Severe subglottic stenosis is a narrowing of the airway below the vocal cords and above the trachea. An estimated 20,000 infants per year are affected by this condition. The most severe cases require laryngotracheal reconstruction (LTR), an open-airway surgery used to enlarge the airway by implanting cartilage taken from the rib cage.

While LTR is used to successfully treat thousands of children with subglottic stenosis, in many cases, young children lack enough costal cartilage—the cartilage connecting the ribs to the sternum—for these grafts. As a result, operations often need to be delayed, leaving the child attached to a tracheostomy tube until they are older, and there is a higher risk of needing follow-up surgery because the airway is at risk of narrowing again.