Extraluminal biodegradable splint to treat upper airway anterior malacia: A preclinical proof of principle

Abstract

Objective: Upper airway malacia highly complicates the treatment of benign laryngotracheal stenosis, and no ideal option is available to date. We here explore the use of extraluminal biodegradable splints in an animal model of long-segment anterior tracheomalacia (TM). We show the efficacy, as well as the tissue tolerance, of a custom-made biodegradable extraluminal device surgically inserted around the trachea.

Study design: Preclinical animal study.

Methods: Anterior TM was induced in rabbits through an anterior neck approach by removing eight consecutive anterior tracheal rings without damaging the underlying mucosa. Malacia was corrected during the same surgery by pexy sutures, suspending the tracheal mucosa to an experimental biodegradable device. Symptoms, survival, and tissue reaction were compared to healthy and sham surgery controls.

Results: The model induced death by respiratory failure within minutes. Ten animals received the experimental treatment, and those who survived the perioperative period remained asymptomatic with a maximum follow-up of 221 days. Histological studies at programmed euthanasia showed complete degradation of the prosthesis, with significant remnant fibrosis around the trachea. However, the tracheal stiffness of test segments was comparatively less than that of control segments.

Conclusion: Extraluminal biodegradable splints rescued animals with a condition otherwise incompatible with life. It was well tolerated, leaving peritracheal fibrosis that was not as stiff as normal trachea. The external tracheal stiffening was sufficient for the test animals to live through the phase of severe acute hypercollapsibility. This represents a valid option to help pediatric patients with laryngotracheal stenosis and associated cartilaginous airway malacia.

Level of evidence: NA. Laryngoscope, 128:E53-E58, 2018.

Keywords: Upper airway malacia; airway malacia; animal model; extraluminal stent; pediatric; pediatric airway; stent; tracheomalacia.