Abstract. Laser radiation provides a means to control the fields of temperature and thermo mechanical stress, mass transfer, and modification of fine structure of the cartilage matrix. The aim of this outlook paper is to review physical and biological aspects of laser-induced regeneration of cartilage and to discuss the possibilities and prospects of its clinical applications. The problems and the pathways of tissue regeneration, the types and features of cartilage will be introduced first. Then we will review various actual and prospective approaches for cartilage repair; consider possible mechanisms of laser-induced regeneration. Finally, we present the results in laser regeneration of joints and spine disks cartilages and discuss some future applications of lasers in regenerative medicine. C 2011 Society of Photo-Optical Instrumentation Engineers (SPIE).
We describe the use of elastographic processing in phase-sensitive optical coherence tomography (OCT) for visualizing dynamics of strain and tissue-shape changes during laser-induced photothermal corneal reshaping, for applications in the emerging field of non-destructive and non-ablative (non-LASIK) laser vision correction. The proposed phase-processing approach based on fairly sparse data acquisition enabled rapid data processing and near-real-time visualization of dynamic strains. The approach avoids conventional phase unwrapping, yet allows for mapping strains even for significantly supra-wavelength inter-frame displacements of scatterers accompanied by multiple phase-wrapping. These developments bode well for real-time feedback systems for controlling the dynamics of corneal deformation with 10-100 ms temporal resolution, and for suitably long-term monitoring of resultant reshaping of the cornea. In ex-vivo experiments with excised rabbit eyes, we demonstrate temporal plastification of cornea that allows shape changes relevant for vision-correction applications without affecting its transparency. We demonstrate OCT's ability to detect achieving of threshold temperatures required for tissue plastification and simultaneously characterize transient and cumulative strain distributions, surface displacements, and scattering tissue properties. Comparison with previously used methods for studying laser-induced reshaping of cartilaginous tissues and numerical simulations is performed.
Demonstration of laser-induced stress relaxation in cartilage in 1992 led to the development of a novel laser surgical procedure in otolaryngology for the non-ablative reshaping of cartilage. Follow-up studies found that non-destructive laser irradiation may activate regeneration processes in cartilaginous tissue. Ongoing studies seek to characterize the physical, chemical and biological processes and mechanisms involved in the reshaping and regeneration of deformed and diseased cartilage under moderate laser heating. A theoretical model is developed considering laser-induced stress relaxation in cartilage as a process of micropore formation. Results obtained provide scientific and engineering data for development of novel laser surgical procedures for correction of the nasal septum and treatment of spine disc cartilage diseases. This review is aimed to present state of art and recent results in laser -induced reshaping and regeneration of cartilage.Histological cross-section of porcine nasal septal cartilage after laser reshaping using 1.56 µm laser radiation with power of 1.5 W, spot diameter 2 mm, exposure time of 5 s. Stained with Hematoxylin and Eosin, ×400
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