Directed pterygomaxillary disjunction versus direct downfracture in Le Fort I osteotomy: Application of a fracture quality framework using bilateral ten-point cone-beam computed tomography in a retrospective cohort of 205 patients

TL;DR

Directed PMJ disjunction in Le Fort I osteotomy improves fracture quality and symmetry compared to direct downfracture, based on a study of 205 patients.

Contribution

The study introduces a fracture quality framework using cone-beam CT to compare directed disjunction and direct downfracture techniques in Le Fort I osteotomy.

Findings

Directed disjunction significantly improved fracture quality, with higher rates of 'excellent' outcomes and fewer 'poor' outcomes.

Directed disjunction achieved better symmetry and alignment, with over 49% showing perfect symmetry compared to 1.3% in the direct downfracture group.

Maxillary tuberosity involvement was significantly reduced with directed disjunction compared to direct downfracture.

Abstract

Control of the pterygomaxillary junction (PMJ) fracture is critical in Le Fort I osteotomy. We tested whether a directed PMJ disjunction (osteotome-assisted intermediate release) improves fracture quality, symmetry, and alignment versus direct downfracture.

Single-center retrospective comparative cohort (January 2019-April 2025). Two hundred five consecutive patients underwent Le Fort I: directed disjunction (n=127) or direct downfracture (n=78). Postoperative cone-beam computed tomography at day 90-110 was scored with a bilateral ten-point map. Primary outcomes were per-side quality (poor/good/excellent) and a patient-level overall quality status (poor/fair/good/very good/excellent). Inclusive and strict "clean-cut," symmetry, and alignment were predefined. Group comparisons used chi-square or Fisher's exact tests (two-sided =0.05).

Directed disjunction shifted side-level quality toward inferior, contained patterns: "excellent" 59.1% vs 6.4% (right) and 48.0% vs 12.8% (left); "poor" 22.0% vs 91.0% and 29.9% vs 85.9% (all p<0.001). Patient-level status improved (poor 38.6% vs 98.7%; excellent 37.8% vs 1.3%; p<0.001). Perfect symmetry rose to 49.6% vs 1.3% and correct alignment to 61.4% vs 1.3% (p<0.001). Maxillary tuberosity involvement decreased from 60.3%/56.4% (right/left) without disjunction to 2.4%/5.5% with disjunction. Inclusive and strict clean-cut were higher with directed disjunction (69.3% vs 37.2% and 53.5% vs 9.6%; p<0.001).

Within a standardized early postoperative window, directed PMJ disjunction was associated with superior fracture quality, greater bilateral coordination, and fewer undesired trajectories than downfracture. Adoption of a targeted release and standardized reporting is supported. Interpretation is limited by the retrospective single-center design and focus on fracture behavior without complication or long-term outcome analysis.

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