basically be performed by two different methods; the dorsiflexion- or distraction method. The objective of this study was to determine the size of the anterior working area for both the dorsiflexion and distraction method. The anterior working area is anteriorly limited by the overlying anatomy which includes the neurovascular bundle. We hypothesize that in ankle dorsiflexion the anterior neurovascular bundle will move away anteriorly from the ankle joint, whereas in ankle distraction the anterior neurovascular bundle is pulled tight towards the joint, thereby decreasing the safe anterior working area. Six fresh frozen ankle specimens, amputated above the knee, were scanned with computed tomography. Prior to scanning the anterior tibial artery was injected with contrast fluid and subsequently each ankle was scanned both in ankle dorsiflexion and in distraction. A special device was developed to reproducibly obtain ankle dorsiflexion and distraction in the computed tomography scanner. The distance between the anterior border of the inferior tibial articular facet and the posterior border of the anterior tibial artery was measured. The median distance from the anterior border of the inferior tibial articular facet to the posterior border of the anterior tibial artery in ankle dorsiflexion and distraction was 0.9 cm (range 0.7–1.5) and 0.7 cm (range 0.5–0.8), respectively. The distance in ankle dorsiflexion significantly exceeded the distance in ankle distraction (P = 0.03). The current study shows a significantly increased distance between the anterior distal tibia and the overlying anterior neurovascular bundle with the ankle in a slightly dorsiflexed position as compared to the distracted ankle position. We thereby conclude that the distracted ankle position puts the neurovascular structures more at risk for iatrogenic damage when performing anterior ankle arthroscopy

Metal-to-Ligand Charge Transfer (MLCT) Photochemistry of fac-Mn(Cl)(CO)3(H-DAB): A Density Functional Study

The title compound has low-energy Mn−3d to 1,4-diaza-1,3-butadiene (H-DAB) π* metal-to-ligand charge transfer (MLCT) excited states, which are not, by their electronic nature, Mn−CO dissociative. Their potential energy curves (PEC) exhibit Mn−COeq and Mn−COax bonding minima around Re. Loss of an equatorial CO ligand upon MLCT excitation is explained by a radiationless transition from the MLCT states to the dissociative continuum of the electronic ground state. According to the calculated PEC of the ground state, the complex will undergo a strong structural rearrangement upon equatorial CO dissociation, during which the chloride shifts to the equatorial open site. This rearrangement explains the experimentally found formation of mer-Mn(Cl)(CO)3(α-diimine) complexes upon back-reaction of their CO-loss product with CO. This mechanism of equatorial CO dissociation is very different from the usual photochemical dissociation directly from a dissociative ligand-field state or through crossing of the photoactive excited state by such a ligand-field state. In contrast, axial CO dissociation, which does not occur readily, does not give rise to structural rearrangement and is predicted to produce the fac complex upon back-reaction with CO