PROPOSED CLINICAL APPLICATIONS OF STEROID-ELUTING SINUS STENTS AND IMPLANTS
Steroid-eluting sinus stents and implants are typically explored as an option for postoperative management following sinus procedures such as endoscopic sinus surgery (ESS). Steroid-eluting sinus stents and implants are intended to stabilize the sinus opening of the turbinates, and/or to serve as a local drug delivery vehicle, thereby reducing inflammation and maintaining patency of the sinuses to achieve optimal sinus drainage.
PEER-REVIEWED LITERATURE
PROPEL (e.g., PROPEL sinus implant, the PROPEL Mini implant, and the PROPEL Contour implant)
The Propel sinus implant group devices, including the PROPEL device, the PROPEL Mini, and the PROPEL Contour, are bioabsorbable drug-eluting sinus stents designed to maintain patency of the ethmoid, frontal, and/or maxillary sinus ostia following ESS. The devices are placed via endoscope guidance using a plunger that is included with the device. Mometasone furoate is embedded in a polyethylene glycol polymer, which allows sustained release of the drug over an approximate duration of 30 days. The devices are completely biodegradable over a period of several weeks and therefore do not require removal. In August 2011, the US Food and Drug Administration (FDA) granted original premarketing approval (PMA) for the PROPEL Sinus Implant that was indicated for use in individuals 18 years of age and older following ethmoid sinus surgery to maintain patency, thereby reducing the need for postoperative intervention such as surgical adhesion lysis and/or use of oral steroids. In August 2012, the FDA approved Intersect ENT's PMA supplement for the PROPEL Mini, and in March 2016 the FDA approved an expanded frontal sinus indication for the PROPEL Mini. The PROPEL Mini is a smaller version of the device that may be used in individuals with less-extensive surgery or smaller anatomy. In February 2017, the FDA approved a PMA supplement for the PROPEL Contour, a differently shaped version of the implant designed to maintain patency of the frontal and maxillary sinus ostia following sinus surgery.
The pilot study by Murr et al. (2011) was a randomized, double-blind, intrapatient control trial sponsored by Intersect ENT Inc. The study included 43 individuals with refractory chronic rhinosinusitis (CRS) receiving PROPEL; 38 of these used an intrapatient control design comparing implantable mometasone furoate–eluting sinus stents to identical nondrug-eluting implantable sinus stents. The other five individuals received bilateral mometasone furoate–eluting PROPEL implants to assess systemic safety. The implants were deployed in 86 sinuses. Endpoints of ethmoid sinus inflammation, polypoid change, middle turbinate position, adhesions/synechiae, and adverse events were assessed by direct endoscopic examination on days 7, 14, 21, 30, 45, and 60. Lower inflammation scores persisted to day 60, although the difference did not achieve statistical significance (P=0.0885). This was perhaps due to the study design, in which the reinitiation of steroid prescriptions began at 30-day follow-up, which likely blunted recorded differences between groups. Implant scaffolding function was present in both the treatment and control sides so that the study tests the value of the drug delivery via a stent, but does not test the value of a stent itself versus treatment without a stent. To ensure blinding of both physician and individual to the sinus treatment assignment, noncommercially available nonsteroidal-eluting sinus stents were used in control sinuses, such that the results from the study may not be generalizable to other FDA-approved nasal spacers. The study reported the number of individuals prescribed steroids but did not address whether disease in the PROPEL-treated and/or control sinus cavity required postoperative interventions in addition to PROPEL or nonsteroid-eluting stent. According to the study authors, there is no widely accepted method to assess the efficacy of this new therapy in the ethmoid sinus, so they developed a new grading form that was not a validated measurement tool for evaluating ethmoid sinus inflammation, polypoid change, middle turbinate position, adhesions/synechiae formation, and the need for postoperative intervention. The clinicians recording the outcomes were the same physicians who were treating the individuals, which may introduce bias. An additional limitation of this study was its small sample size (n=43).
The ADVANCE study, by Forwith et al. (2011), was a nonrandomized, open-label, multicenter, single-arm trial that studied the placement of a PROPEL mometasone furoate–eluting absorbable sinus stent in 50 individuals who were scheduled to undergo ESS. The study allowed bilateral or unilateral steroid–eluting sinus implant placement at the end of the ESS procedure. The endpoints included the degree of inflammation and semiquantitative grading for polypoid changes, middle turbinate position, and adhesions. Oral or intranasal steroids were withheld during the first 60 days postoperatively to avoid overlapping routes of steroid administration, although clinicians were given the option to prescribe steroids if they deemed medically necessary. Individual reported outcomes were collected to 6 months. Individuals who received the stents had significant improvement in symptoms 6 months after surgery. The study included specific evaluation of ocular safety, the incorporation of individual symptom scores, and the withholding of systemic steroids for an expanded period of time. Although topical ophthalmic corticosteroids may lead to increased intraocular pressure (IOP) and ocular hypertension, the overall risk of IOP elevation and glaucoma reportedly does not seem to be increased with intranasal corticosteroids at regularly prescribed doses. The authors concluded that the stent appears to optimize surgical results by minimizing the occurrence of inflammation, adhesions, and polypoid tissue formation with negligible potential for ocular adverse effects. No evidence from this case series is available to determine whether mometasone furoate–eluting absorbable sinus stent maintains sinus patency long-term. Additional limitations of this study were its small sample size (n=50) and lack of randomization.
The ADVANCE II pivotal trial, by Marple et al. (2012), was a prospective, randomized, double-blind, multicenter, intrapatient control trial sponsored by Intersect ENT that assessed the safety and efficacy of bioabsorbable steroid-releasing sinus implants. Implants were deployed in 210 ethmoid sinuses of 105 individuals with CRS refractory to medical management. Each individual received a drug-eluting stent on one side and a nondrug-eluting stent on the other via random assignment. No additional steroids were administered 30 days after the procedure. The primary safety endpoint of the absence of clinically significant increased IOP through day 90 following the procedure was met. The rate of postoperative intervention was 46.9% on the control implant sides compared with 33.3% on the treatment implant sides (P=0.0280, statistically significant). The drug-releasing implant provided a 29% relative reduction in postoperative interventions (P=0.028) and a 52% (P=0.005) decrease in lysis of adhesions. The relative reduction in frank polyposis was 44.9% (P=0.002). However, an independent panel, which assessed polyposis based on endoscopic video, found the decreased rate of polyposis in PROPEL-treated sinuses, yet treating clinicians found no difference in the rate of polyposis in sinuses treated with PROPEL versus sinuses treated with the control stent. The reported ratings were significantly different between the two groups regarding the need for postoperative intervention and the presence of frank polyposis. The authors did not explain the reason for these differences.
Han et al. (2012) performed an efficacy meta-analysis of the two published randomized control trials (RCTs) of the PROPEL implant, both of which compared a steroid-eluting stent with a nonsteroid-eluting stent. Postoperative day 30 videos were obtained for each individual, randomly ordered, and presented to an independent panel of three otolaryngologists for grading of efficacy endpoints. The combined results of implants placed in 286 ethmoid sinuses revealed that the mometasone furoate implant provided a 35% (P<0.001) reduction in postoperative interventions, reduced lysis of adhesions by 51% (P<0.001), and reduced oral steroid need by 40% (P<0.001) compared with controls. The relative reduction in frank polyposis was 46% (P<0.001).
In a prospective single-arm case series, Matheny et al. (2014) reported on the safety, feasibility, and efficacy of placement of steroid-eluting bioabsorbable sinus implants in the office setting. The steroid-eluting implant was deployed 7 days after ESS including bilateral ethmoidectomy in a separate office-based procedure. At 1 month there were no significant adhesions or frank polyposis, and middle turbinate lateralization was only 5%. Compared to baseline, ethmoid sinus inflammation was significantly reduced (P=0.03) and the mean Sino-Nasal Outcome Test (SNOT-20) score was significantly improved (P<0.001).
In a randomized prospective trial, Luong et al. (2017) reported that on day 30, the steroid-releasing PROPEL Contour implant, placed in 80 randomized treatment sinuses, significantly reduced the need for postoperative interventions to 11.5% compared with 32.8% by surgery alone in a setting where no other immediate postoperative corticosteroids were administered.
In a randomized controlled trial, Rawl et al. (2020) compared nonabsorbable Merocel packs wrapped in non-latex glove material (n=18) to PROPEL steroid-eluting absorbable stents (n=22) after ESS in individuals with CRS. The authors reported at least a 50% reduction in total SNOT-20 scores from baseline regardless of packing type (13.3 ± 9.3 in the control group vs. 12.0 ± 5.6 in the Propel group; no P value provided). The authors concluded, “This study showed that there was no significant improvement in postoperative outcomes with drug-eluting stents when compared to nonabsorbable packing."
In a single-center RCT by Fieux et al. (2025), all individuals (n=62) received standardized postoperative care including high-volume nasal saline irrigation with one sinus side randomly assigned to stent implantation with either the PROPEL Mini or PROPEL Contour. Across follow-up at 1, 3, 12, and 24 weeks, scarring, edema, patency, and need for additional treatments were similar between stented and non-stented sides, with no statistically significant differences at 24 weeks. The authors concluded, “For CRSwNP, with or without asthma, without other underlying systemic disease factors, steroid-eluting stents may not add benefit over steroid rinses in reducing postoperative scarring and edema, improving long-term frontal sinus patency, or reducing the need for additional treatments, as long as patients continue topical therapy and know how to rinse effectively."
SINUVA
The SINUVA™ sinus implant (Medtronic, formerly Intersect ENT Inc., Menlo Park, CA) was initially approved in 1987. In 2017, the SINUVA sinus implant was approved with a new dose (1350 μg mometasone furoate) under a New Drug Application (NDA 209310). The corticosteroid is released over 90 days and the bioabsorbable polymers soften over this time. The implant is removed at day 90 or earlier using standard surgical instruments. The SINUVA sinus implant is indicated for the treatment of nasal polyps in adult individuals who have had ethmoid sinus surgery.
In a prospective, multicenter study, Lavigne et al. (2014) reported results from a case series that enrolled 12 individuals with recurrent nasal polyposis, refractory to medical therapy, and studied the feasibility, safety, and effectiveness of steroid-eluting implants placed in the office setting in individuals who were candidates for revision ESS. Implants were placed bilaterally under topical anesthesia in an office setting. Follow-up through 6 months included endoscopic grading, patient-reported outcomes (SNOT-22), and need for revision ESS. Implants were successfully inserted in 21 of 24 (88%) ethmoid sinuses. No serious adverse events occurred. At the 1-month follow-up, mean bilateral polyp grade was reduced from 4.5 to 2.3 (P=0.008) and sustained through 6 months (2.33; P=0.008). Mean SNOT-22 score was significantly improved from 2.19 to 0.90 within 1 month (P=0.001) and sustained to 6 months (1.03; P=0.012); 64% of individuals were no longer considered for revision ESS candidates at 6 months. The authors concluded that these findings provided initial clinical evidence of the feasibility, safety, and effectiveness of in-office steroid-eluting implant placement in individuals with recurrent nasal polyposis after ESS, refractory to medical therapy. Moreover, the authors concluded that although further studies are needed, the results suggest steroid-eluting implants may provide a safe and effective, office-based option for the treatment of polyposis. The limitations of this study include its small sample size (n=12), lack of randomization, and lack of a concurrent control group. Well-designed studies are needed to address these limitations and provide further clinical evidence of the safety and efficacy of sinus implants for individuals with CRS with recurrent polyposis as an in-office treatment.In a prospective, single-center study, Ow et al. (2014) reported on the treatment of five adult individuals with recurrent nasal polyposis after bilateral total ethmoidectomy. Each individual successfully received two PROPEL steroid-releasing implants (10 ethmoid sinuses) in the office under local/topical anesthesia. Plasma mometasone and cortisol concentrations were determined before placement and through 30-day follow-up, which also included endoscopic grading along with patient-reported outcomes. There were no serious adverse events. The plasma concentrations of mometasone furoate were in the undetectable range, generally below the lower limit (30 pg/mL). Cortisol concentrations at follow-up ranged from 3.9 to 5.7 mg/dL compared to 4.7 mg/dL at baseline. At 1 month, there was a significant improvement in bilateral polyp grade (P=0.037), nasal obstruction score (P=0.002), and SNOT-22 (P=0.010) compared to baseline. These study results suggest that the implant provides a valid and safe option for the in-office treatment of recurrent nasal polyposis. Furthermore, randomized, controlled, blinded clinical studies are underway to provide additional evidence of safety and efficacy.
Han et al. (2014) reported results of the RESOLVE trial, a sham-controlled RCT evaluating the use of office-based placement of a mometasone-eluting nasal stent for individuals with recurrence of nasal polyposis after ESS (n=53 treated with SINUVA, n=47 sham procedure). Eligible participants had CRS, had undergone prior bilateral total ethmoidectomy more than 3 months earlier, had endoscopically confirmed recurrent bilateral ethmoid sinus obstruction due to polyposis that was refractory to medical therapy, and were considered candidates for repeat surgery. The study authors concluded that the symptomatic improvement and statistically significant reduction in polyp grade and ethmoid sinus obstruction supported the efficacy of the steroid-eluting implant for in-office treatment of CRS individuals with recurrent polyposis after ESS. Limitations included short duration of follow-up (3 months), no defined medical treatment prior to study enrollment, and the clinicians were not blinded to the treatment assignment.
Kern et al. (2018) reported results of the RESOLVE II trial, a randomized, sham-controlled, double-blind trial of 300 adults with refractory CRS with nasal polyposis (CRSwNP) who were candidates for repeat surgery. Eligible individuals were randomly assigned (2:1) and underwent in-office bilateral placement of two implants or a sham procedure. All individuals used the mometasone furoate intranasal corticosteroid spray 200 μg once daily. Co-primary efficacy endpoints were the change from baseline in nasal obstruction/congestion score and bilateral polyp grade, as determined by an independent panel based on centralized, blinded videoendoscopy review. Individuals treated with implants experienced significant reductions in both nasal obstruction/congestion score (P=0.0074) and bilateral polyp grade (P=0.0073) compared to controls. At day 90, implants were also associated with significant reductions in four of five prespecified secondary endpoints compared to control: proportion of individuals still indicated for repeat sinus surgery (P=0.0004), percent ethmoid sinus obstruction (P=0.0007), nasal obstruction/congestion (P=0.0248), and decreased sense of smell (P=0.0470), but not facial pain/pressure (P=0.9130). One individual experienced an implant-related serious adverse event (epistaxis). The authors concluded that significant improvements over a range of subjective and objective endpoints, including a reduction in the need for sinus surgery by 61%, suggest that mometasone furoate sinus implants may play an important role in management of recurrent nasal polyposis. Limitations included a 90-day follow-up that was insufficient to evaluate the durability of this treatment. Additional trials with longer follow-up beyond 90 days are needed to assess duration of the effect of the implant on recurrent nasal polyps.
Feldman et al. (2025) conducted a retrospective, observational case-control study of 534 individuals with CRS and recurrent polyps, comparing 267 individuals treated with SINUVA to 267 matched individuals undergoing repeat ESS over 18 months of follow-up. Notably, repeat SINUVA implant replacement was required in 46.1% of the SINUVA group, with 93.5% of those repeat placements occurring within the first 6 months—indicating that nearly half of the individuals needed the implant readministered relatively soon after the index procedure. Given the high repeat-implant rate and absence of safety data, the authors concluded that while resource use was comparable to repeat surgery, it remains unclear how SINUVA truly compares to repeat ESS in overall clinical utility.
SUMMARY
The applicable FDA approvals for the commercially available stents generally state that the technology is intended to be used following ESS to maintain patency and reduce the need for postoperative intervention (PROPEL, PROPEL Mini, PROPEL Contour), or for recurrent nasal polyps in adults who have previously had ethmoid sinus surgery (SINUVA).
The majority of the published literature, albeit limited in regard to methodological quality, has evaluated the safety and efficacy of the technology when implanted immediately following surgery. The literature consists of a few small randomized trials, single-arm case series, and systematic reviews of these studies. Identified studies reported on outcomes of interest from a limited number of individuals compared with the number of individuals with CRS who undergo sinus surgery annually. Most trials compare a steroid-eluting implant to an otherwise identical nondrug-eluting implant, rather than to standard postoperative care (e.g., saline irrigation, oral or topical steroids, topical decongestants, debridement, or nasal packing); this design isolates the effect to local steroid delivery but does not establish whether the device itself, or steroid therapy by any route, offers benefit over usual care. Notably, at least one comparative study found no clear benefit of the PROPEL device over standard nasal packing, and another comparative study found no clear benefit of the PROPEL Mini or PROPEL Contour device over steroid rinses. There is insufficient evidence to determine whether implantable steroid-eluting sinus stents maintain sinus patency long-term, improve quality of life, reduce the need for steroids, or obviate the need for subsequent sinus surgery compared with other nonsurgical methods of postoperative management. Additional RCTs are needed that compare the device with optimal care without the device to determine whether they can improve outcomes for individuals undergoing sinus surgery or other sinus procedures.
For individuals with recurrent sinonasal polyposis who have undergone ESS and who receive steroid-eluting sinus implants, the evidence includes a relatively small body of literature with two RESOLVE RCTs. The RESOLVE RCTs evaluated the use of steroid-eluting nasal implants for recurrent or persistent nasal polyposis after ESS, which demonstrated improvements in polyp grade and ethmoid obstruction. Strengths of these trials included the use of sham control and adequate statistical power for its primary outcome. However, the trials had a high risk of bias due to unblinded outcome assessment. Although avoidance of repeat ESS and oral steroids may be relevant outcomes for this indication, it would be more important if decisions about repeat ESS or other treatments were standardized and, in the trial setting, if decisions were prespecified or made by a clinician blinded to the treatment group. The evidence is insufficient to determine that the technology results in an improvement in the net health outcome. Well-designed studies are needed to address the limitations such as small sample size, lack of randomization, and lack of concurrent control group. Studies are needed to provide further clinical evidence of the safety and efficacy of steroid-eluting sinus implants for individuals with CRSwNP as an in-office treatment.
The overall body of literature, irrespective of setting (i.e., operative or office) is limited by small sample size(s), lack of applicable control groups, and limited follow-up periods, and preclude the establishment of generalizable conclusions. No data evaluating the safety, efficacy, and effectiveness of the technology in other non-FDA– labeled indications have been published.
