To demonstrate feedback-controlled lasermediated cartilage reshaping using dynamic measurements of tissue optical properties and radiometric surface temperatures.Design: Flat cartilage specimens were reshaped into curved configurations using a feedback-controlled laser device.Materials: Fresh porcine nasal septum, stripped of perichondrium and cut into uniform strips (25 ϫ 10 ϫ 1.5-2.1 mm) with a custom guillotine microtome.Interventions: Cartilage specimens secured in a cylindrical reshaping jig (2.5 cm in diameter) and irradiated with an Nd:YAG laser ( = 1.32 µm, 25 W/cm 2 , 50-Hz pulse repetition rate). During laser irradiation, radiometric surface temperature was measured along with changes in forward-scattered light from a diode probe la-ser ( = 650 nm, 5 mW), using a lock-in detection technique. Sequential irradiation of the specimen outer surface was made (3 laser passes). Characteristic changes in tissue temperature and light-scattering signals were used to terminate laser irradiation.Results: Effective reshaping was accomplished for both thin (1.5-mm) and thick (2.1-mm) specimens. Following reshaping, specimens were stored in saline solution at 4°C for 21 days. No return to the original flat configuration was noted during this period.
Conclusions:The prototype device effectively reshapes flat native porcine cartilage into curve configurations. The use of optical and thermal signals provides effective feedback control for optimizing the reshaping process.