Maintenance of arytenoid abduction following carbon dioxide laser debridement of the articular cartilage and joint capsule of the cricoarytenoid joint combined with prosthetic laryngoplasty in horses: an in vivo and in vitro study.

This study examined the effectiveness of using carbon dioxide (CO2) laser treatment on the cricoarytenoid joint (CAJ) in combination with prosthetic laryngoplasty to avoid loss of arytenoid abduction (control of voice box muscles) in horses post-surgery. The analysis, both in vivo and in vitro, revealed that the treatment helped maintain arytenoid abduction, although some damage to articular cartilage was detected.

Methodology

• Seven horses were part of the study. Five were selected for CO2 laser treatment of the CAJ along with laryngoplasty, and the other two were used as controls and only underwent laryngoplasty.
• Endoscopic examinations and measurements of right to left angle quotients (RLQ) were carried out to assess the maintenance of arytenoid abduction.
• The horses were euthanized at various intervals post-surgery and their larynxes were harvested for further post-mortem tests.
• This included measuring translaryngeal flow, pressure, impedance, and RLQ at increasing levels of vacuum-generated negative pressure, both with and without the knot/crimp of the laryngoplasty sutures.
• Histological examination of the cricoarytenoid joints was also carried out post-mortem.

Results

• No significant differences were observed in RLQ measurements from post-operative day 1 to the end of the study for all horses.
• Post-mortem tests revealed RLQ at airflows of 10 and 60 L/s was significantly higher in controls than in laser-treated horses both before and after the removal of knot/crimp.
• There was no significant difference found in translaryngeal impedance (resistance to airflow through the larynx) at 10 and 60 L/s between the two groups.
• The histopathological examinations revealed necrosis and loss of articular cartilage in the laser-treated horses. While infiltration of lymphoid (immune) cells was observed to subside over time, joint capsule and periarticular fibrosis (excessive formation of fibrous connective tissue) increased over the study duration.

Conclusion

The post-operative loss of arytenoid abduction following laryngoplasty (a surgical procedure to correct the function of the larynx) in horses can be minimized with CO2 laser treatment of the CAJ, even though the treatment may cause some cartilage damage.