Effect of anisotropy and drying of costal cartilage on its optical transmittance in laser reshaping of implants with 1, 2, and 3 mm in thickness.

BACKGROUND AND OBJECTIVE: Laser reshaping of cartilage is a prospective technique which can be applied for manufacturing the natural implants for otolaryngology and reconstructive surgery. Optical properties and optimal laser settings for laser reshaping of costal cartilage depend on its thickness, water content, and structural anisotropy of the tissue, in particular, the distinct orientation of collagen packing. The aim of the work is to study the effect of different collagen orientation, thickness, and drying of costal cartilage on its interaction with laser radiation. MATERIALS AND METHODS: Costal cartilage was cut along and crosswise the distinct collagen orientation. The dried and normal cartilage was used for the comparative analysis. The collagen package was studied using atomic force microscopy. The dried tissue was analyzed with thermogravimetry-differential scanning calorimetry (TG-DSC) analysis to reveal the residual water content. The optical transmittance was measured for two wavelengths λ: 1,560 and 532 nm. The reshaping of cartilage of 1-3 mm in thickness was performed with infrared laser with λ = 1560 nm while, the radiation with λ = 532 nm was used to determine the location of the IR beam. RESULTS: The transmittance of 532 nm radiation does not depend on collagen orientation and tissue drying. The IR radiation transmits better along the distinct collagen direction in dried cartilage while in normal cartilage the intensity of transmitted IR radiation increases intermittently passing crosswise and does not change dramatically with time along the collagen orientation. CONCLUSIONS: The effect of structural anisotropy of costal cartilage reveals itself in the increasing scattering of IR radiation with λ = 1,560 nm passing crosswise the collagen orientation when tissue water content is decreased. The radiation with λ = 1,560 nm is effective to perform the reshaping for cartilage of 1-3 mm in thickness; however, for 3 mm, the residual mechanical stress should be taken into account. Lasers Surg. Med. 48:887-892, 2016. © 2016 Wiley Periodicals, Inc.

Laser radiation effect on chondrocytes and intercellular matrix of costal and articular cartilage impregnated with magnetite nanoparticles.

BACKGROUND AND OBJECTIVE: Magnetic nanoparticles with the ability to absorb laser radiation are the perspective agents for the early diagnostics and laser therapy of degenerative cartilage. The effect of starch stabilized magnetite nanoparticles (SSNPs) on the cartilage structure components has never been studied before. The aim of the work is to establish the Erbium:glass laser effect on costal and articular cartilage impregnated with SSNPs. MATERIALS AND METHODS: Porcine articular and costal cartilage disks (2.0 mm in diameter and 1.5-2 mm in thickness) were impregnated with SSNPs and irradiated using a 1.56 µm laser in therapeutic laser setting. The one sample group underwent the second irradiation after the SSNPs impregnation. The samples were analyzed by the means of histology, histochemistry and transmission electron microscopy (TEM) to reveal the alterations of cells, glycosaminoglycans and collagen network. RESULTS: The irradiated cartilage demonstrates the higher content of cell alterations than the intact one due to the heat and mechanical affection in the course of laser irradiation. However the alterations are localized at the areas near the irradiated surfaces and not dramatic. The impregnation of SSNPs does not cause any additional cell alterations. For both costal and articular cartilage the matrix alterations of irradiated samples are not critical: there is the slight decrease in acid proteoglycan content at the irradiated areas while the collagen network is not altered. Distribution and localization of impregnated SSNPs is described: agglomerates of 150-230 nm are observed located at the borders between matrix and cell lacunas of articular cartilage; SSNPs of 15-45 nm are found in the collagen network of costal cartilage. CONCLUSIONS: It was shown that SSNPs do not appreciably affect the structural components of both articular and costal cartilage and can be safely used for the laser diagnostics and therapy. The area of structural alterations is diffuse and local as the result of the mechanical and heat effect of laser impact. SSNPs reveal the areas of the structural alterations of cartilage matrix and give information about the size of the pores and defects.

Laser reshaping of costal cartilage for transplantation.

BACKGROUND AND OBJECTIVE: Laser reshaping of cartilage is a new effective and safe technique for correction of nasal septum and ear deformities. Costal cartilage is a most suitable natural material for transplantation. The problem is to obtain stable proper shape of cartilage implants. The objective of this article is to study reshaping of porcine costal cartilage for larynx stenosis surgery using Erbium glass fiber laser. MATERIALS AND METHODS: Porcine cartilage plates 3 mm in thickness were mechanically curved and irradiated (1) on one side (stretched or compressed) and (2) on both sides with different sequence. Irradiation was performed using a 1.56 µm laser with power varied from 1 to 2.5 W, exposure time from 5 to 20 seconds, spot diameter of 2.5 mm, pulse duration of 500 milliseconds, pulse repetition rate of 1.4 Hz. For each laser setting, stable curvature radius was measured during 24 hours after the experiment. Irradiated samples were analyzed by means of differential scanning calorimerty (DSC) to reveal the collagen denaturation degree. RESULTS: The optimum laser setting for stable reshaping of costal cartilage without visual thermal damage of cartilage matrix was established: laser power of 2.2 W, exposure time of 6 seconds. Nonlinear thermomechanical behavior of cartilage in the course of its laser reshaping is experimentally revealed. The influence of irradiation sequence on the curvature radius of cartilage implant is found for the first time. It is shown that (1) it is possible to use laser reshaping technique for making stable proper shape of costal cartilage, and (2) primary irradiation of compressed side followed with an irradiation of stretched side is more effective than reverse sequence of laser treatment. DSC analysis showed that thermal effect of irradiated specimens (2.58-3.79 J/g) was slightly lower that that for intact cartilage specimens and considerably lower than that for denaturation of collagen (65 ± 5 J/g). CONCLUSIONS: It is possible to use laser reshaping technique for preparation of stable cartilage implants. Nonlinear thermomechanical behavior of cartilage is experimentally revealed. The influence of irradiation sequence on curvature radius of cartilage grafts is established for the first time.