Opening gap width influences distal tibial rotation below the osteotomy site following open wedge high tibial osteotomy.

PURPOSE: Although rotation of the distal portion of the tibia below the osteotomy site is considered an inevitable change in the axial plane in open wedge high tibial osteotomy (HTO), several studies on this issue have shown contradictory results. The purpose of this study was, therefore, to determine the direction and amount of distal tibial rotation following open wedge HTO using a three-dimensional reconstructed model. METHODS: This study involved 41 patients (42 knees) undergoing open wedge HTO for primary medial osteoarthritis. Distal tibial rotation was measured on the overlaid tibial plateau of a preoperative and postoperative 3-dimensional reconstructed model based on computed tomography. RESULTS: The mean distal tibial external rotation was 2.7° ± 2.3° (range, -0.9° to 9.9°), and the opening gap was larger in the group with > 3° distal tibial rotation than in the group with ≤ 3° distal tibial rotation (11.4 mm vs. 9.6 mm, P = 0.027). Multiple regression analysis showed that the opening gap was the only predictor of distal tibial rotation. On receiver operating characteristics analysis, an opening gap of 10 mm was found to be the optimal cutoff value for achieving greater than 3° of distal tibial rotation. CONCLUSIONS: Following medial opening wedge HTO, the distal tibial portion below the osteotomy site rotated approximately 3° externally. The magnitude of the external rotation of the distal tibia was affected by the opening gap width.

Photochemical Reduction of Silver Precursor and Elastomer Composite for Flexible and Conductive Patterning.

The development of ink-based printing techniques has enabled the fabrication of electric circuits on flexible substrates. Previous studies have shown that the process method which uses a silver (Ag) precursor (AgCF3COO) and electrospun poly(styrene-block-butadiene-block-styrene) (SBS) can yield patterns with high conductivity and stretchability. However, the only method to reduce the Ag precursor absorbed in SBS is chemical reduction using a toxic solution. Here, we developed a process to fabricate a high-conductivity pattern via laser reduction by photo-chemical reaction without toxic solutions. The Ag precursor was absorbed in electrospun SBS to form a composite layer (composite SBS) with modified properties, that could more effectively absorb the photon energy than SBS without the Ag precursor. We analyzed the properties of this material, such as its light absorption coefficient, heat conductivity, and the density of both SBS and composite SBS to allow comparison of the two materials by numerical simulation. In addition, we fabricated patterns on highly heat-sensitive substrates such as burning paper and a polyethylene terephthalate (PET) thin film, as the pattern can be implemented using very low laser energy. We expect the proposed approach to become a key technology for implementing user-designed circuits for wearable sensors and devices on various flexible substrates.

Location of the femoral tunnel aperture during single-bundle posterior cruciate ligament reconstruction: outside-in versus inside-out techniques.

PURPOSE: Placement of the femoral tunnel is critical to graft function after posterior cruciate ligament (PCL) reconstruction. To date, however, the location of the femoral tunnel aperture has not been compared by in vivo 3-dimensional computed tomography (3D-CT) during PCL reconstruction with the outside-in (OI) and inside-out (IO) techniques. This study used 3D-CT analysis to compare the location of the femoral tunnel aperture in patients who underwent PCL reconstruction with the OI and IO techniques. METHODS: A total of 77 patients underwent single-bundle PCL reconstruction using the OI (n = 46) or IO (n = 31) technique. The location of the femoral tunnel aperture was assessed by 3D-CT and measured by the anatomic coordinate axis method to construct 3D surface models. RESULTS: The mean location of the femoral tunnel aperture in the low-to-high direction did not differ significantly in the OI and IO groups (75.0 vs. 75.2%, P = 0.869). However, in the deep-to-shallow direction, the femoral tunnel aperture was positioned more shallowly in the IO than in the OI group (75.7 vs. 81.1%, P < 0.001). CONCLUSION: The IO technique of single-bundle PCL reconstruction yielded a shallower femoral tunnel in the deep-to-shallow direction than did the OI technique. However, femoral tunnel location in the low-to-high direction was similar using the two techniques.

Ridge Minimization of Ablated Morphologies on ITO Thin Films Using Squared Quasi-Flat Top Beam.

In this study, we explore the improvements in pattern quality that was obtained with a femtosecond laser with quasi-flat top beam profiles at the ablated edge of indium tin oxide (ITO) thin films for the patterning of optoelectronic devices. To ablate the ITO thin films, a femtosecond laser is used that has a wavelength and pulse duration of 1030 nm and 190 fs, respectively. The squared quasi-flat top beam is obtained from a circular Gaussian beam using slits with varying x-y axes. Then, the patterned ITO thin films are measured using both scanning electron and atomic force microscopes. In the case of the Gaussian beam, the ridge height and width are approximately 39 nm and 1.1 µm, respectively, whereas, when the quasi-flat top beam is used, the ridge height and width are approximately 7 nm and 0.25 µm, respectively.

Fully Solution-Processable Fabrication of Multi-Layered Circuits on a Flexible Substrate Using Laser Processing.

The development of printing technologies has enabled the realization of electric circuit fabrication on a flexible substrate. However, the current technique remains restricted to single-layer patterning. In this paper, we demonstrate a fully solution-processable patterning approach for multi-layer circuits using a combined method of laser sintering and ablation. Selective laser sintering of silver (Ag) nanoparticle-based ink is applied to make conductive patterns on a heat-sensitive substrate and insulating layer. The laser beam path and irradiation fluence are controlled to create circuit patterns for flexible electronics. Microvia drilling using femtosecond laser through the polyvinylphenol-film insulating layer by laser ablation, as well as sequential coating of Ag ink and laser sintering, achieves an interlayer interconnection between multi-layer circuits. The dimension of microvia is determined by a sophisticated adjustment of the laser focal position and intensity. Based on these methods, a flexible electronic circuit with chip-size-package light-emitting diodes was successfully fabricated and demonstrated to have functional operations.

Vibration-Assisted Femtosecond Laser Drilling with Controllable Taper Angles for AMOLED Fine Metal Mask Fabrication.

This study investigates the effect of focal plane variation using vibration in a femtosecond laser hole drilling process on Invar alloy fabrication quality for the production of fine metal masks (FMMs). FMMs are used in the red, green, blue (RGB) evaporation process in Active Matrix Organic Light-Emitting Diode (AMOLED) manufacturing. The taper angle of the hole is adjusted by attaching the objective lens to a micro-vibrator and continuously changing the focal plane position. Eight laser pulses were used to examine how the hole characteristics vary with the first focal plane's position, where the first pulse is focused at an initial position and the focal planes of subsequent pulses move downward. The results showed that the hole taper angle can be controlled by varying the amplitude of the continuously operating vibrator during femtosecond laser hole machining. The taper angles were changed between 31.8° and 43.9° by adjusting the vibrator amplitude at a frequency of 100 Hz. Femtosecond laser hole drilling with controllable taper angles is expected to be used in the precision micro-machining of various smart devices.