BACKGROUND: Alignment of the zygomaticosphenoid (ZS) suture is fundamental to reduction of zygomaticomaxillary complex (ZMC) fractures.1–3 Lateral displacement and anteroposterior impaction of the anterior segment must be corrected. Furthermore, to prevent a rotational deformity, the correct angle of the zygoma relative to the cranial base must be restored. Clinically, this can be a challenge, especially when there is comminution of the ZS suture. The purpose of this study was to define normative values for a ZS angle. These data may be used as a reference in conjunction with stereotactic navigation to achieve anatomic orientation of the anterior fracture segment in ZMC fracture reduction. Normative data of this angle could be used in bilateral fractures, and if constant across laterality, patient-specific data could be used as a guide in unilateral injuries.
METHODS AND MATERIALS: A single-center retrospective analysis of 100 patients was designed to determine normative ZS angle values. Computed tomography (CT) data of patients with isolated mandibular fractures were used to select for a craniofacial trauma demographic with available CT and intact midface skeletal anatomy. An angle subtended by the midline and a best fit line through the ZS on axial CT was measured bilaterally. The mean value of this measurement for 3 vertically adjacent cuts was calculated with the position of central cut determined by the equator of the globe and trigone of the sphenoid. Measurements and assessment of cuts were performed and verified by 2 investigators to ensure consensus. Demographic data including age, sex, and ethnicity were collected for comparison.
RESULTS: The mean ZS angle was 47° (range, 39°–55°). Ninety-seven percent of angles were within 2 SDs (8°) of the mean. Subgroup analysis demonstrated no significant difference of ZS angle across age (P = 0.74) or sex (P = 0.89). White patients (45.60°) were found to have more acute ZS angles than black (47.73°; P = 0.02) or Hispanic (47.45°; P = 0.04) patients. For each angle, the variation across the 3 sample cuts was ≤4.5° in all cases. Patients demonstrated high fidelity of ZS angle bilaterally with a mean difference of 3°.
CONCLUSIONS: The ZS angle is a useful reference, in conjunction with stereotactic navigation, for anatomic reduction of ZMC fractures. Contralaterally obtained patient-specific data may be used to guide unilateral repair. Normative values may serve as reference in bilateral injury.
REFERENCES:
1. Zingg M, Laedrach K, Chen J, et al. Classification and treatment of zygomatic fractures: a review of 1,025 cases. J Oral Maxillofac Surg. 1992;50:778–790.
2. Kelley P, Hopper R, Gruss J. Evaluation and treatment of zygomatic fractures. Plast Reconstr Surg. 2007;120(7 Suppl 2):5S–15S.
3. Lee EI, Mohan K, Koshy JC, et al. Optimizing the surgical management of zygomaticomaxillary complex fractures. Semin Plast Surg. 2010;24:389–397.