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Quantification of Laser-Induced Cartilage Injury by Confocal Microscopy in an ex Vivo Model
P. Mainil-Varlet, MDPhD; D. Monin, MD; C. Weiler, MD; S. Grogan, PhD; T. Schaffner, MD; B. Züger, MSc; M. Frenz, PhD
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Investigation performed at the Institutes of Pathology and Applied Physics, University of Bern, Bern, Switzerland
P. Mainil-Varlet, MD, PhD D. Monin, MD S. Grogan, PhD T. Schaffner, MD B. Züger, MSc M. Frenz, PhD Institutes of Pathology (P.M.-V., D.M., S.G., and T.S.) and Applied Physics (B.Z. and M.F.), University of Bern, Murtenstrasse 31, CH-3010 Bern, Switzerland. E-mail address for P. Mainil-Varlet: mainil@patho.unibe.ch
C. Weiler, MD Institut für Pathologie, Institutsbereich Innenstadt, Thalkirchner Strasse 36, D-80337 Munich, Germany
In support of their research or preparation of this manuscript, one or more of the authors received grants or outside funding from the Swiss Commission for Technology and Innovation and Stiftung zur Förderung der wissenschaftlichen Forschung an der Universität Bern. None of the authors received payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity. No commercial entity paid or directed, or agreed to pay or direct, any benefits to any research fund, foundation, educational institution, or other charitable or nonprofit organization with which the authors are affiliated or associated.

J Bone Joint Surg Am, 2001 Apr 01;83(4):566-566
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The application of lasers in orthopaedic surgery is increasing. However, some investigators have reported that osteonecrosis may occur after laser meniscectomy. The objective of the present study was to evaluate the effect of laser wavelength and energy on cartilage injury in an ex vivo model.


Fresh bovine articular cartilage was exposed to either holmium:yttrium-aluminum-garnet (Ho:YAG) or erbium:YAG-laser (Er:YAG) irradiation. Both lasers were operated in a free-running mode and at a pulse-repetition rate of 8 Hz. The effect of laser treatment at several energy levels (Er:YAG at 100 and 150 mJ and Ho:YAG at 500 and 800 mJ) was examined. For each light source and energy level, ten cartilage samples were assessed by conventional histological analysis and by confocal microscopy. Thermal damage was assessed by determining cell viability.


The extent of thermal damage demonstrated by confocal microscopy was much greater than that demonstrated by histological analysis. The extent of thermal injury after Ho:YAG-laser irradiation was much greater than that after Er:YAG-laser irradiation, which was associated with almost no damage. In addition, the ablation depth was greater after treatment with the Er:YAG laser than after treatment with the Ho:YAG laser.


In the present study, histological analysis underestimated thermal damage after laser irradiation. In addition, our findings highlighted problems associated with use of high-power settings of Ho:YAG lasers during arthroscopic surgery.

Clinical Relevance:

Débridement and smoothing of cartilage in patients with osteoarthritis or cartilage defects should cause minimal injury to the surrounding cartilage in order to avoid additional tissue destruction.

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    These activities have been planned and implemented in accordance with the Essential Areas and policies of the Accreditation Council for Continuing Medical Education (ACCME) through the joint sponsorship of the American Academy of Orthopaedic Surgeons and The Journal of Bone and Joint Surgery, Inc. The American Academy of Orthopaedic Surgeons is accredited by the ACCME to provide continuing medical education for physicians.
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