The purpose of this study is to assess the safety and efficacy of the Propel mometasone furoate implant when used following Functional Endoscopic Sinus Surgery (FESS) in patients with Chronic Sinusitis (CS).

The purpose of this study is to assess the safety and efficacy of the Propel mometasone furoate implant when used following Functional Endoscopic Sinus Surgery (FESS) in patients with Chronic Sinusitis (CS). The Propel implant is designed to provide a mechanical spacing function within the sinus anatomy to separate mucosal tissues, provide stabilization of the middle turbinate, and thereby prevent tissue adhesions from forming. The implant is coated with a small amount of mometasone furoate (a corticosteroid) in order to help minimize post surgical inflammation within the supported tissues.

The study utilizes an intra-patient control design to assess the safety and efficacy of the drug-coated implant compared to the non-drug coated implant that is identical in appearance.

Inclusion Criteria:

• Patient has bilateral chronic sinusitis confirmed by CT scan and defined as inflammation of the mucosa of the nose and paranasal sinuses of at least 8 consecutive weeks' duration.
• Patient is indicated for and has consented to FESS.
• FESS successfully completed without significant complication that in the opinion of the physician would confound study results and the patient's anatomy remains amenable to Sinus Stent placement.

CT Imaging Inclusion Criteria:

• CS diagnosis confirmed and documented by CT Scan within 6 months of the procedure.
• Patient has minimum total CT score (Lund-Mackay method) of 6. • Patient has bilateral ethmoid sinus disease confirmed by CT.

Exclusion Criteria:

• insulin dependent diabetics
• oral steroid dependent condition
• glaucoma, ocular hypertension, posterior subcapsular cataracts
• middle turbinate resection