Effects of holmium: YAG laser energy on cartilage metabolism, healing, and biochemical properties of lesional and perilesional tissue in a weight-bearing model.

The study investigates the effects of a specific type of laser therapy (holmium-yttrium-aluminum-garnet or Ho:YAG laser) on the metabolism and healing properties of damaged cartilage in weight-bearing joints of adult horses. The results indicate some significant changes in cell behavior and biochemical synthesis, suggesting further research is needed before considering this therapy for surgical management and repair of cartilage damage.

Study Methodology

• This research used a chronic, weight-bearing model with Full Thickness (FT) circular articular cartilage craters created in horses.
• A Ho:YAG laser, known for its 2.1-microns wavelength, was applied to the cartilage lesions using a near-contact mode using arthroscopic surgery in a saline medium.
• The laser treatment period was followed by a 6-month long Intermittent Active Motion (IAM) in a free exercise environment.
• Examination and comparison involved perilesional cartilage (tissue surrounding the lesion), lesional repair tissue (tissue within the lesion), and subchondral bone activity. The right limb craters served as sham operated controls.

Results & Findings

• The histological analysis done post-6 months indicated a significant ‘clustering’ of chondrocytes, known as Perilesional Zonal Cloning (PZC), in 83% of laser-treated lesions, while no control lesions showed this behavior.
• In terms of “lesional repair activity,” there were no visible differences noted between the laser-treated and the control group.
• However, the laser-treated perilesional cartilage showed a significant decrease in glycosaminoglycan (GAG) synthesis, which are vital compounds for cartilage structure.
• The application of laser energy did not show any adverse effects in terms of cell proliferation or GAG synthesis on the non-immediate, i.e., ‘distant’, cartilage areas.

Conclusion

• The significance of the observed changes associated with the laser treatment, like the decrease in GAG synthesis and the perilesional zonal cloning of chondrocytes in treated cartilage, is not yet known.
• This study concludes that even though Ho:YAG laser energy application showed some interesting results, more research is needed before it can be considered as a viable therapeutic tool for cartilage repair in surgical practices.