The term "collagen" refers to any one of more that 28 types of polymeric glycoproteins that form elongated fibers. Collagen is commonly found in extracellular matrices.

The cover on the AMStent(r) is a sheet of type III & IV collagen which is obtained from human amniotic membrance.

Complication/reintervention rates for current metallic tracheal stents range approximately 20-40%. REFERENCES Breitenbücher A, et al. Long-term follow-up and survival after Ultraflex stent insertion in the management of complex malignant airway stenoses. Respiration. 2008;75(4):443-9. doi: 10.1159/000119053. Epub 2008 Mar 20. Chhajed PN, et al. Therapeutic bronchoscopy for malignant airway stenoses: choice of modality and survival. J Cancer Res Ther. 2010 Apr-Jun;6(2):204-9. doi: 10.4103/0973-1482.65250. Han X, et al. Individualized airway-covered stent implantation therapy for thoracogastric airway fistula after esophagectomy. Surg Endosc. 2017 Apr;31(4):1713-8. doi: 10.1007/s00464-016-5162-9. Epub 2016 Aug 12. Lemaire A, et al. Outcomes of tracheobronchial stents in patients with malignant airway disease. Ann Thorac Surg. 2005 Aug;80(2):434-7; discussion 437-8. Marchese R, et al. Fully covered self-expandable metal stent in tracheobronchial disorders: clinical experience. Respiration. 2015;89(1):49-56. doi: 10.1159/000368614. Epub 2015 Jan 15. McGrath EE, et al. The insertion of self expanding metal stents with flexible bronchoscopy under sedation for malignant tracheobronchial stenosis: a single-center retrospective analysis. Arch Bronconeumol. 2012 Feb;48(2):43-8. doi: 10.1016/j.arbres.2011.09.008. Epub 2011 Dec 2. Miyazawa T, et al. Implantation of ultraflex nitinol stents in malignant tracheobronchial stenosis. CHEST. 2000;69(2):398-401. Nasir BS, et al. Palliation of Concomitant Tracheobronchial and Esophageal Disease Using a Combined Airway and Esophageal Approach. Ann Thorac Surg. 2016 Aug;102(2):400-6. doi: 10.1016/j.athoracsur.2016.03.021. Epub 2016 May 5. Razi SS, et al. Timely airway stenting improves survival in patients with malignant central airway obstruction. Ann Thorac Surg. 2010 Oct;90(4):1088-93. doi: 10.1016/j.athoracsur.2010.06.093. Saad CP, et al. Self-expandable metallic airway stents and flexible bronchoscopy: long-term outcomes analysis. Chest. 2003 Nov;124(5):1993-9