Experimental modeling of laser thermoplasty of costal cartilage

Shaping of whole costal cartilage of human using laser radiation is modeled. Such problem arises at medical cure of chest wall deformities of kids or when one fabricated some kind of cartilage implants. By now in the medical practice doctors performed successfully the laser thermoplasty of nasal septum and auricular, the technology of trachea implants is developed using costal cartilage plates of appropriate thickness. The distinctive feature of assigned task is that the thickness of costal cartilage attained 5-10 mm. For reshaping it is necessary to provide the heating of considerable volume of the tissue up to 70-80 С. Moreover, the temperature rise of cartilage areas which adjoined to chest pleura should be not exceeds 10-15 С. The required conditions were succeeded to realize with Raman fiber laser emitted at wavelength 1.68 m. This laser was recently developed in «IRE Polus» (Fryazino, Russia) and is very perspective for solving a number of specific medical problems. For cartilage thermoplasty it used for a first time. The dynamic of temperature fields induced in the pig costal cartilage under the laser irradiation was studied ex vivo using thermograph. Analysis of the thermometry data allowed us to determine optimal regimes of laser treatment satisfying the requirements to temperature field. The dynamic of supporting force of cartilage during reshaping procedure was studied using tensometric device.

Conditions of stable relaxation of internal mechanical stresses when cartilage attained a new shape were determined. After the procedure of laser treatment the bent cartilage partially recover its initial shape. It is shown that the main return of deformed cartilage to its initial shape occur during first hours after laser procedure. The stable bend measured as the ratio of arc high and base appeared to about 60% of its initial value.

Thus, the ability of stable laser thermoplasty of whole costal cartilage was demonstrated in this work and parameters of laser irradiation and regimes of laser treatment were determined. It opened good perspectives for development of new approaches of curing wall chest deformities, based on the laser engineering of cartilage.