Establishment of a Numerical Model to Design an Electro-Stimulating System for a Porcine Mandibular Critical Size Defect

Electrical stimulation is a promising therapeutic approach for the regeneration of large bone defects. Innovative electrically stimulating implants for critical size defects in the lower jaw are under development and need to be optimized in silico and tested in vivo prior to application. In this context, numerical modelling and simulation are useful tools in the design process. In this study, a numerical model of an electrically stimulated minipig mandible was established to find optimal stimulation parameters that allow for a maximum area of beneficially stimulated tissue. Finite-element simulations were performed to determine the stimulation impact of the proposed implant design and to optimize the electric field distribution resulting from sinusoidal low-frequency ( f = 20 Hz ) electric stimulation. Optimal stimulation parameters of the electrode length h el = 25 m m and the stimulation potential φ stim = 0.5 V were determined. These parameter sets shall be applied in future in vivo validation studies. Furthermore, our results suggest that changing tissue properties during the course of the healing process might make a feedback-controlled stimulation system necessary.

Biophysical and biochemical roles of Moringa oleifera leaves as radioprotector

It has been found that medicinal plants have chemical and/or therapeutic effects on different diseases related to oxidative damage. This work investigates the use of ethanolic Moringa oleifera leaves extract; as a protective and/or therapeutic agent against damage induced by high acute dose of ionizing radiation. Also, this study aims to explore the associations of electrical properties (relaxation time and DC conductivity of bone marrow) with biochemical markers (SOD, CAT and GSH) to detect and prognosticate radiation effects. Biophysical and biochemical data revealed that Moringa extract can improve the electrical properties of bone marrow and the antioxidants levels in the blood. They also showed that the feeding of Moringa leaves extract post irradiation is preferred to recover rapidly and continuously from radiation effects.

New opportunities for fracture healing detection: Impedance spectroscopy measurements correlate to tissue composition in fractures

Accurate evaluation of fracture healing is important for clinical decisions on when to begin weight-bearing and when early intervention is necessary in cases of fracture nonunion. While the stages of healing involving hematoma, cartilage, trabecular bone, and cortical bone have been well characterized histologically, physicians typically track fracture healing by using subjective physical examinations and radiographic techniques that are only able to detect mineralized stages of bone healing. This exposes the need for a quantitative, reliable technique to monitor fracture healing, and particularly to track healing progression during the early stages of repair. The goal of this study was to validate the use of impedance spectroscopy to monitor fracture healing and perform comprehensive evaluation comparing measurements with histological evidence. Here, we show that impedance spectroscopy not only can distinguish between cadaver tissues involved throughout fracture repair, but also correlates to fracture callus composition over the middle stages of healing in wild-type C57BL/6 mice. Specifically, impedance magnitude has a positive relationship with % trabecular bone and a negative relationship with % cartilage, and the opposite relationships are found when comparing phase angle to these same volume fractions of tissues. With this information, we can quantitatively evaluate how far a fracture has progressed through the healing stages. Our results demonstrate the feasibility of impedance spectroscopy for detection of fracture callus composition and reveals its potential as a method for early detection of bone healing and fracture nonunion. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2620-2629, 2017.

Using impedance to track fracture healing rates in mice in vivo: A pilot study

Fracture injuries are highly prevalent worldwide, with treatment of problematic fractures causing a significant burden on the U.S. healthcare system. Physicians typically monitor fracture healing by conducting physical examinations and taking radiographic images. However, nonunions currently take over 6 months to be diagnosed because these techniques are not sensitive enough to adequately assess fracture union. In this study, we display the utility of impedance spectroscopy to track different healing rates in a pilot study of an in vivo mouse tibia fracture model. We have developed small (56 μm) sensors and implanted them in an externally-stabilized fracture for twice-weekly measurement. We found that impedance magnitude increases steadily over time in healing mice but stalls in non-healing mice, and phase angle displays frequency-dependent behavior that also reflects the extent of healing at the fracture site. Our results demonstrate that impedance can track differences in healing rates early on, highlighting the potential of this technique as a method for early detection of fracture nonunion.