Overcoming the absence of pre-traumatic imaging: a multiplanar three-dimensional virtual reduction workflow for...

A fundamental challenge in condylar fracture reconstruction with patient-specific implants is the absence of a pre-traumatic baseline, making direct intra-individual comparison impossible. Several virtual reduction workflows for mandibular condylar fractures have been introduced, but all currently available approaches rely on mirroring the healthy, unaffected condyle as a template for the affected side. However, contralateral mirroring is not feasible in bilateral fractures or cases with contralateral compromise. To address this limitation, the present study introduces a three-dimensional virtual reduction workflow for mandibular condylar fractures in situations where pre-injury imaging data are unavailable or the contralateral side is compromised.

This study included 45 consecutive patients with unilateral mandibular condylar fractures. Post-traumatic computed tomography data were imported into Mimics Medical software to generate a 3D bone model of the skull. Image segmentation was performed using the default bone threshold. A split mask approach was applied twice: first to separate the mandible from the maxilla and craniofacial bones, and second to isolate the fractured fragment from the residual mandibular portion. Virtual reduction of the fractured fragment was performed directly on the post-traumatic CT scan using the three orthogonal imaging planes, rather than on the 3D model. All linear and angular measurements were obtained from the 3D-reconstructed mid-sagittal slice of the hemimandible using the caliper and angle tools in Slicer software. The Wilcoxon signed-rank test was used to compare paired measurements.

The study included 45 patients with unilateral condylar fractures (64.5% male, 35.5% female). Fracture distribution was as follows: 28.9% involved the condylar head, 37.7% the condylar neck, and 33.4% the sub-condylar region. No statistically significant differences were found between the virtually reduced side and the mirrored contralateral control side. The median total ramus height was 61.5 mm versus 61.0 mm, gonial angle was 116.6° versus 116.2°, head-notch angle was 100.7° versus 101.0°, and head-coronoid process distance was 40.8 mm versus 41.0 mm.

The findings demonstrate that the multiplanar virtual reduction workflow restores ramus symmetry and condylar position. It offers a feasible alternative to pre-traumatic imaging in the management of condylar fractures, as it does not rely on mirroring the contralateral side.