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Background Tendon without paratenon presents the reconstructive surgeon with a tissue coverage challenge. Integra® dermal regenerative template has been shown to initiate a stable, vascularized bed for skin grafting over tendon. However, histological processes that occur during incorporation have not been described. The purpose of this study is to characterize the pattern of changes that occur when Integra® is applied to an avascular tendon. We hypothesize that vascular incorporation will originate from the wound periphery and proceed toward the tendon center. Methods A full-thickness defect was created over a denuded Achilles tendon in a single hind limb in eight New Zealand white rabbits. Integra was placed over the avascular tendon, and the limb was dressed and splinted. Two animals were euthanized at each timepoint (weeks 1, 2, 3, and 4), and hematoxylin and eosin (H&E)-stained tissue specimens were microscopically evaluated. Results Week 1 specimens demonstrated limited adherence between Integra and the tendon, while myofibroblasts were found encircling the tendon. No cellularity was noted centrally. At week 2, the dermis–Integra junction had increasing vascularity and the central portion developed increasing cellularity. By week 3, Integra was completely revascularized. At week 4, Integra had the histological appearance of normal dermis. Conclusion Neovascularization of Integra® over exposed tendon occurs from the peripheral tissue. Ingrowth proceeds from the dermis–Integra interface toward the center of the graft. Four weeks after application to the denuded tendon, Integra has the histological appearance of native dermis.

Clinicians often place patients in heated rooms following muscle flap transfers. We hypothesize that exposure of flaps to heated room temperatures could result in an unnecessary hyperthermic ischemic insult if the flaps were to be compromised by venous outflow obstruction, while exposure of elective flaps to local cooling during early perfusion may provide protection in the event of venous occlusion. The rat rectus femoris muscle flap was elevated and clamped for 1 h. The muscle was then exposed to various temperatures for 1 h of perfusion followed by complete venous occlusion for 3 h. Occlusion clamps were removed and flaps were allowed to reperfuse for 24 h. Flaps were assessed for muscle necrosis and edema. Venous occluded muscles demonstrated decreased muscle necrosis and edema in the locally cooled group (8.5 +/- 6.7%, 3.06 +/- 0.14; P0.001) compared to the room temperature group (76.2 +/- 23.0%, 3.73 +/- 0.13), and the local warming group (97.3 +/- 1.4%, 3.84 +/- 0.29) respectively. No difference was noted in muscle necrosis nor edema amongst non-ischemic muscles irrespective of temperature exposure. These results suggest a beneficial role for exposure of elective flaps to local cooling during the early perfusion period in order to provide protection from ischemia reperfusion injury in the event of a venous occlusion insult. The prophylactic exposure of flaps to local cooling is further supported by the lack of a harmful effect when flaps were not compromised by venous occlusion.