Effects of Altering Magnesium Metal Surfaces on Degradation In Vitro and In Vivo during Peripheral Nerve Regeneration.

In vivo use of biodegradable magnesium (Mg) metal can be plagued by too rapid a degradation rate that removes metal support before physiological function is repaired. To advance the use of Mg biomedical implants, the degradation rate may need to be adjusted. We previously demonstrated that pure Mg filaments used in a nerve repair scaffold were compatible with regenerating peripheral nerve tissues, reduced inflammation, and improved axonal numbers across a short-but not long-gap in sciatic nerves in rats. To determine if the repair of longer gaps would be improved by a slower Mg degradation rate, we tested, in vitro and in vivo, the effects of Mg filament polishing followed by anodization using plasma electrolytic oxidation (PEO) with non-toxic electrolytes. Polishing removed oxidation products from the surface of as-received (unpolished) filaments, exposed more Mg on the surface, produced a smoother surface, slowed in vitro Mg degradation over four weeks after immersion in a physiological solution, and improved attachment of cultured epithelial cells. In vivo, treated Mg filaments were used to repair longer (15 mm) injury gaps in adult rat sciatic nerves after placement inside hollow poly (caprolactone) nerve conduits. The addition of single Mg or control titanium filaments was compared to empty conduits (negative control) and isografts (nerves from donor rats, positive control). After six weeks in vivo, live animal imaging with micro computed tomography (micro-CT) showed that Mg metal degradation rates were slowed by polishing vs. as-received Mg, but not by anodization, which introduced greater variability. After 14 weeks in vivo, functional return was seen only with isograft controls. However, within Mg filament groups, the amount of axonal growth across the injury site was improved with slower Mg degradation rates. Thus, anodization slowed degradation in vitro but not in vivo, and degradation rates do affect nerve regeneration.

Management of the midface during rhytidectomy.

No nonsurgical technique can come close to rejuvenating the face like a cervicofacial rhytidectomy. However, one of the most difficult areas to improve during a facelift is the midface. The multi-vector high superficial musculoaponeurotic system (SMAS) facelift and extended lower-lid midface lift are important techniques that can adequately address the midface during rhytidectomy. The multi-vector high SMAS facelift is a natural extension of a traditional SMAS plication or imbrication facelift. The extended lower-lid midface lift can be an important adjunct during a facelift or as an independent procedure to address the midface.

Update in wound healing in facial plastic surgery.

Many advances in wound healing have relevance to facial plastic surgery. We briefly highlight some of these advances, including new biological and synthetic products and other potential technologies to improve wound healing, as well as the literature describing them.