In-office Placement of the Propel Mini Sinus Implant in the Frontal Sinus Ostia

Inclusion Criteria * Patient has provided written informed consent using a form approved by the reviewing IRB. * Patient is 18 years of age or older. * Patient is willing and able to comply with protocol requirements. * Patient has CRS defined as sinonasal inflammation persisting for more than 12 weeks and complains of at least 2 of the 4 following symptoms: nasal blockage/obstruction/congestion, nasal blockage/obstruction/congestion, nasal discharge (anterior/posterior), facial pain/pressure, reduction/loss of smell * CRS diagnosis confirmed by CT scan within 3 months prior to enrollment * Bilateral frontal sinusitis confirmed by Lund-Mackay score of ≥1 on each side * Post-endoscopic sinus surgery, patient has bilateral obstruction of the frontal sinus ostia by scarring and/or polypoid edema. * Patient is a candidate for an in-office balloon dilation procedure. * In the opinion of the investigator, treatment with the Propel Mini Sinus Implant as an adjunct to balloon sinus dilation is technically feasible and clinically indicated in the frontal sinus ostia. Exclusion Criteria: * Expanded amount of ethmoid sinonasal polyps extending beyond the middle meatus of grade 3 or 4 unless reduced prior to randomization in the study. * Oral-steroid dependent condition such as chronic obstructive pulmonary disease (COPD) or other conditions. * Known history of allergy or intolerance to corticosteroids or mometasone furoate. * Clinical evidence of acute bacterial sinusitis or invasive fungal sinusitis. * Active viral illness (e.g., flu, shingles). * Clinical evidence of disease or condition expected to compromise survival or ability to complete follow-up assessments through Day 180 post-procedure. * Currently participating in another clinical trial.