Composite cartilage grafts were excised from New Zealand rabbit ears. An incision through the perichondrium exposed a 5mm wide strip of cartilage on the posterior auricle surface. Flat specimens were manually deformed with a jig and maintained in this new position during irradiation. The exposed cartilage was irradiated on the concave surface with an Nd:YAG laser (1064 nm, 3 mm spot) at 10W, 15W, 20W. Cryogen spray (CSC) was applied to the convex, non-irradiated surface of the tissue to reduce thermal injury to the graft. The specimens were maintained in a deformation for 15 minutes after irradiation and serially examined for 14 days. Reshaping and acute thermal injury were assessed by photography. For 15 and 20 W, CSC was delivered: (1) continuously (constant delivery of cryogen active through the entire irradiation period) and (2) under control (cryogen released when surface reached 40°C, and (3) a third group received no CSC. 20W with no CSC caused full thickness injury, while 15W with no CSC caused only minor epidermal thermal injury. The specimen exposed to 20W with controlled CSC retained its new shape to the highest degree over all others, and thermal injury was minimal. Although most levels of laser and CSC yielded a high degree of reshaping over an acute time period, after 14 days specimens exposed to 15W or 20W retained shape better than those treated at 10W.
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