Regional hemodynamics in patients with femoral shaft nonunions treated with combined external fixation and intramedullary nail

Objective The purpose of the study was to explore peripheral hemodynamics in patients with femoral shaft nonunions treated with combined external fixation and intramedullary nail. Material and methods Two groups of patients were identified. Group I included 11 patients with a deformity at the apex of nonunion treated with consecutive combined osteosynthesis. Group II consisted of 15 patients with nonunions and femoral shortening treated with synchronous combined distraction-compression osteosynthesis. Methods of examination comprised duplex ultrasound of veins and paraosseous vessels at the regeneration site (HITACHI HI Vision Avius), USDG (ANGIO-PLUS, Moscow) and tetrapolar rheovasography (RVG) of lower limbs (Rheograph RGPA-6/12, Taganrog). Results and discussion Volumetric blood flow of the femur and tibia measured postoperatively with RVG showed no differences in the intact and operated limb whatever technique was applied. In all patients, major blood flow was recorded at stages of combined fixation and Ilizarov fixation, linear systolic velocity and pulsatility index were not significantly different from normal and intact limb values, hemodynamic criteria of vasoconstriction of major vessels were not identified. The steal syndrome of distal segments due to functional bypass was observed in patients with unstable metal constructs and did not aggravate after surgical treatment in Group I. Duplex ultrasound scan of the femoral shaft cortical bone showed expressed arterial and venous color map in all patients with high peripheral indices reflecting vascular tone and measuring PI = 12 ± 3.5; RI = 0.9 ± 0.1. Conclusion No significant hemodynamic changes were detected in major arteries during treatment of patients with femoral nonunions using combined techniques of external fixation and intramedullary nail. Vasodilatation of veins recorded during treatment of patients with femoral nonunions using combined techniques of external fixation and intramedullary nail was determined as a risk factor for venous thromboembolism. A local increase in the arterial and venous paraosseous blood flow was recorded at the cortical site of nonunion with combined intramedullary osteosynthesis

Magellan/M2FS Spectroscopy of Tucana 2 and Grus 1

We present results from spectroscopic observations with the Michigan/Magellan Fiber System (M2FS) of $147$ stellar targets along the line of sight to the newly-discovered `ultrafaint' stellar systems Tucana 2 (Tuc 2) and Grus 1 (Gru 1). Based on simultaneous estimates of line-of-sight velocity and stellar-atmospheric parameters, we identify 8 and 7 stars as probable members of Tuc 2 and and Gru 1, respectively. Our sample for Tuc 2 is sufficient to resolve an internal velocity dispersion of $8.6_{-2.7}^{+4.4}$ km s$^{-1}$ about a mean of $-129.1_{-3.5}^{+3.5}$ km s$^{-1}$ (solar rest frame), and to estimate a mean metallicity of [Fe/H]= $-2.23_{-0.12}^{+0.18}$. These results place Tuc 2 on chemodynamical scaling relations followed by dwarf galaxies, suggesting a dominant dark matter component with dynamical mass $2.7_{-1.3}^{+3.1}\times 10^6$ $\mathrm{M}_{\odot}$ enclosed within the central $\sim 160$ pc, and dynamical mass-to-light ratio $1900_{-900}^{+2200}$ $\mathrm{M}_{\odot}/L_{V,\odot}$. For Gru 1 we estimate a mean velocity of $-140.5_{-1.6}^{+2.4}$ km s$^{-1}$ and a mean metallicity of [Fe/H]=$-1.42_{-0.42}^{+0.55}$, but our sample does not resolve Gru 1's velocity dispersion. The radial coordinates of Tuc 2 and Gru 1 in Galactic phase space suggest that their orbits are among the most energetic within distance $\leq 300$ kpc. Moreover, their proximity to each other in this space arises naturally if both objects are trailing the Large Magellanic Cloud.Comment: replaced with ApJ-accepted version, all spectra and data products (including samples from posterior PDFs) are available at http://www.andrew.cmu.edu/user/mgwalker/tuc2gru1_dataproducts.tar.g