This is a multi-center, randomized, single-blinded comparative 3-arm clinical study. This clinical study is designed to compare the efficacy of the ArchSinus stent to the Propel stent (Intersect ENT), and to NasoPore (Stryker) in preventing post-FESS middle turbinate lateralization 3 weeks, 6 weeks, 3 months and 12 months post FESS.

50 chronic rhinosinusitis patients, that met the inclusion criteria will undergo bilateral FESS and subsequent bilateral placement of the ArchSinus into the randomized ethmoid sinus cavity and NasoPore / Propel into the other ethmoid sinus cavity. Comparative treatment sides will be randomly assigned; 50 sinuses treated with ArchSinus stent, 25 sinus treated with Propel stent, 25 sinuses treated with Nasopore. Standard Propel implant and 4cm whole NasoPore will be used.

ArchSinus stent will be removed 2 weeks (13-15 days) post FESS. Propel will be removed as necessary 2 weeks (13-15 days) post FESS. NasoPore arm will be debrided as necessary 2 weeks (13-15 days) post-FESS. Prior to removal / debridement procedures, the patients will be blindfolded, to keep them blinded for the treatment type on each side of their nose.

All patients will be followed up at 2, 6 and 12 weeks and 12 months post FESS and examined endoscopically. The endoscopic videos will be analyzed by independent pannel of 3 ENT surgeons, blinded to the treatment type, to assess middle turbinate lateralization on a 4-point scale.

CT scan will be performed pre-FESS and 12 weeks after the operation, to assess middle turbinate lateralization, as demonstrated by percent change in middle meatus (MM) area pre-FESS and 12 weeks after the surgery. Inflammatory mucosal thickening will be quantified using the Zinreich staging system. CT scans will be analyzed blindly by Medical Metrics Inc.

Symptomatic improvement will be analyzed weekly within 3 months follow up, using Side-specific Nasal SNOT-22 questioner.

Patient symptomatic relief during the implantation time will be analyzed 2 weeks post FESS, with Side-specific Nasal SNOT-22 questioner.

Inclusion Criteria:

• Diagnosis of chronic rhinosinusitis defined as symptomatic inflammation of the sinuses of at least 12 consecutive weeks duration despite medical management
• CT scan examination with a minimum Zinreich score of 5 prior to study entry
• Less than 2-point Zinreich score difference between two sides
• Primary FESS including bilateral total ethmoidectomy; symmetrical uncinate process reduction

Exclusion Criteria:

• Inferior turbinectomy, reduction or outfracture
• Polyp grade ˃ 4 bilaterally on Lildholdt's scale (1-3)
• Concha bullosa
• Severe nasal septal deviation at the level of OMC
• Sinonasal tumors
• FESS including asymmetrical resection of the middle turbinate
• Known allergy to nickel
• Known polyurethane induced dermatitis
• Oral steroid-dependent condition
• Momometasone furoate intolerance
• Known hypersensitivity to lactide, glycolide or caprolactone copolymers.
• Glaucoma or cataract
• History of immune deficiency
• Cystic fibrosis
• Pregnant or lactating female
• Acute sinus inflammation
• Coagulation disorders

Primary objective will be analyzed using nasal video endoscopy and a CT scan, by an external experts in a blinded fashion. Secondary objective will be analyzed using side-specific SNOT-22 questioner, subjects will be blinded to the treatment type.