Intra-articular stabilisation of the equine cricoarytenoid joint.

This research explores the use of polymethylmethacrylate (PMMA) in strengthening the cricoarytenoid joint (CAJ), potentially reducing the force exerted on the laryngoplasty sutures and potentially improving the outcomes in the post-operative phase, particularly preventing arytenoid abduction loss.

Objective and Methodology

• The main goal of this research was to evaluate the effectiveness of polymethylmethacrylate (PMMA), when injected into the cricoarytenoid joint (CAJ), in resisting the force produced by laryngeal air flows and pressures.
• Laryngoplasty, often used to treat laryngeal hemiplegia (paralysis of the larynx in horses) can experience early post-operative complications, specifically, loss of arytenoid abduction, which may restrict the airflow and cause voice changes.
• The researchers collected ten cadaver larynges and selected one for injection with PMMA into the CAJ. The larynges were then subjected to physiological conditions with either constant (static) or cycling (dynamic) flow.
• Each larynx was tested in four different experimental conditions; full bilateral abduction of the larynx, cutting the suture on the side without PMMA, reapplying the suture for bilateral abduction (control 2), and finally cutting the suture on the PMMA side.
• This process helped to compare the impact of PMMA on the force experienced by the laryngoplasty suture under normal and altered conditions.

Findings

• The first thing observed was that when the suture on the side without PMMA was cut, both the tracheal pressure increased and the tracheal flow decreased. This outcome indicates that PMMA has a measurable effect on these pressure metrics.
• This difference was statistically significant (P < 0.05), indicating a low chance that the results were due to chance alone.
• On the other hand, there was no significant difference in any outcome measure when PMMA was injected into the CAJ in comparison with the conditions where the bilateral abduction was left intact (Control 1 and 2). This suggests that PMMA does not negatively influence these metrics compared to a non-augmented bilateral abduction.
• The rate of increase in strain – with increasing translaryngeal pressure – was significantly less on the suture with PMMA positioned in the CAJ. This suggests that PMMA injection may reduce the force experienced by the laryngoplasty suture, potentially leading to better post-operation outcomes.

Conclusions

• The outcome of this research suggests that injecting PMMA into the Equine CAJ could potentially improve laryngoplasty outcomes by resisting the collapsing effect of physiological airflows and pressures in the larynx.
• Furthermore, this augmentation might reduce arytenoid abduction loss in the early post operative period. Thus, using PMMA could potentially help avoid post-operative complications and promote better recovery outcomes for laryngoplasty procedures.