Middle Meatal Spacers for Synechiae Prevention Following Endoscopic Sinus Surgery: An Updated Systematic Review and Meta‐Analysis of Randomized Controlled Trials

ABSTRACT

Objective

To determine whether middle meatal spacers reduce postoperative synechiae following endoscopic sinus surgery (ESS) and to compare the effectiveness of absorbable versus nonabsorbable spacer materials.

Methods

A PRISMA 2020‐guided systematic review and meta‐analysis was performed. PubMed/MEDLINE, Embase, and Web of Science were searched (January 2012–March 2025) for randomized controlled trials in adults undergoing ESS comparing middle meatal spacers versus no‐spacer controls. The primary outcome was synechiae within 3 months. Random‐effects meta‐analysis generated pooled relative risks (RR) with 95% confidence intervals (CI); prespecified subgroup and sensitivity analyses assessed robustness.

Results

Nine randomized controlled trials comprising 703 patients met inclusion criteria, with eight studies providing dichotomous synechiae data for meta‐analysis. Middle meatal spacers significantly reduced postoperative synechiae compared with no spacer (RR 0.43; 95% CI 0.26–0.71; p = 0.001), with moderate heterogeneity (I ² = 52.3%). Absorbable spacers demonstrated a statistically significant protective effect (RR 0.48; 95% CI 0.25–0.93; p = 0.03), whereas nonabsorbable spacers showed a nonsignificant protective trend under random‐effects modeling. No significant difference was observed between absorbable and nonabsorbable spacer subgroups. Trials evaluating steroid‐eluting spacers did not demonstrate clear superiority over nonsteroid absorbable spacers for synechiae prevention.

Conclusion

Middle meatal spacers reduce postoperative synechiae after ESS, with the most consistent evidence supporting absorbable materials. Given wide variation in baseline synechiae risk, selective rather than routine use is supported.

1. Introduction

Chronic rhinosinusitis (CRS) affects 5%–12% of the population and substantially impacts quality of life [1, 2]. CRS is defined by sinonasal inflammation lasting > 12 weeks with symptoms including obstruction, rhinorrhea, facial pain/pressure, and hyposmia [3], and is associated with substantial direct and indirect healthcare costs [4, 5].

When maximal medical therapy fails, endoscopic sinus surgery (ESS) is indicated [6, 7]. ESS improves outcomes by restoring sinus drainage and ventilation while preserving mucosa [8, 9], with high rates of symptomatic improvement reported in contemporary series [10, 11].

However, postoperative complications can compromise surgical outcomes, with middle meatal (MM) synechiae formation representing the most frequent adverse event [12, 13]. These adhesions occur in 4%–27% of cases depending on disease severity, surgical extent, and postoperative care [14, 15], and typically form within the first 4–6 postoperative weeks [16]. Once formed, synechiae can obstruct drainage pathways, impair mucociliary clearance, create mucus stasis, and ultimately precipitate disease recurrence requiring revision surgery [17, 18].

Recognition of this pathophysiology has driven development of MM spacers to maintain mucosal separation until re‐epithelialization occurs [19]. These devices broadly divide into two categories. Nonabsorbable spacers (NAS) provide consistent mechanical separation but require removal typically 1–2 weeks postoperatively [20, 21], which may cause discomfort and mucosal trauma [22]. Absorbable spacers (AS) gradually degrade over 2–4 weeks, eliminating the need for removal [23, 24]. However, concerns exist about incomplete degradation potentially serving as a scaffold for granulation tissue or delayed scarring [25].

Lee and Grewal's meta‐analysis (2012) was one of the first evidence‐based reviews of MM spacer efficacy [26]. Their analysis of eight randomized controlled trials (RCTs) found a clinically meaningful but statistically nonsignificant trend favoring spacers and highlighted substantial heterogeneity and methodological limitations [26].

Since the review by Lee and Grewal, several additional RCTs comparing MM spacers with no‐spacer controls have been published, including trials of absorbable devices. These additional trials provide a rationale for updating the prior review and reassessing spacer efficacy by material class.

Uncertainty remains regarding which spacer types provide the greatest benefit and in which patient populations. Recent studies have reported conflicting findings: while some randomized trials demonstrate a significant reduction in synechiae formation with AS, others suggest limited benefit when compared to nonmedicated packing or no packing at all [27, 28]. Therefore, the primary objective of this systematic review and meta‐analysis was to determine whether MM spacers reduce postoperative synechiae following ESS compared with no‐spacer controls. Secondary objectives were to compare the effectiveness of absorbable versus NAS materials and to synthesize reported effects on secondary outcomes, including postoperative bleeding, pain, infection requiring antibiotics, and validated quality‐of‐life measures, where reported.

2. Materials and Methods

2.1. Study Design and Protocol Registration

This review followed PRISMA 2020 guidelines [29]. The protocol was prospectively developed and retrospectively registered with PROSPERO (CRD42024618301). We expanded upon Lee and Grewal's 2012 review by incorporating subsequent evidence [26].

2.2. Eligibility Criteria

2.2.1. PICOS Framework

• Population: Adults (≥ 18 years) undergoing ESS for CRS, with or without nasal polyps; primary and revision cases were included when separately reported.

• Intervention: MM spacers (absorbable or nonabsorbable) placed post‐ESS. Studies evaluating nasal packing or dressings primarily intended for drug delivery or hemostasis, including steroid‐impregnated absorbable dressings, were excluded unless the device functioned as a defined MM spacer/stent with mechanical separation as its primary mechanism.

• Comparator: No spacer (standard postoperative care). Studies comparing spacer types without a true control were excluded from the primary analysis but included in secondary evaluations.

• Outcomes: Primary—MM synechiae formation (yes/no) within 3 months postsurgery. Secondary—bleeding, postoperative pain, infection requiring antibiotics, and validated quality‐of‐life instruments (SNOT‐20/22/25, RSOM‐31).

• Study design: Published RCTs; nonrandomized studies, case series, and abstracts were excluded.

2.3. Information Sources and Search Strategy

We searched PubMed/MEDLINE, Embase, and Web of Science from January 1, 2012 to March 1, 2025 using terms related to sinus surgery, MM spacers, and RCTs (Table S1). ClinicalTrials.gov and the WHO International Clinical Trials Registry Platform were also searched.

2.4. Study Selection Process

Two reviewers (R.C. and J.H.) independently screened titles/abstracts and full texts. Disagreements were resolved by consensus or third‐reviewer (M.K.) adjudication. Studies were categorized into three groups:

1. Primary analysis (spacer vs. no‐spacer controls with dichotomous synechiae outcomes).

2. Spacer comparison (spacer vs. spacer without no‐spacer control).

3. Alternative outcome (studies with nondichotomous or nonstandard outcomes).

2.5. Statistical Analysis

Meta‐analyses were conducted using Review Manager 5.4. Relative risks (RR) and 95% confidence intervals (CI) were pooled using Mantel–Haenszel random‐effects models. Cochran's Q and I ² statistics assessed heterogeneity [30]. Prespecified subgroup (AS vs. NAS) and sensitivity analyses were performed. Risk of bias assessment used Cochrane RoB 2 tool [31]. The overall quality of evidence was evaluated with GRADE [32]. Funnel plots were used to visually assess potential publication bias [33].

3. Results

3.1. Study Selection and Characteristics

Our systematic search yielded 623 citations across all databases. After removing 27 duplicates, 596 unique records underwent title and abstract screening. Of these, 521 were excluded for not meeting eligibility criteria, leaving 75 articles for full‐text review. Following detailed evaluation, 66 articles were excluded for the following reasons: inappropriate study design (n = 28), lack of randomization (n = 15), wrong comparator group (n = 12), and missing primary outcome data (n = 11). Following screening, nine RCTs met inclusion criteria. Eight trials contributed to the primary spacer–vs.–no‐spacer meta‐analysis, including four trials from Lee and Grewal's original review [34, 35, 36, 37] and four additional randomized trials identified in the updated search [38, 39, 40, 41]. One additional randomized trial without a no‐spacer comparator was reviewed qualitatively to contextualize steroid‐eluting devices and other comparative designs [42] (Figure 1).

FIGURE 1.

PRISMA flow chart.

The nine included RCTs enrolled a total of 703 patients undergoing ESS for CRS. Key study characteristics from the 2012 review and current review are summarized in Table 1 [34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46]. Out of these, six studies employed a split‐face design where each patient served as their own control [34, 35, 36, 37, 38, 39], while three studies randomized patients to spacer or control groups [40, 41, 42].

TABLE 1.

Summary of randomized trials identified evaluating middle meatal spacers (included and nonprimary comparative designs).

Study	Year	Design	Sample size	Intervention	Control	Outcomes measured	Follow‐up duration	Source
Bugten et al. [34]	2006	RCT, split‐side	58	Merocel spacer	No spacer	Synechiae, pain, bleeding	3 months	2012 review
Wormald et al. [35]	2006	RCT, split‐side	42	Silastic spacer	No spacer	Synechiae, adhesions, patency	12 weeks	2012 review
Kastl et al. [36]	2009	RCT, split‐side	43	Merocel spacer	No spacer	Synechiae, infection	8 weeks	2012 review
Valentine et al. [37]	2010	RCT	40	Silastic sheet	No spacer	Synechiae, ostial patency	6 months	2012 review
Chan et al. [42]	2015	RCT, split‐side	36	Silastic stent	No stent	Synechiae, bleeding	3 months	New RCT
Smith et al. [40]	2016	RCT	80	Steroid‐releasing implant	No implant	Synechiae, inflammation	6 months	New RCT
Manji et al. [38]	2018	RCT	48	Silastic vs. gloved Merocel	N/A (compared spacers)	Synechiae, pain, bleeding	3 months	New RCT
Odat et al. [39]	2020	RCT, split‐side	49	U‐shaped Silastic splint	No splint	Synechiae, infection	3 months	New RCT
Huang et al. [41]	2022	RCT	181	Steroid‐eluting stent	No stent	Synechiae, pain, bleeding	3 months	New RCT
Huang et al. [43]	2023	RCT	63	Nasopore vs. steroid‐eluting	N/A (compared spacers)	Synechiae, ostial patency	6 months	New RCT
Dautremont et al. [44]	2014	RCT	36	Steroid‐eluting with/without steroids	N/A (compared regimens)	SNOT‐22, endoscopic scores	6 months	New RCT
Businco et al. [45]	2016	RCT	78	Steroid‐eluting stent	Conventional ethmoidectomy	Symptoms, nasal obstruction	3 months	New RCT
Taulu et al. [46]	2017	RCT	49	Drug‐eluting stent	Nasal spray	SNOT‐22, symptom scores	3 months	New RCT

3.2. Patient Demographics and Disease Characteristics

Across the eight studies in the primary analysis, mean age ranged from 42 to 56 years. Disease phenotype reporting was inconsistent, with only three studies specifying the proportion of patients with nasal polyps (45%–78%). Most studies excluded revision surgery.

3.3. Intervention Characteristics

NAS were evaluated in four studies, including Merocel sponges [34, 36] and Silastic sheets [35, 37]. AS were examined in five studies, including hyaluronic acid derivatives [35], carboxymethylcellulose [36], chitosan gel [37], and steroid‐eluting implants in two recent trials [40, 41].

Postoperative care varied across trials, limiting comparability and precluding postoperative‐care subgroup analyses.

3.4. Primary Outcome: Synechiae Formation

Eight studies provided dichotomous synechiae data and were pooled to evaluate all MM spacers versus no‐spacer controls. This analysis demonstrated a significant reduction in postoperative synechiae formation favoring spacer use (RR 0.432; 95% CI 0.264–0.705; p = 0.001), with moderate heterogeneity (I ² = 52.3%, p = 0.040) (Figure 2).

FIGURE 2.

Primary forest plot.

The absolute risk reduction varied considerably across studies, ranging from 3% to 24%, with control group synechiae rates spanning 7%–41%. Large protective effects were reported by Valentine et al. [37] (RR 0.167; 95% CI 0.040–0.695) and Bugten et al. [34] (RR 0.210; 95% CI 0.100–0.441). Two studies reported nonsignificant increases in synechiae with spacers: Kastl et al. [36] (RR 3.000; 95% CI 0.128–70.418) and Manji et al. [38] (RR 2.500; 95% CI 0.510–12.263).

3.5. Subgroup Analysis by Spacer Type

To further contextualize spacer efficacy, pooled analyses were stratified by spacer material class and restricted to trials with true no‐spacer control groups.

Subgroup analysis by spacer type is shown in Figure 3.

FIGURE 3.

Subgroup analysis.

AS versus no‐spacer controls (four studies, 212 patients) demonstrated a statistically significant reduction in postoperative synechiae formation under random‐effects modeling (RR 0.484; 95% CI 0.252–0.932; p = 0.030; I ² = 36.6%).

NAS versus no‐spacer controls (three studies, 154 patients) showed a nonsignificant protective effect under random‐effects modeling (RR 0.490; 95% CI 0.184–1.305; p = 0.153; I ² = 75.8%). Fixed‐effects analysis showed significant protection (RR 0.405; 95% CI 0.271–0.606; p < 0.001).

No difference was observed between spacer subgroups (p = 0.94). Steroid‐eluting spacers showed efficacy similar to nonsteroid AS [40, 41]. Randomized trials evaluating absorbable or steroid‐eluting spacers without no‐spacer controls (e.g., Businco; Taulu) were synthesized qualitatively, with findings contextualized alongside pooled estimates rather than incorporated into meta‐analysis due to indirect comparators.

3.6. Sensitivity and Cumulative Analyses

Sensitivity analysis demonstrated stable pooled estimates across all iterations (RR range: 0.376–0.495; p < 0.05) (Figure 4). Cumulative meta‐analysis reached statistical significance after inclusion of Smith et al. [40] (Figure 5). Visual inspection of the funnel plot did not suggest marked asymmetry; however, interpretation is limited by the small number of included trials (Figure S1).

FIGURE 4.

One study removed.

FIGURE 5.

Cumulative analysis.

3.7. Secondary Outcomes

Secondary outcomes were inconsistently reported. Bleeding outcomes were heterogeneous across five studies. Pain outcomes showed minimal differences. Three studies reported infection rates, with no difference between groups (RR 0.89; 95% CI 0.52–1.52; p = 0.74; I ² = 0%). Quality‐of‐life outcomes were sparsely reported.

4. Discussion

This updated systematic review and meta‐analysis demonstrates a significant reduction in postoperative MM synechiae with spacer use compared with no spacer, representing an important evolution of the evidence since the 2012 review by Lee and Grewal, which identified only a nonsignificant trend favoring spacers. With the inclusion of newer RCTs, the evidence base has matured, allowing clearer inference regarding spacer effectiveness. AS accounted for most of the observed benefit in prespecified subgroup analyses, while steroid‐eluting stents did not demonstrate clear superiority over nonsteroid AS for synechiae prevention. Randomized trials evaluating absorbable or steroid‐eluting spacers without no‐spacer controls were therefore interpreted qualitatively to contextualize spacer‐related benefits beyond synechiae prevention rather than pooled due to indirect comparators.

By stratifying outcomes by spacer material class, this analysis clarifies where evidence is strongest and where anticipated benefits remain unproven for synechiae prevention, supporting a more selective approach to postoperative spacer use.

A key clinical observation is the marked variation in baseline synechiae risk across studies. Control‐group synechiae rates ranging from 7% to 41% suggest that uniform spacer use may offer limited value in low‐risk patients while providing greater benefit in higher‐risk populations [15, 47].

Theoretical advantages of localized corticosteroid delivery include reduced mucosal inflammation and modulation of wound healing [48, 49]. While some studies report improvements in secondary outcomes such as polyp recurrence and reduced need for oral steroids, these endpoints were not systematically evaluated in trials meeting our inclusion criteria [50, 51].

5. Methodological Considerations

Despite inclusion of RCTs only, overall evidence quality remains moderate. Lack of blinding of outcome assessors in six of nine studies may bias results toward overestimating spacer benefit [52, 53]. Substantial heterogeneity in postoperative care protocols limits attribution of observed effects solely to spacer use [54, 55].

6. Future Research Directions

Future research should prioritize development and validation of multivariable risk stratification models [56, 57]; head‐to‐head trials comparing steroid‐eluting and nonsteroid spacers in high‐risk populations; and evaluation of long‐term outcomes including revision surgery, quality of life, and healthcare utilization.

7. Limitations

Several limitations should be acknowledged. Definitions of postoperative synechiae and related endoscopic outcomes, as well as timing of assessment, were not uniform across studies, contributing to between‐study variability. Although only RCTs were included, several employed split‐side designs and lacked blinding of outcome assessors, which may introduce bias and limit independence of observations. Variation in disease phenotype, surgical extent, and postoperative management protocols further limits attribution of observed effects solely to spacer use. In addition, limited reporting of economic outcomes and absence of individual patient data precluded cost‐effectiveness analyses and patient‐level risk stratification. Finally, exclusion of non‐English publications may introduce language bias.

8. Conclusion

This systematic review and meta‐analysis confirms that MM spacers reduce postoperative synechiae following ESS, with the most consistent evidence supporting absorbable materials. Steroid‐eluting spacers did not demonstrate clear superiority for synechiae prevention, suggesting that routine use for this indication alone is not currently justified.

As healthcare increasingly emphasizes value‐based care, transitioning from population‐level evidence to risk‐informed postoperative strategies is essential. Future studies should focus on patient stratification and economic evaluation to guide targeted spacer use and optimize clinical value.

Funding

The authors have nothing to report.

Conflicts of Interest

The authors declare no conflicts of interest.

Supporting information

Table S1: Comprehensive search strategy across databases.

Figure S1: Funnel plot of standard error by log odds ratio for studies included in the primary meta‐analysis assessing postoperative synechiae.

Data Availability Statement

Data sharing not applicable to this article as no datasets were generated or analysed during the current study.