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The current standard of care for bone reconstruction, whether secondary to injury, nonunion, cancer resection, or idiopathic bone loss, is autologous bone grafting. Alternatives to autograft and allograft bone substitutes currently being researched are synthetic and natural graft materials that are able to guide bone regeneration. One promising material currently being researched is chitosan, a highly versatile, naturally occurring polysaccharide, derived from the exoskeleton of arthropods that is comprised of glucosamine and N-acetylglucosamine. Research on chitosan as a bone scaffold has been promising. Chitosan is efficacious in bone regeneration due to its lack of immunogenicity, its biodegradability, and its physiologic features. Chitosan combined with growth factors and/or other scaffold materials has proven to be an effective alternative to autologous bone grafts. Additionally, current studies have shown that it can provide the additional benefit of a local drug delivery system. As research in the area of bone scaffolding continues to grow, further clinical research on chitosan in conjunction with growth factors, proteins, and alloplastic materials will likely be at the forefront.

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).Microsurgical techniques have allowed the performance of complex reconstructive endeavors with a good rate of success. Compromise of the arterial or venous anastomosis is commonly responsible for free flap failure. This most frequently occurs during the first 48 hours postoperatively. 1 The early detection of microvascular complications improves flap salvage rate. 2 Detecting the complication alone is insufficient if it is only detected after salvage is no longer feasible. Therefore, ideal flap monitoring modalities should detect potentially catastrophic events early, allowing a microsurgeon an opportunity to salvage the flap.Conventional free flap monitoring includes assessing the color, turgor, temperature, capillary refill, and arterial and venous Doppler signals with a handheld Doppler probe. The potential drawback with conventional monitoring techniques is that they may only detect the problem after it has progressed Keywords ► microsurgeon ► tissue oximetry ► near-infrared spectroscopy AbstractBackground Microvascular compromise from arterial or venous occlusion is a common cause of free flap failure. The salvage rate following a microvascular compromise is dependent on detecting the problem early and intervening quickly. Methods The ViOptix tissue oximeter measures tissue oxygen saturation using the nearinfrared spectroscopy technology. The ViOptix device has an alarm capability to warn of potential compromise to tissue perfusion. The tissue oximetry readings are visible on the bedside monitor and are relayed to a webpage link, which is accessible on a personal computer or mobile device, allowing real-time monitoring. This article presents a case where real-time monitoring allowed almost immediate detection of inadvertent pedicle compromise allowing flap salvage by repositioning without surgical intervention. Results In the case presented, the patient's nurse inadvertently positioned a pillow under the location of the vascular pedicle likely causing microvascular compression. The ViOptix reading dropped and for this reason the nurse contacted the Plastic Surgery team. The drop was confirmed remotely and the flap was urgently evaluated in person. Once the pillow was removed, the ViOptix readings normalized and Doppler signals strengthened in the flap. Discussion While tissue oximetry monitoring does not by itself ensure flap survival, it provides critical information than conventional flap monitoring would allow giving the microsurgeon the opportunity to make a quicker decision. ViOptix tissue oximeters are able to detect vascular compromise even before conventional clinical symptoms are present. Alas in several cases by the time clinical symptoms develop the flap may be beyond salvage.