Treating Knee Osteoarthritis With Platelet-Rich Plasma and Hyaluronic Acid Combination Therapy: A Systematic Review.

BACKGROUND: Platelet-rich plasma (PRP) and hyaluronic acid (HA) are injectable treatments for knee osteoarthritis. The focus of previous studies has compared their efficacy against each other as monotherapy. However, a new trend of combining these 2 injections has emerged in an attempt to have a synergistic effect. PURPOSE: To systematically review the clinical literature examining the combined use of PRP + HA. DESIGN: Systematic review. METHODS: A systematic review was performed according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines using PubMed and Embase. The following search terms were used: knee osteoarthritis AND platelet rich plasma AND hyaluronic acid. The review was performed by 2 independent reviewers who applied the inclusion/exclusion criteria and independently extracted data, including methodologic scoring, PRP preparation technique, HA composition, and patient-reported outcomes (PROs). RESULTS: A total of 431 articles were screened, 12 reviewed in full, and 8 included in the final analysis: 2 case series, 3 comparative, and 3 randomized studies. Average follow-up was 9 months. The modified Coleman Methodology Score was 38.13 ± 13.1 (mean ± SD). Combination therapy resulted in improved PROs in all studies. Of the comparative and randomized studies, 2 demonstrated that combination therapy was superior to HA alone. However, when PRP alone was used as the control arm (4 studies), combination therapy was not superior to PRP alone. CONCLUSION: Combination therapy with PRP + HA improves PROs and is superior to HA alone but is not superior to PRP alone.

Maximized Hole Trapping in a Polystyrene Transistor Dielectric from a Highly Branched Iminobis(aminoarene) Side Chain.

We synthesized highly branched and electron-donating side chain subunits and attached them to polystyrene (PS) used as a dielectric layer in a pentacene field-effect transistor. The influence of these groups on dielectric function, charge retention, and threshold voltage shifts (ΔVth) depending on their positions in dielectric multilayers was determined. We compared the observations made on an N-perphenylated iminobisaniline side chain with those from the same side chains modified with ZnO nanoparticles and with an adduct formed from tetracyanoethylene (TCNE). We also synthesized an analogue in which six methoxy groups are present instead of two amine nitrogens. At 6 mol % side chain, hopping transport was sufficient to cause shorting of the gate, while at 2 mol %, charge trapping was observable as transistor threshold voltage shifts (ΔVth). We created three types of devices: with the substituted PS layer as single-layer dielectric, on top of a cross-linked PS layer but in contact with the pentacene (bilayers), and sandwiched between two PS layers in trilayers. Especially large bias stress effects and ΔVth, larger than those in the case of the hexamethoxy and previously studied dimethoxy analogues, were observed in the second case, and the effects increased with the increasing electron-donating properties of the modified side chains. The highest ΔVth was consistent with a majority of the side chains stabilizing the trapped charge. Trilayer devices showed decreased charge storage capability compared to previous work in which we used less donating side chains but in higher concentrations. The ZnO and TCNE modifications resulted in slightly more and less negative ΔVth, respectively, when the side chain polystyrene was not in contact with the pentacene and isolated from the gate electrode. The results indicate a likely maximum combination of molecular charge stabilizing activity and side chain concentration that still allows gate dielectric function.

Highly Contrasting Static Charging and Bias Stress Effects in Pentacene Transistors with Polystyrene Heterostructures Incorporating Oxidizable N,N'-Bis(4-methoxyphenyl)aniline Side Chains as Gate Dielectrics.

Charge storage and trapping properties of polymer dielectrics govern the charge densities of adjacent semiconductors and greatly influence the on-off switching voltage (threshold voltage, V t h ) of organic field-effect transistors (OFETs) when the polymers are used as gate insulators. Intentional charging of polymer dielectrics in OFETs can change V t h and affect the bias stress. We describe a chemical design and fabrication protocol to construct multilayer-stack dielectrics for pentacene-based OFETs using different polystyrene (PS)-based polymers in each layer, with oxidizable N,N-bis(4-methoxyphenyl)anilino (TPAOMe)-substituted styrene copolymers in arbitrary vertical positions in the stacks. Thermal, byproduct-free cross-linking of benzocyclobutene subunits provides integrity to the multilayer structure by preventing dissolution of the previous deposited layer. Neutron reflectivity data verified the multilayer morphology. We compared the V t h shift before and after charging the stacks by application of ±100 V across 0.5-1 µm total film thicknesses. Bias stress was the dominant effect in bilayer devices with a TPAOMe layer in contact with the pentacene, indicated by the direction of V t h shift associated with either polarity of external electric field. In structures with no TPAOMe subunit in contact with the pentacene, when charging with -100 V on top of the source and drain electrodes, electron injection from pentacene to dielectric was the major charging mechanism, again consistent with the bias stress direction. When charging with +100 V, bilayer devices without TPAOMe showed little change in V t h , suggesting there was no bias stress effect or charge injection in these devices for this charging polarity. For the bilayer devices with the TPAOMe layer in the bottom, and the trilayer devices with TPOMe in the middle, when +100 V was applied, the V t h shifts were opposite those expected from bias stress. Dipole formation or partial ionization of chargeable groups at the interface between the dielectric layers are likely polarization mechanisms in these cases. A simple analytical model levelports the plausibility of these mechanisms. This work provides examples of both stabilization and shifting of V t h , and therefore controlling charge carrier density, in semiconductors overlying the dielectric multilayers.