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

Abstract

Background

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.

Methods

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.

Results

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.

Conclusion

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.

Background

Mandibular condylar fractures are a common and clinically significant category of maxillofacial trauma. These injuries frequently lead to temporomandibular joint (TMJ) dysfunction, characterized by pain, malocclusion, and restricted mandibular mobility [1]. Despite their prevalence, establishing a definitive diagnosis and treatment plan remains challenging, particularly for less experienced surgeons. Successful surgical management including planning, preoperative simulation, guide fabrication, reduction assessment, and the design of patient-specific implants depends on a detailed understanding of the original condylar morphology. A fundamental methodological challenge is the inherent lack of a pre-traumatic baseline for the fractured condyle, which precludes direct intra-individual comparison.

Recent advances in digital surgery have introduced several solutions to this challenge. Virtual surgical planning (VSP), one such innovation, is now well established in plastic and maxillofacial surgery [2–4], with increasing interest in its application—alongside patient-specific implants (PSIs)—to improve the accuracy and predictability of open reduction and internal fixation in the condylar region [5].

Liokatis et al. evaluated the accuracy and clinical utility of VSP combined with computer-aided design and computer-aided manufacturing (CAD/CAM) fabricated PSIs for the secondary correction of post-traumatic mandibular condyle deformities [5]. Similarly, Matschke et al. introduced a workflow for the virtual repositioning of mandibular condyle fractures to create PSIs that precisely match the surface of the fractured side [2]. Moreover, Shakya et al. conducted a randomized controlled study to assess the application value of VSP in mandibular condylar fractures, aiming to provide a reliable reference for its clinical use in diagnosis and treatment [4]. Batbayar et al. [6] introduced a workflow in which the condylar fracture was virtually reduced to its anatomical position using a template mirrored from the non-fractured contralateral condyle as a reduction guide. All of these approaches [2, 4–6] rely on mirroring the healthy, unaffected condyle to serve as a template for the affected side. This method is predicated on the assumption of symmetrical bilateral condylar morphology. However, the contralateral mirroring is not applicable in cases of bilateral fractures or when contralateral abnormalities—such as prior trauma, ankylosis, or degenerative changes—invalidate this assumption. Additionally, some of these workflows were perform virtual repositioning on 3D surface models rather than directly on multiplanar CT images, potentially compromising accuracy. In such scenarios, alternative strategies are required to achieve satisfactory reconstructive outcomes [7]. To address these challenges, Elayah S. introduces a novel three-dimensional virtual reduction workflow for mandibular condylar fractures, specifically designed for situations where pre-injury imaging data are unavailable.

Materials and methods

Study population

This retrospective study was designed to validate a virtual reduction workflow. A cohort of 45 consecutive computed tomography (CT) scans was retrieved from the imaging database of the Department of Oral and Maxillofacial Surgery at the West China Hospital of Stomatology, Sichuan University. All scans were from patients diagnosed with unilateral mandibular condylar fractures. Based on anatomical location, the fractures were classified as follows: condylar head fractures, condylar neck fractures, and subcondylar fractures.

The study protocol was reviewed and approved by the Medical Ethics Committee of West China Hospital of Stomatology, Sichuan University, and conducted in accordance with the principles of the Declaration of Helsinki. At the time of original data collection, all participants provided broad written informed consent permitting the use of their data for future research purposes, in accordance with institutional protocols.

Inclusion criteria were: (1) unilateral condylar fracture, with or without associated fractures, and (2) availability of CT scans performed within one-week post-trauma. Exclusion criteria were: (1) bilateral condylar fractures; (2) abnormalities of the contralateral condyle, including prior trauma, ankylosis, or degenerative changes; (3) presence of other mandibular pathologies, such as osteomyelitis, deformities, or temporomandibular joint ankylosis; (4) pathological fractures; or (5) a history of surgery involving the mandibular condyle.

Classification of the condylar process fractures

Mandibular condylar fractures were classified according to the system proposed by Loukota et al. [8] into three main types:

• Condylar head fracture: The fracture line originates within the articular surface and may extend beyond the articular capsule.

• Condylar neck fracture: The fracture line is located in the upper half of the condylar region, more than halfway above a perpendicular line drawn from the sigmoid notch to the tangent of the posterior mandibular ramus.

• Subcondylar fracture: The fracture line is located in the lower half, more than halfway below the same perpendicular reference line.

Condylar head fractures were further subclassified according to Neff et al. [9] classification into three subtypes:

• Type A: The fracture line begins in the articular surface, extends through the medial portion of the condylar head, and may extend extracapsularly.

• Type B: The fracture involves the lateral intracapsular region of the condylar pole.

• Type C: The fracture line is situated inferior to the lateral condylar pole, near the attachment site of the lateral joint capsule.

Description of the multiplanar 3D virtual reconstruction

Segmentation and 3D model reconstruction

Image acquisition was performed using a 16-slice spiral CT scanner (Philips Brilliance 16, Best, The Netherlands) with the following parameters: tube voltage of 120 kV, tube current of 282 mA, matrix size of 512 × 512 pixels, and slice thickness of 0.5 mm. Total scan time was 26.3 s. Images were reconstructed with a voxel size of 0.3 mm, yielding isotropic resolution. All datasets, stored in Digital Imaging and Communications in Medicine (DICOM) format, were transferred to Mimics Medical software (v21.0, Materialise, Leuven, Belgium) to generate a 3D bone model of the skull and mandible (Fig. 1).

Fig. 1.

Post-traumatic CT scan of a 28-year-old male with a right unilateral subcondylar fracture. A Coronal CT slice showing the fracture line in the right subcondylar region. B 3D model showing the maxilla and cranial base (pink), the residual mandibular segment (green), and the fractured fragment (yellow). C, D Anterior (C) and posterior (D) views showing the spatial displacement of the condylar fragment (yellow)

Prior to segmentation, image quality was verified to ensure the absence of motion artifacts, which could compromise model accuracy. No additional smoothing or filtering was applied, thereby preserving the original fracture line topography. Image segmentation was performed using the default bone threshold (Hounsfield Unit ≥ 226) to isolate skeletal structures from soft tissue (Fig. 2).

Fig. 2.

3D skull model following initial bone segmentation (HU ≥ 226). A Sagittal, (B) axial, and (C) coronal CT slices. D 3D surface model of the skull

To facilitate region-specific analysis, a sequential split mask approach was applied in two stages:

• A.Craniofacial Separation: The first split mask was applied to separate Region A (colored blue), which included the intact mandibular body, ramus, and the fractured fragment, from Region B (colored red), which encompassed the maxilla and all supra-mandibular craniofacial bones (Fig. 3).
• B.Fragment Isolation: The mandible (Region A) was then divided into its individual components: the main residual mandibular segment (comprising the lower border and ramus) and the fractured condylar fragment (Fig. 4).

Fig. 3.

Split-mask segmentation splitting Region A (blue: mandible) and Region B (pink: maxilla and cranial base). A Sagittal, (B) axial, and (C) coronal CT slices. D 3D surface model of the skull

Fig. 4.

Isolated mandible segmented into the fractured fragment (red) and residual mandible (green). A Sagittal, (B) axial, and (C) coronal CT slices. D 3D surface model of the mandible

Following automated thresholding, manual delineation was performed slice-by-slice using Mimics’ editing tools to ensure accurate separation of these regions and to correct any segmentation errors at the fracture interface. Once segmentation was finalized, a two-part 3D reconstruction of the hemimandible was generated, with each component assigned a distinct color for visual differentiation and manipulation during virtual reduction.

The multiplanar 3D virtual reduction workflow

Prior to reduction, the fractured fragment and adjacent intact mandibular segment were individually activated in the 3D software environment. Their outer and inner cortical borders, as well as fracture line contours, were distinctly highlighted using assigned colors to facilitate precise identification and spatial orientation (Fig. 5).

Fig. 5.

A Coronal CT slice showing the individually activated fractured fragments (red) and residual mandible (green), with inner and outer cortical borders and fracture line contours color-coded to facilitate spatial alignment. The natural fracture line irregularities (arrowheads), including triangular interlocks and notches, function as intrinsic "key-lock" guides for anatomically accurate repositioning. B 3D surface model of the fractured fragments

This workflow uses the fractured fragment as it appears on the post-traumatic CT scan, rather than relying on the 3D surface model. To preserve anatomical fidelity, the skull and intact portions of the mandible were rigidly fixed as stable reference structures. Virtual reduction was performed iteratively using the three orthogonal imaging planes axial, coronal, and sagittal, guided by anatomical landmarks, including the residual intact mandibular segment and fracture line morphology (Fig. 6). Using the software’s movement and rotation tools, the fragment was repositioned to achieve optimal congruence. Notably, natural fracture line irregularities, such as triangular interlocks and notches, functioned as intrinsic “key-lock” guides for anatomically accurate repositioning (Fig. 6).

Fig. 6.

Virtual reduction of the fractured fragment performed iteratively using the software’s movement (A–D) and rotation (E–H) tools across the three orthogonal imaging planes: sagittal (A, E), axial (B, F), and coronal (C, G)

Final reduction accuracy was confirmed by evaluating the continuity of the inner and outer cortical borders and by matching fracture line topography across the three orthogonal imaging planes. The virtually reduced fragment was then integrated with the residual mandible to form a unified 3D model. Reduction success was further confirmed by continuity of the cortical borders, consistent fracture line topography, and a symmetric spatial relationship of both condyles relative to the cranial base (Fig. 7).

Fig. 7.

Following virtual reduction. A–C Coronal, sagittal, and axial CT slices showing the reduced fragment. D, E Anterior and posterior 3D views showing the virtually reduced fragment integrated with the residual mandible. F Coronal view comparing the virtually reduced condyle to the contralateral condyle. G 3D surface model illustrating bilateral condylar positioning within the glenoid fossae. Note: Successful reduction was confirmed by continuity of the inner and outer cortical borders, matching fracture line topography across the three orthogonal imaging planes, and a symmetric spatial relationship of both condyles relative to the cranial base

Validation and reproducibility

In the absence of pre-traumatic imaging, direct comparison between the virtual reduction and the actual surgical fixation using postoperative images is an unreliable validation method. Surgical reduction depends on the surgeon’s experience and is often complicated by fragment misalignment, bone loss, or intraoperative bone trimming. Consequently, the postoperative outcome may deviate from the ideal pre-traumatic anatomy, limiting its value as a validation reference.

The literature confirms that the mandibular ramus exhibits bilateral symmetry in linear and angular dimensions. However, the condylar head often displays volumetric and surface asymmetry, likely due to functional adaptation. Therefore, using linear and angular measurements from the mirrored contralateral (non-fractured) condyle as a reference control is acceptable in unilateral fractures with an intact contralateral side.

In this study, the virtually reduced side was quantitatively compared with the mirrored control side using two linear and two angular measurements:

• Linear: (1) total mandibular ramus height (gonion to condylion), and (2) distance between the most lateral border of the condylar head and the most lateral border of the coronoid process.

• Angular: (1) gonial angle (formed by the intersection of the mandibular body and ramus), and (2) condylar head–mandibular notch angle (defined by connecting the condylion, mandibular notch, and coronoid process).

All linear and angular measurements (Fig. 8) were obtained from the 3D-reconstructed mid-sagittal slice of the hemimandible using the caliper and angle tools in 3D Slicer v5.2. To assess the reproducibility of the virtual reduction workflow, two oral and maxillofacial surgeons, blinded to each other’s outcomes, independently performed the segmentation and virtual reduction for all cases. Following reconstruction, the same two observers independently repeated all linear and angular measurements on the virtually reduced models for every case.

Fig. 8.

Linear and angular measurements. (A–B) Total mandibular ramus height (gonion to condylion). (A–B–C) Gonial angle, formed by the intersection of the posterior border of the mandibular ramus and the lower border of the mandibular body. (A–D–E) Condylar head–mandibular notch angle, defined by the lines connecting the condylion (A), mandibular notch (D), and coronoid process (E). (F–G) Distance between the most lateral borders of the condylar head (F) and the coronoid process (G), measured along a horizontal tangent line touching the most lateral point of each structure

Statistical analysis

Statistical analyses were performed using IBM SPSS Statistics (v27.0, IBM Corp., Armonk, NY, USA). Descriptive statistics were reported as frequencies, medians, and interquartile ranges (IQRs). Shapiro–Wilk tests indicated non-normal distribution for all four morphometric variables; therefore, the Wilcoxon signed-rank test was used to compare paired measurements. Equivalence between virtual reduction and contralateral mirroring was formally tested using the Two One-Sided Tests (TOST) procedure for paired samples (primary and sensitivity analysis). Interobserver reliability was evaluated using intraclass correlation coefficients (ICCs) with a two-way random-effects model for absolute agreement. Ninety-five percent confidence intervals were calculated for all ICC estimates. Statistical significance was set at p < 0.05.

Outcomes

The study included 45 patients with unilateral mandibular condylar fractures, comprising 29 males (64.5%) and 16 females (35.5%). Fractures occurred on the left side in 53.3% of cases and on the right side in 46.7%. Based on anatomical location, the fractures were classified as condylar head (Types B and C; 28.9%, n = 13), condylar neck (37.7%, n = 17), and subcondylar (33.4%, n = 15). Traffic accidents were the leading etiology (51.1%, n = 23), followed by falls (42.2%, n = 19). Concomitant mandibular fractures were common: 33.3% presented with midline fractures, 26.7% with symphysis fractures, while isolated condylar fractures occurred in 24.4% of cases (Table 1).

Table 1.

Demographic features for patients

Demographics	Number
Gender
Male	29 (64.5%)
Female	16 (35.5%)
Fracture side
Right	21 (46.7%)
Left	24 (53.3%)
Fracture Classification
Condylar Head fracture	13 (28.9%)
Type A	0
Type B	8
Type C	5
Condylar Neck fracture	17 (37.7%)
Subcondylar fracture	15 (33.4%)
Cause of fracture
Fall down	19 (42.2%)
Traffic Accident	23 (51.1%)
Fighting	3 (6.7%)
Concomitant fracture
Midline fracture	15 (33.3%)
Symphysis fracture	12 (26.7%)
Contralateral body fracture	7 (15.6%)
No other fracture	11 (24.4%)

Table 2 presents a paired comparison of four morphometric parameters between the virtually reduced side and the mirrored contralateral control side. No statistically significant differences were observed: total ramus height (61.5 mm vs. 61.0 mm; p = 0.59), gonial angle (116.6° vs. 116.2°; p = 0.48), head–notch angle (100.7° vs. 101.0°; p = 0.38), and head–coronoid process distance (40.8 mm vs. 41.0 mm; p = 0.73). Median differences were clinically negligible (≤ 0.5 mm and ≤ 0.4°), and overlapping interquartile ranges confirmed high consistency. These findings confirm that the virtual reduction protocol accurately restored native mandibular morphology.

Table 2.

Morphometric comparison between the multiplanar virtually reduced side and the mirrored contralateral control side using the Wilcoxon signed-rank test

Variable Measurements	Multiplanar virtually reduced side Median (IQR)	Mirrored contralateral side Median (IQR)	p-value
Total height of the vertical ramus (mm)	61.5 (59.75–67.1)	61 (59.4–67.2)	0.59
Head - Coronoid process distance (mm)	40.8 (36.8–44.2)	41 (36.55–44.3)	0.73
Gonial angle (°)	116.6 (110.95–120.4)	116.2 (112–121)	0.48
Head - Notch angle (°)	100.7 (95.4–101.85)	101 (95.35–102)	0.38

Linear measurements (mm) and angular measurements (°)

The virtual reduction workflow demonstrated excellent interobserver reliability, with ICCs ranging from 0.96 to 0.97. Similarly, repeated morphometric measurements, including both linear and angular parameters exhibited excellent reproducibility, with ICCs ranging from 0.97 to 0.98 (Tables 3 and 4).

Table 3.

Intraclass Correlation Coefficients (ICC) for Interobserver Reliability of Linear and Angular Morphometric Measurements in the Virtually Reduced Models

Variable Measurements	ICC	95% Confidence Interval
		Lower Bound	Upper Bound
Total height of the vertical ramus (mm)	0.989	0.980	0.994
Head - Coronoid process distance (mm)	0.986	0.971	0.992
Gonial angle (°)	0.979	0.962	0.988
Head - Notch angle (°)	0.988	0.978	0.993

Table 4.

Intraclass Correlation Coefficients (ICC) for Interobserver Reliability of Linear and Angular Morphometric Measurements in the Mirrored Contralateral Models

Variable Measurements	ICC	95% Confidence Interval
		Lower Bound	Upper Bound
Total height of the vertical ramus (mm)	0.988	0.978	0.993
Head - Coronoid process distance (mm)	0.984	0.966	0.991
Gonial angle (°)	0.988	0.979	0.994
Head - Notch angle (°)	0.989	0.980	0.994

Equivalence Testing: primary and sensitivity Analysis

Equivalence testing using the TOST procedure confirmed that the virtually reduced condylar morphology was statistically equivalent to the mirrored contralateral reference across all four evaluated parameters (p-TOST < 0.05 for all), (Table 5). A sensitivity analysis using more conservative margins (± 1.0 mm / ±2.5°) confirmed these findings (Table 5).

Table 5.

Equivalence testing between virtual reduction and contralateral mirroring

Measurement	Mean Diff.	90% CI	Equivalence Margin	TOST p-value	Equivalent?
Primary Analysis: Pre-specified equivalence margins (Linear ± 2.5 mm, Angular ± 3°)
Total ramus height	+ 0.112	(-0.099, + 0.324)	± 2.0 mm	< 0.0001	Yes
Head–coronoid distance	-0.040	(-0.241, + 0.161)	± 2.0 mm	< 0.0001
Gonial angle	-0.724	(-2.430, + 0.981)	± 3.0°	0.0150
Head–notch angle	-0.058	(-0.162, + 0.047)	± 3.0°	< 0.0001
Sensitivity Analysis: Conservative Margins (Linear ± 1 mm, Angular ± 2.5°)
Total ramus height	+ 0.112	(-0.099, + 0.324)	± 1.0 mm	< 0.0001	Yes
Head–coronoid distance	-0.040	(-0.241, + 0.161)	± 1.0 mm	< 0.0001
Gonial angle	-0.724	(-2.430, + 0.981)	± 2.5°	0.0436
Head–notch angle	-0.058	(-0.162, + 0.047)	± 2.5°	< 0.0001

Linear measurements (mm) and angular measurements (°)

Discussion

A variety of implant systems are currently available for managing fractures of the mandibular ramus, condylar neck, and condylar head [10–12]. However, conventional rigid prefabricated implants cannot be adjusted intraoperatively to accommodate anatomical variations. VSP addresses this limitation by aiding in diagnosis, improving surgical precision, and facilitating hardware selection, with studies reporting reduced operation time and enhanced fixation planning [13, 14]. PSIs designed through virtual fracture reduction, have emerged as a promising alternative [2, 15, 16]. The current study presents a reproducible, anatomy-driven virtual reduction protocol that reconstructs the pre-injury condylar configuration using post-traumatic CT data.

In the current study, no statistically significant differences were observed between the virtually reduced side and the mirrored contralateral control across all morphometric parameters. These findings indicate that the virtual reduction protocol effectively restored both linear and angular dimensions to align with the unfractured contralateral anatomy. This approach is anatomically supported by an independent cadaveric study of 40 adult human mandibles, which demonstrated bilateral symmetry of the mandibular ramus: condylar height, mandibular notch height, and minimum ramus breadth showed no significant inter-side differences when measured with a digital caliper [17]. These findings validate the use of the contralateral side as a control. Consistent with this premise, our virtual reduction yielded near-identical measurements between the reduced and mirrored sides, including total ramus height (61.5 mm vs. 61.0 mm), gonial angle (116.6° vs. 116.2°), head–notch angle (100.7° vs. 101.0°), and head–coronoid process distance (40.8 mm vs. 41.0 mm).

Our findings also align with prior anthropometric studies confirming mandibular bilateral symmetry in normo-occlusal populations. Thiesen et al. [18] evaluated symmetry in a Class I cohort and reported no significant inter-side differences, with mean bilateral discrepancies ranging from − 0.54 ± 2.41 mm to 0.41 ± 2.42 mm across multiple ramus-related dimensions. Similarly, Mendoza et al. [19] assessed linear symmetry in a normal population, finding negligible mean differences for condylar height (− 0.44 to 0.02 mm) and ramus height (− 0.43 to 0.40 mm), with no statistically significant asymmetry in any parameter.

While several virtual reduction workflows for mandibular condylar fractures have been introduced [2, 4–6], they typically rely on mirroring the healthy contralateral condyle as a template for the affected side. However, contralateral mirroring is not applicable in bilateral fractures or cases with contralateral compromise. Additionally, some workflows perform virtual repositioning on 3D surface models rather than directly on multiplanar CT images, which may compromise accuracy. For instance, Liokatis et al. [5] evaluated the accuracy and clinical utility of VSP combined with CAD/CAM-fabricated PSIs for secondary correction of post-traumatic mandibular condyle deformities. Similarly, Matschke et al. [2] introduced a workflow for virtual repositioning of mandibular condyle fractures to create PSIs that precisely match the fractured side’s surface. However, they noted that their workflow is not applicable in bilateral fractures, comminuted fractures, or patients with asymmetric mandibular rami. Shakya et al. [4] conducted a randomized controlled study assessing VSP’s application value in mandibular condylar fractures, performing virtual repositioning on a 3D surface model rather than directly on multiplanar CT images. Likewise, Batbayar et al. [6] presented a workflow in which the condylar fracture was virtually reduced on a 3D surface model using a mirrored template from the non-fractured contralateral condyle as a reduction guide.

In contrast, several studies have reported statistically significant right-sided predominance in condylar morphology, particularly in volumetric and surface parameters. Shetty et al. [20], in a cadaveric study of 96 temporomandibular joints, reported a significant difference in mean condylar volume between right and left sides. This finding was corroborated in a Caucasian cohort [21], in which the right condyle exhibited, on average, 25.39 mm³ greater volume (+ 3.9%) and 17.15 mm² greater surface area (+ 5.45%) than the left (p < 0.01).

According to the literature, condylar morphology can be influenced by both functional adaptation and pathological factors. Functional adaptation includes bone apposition on the dominant chewing side due to muscle hypertrophy and increased loading [22], while pathological factors include tooth loss, malocclusion, or asymmetric occlusal forces. The articular cartilage acts as a growth center that responds to altered biomechanics through changes in thickness and maturation, thereby affecting condylar dimensions [23].

Collectively, these findings suggest a key anatomical distinction: while the mandibular ramus exhibits bilateral symmetry in linear and angular dimensions, the condylar head often displays volumetric and surface asymmetry, likely due to functional adaptation. This supports the validity of using the contralateral side as a reliable reference for ramus-based linear and angular measurements in virtual reduction. Comparing virtual reductions to postoperative fixation is unreliable, as surgical outcomes are influenced by technique, bone loss, or intraoperative adjustments, and may not reflect true pre-injury anatomy. Thus, the contralateral condyle remains the only available reference for assessing anatomical accuracy. However, the contralateral condylar head alone may not serve as an exact volumetric or morphological surrogate for pre-traumatic condylar anatomy, particularly in cases requiring patient-specific implant design. This limitation necessitates complementary strategies. The key innovation of our workflow is that the reduction is performed directly on multiplanar CT rather than on a 3D surface model. This approach enables precise, landmark-guided realignment that leverages cortical continuity and fracture-line topography. Importantly, it does not use contralateral mirroring as a template during the reduction process.

Intracapsular and condylar head fractures are routinely managed conservatively, and our 3D virtual reconstruction workflow does not imply that surgical reduction is indicated. Rather, it enables quantitative comparison between the virtually reduced model (T0) and post-closed reduction images to assess fragment healing, TMJ fossa adaptation, and repositioning accuracy. This approach yields insights into remodeling after conservative care that conventional radiography alone cannot provide.

Several limitations of this study should be acknowledged. These include the absence of pre-traumatic CT scans, which precluded intra-individual validation of the reconstructions, and the lack of clinical validation. Furthermore, all cases involved unilateral fractures, many with associated mandibular fractures, which may complicate the reliability of TMJ landmark referencing. The morphometric analysis itself is also subject to constraints, including operator dependency in the analytical process. Future research should extend this method to bilateral cases and correlate virtual accuracy with postoperative clinical and functional outcomes.

Conclusion

While surgical expertise remains paramount for successful outcomes, Elayah’s multiplanar anatomy-driven virtual reduction workflow offers a reliable and feasible adjunct to traditional planning methods for condylar fractures, particularly when pre-traumatic imaging is unavailable. Its key innovation is that the virtual reduction is performed directly on multiplanar CT rather than on a 3D surface model. This workflow does not rely on mirroring the contralateral side, instead enabling precise, landmark-guided realignment that leverages cortical continuity and fracture-line topography.

Authors’ contributions

S.A.E. introduced the virtual reduction workflow and contributed to the acquisition of data, analysis and interpretation of data, the writing of the original manuscript, and agreed to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. R.Z., J.C., and R.A. contributed to the drafting and critical revision of the manuscript. L.J. contributed to the study conception and design and critically reviewed the manuscript. All authors have reviewed and approved the final version before its submission.

Funding

This research was supported by the National Nature Science Foundation of China (No.31570950) and the Science and Technology Foundation of Sichuan Province (No. 2024YFFK0376).

Data availability

The datasets used and/or analyzed during the study are available from the corresponding author upon reasonable request.

Declarations

Ethics approval and consent to participate

This study was conducted in compliance with the principles of the Helsinki Declaration. The Institutional Ethics Committee of West China Hospital of Stomatology, Sichuan University, approved the study. At the time of the original data collection, all participants provided broad written informed consent permitting the use of their data for future research purposes, as per institutional protocols.

Consent for publication

‘Not applicable’.

Competing interests

The authors declare no competing interests.