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.
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