Impact of Le Fort I osteotomy on the sinus mucosa: a CT analysis

Le Fort I osteotomy is a pivotal procedure in orthognathic surgery, but its direct impact on maxillary sinus homeostasis remains a subject of vigilance for the surgeon. The tissue remodelling induced by the osteotomy and the displacement of the bony bases raise a concrete clinical question: how does the sinus mucosa react in the medium term? Between the risk of sinus complications and changes in mucosal thickness (MT), understanding the postoperative tissue response is fundamental to refining patient follow-up.

This retrospective study, conducted on a cohort of 57 adult patients who underwent surgery between 2018 and 2022, sets a specific objective: to quantify the variations in sinus mucosal thickness using CT imaging at six months post-intervention. The authors seek to determine whether these morphological changes are predictable based on the initial inflammatory status of the sinus, classified according to the Tadinada et al. system.

The tested hypothesis is based on the variability of the mucosal response according to the preoperative classification. The researchers evaluate whether surgery induces a different reaction in patients with an initially thin mucosa (Type I) compared to those presenting with severe thickening (Type IV), postulating that the surgical procedure could alter the physiological sinus dynamics in a divergent manner depending on the baseline condition.

Methodology: CT scan analysis of 57 clinical cases

This retrospective study included a cohort of 57 adult patients who underwent a Le Fort I osteotomy, either isolated or combined with a bilateral sagittal split ramus osteotomy (BSSRO), between 2018 and 2022. In order to isolate the surgical impact, the authors excluded patients suffering from systemic diseases, sinusitis, a history of sinus surgery or maxillofacial trauma.

The experimental protocol was based on a rigorous CT imaging evaluation, performed at two specific stages: preoperatively and at the six-month postoperative follow-up. Mucosal thickness (MT) was quantified using a standardised method and classified according to the Tadinada et al. system, which defines four experimental groups based on the initial condition of the sinus:

• Type I: Minimal mucosal thickening.
• Type II and III: Intermediate thickening levels.
• Type IV: Severe mucosal thickening.

Data analysis was performed using paired t-tests to determine the statistical significance of changes in mucosal thickness between pre- and postoperative measurements, with a significance level set at p < 0.05.

Dynamics of sinus mucosal remodelling at 6 months

The analysis of the CT scans performed on the 57 patients in the cohort reveals that Le Fort I osteotomy induces significant structural changes in the sinus mucosa, but that the direction of these changes is highly dependent on the pre-operative inflammatory status.

Preoperative classification (Tadinada et al.)	Evolution of mucosal thickness (MT)	Statistical significance (p-value)
Type I (Minimal thickening)	Significant increase	p = 0.002
Type II	Non-significant trend	p > 0.05
Type III	Non-significant trend	p > 0.05
Type IV (Severe thickening)	Significant reduction	p = 0.023

Correlation between baseline condition and post-surgical response

The results highlight two distinct phenomena depending on the patient profile:

• Induced tissue reaction: In patients presenting with an initially healthy or very thin mucosa (Type I), an increase in thickness is consistently observed six months after the procedure. This result suggests a physiological or residual inflammatory response to the surgical procedure itself.
• Regulatory effect on pathological mucosa: Conversely, patients exhibiting severe thickening preoperatively (Type IV) experience a notable reduction in this thickening postoperatively. The osteotomy appears here to promote a form of resolution of the pre-existing congestive state.

For intermediate classifications (Types II and III), although variations were recorded, the observed trends did not reach statistical significance in paired t-tests. These data confirm that preoperative radiographic evaluation by CT is an essential predictor of sinus mucosa behaviour following orthognathic surgery.

Analysis of the post-osteotomy mucosal response

The results of this retrospective study conducted on 57 patients reveal an interesting biphasic phenomenon: the impact of Le Fort I osteotomy on the sinus mucosa is dictated by the preoperative condition. For the clinician, the observation is striking: patients presenting with an initially healthy or thin mucosa (Type I) develop significant thickening at 6 months (p = 0.002). Conversely, cases of severe congestion (Type IV) show a notable reduction in mucosal thickness (p = 0.023). This suggests that while surgery induces a residual inflammatory reaction on healthy tissue, it could promote a form of "normalisation" or better ventilation in pathological patients.

Comparison and methodological limitations

These observations corroborate certain data from the literature (notably Akbulut et al., 2020) highlighting the sensitivity of the sinus membrane to maxillary repositioning manoeuvres. However, the study presents limitations: a modest sample (n=57) and a follow-up stopped at 6 months postoperatively. This timeframe, although standard, does not preclude a subsequent normalisation of the mucosa for Type I. The absence of significant results for the intermediate stages (Types II and III) also indicates that the tissue response may be more unpredictable in these transition zones.

Implications for practice

The systematic use of the Tadinada classification via preoperative CT imaging proves crucial here. It enables the anticipation of mucosal remodelling and the identification of patients requiring more rigorous radiological follow-up after the osteotomy. These data confirm that the surgical procedure durably alters the homeostasis of the maxillary sinus, making postoperative CT evaluation essential to prevent potential sinus complications in the medium term.

Summary of results

This retrospective study conducted on 57 patients shows that Le Fort I osteotomy induces significant mucosal remodelling at 6 months: an increase in mucosal thickness in initially healthy patients (Type I, p=0.002) and a notable reduction in those presenting with severe thickening (Type IV, p=0.023).

In practical terms, for the practitioner:

• Systematically assess the initial profile: Use the Tadinada classification on your pre-operative CT scans; the impact of the surgery is directly correlated with the baseline mucosal condition.
• Monitor healthy sinuses: Anticipate a delayed inflammatory reaction (increase in thickness) in patients without prior sinus pathology, warranting rigorous post-operative clinical follow-up.
• Drainage perspectives: Consider that osteotomy may paradoxically improve the condition of severely congested sinuses (Type IV) by potentially modifying sinus ventilation or drainage.

Le Fort I osteotomy is a routine procedure in orthognathic surgery, but its actual impact on sinus health in the medium term remains a subject of clinical discussion. This retrospective study conducted between 2018 and 2022 on 57 adult patients provides precise insight into the changes in sinus mucosal thickness (MT) six months after the procedure.

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