PurposeTo evaluate the factors affecting the bone union time and the occurrence of nonunion after intramedullary nailing of subtrochanteric femoral fractures in adults.Materials and MethodsWe retrospectively reviewed data from 31 patients (22 men and 9 women) who had undergone femoral intramedullary nailing at least 1 year post-operatively and analyzed the bone union time, nonunion rates, and factors that affected the bone union time according to the fracture classification (AO and Fielding classifications), comminution of the medial cortex, reduction method, and additional cerclage wiring.ResultsThe average union time was 26.4 weeks. There were no differences in the bone union time according to the fracture classification, reduction method, or additional cerclage wiring. Significant differences were found in the bone union time between the medial cortex comminution and non-comminution groups. A relatively strong positive correlation was detected between the degree of post-operative displacement and the bone union time. Nonunion occurred in three cases and there was no failure of implants.ConclusionThe bone union time was not affected by the reduction method nor additional cerclage wiring in intramedullary nailing of subtrochanteric femur fractures. Comminution of the medial cortex and the degree of the postoperative displacement of fractures contributed to the delayed time of union.

Optical-resolution photoacoustic microscopy (OR-PAM) enables both high-resolution and high-contrast imaging of optical chromophores ranging from biological tissues to inorganic samples. The lateral spatial resolution of OR-PAM depends on its optical configuration and is primarily determined by the numerical aperture of the objective lens. This study demonstrates a novel, lens-free, shear-force photoacoustic microscopy system using a tapered fiber, serving as a proof-of-concept toward the implementation of super-resolution, near-field scanning photoacoustic microscopy. An uncoated tapered fiber is attached to a quartz tuning fork, thereby maintaining the near-field distance between the fiber and sample surface via a shear-force detection mechanism. Light-field simulation confirms an evanescent wave at the end of the uncoated, tapered fiber. Based on the photoacoustic simulation and 2D photoacoustic scanning experimental results, targets are imaged with high-lateral resolutions of the order of 1.0 ± 0.3 µm. These results demonstrate the existence of near-field photoacoustic signals and the potential for future development of super-resolution, near-field, scanning photoacoustic microscopy.

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