Effects of holmium:YAG laser on equine articular cartilage and subchondral bone adjacent to traumatic lesions: a histopathological assessment.

This study was performed to investigate the effects of holmium:yttrium-aluminum-garnet (Ho:YAG) laser energy on articular cartilage and subchondral bone adjacent to traumatically created cartilage lesions in a continuous weight-bearing model. The 2.1-microns wavelength was delivered efficiently and precisely in hand-controlled contact and near-contact hard tissue arthroscopic surgery in a saline medium. Bilateral arthroscopy was performed on normal antebrachiocarpal and intercarpal joints of four adult horses. One hundred twenty traumatic lesions were created on three weight-bearing articular surfaces with a knife, curet, or motorized burr. Depths of the lesions were partial and full thickness. Configurations of the lesions were lacerations, scrapes, and craters. Left limbs were used as controls. Right limb lesions were treated with various intensities of laser energy: 0.1. 0.16, and 0.2 J. Animals were killed at intervals of 1, 3, and 8 weeks. Gross microscopic anatomy was documented, and tissue sections were subjected to blind review by a pathologist. Mankin grading for cellularity and proteoglycan content was used to qualitatively evaluate cartilage response. Cartilage adjacent to all lesions exposed to laser energy had better cellularity and proteoglycan content (p < 0.05) than did corresponding controls by Mankin grading. Mankin grades for levels of 0.16 and 0.2 J were lower (p < 0.05) than were those of controls or lesions exposed to 0.1 J. There was loss of cellularity and necrosis in subchondral bone at higher energy levels (0.16 and 0.2 J). This study examined the effects of Ho:YAG laser on articular cartilage and subchondral bone in terms of depth of damage and healing response over time in a weight-bearing model. Additional research to define dose-response curves for Ho:YAG laser treatment of cartilage and subchondral bone are indicated.

The effect of CO2 laser neurectomy on neuroma formation and axonal regeneration.

In an attempt to prevent neuroma formation and digital reinnervation after sharp palmar digital neurectomy in 10 adult horses with navicular disease, 18,426 W/cm2 of CO2 laser energy was applied to the proximal nerve stump. Clinical follow-up was 4 to 23 months. In two horses, palmar digital nerve biopsies were taken at month 4 (four nerves) and month 7 (two nerves). Nine horses were sound immediately and at all follow-up examinations. None had clinical evidence of painful neuroma or digital reinnervation. Histologically, there was minimal scar tissue at the surgical site; axonal sprouts were comingled with fibrous tissue.