Feedback controlled laser mediated cartilage reshaping

Real-time measurements of diffuse reflectance from backscattered HeNe laser light (λ=632.8 nm) and radiometric surface temperature can be used as input to a feedback procedure to control the process of laser mediated cartilage reshaping. A prototype device for reshaping cartilage was constructed using modulated laser irradiation emitted from an Nd:YAG laser (25 W/cm², λ=1.32 μm, NewStar Lasers, Auburn, CA). Using measurements of diffuse reflectance and radiometric surface temperature as input signals, a control system was constructed using LabView software (National Instruments, Austin, TX) that repositioned the specimen using translational and rotational motion control devices (LEGO-Dacta, Enfield, CT). The control system was used to reshape initially flat porcine nasal septal cartilage specimens (25×10×2 mm) into curved shapes. Preliminary histologic and biochemical analysis suggest that chondrocytes in the reshaped cartilage grafts remain viable