Comparison of ultrasound and dorsal tangential view for dorsal cortex screw penetration in volar plating of the distal radius.

We compared the accuracy of the fluoroscopic dorsal tangential view (DTV) and an ultrasound (US) examination in detecting dorsal screw penetration during volar distal radius plating. In six fresh cadaveric distal radii, seven periarticular locking screws in two rows for each plate were inserted according to the measured length using a depth gauge and then replaced with another that was 1 and 2 mm longer, respectively. The actual protruded length of each screw was determined using computed tomography (CT) images. The accuracy of US and DTV measurements was determined using the intraclass correlation coefficient (ICC), as both measurements were compared with CT measurements. The ICC of US and DTV was 0.96 and 0.75, respectively, for all screws. After excluding the data for proximal-row screws, the ICC of US remained unchanged at 0.96, and that of DTV improved to 0.86. The ICC of US was significantly higher than that of DTV (p < 0.01). US had a 100% detection rate for screw protrusion of more than 1.0 mm. US examination showed excellent consistency with CT measurements and its accuracy was not affected by screw location. US might thus be a practical tool for detecting dorsal cortex screw penetration during volar distal radius plating.

Isolated and early-onset cerebral fat embolism syndrome in a multiply injured patient: a rare case.

BACKGROUND: Fat embolism syndrome (FES) is a rare complication that can occur between 12 and 72 h after the initial insult. Isolated cerebral FES without pulmonary symptoms is rarer. Early fracture fixation might prevent FES. We report a case of multiple-fracture with FES despite definite fixation three hours post-injury. CASE PRESENTATION: A 54-year-old man presented with multiple fractures: left femoral shaft (AO B2), left distal radius (AO C3), left comminuted patella, right comminuted 1st metatarsal base and left 2nd-4th metatarsal neck. Because he was stable, we gave him early total care and definite fixation, which required seven hours and yielded no complications. After he recovered from anesthesia, however, his eyes deviated right, his right upper arm was paralyzed, his consciousness level was poor, and his Glasgow Coma Scale score was E3VeM4. Chest X-rays showed clear lung fields, and brain computed tomography showed no intracranial hemorrhage. He did, however, have tachycardia, anemia, and thrombocytopenia. Brain magnetic resonance images showed a hyperintensive starfield pattern on diffuse weighted images, which suggested cerebral FES. After supportive care, his consciousness cleared on postoperative day 17, and he recovered full right upper arm muscle power after four months; however, he had a significant cognitive deficit. One-year post-injury, after regular rehabilitation therapy, he was able to independently perform his activities of daily living but still had a residual mild cognitive deficit. CONCLUSION: Early fixation can attenuate but not eliminate the incidence of FES. Early assessment and rehabilitation therapy might be required for patients with cerebral FES and cognitive deficits; however, such deficits are difficult to predict and need long-term follow-ups.

Clinical outcomes in distal radial fractures with ipsilateral arteriovenous fistulas.

BACKGROUND: We evaluated the effects on arteriovenous fistula (AVF) function and clinical outcomes in patients given cast fixation, external skeletal fixation [ESF], or volar locking plate fixation [VLPF] for an ipsilateral distal radial fracture (DRF). METHODS: Thirteen patients were assigned to the surgery group or the cast group; follow-up was ≥12 months. One-year clinical outcomes and serial AVF function and radiographic outcomes were recorded and analyzed. RESULTS: All fractures were union and all AVFs were preserved with continuous hemodialysis. The surgery group had better immediately (radial inclination and articular step-off) and 1-year post-index procedure radiographic findings (radial height, radial inclination, volar tilting, ulnar variance, and articular step-off) and better 1-year functional outcomes (Mayo and QuickDASH score) than did the cast group. The VLPF subgroup had better QuickDASH scores and radiographic outcomes (radial inclination and ulnar variance) than did the ESF subgroup. CONCLUSIONS: One year after the index procedure, none of the treatment affected shunt function in DRFs ipsilateral to AVFs. ESF and VLPF yielded better functional and radiographic outcomes than did cast fixation in patients with ipsilateral DRFs and AVFs. LEVEL OF EVIDENCE: III.

Superior biomechanical properties and tying time with the modified Prusik knot and Wittstein suture loop to the Krackow stitch.

INTRODUCTION: The purposes of the study were to compare (1) the biomechanical properties of the modified Prusik knot, Wittstein suture loop, and Krackow stitch fixation, and (2) the knot tying times for tendon graft fixation among the Krackow stitch, modified rolling hitch, modified Prusik knot, and Wittstein suture loop. MATERIALS AND METHODS: First, 33 fresh-frozen porcine flexor profundus tendons were randomly divided into three groups of 11 specimens. The experimental procedure was designed to assess elongation of the suture-tendon construct across the modified Prusik knot, Wittstein suture loop, and the Krackow stitch. Multistranded nonabsorbable sutures were used. Each specimen was pre-tensioned to 100 N for three cycles, cyclically loaded to 200 N for 200 cycles, and finally loaded to failure. Elongation, load to failure, and failure mode of each specimen were recorded. Second, the knot tying times for modified rolling hitch, modified Prusik knot, Wittstein suture loop, and Krackow stitch were investigated. The measurements were taken on three different occasions to account for intraobserver repeatability and interobserver reproducibility. RESULTS: The elongation after cyclic loading of the modified Prusik knot (22 ± 6%), Wittstein suture loop (25 ± 2%) were significantly smaller than the Krackow stitch (31 ± 5%) (p = 0.001 and 0.003, respectively). The failure loads of three groups were not significantly from one another. Meanwhile, the Krackow stitch group (80.9 ± 16.7 s) had significantly longer average procedure time than the modified rolling hitch group (9.2. ± 1.9 s) (p < 0.001), modified Prusik knot group (9.1 ± 1.8 s) (p < 0.001), and Wittstein suture loop group (9.0 ± 2.2 s) (p < 0.001). CONCLUSIONS: Compared to the Krackow stitch, the modified Prusik knot and Wittstein suture loop had less elongation after cyclic loading and similar ultimate load to failure in this porcine in vitro biomechanical study. Shorter knot tying times were required to complete the modified rolling hitch, modified Prusik knot, and Wittstein suture loop than the Krackow stitch.

Correction to: Superior biomechanical properties and tying time with the modified Prusik knot and Wittstein suture loop to the Krackow stitch.

Due to an error during the production process, the legend.

Quantum dot nano thermometers reveal heterogeneous local thermogenesis in living cells.

The local temperature response inside single living cells upon external chemical and physical stimuli was characterized using quantum dots as nano thermometers. The photoluminescence spectral shifts from endocytosed quantum dots were used to map intracellular heat generation in NIH/3T3 cells following Ca(2+) stress and cold shock. The direct observation of inhomogeneous intracellular temperature progression raises interesting new possibilities, including further innovations in nanomaterials for sensing local responses, as well as the concept of subcellular temperature gradient for signaling and regulation in cells.

Dynamics of individual polymers using microfluidic based microcurvilinear flow.

Polymer dynamics play an important role in a diversity of fields including materials science, physics, biology and medicine. The spatiotemporal responses of individual molecules such as biopolymers have been critical to the development of new materials, the expanded understanding of cell structures including cytoskeletal dynamics, and DNA replication. The ability to probe single molecule dynamics however is often limited by the availability of small-scale technologies that can manipulate these systems to uncover highly intricate behaviors. Advances in micro- and nano-scale technologies have simultaneously provided us with valuable tools that can interface with these systems including methods such as microfluidics. Here, we report on the creation of micro-curvilinear flow through a small-scale fluidic approach, which we have been used to impose a flow-based high radial acceleration ( approximately 10(3) g) on individual flexible polymers. We were able to employ this microfluidic-based approach to adjust and control flow velocity and acceleration to observe real-time dynamics of fluorescently labeled lambda-phage DNA molecules in our device. This allowed us to impose mechanical stimulation including stretching and bending on single molecules in localized regimes through a simple and straightforward technology-based method. We found that the flexible DNA molecules exhibited multimodal responses including distinct conformations and controllable curvatures; these characteristics were directly related to both the elongation and bending dynamics dictated by their locations within the curvilinear flow. We analyzed the dynamics of these individual molecules to determine their elongation strain rates and curvatures ( approximately 0.09 microm(-1)) at different locations in this system to probe the individual polymer structural response. These results demonstrate our ability to create high radial acceleration flow and observe real-time dynamic responses applied directly to individual DNA molecules. This approach may also be useful for studying other biologically based polymers including additional nucleic acids, actin filaments, and microtubules and provide a platform to understand the material properties of flexible polymers at a small scale.

Spatiotemporal control of apical and basal living subcellular chemical environments through vertical phase separation.

Molecular distribution within living cells is organized through multiscaled compartmentalization that enables specialized processes to occur with high efficiency. The ability to control the chemical environment at a subcellular level is limited due to deficient positional control over the aqueous stimulant. Here, a multilayered microfluidic system built from polydimethylsiloxane to separate chemical stimulants over single living cells vertically through aqueous-phase separation under laminar flow is demonstrated. Cells are cultured on top of single micrometer-scale channels inside a larger channel, allowing labeling of the apical domain of single cells through the main channel with simultaneous and distinct labeling of the basal domain via the lower microchannels. The system is transparent, which allows the use of optical microscopy to investigate the spatiotemporal response of labeled components. By employing this technique, the examination of localized subcellular domain responses in polarization, lipid bilayer mobility, and apical-to-basal signal transduction can be explored.

Single quantum dots as local temperature markers.

This work describes noncontact, local temperature measurements using wavelength shifts of CdSe quantum dots (QDs). Individual QDs are demonstrated to be capable of sensing temperature variations and reporting temperature changes remotely through optical readout. Temperature profiles of a microheater under different input voltages are evaluated based on the spectral shift of QDs on the heater, and results are consistent with a one-dimensional electrothermal model. The theoretical resolution of this technique could go down to the size of a single quantum dot using far-field optics for temperature characterizations of micro/nanostructures.