A Histological Comparative Analysis of Thermal Side Effects of Excimer Laser Versus Holmium : YAG Laser in the Human Articular Cartilage

Lee, Byung Ill; Min, Kyung Dae; Lee, Dong Hwa; Koh, Jae Hyun

Abstract

The methods available for arthroscopic debridement vary widely in cost and efficiency. The use of laser treatment is growing rapidly with advantages of production of smooth surface and avoidance of direct contact. Nevertheless, growing attention is directed to the negative side effects of laser-controlled cartilage ablation, especially to the depth effects of the various lasers on which various scientific studies have focused. The purpose of this study is to evaluate the thermal side effects of Ho: YAG laser and Excimer laser on human articular cartilage hy histological analysis. Sixteen human articular cartilages were obtained during total knee arthroplasty for patients with advanced degenerative arthritis. Three craters, 1cm in diameter, were created on each articular cartilage by shaver, Holmium: YAG laser and Excimer laser in the saline medium. These total 48 craters were prepared to tissue specimen by paraffin blocks and stained with Hematoxylin-Eosin(HE) and Massons trichrome. Under the light microscope, we analysed extents of thermal necrosis and thermal change in craters. Also some specimens were fixed by 2.5% glutaraldehyde and ohserved in changes of three different methods under scanning electron microscope. We report the results as follow: 1. The average times to making one crater were 25 seconds in shaver, 33 seconds in Holmium: YAG laser, and 65 seconds in Excimer laser respecti vely. 2. In gross inspection, the most smoothing surface of crater was seen on the specimens of Excimer laser. 3. In histological findings, thermal necrosis on hematoxylin and eosin sections was not noted after shaver use, whereas seen average of 243.8+/-159.6micrometer in Molmium: YAC laser and 36.6+/-17.1micrometer in Excimer laser(p=0.000). Thermal change on trichrome-stained sections was not noted after shaver use, hut showed average of 372.1 +/-203.1micrometer in Holmium: YAG laser and 76.0+/-47. Imicrometer in Excimer laser(p=0.000). 4. In scanning electron micrograph, coagulation of collagen fiher in the matrix was ohserved, with less extents in Excimer than Holmium: YAG laser. In conclusion, Excimer laser was superior to Holmium: YAG laser in terms of thermal necrosis and precision, whereas Holmium: YAG laser was more effective due to rapid time for procedure. To minimize the thermal necrosis during laser chondroplasty, we suggest it is desirable to less energy and reduce exposure time to laser beam on the articular surface.