Long-term Comparison of Retrograde and Antegrade Femoral Nailing.

Antegrade or retrograde nailing for femoral shaft fractures remains the gold standard, but long-term data on functional outcomes after intramedullary nailing are lacking. In a retrospective review of prospectively collected patient registry data, patients with an isolated femoral shaft fracture treated with antegrade or retrograde femoral nailing from 1997 to 2012 were interviewed and their medical records analyzed. Functional reported outcome data were obtained via the visual analog scale (VAS) for pain and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) at 5 to 17 years postoperatively. Antegrade and retrograde intramedullary nailing of diaphyseal femur shaft fractures demonstrated a mean WOMAC of 23.5%±23.6% (range, 0%-82.3%) and 29.7%±24.0% (range, 0%-88%), respectively (P=.23). The mean VAS scores of the antegrade vs retrograde intramedullary nailing groups were 2.5±2.6 (range, 0-8) and 3.4±2.8 (range, 0-10), respectively (P=.11). Location of pain differed between groups as well, with the antegrade group noting an increased rate of hip pain (25.6% vs 7.0%, P=.01), but a nonsignificant difference in the rate of thigh pain (27.9% vs 15.5%, P=.15) and knee pain (18.6% vs 26.7%, P=.49) as compared with the retrograde group. Diaphyseal femur fractures are successfully treated with either antegrade or retrograde intramedullary nails without significantly differing long-term functional outcomes, which correlates with other reported findings in the literature at short-term follow-up. [Orthopedics. 2020;43(4):e278-e282.].

Ankle Arthrodesis With Structural Grafts Can Work for the Salvage of Failed Total Ankle Arthroplasty.

Background. Treatment options after failed total ankle arthroplasty (TAA) are limited. This study reports midterm outcomes and radiographic results in a single-surgeon group of patients who have undergone ankle arthrodesis with intramedullary nail fixation and structural allograft augmentation following failed TAA. Methods. A retrospective review on patients who underwent failed TAA revision with structural femoral head allograft and intramedullary tibiotalocalcaneal (TTC) nail fixation was completed. Foot Function Index (FFI), American Orthopaedic Foot & Ankle Society (AOFAS) outcome scores, and radiographs were obtained at each visit with 5-year follow-up. Results. Five patients were followed to an average of 5.2 years (range 4.7-5.6). Enrollment FFI was 34.82 (range 8.82-75.88); at midterm follow-up it was 20.42 (range 0-35.38). Enrollment AOFAS scores averaged 66.6 (range 61-77); at midterm follow-up it was 70.33 (range 54-88). Radiographs showed union in 4 of 5 patients at enrollment and 2 of 3 patients at midterm. Conclusions. Utilization of TTC fusion with femoral head allograft is a salvage technique that can produce a functional limb salvage. Our results show continued improvement in patient-reported outcomes, with preservation of limb length and reasonable union rate. Levels of Evidence: Therapeutic, Level II: Prospective, comparative trial.

Minimally Invasive Retrograde Method of Harvesting the Flexor Hallucis Longus Tendon: A Cadaveric Study.

BACKGROUND: Use of the flexor hallucis longus (FHL) tendon is well described for several tendon augmentation procedures. Harvesting the FHL through an open medial approach is commonly done, but is associated with anatomic risks. Recently, several authors have described a minimally invasive (MI) technique to harvest the FHL tendon utilizing a hamstring tendon stripper commonly used in ACL reconstruction. The purpose of this study was to evaluate the safety and effectiveness of harvesting the FHL tendon using this novel minimally invasive retrograde approach. METHODS: The FHL tendon was harvested through a transverse plantar incision over the interphalangeal joint of the great toe in 10 fresh-frozen cadaver lower extremities. A lateral-based incision for peroneal tendon repair was made and the FHL was retrieved. Tendon length, complications, and interconnections between the FHL and flexor digitorum longus (FDL) were recorded and classified. The specimens were then dissected by a single surgeon in a standardized fashion, and damage to any surrounding structures was recorded. RESULTS: The average length of the FHL tendon from the distal stump to the first intertendinous connection was 13.3 cm (range 8.8-16 cm, SD 2.3 cm). Eight cadavers demonstrated Plaass type 1 interconnections whereas 2 demonstrated type 3. There was no injury to the medial and lateral plantar arteries and nerves, plantar plate, or FDL tendons. One FHL tendon was amputated at the level of the sustentaculum during graft harvest. No injury of the medial neurovascular structures occurred with retrieval of the FHL tendon through the lateral incision. CONCLUSIONS: We found that care must be taken when approaching the sustentaculum with the tendon harvester in order to avoid amputation of the graft against a hard bony endpoint. Additionally, flexion and extension of the lesser toes could aid in successful tendon harvest when tendon interconnections were encountered. CLINICAL RELEVANCE: Using this MI technique appears to be a safe and effective way to obtain a long FHL tendon graft for tissue augmentation.

Trap-free transport in ordered and disordered TiO2 nanostructures.

Understanding the influence of different film structures on electron diffusion in nanoporous metal oxide films has been challenging. Because of the rate-limiting role that traps play in controlling the transport properties, the structural effects of different film architectures are largely obscured or reduced. We describe a general approach to probe the impact of structural order and disorder on the charge-carrier dynamics without the interference of transport-limiting traps. As an illustration of this approach, we explore the consequences of trap-free diffusion in vertically aligned nanotube structures and random nanoparticle networks in sensitized titanium dioxide solar cells. Values of the electron diffusion coefficients in the nanotubes approached those observed for the single crystal and were up to 2 orders of magnitude greater than those measured for nanoparticle films with various average crystallites sizes. Transport measurements together with modeling show that electron scattering at grain boundaries in particle networks limits trap-free diffusion. In presence of traps, transport was 10(3)-10(5) times slower in nanoparticle films than in the single crystal. Understanding the link between structure and carrier dynamics is important for systematically altering and eventually controlling the electronic properties of nanoscaled materials.

Perturbation of the electron transport mechanism by proton intercalation in nanoporous TiO2 films.

This study addresses a long-standing controversy about the electron-transport mechanism in porous metal oxide semiconductor films that are commonly used in dye-sensitized solar cells and related systems. We investigated, by temperature-dependent time-of-flight measurements, the influence of proton intercalation on the electron-transport properties of nanoporous TiO(2) films exposed to an ethanol electrolyte containing different percentages of water (0-10%). These measurements revealed that increasing the water content in the electrolyte led to increased proton intercalation into the TiO(2) films, slower transport, and a dramatic change in the dependence of the thermal activation energy (E(a)) of the electron diffusion coefficient on the photogenerated electron density in the films. Random walk simulations based on a microscopic model incorporating exponential conduction band tail (CBT) trap states combined with a proton-induced shallow trap level with a long residence time accounted for the observed effects of proton intercalation on E(a). Application of this model to the experimental results explains the conditions under which E(a) dependence on the photoelectron density is consistent with multiple trapping in exponential CBT states and under which it appears at variance with this model.

General strategy for fabricating transparent TiO2 nanotube arrays for dye-sensitized photoelectrodes: illumination geometry and transport properties.

We report on the preparation of transparent oriented titania nanotube (NT) photoelectrodes and the effect of illumination direction on light harvesting, electron transport, and recombination in dye-sensitized solar cells (DSSCs) incorporating these electrodes. High solar conversion efficiency requires that the incident light enters the cell from the photoelectrode side. However, it has been synthetically challenging to prepare transparent TiO(2) NT electrodes by directly anodizing Ti metal films on transparent conducting oxide (TCO) substrates because of the difficulties of controlling the synthetic conditions. We describe a general synthetic strategy for fabricating transparent TiO(2) NT films on TCO substrates. With the aid of a conducting Nb-doped TiO(2) (NTO) layer between the Ti film and TCO substrate, the Ti film was anodized completely without degrading the TCO. The NTO layer was found to protect the TCO from degradation through a self-terminating mechanism by arresting the electric field-assisted dissolution process at the NT-NTO interface. The illumination direction and wavelength of the light incident on the DSSCs were shown to strongly influence the incident photon-to-current conversion efficiency, light-harvesting, and charge-collection properties, which, in turn, affect the photocurrent density, photovoltage, and solar energy conversion efficiency. Effects of NT film thickness on the properties and performance of DSSCs were also examined. Illuminating the cell from the photoelectrode substantially increased the conversion efficiency compared with illuminating it from the counter-electrode side.