The zygomatic bone, commonly known as the cheekbone, connects to four neighbouring bones through four sutures: the zygomaticomaxillary suture where it meets the upper jaw, the sphenozygomatic suture where it meets the sphenoid bone deep within the skull, the temporozygomatic suture where it meets the temporal bone, and the frontozygomatic suture where it meets the frontal bone of the forehead. Together, these junctions form the architectural framework of the zygomaticomaxillary complex, a structure that is frequently fractured in facial trauma from road accidents, sports injuries and assaults. When surgeons repair such fractures, they rely on anatomical landmarks to restore the original position of the bone, but until now there has been limited comparative data on the projected geometry of all four sutures measured within a single, consistent imaging protocol.

The research team took a retrospective cross-sectional approach, analysing cranial CT examinations that yielded 762 measurable sides across 381 adult patients. Rather than measuring the sutures directly on individual axial slices, which can distort their true course, the researchers used a technique called maximum intensity projection reformats with standardised thick slabs. This method projects the brightest bone signals along a viewing axis onto a single plane, allowing the entire winding course of each suture to be visualised and measured as a continuous line. On these projected images, the team recorded four parameters for each suture on both sides of every patient: the projected length along the suture’s full course, the end-to-end straight-line distance between its endpoints, the sinuosity, which is the ratio of the full course length to the straight-line distance and captures how winding the suture is, and the angle the suture makes with the Frankfort horizontal plane, a standard cranial reference plane that runs from the lower edge of the eye socket to the upper edge of the ear canal.

The statistical analysis was designed with care for the fact that measurements from the two sides of the same patient are not independent observations. The researchers used generalised estimating equations, a method that accounts for this within-patient correlation, and applied false discovery rate adjustment to control for the many comparisons being made simultaneously. They also calculated patient-level Spearman correlations to explore whether the dimensions of one suture predict those of another within the same individual, and intraclass correlation coefficients to quantify how closely the left and right sides of each suture matched within a single person. This combination of approaches allowed the team to distinguish genuine group-level patterns from individual variability, a distinction that proved central to their findings.

The results revealed that each of the four sutures possesses its own characteristic geometric signature. Among the defined projected measurement courses, the zygomaticomaxillary suture showed the greatest mean length and the greatest end-to-end distance, reflecting its role as the long horizontal junction between the cheekbone and the upper jaw. The orientation measurements were particularly striking: the mean angles to the Frankfort horizontal plane ranged from 15.3 degrees for the frontozygomatic suture, which runs nearly parallel to that reference plane, to 67.1 degrees for the sphenozygomatic suture, which plunges steeply into the depth of the skull. In other words, the four sutures are not variations on a theme but genuinely different structures in terms of size, winding pattern and three-dimensional orientation, each demanding its own reference values in any clinical or anatomical application.

The correlations between sutures added another layer of nuance. For dimensional parameters such as length and distance, and for sinuosity, the intersuture correlations were weak to moderate, with the largest Spearman coefficient reaching only 0.40. This suggests that a person with a long zygomaticomaxillary suture cannot be assumed to have correspondingly long other zygomatic sutures; each suture appears to develop largely on its own geometric trajectory. The angular correlations were even smaller, with the largest absolute coefficient at just 0.12, and none of the angular correlations remained statistically significant after false discovery rate adjustment. The orientation of one suture, in short, tells you essentially nothing about the orientation of its neighbours, reinforcing the picture of four independently patterned anatomical features.

Sex and side differences emerged in a pattern that clinicians will find informative. Length and end-to-end distance were greater in males for all four sutures, consistent with the overall sexual dimorphism of the craniofacial skeleton. Side differences, however, were remarkably limited at the group level: the only directional left-right difference detected was in the sphenozygomatic straight-line distance. This near-symmetry at the population level might suggest that the two sides of any individual’s face are mirror images, but the bilateral intraclass correlation coefficients told a more complicated story. These coefficients, which measure how strongly the left and right measurements correspond within the same person, ranged from 0.37 to 0.80 across the different sutures and parameters. Small average side differences, in other words, coexist with considerable individual variation in symmetry, meaning that some people have closely matched pairs of sutures while others show substantial left-right divergence even though the group averages look balanced.

This distinction between group-level symmetry and individual-level agreement has practical implications for the concept of using the uninjured side as a template for reconstructing the injured side, a common strategy in maxillofacial surgery. If bilateral agreement varies substantially from person to person, then the healthy side of a patient with a zygomaticomaxillary complex fracture may be a more or less reliable guide depending on which suture is involved and which parameter is being compared. The authors are careful to stress, however, that their data come from a single centre and a single scanner, and that the measurements were descriptive projected morphometric values obtained from a general adult population rather than from fracture patients. Before these reference values can be used in fracture reduction assessment or surgical planning, they require external validation in independent cohorts and direct evaluation in patients with actual zygomatic fractures.

The study also stands as an example of methodological transparency in modern anatomical research. The protocol was approved by the İstanbul Medipol University Non-Interventional Clinical Research Ethics Committee, and the requirement for individual informed consent was waived because of the retrospective design and the use of fully anonymised archival imaging data. The authors disclosed that a generative artificial intelligence tool was used for English-language editing, assistance with statistical coding and document formatting, but not for autonomous data analysis or interpretation, with all statistical analyses executed, reviewed and interpreted by the researchers themselves. The work received no specific external funding, and the authors declared no competing interests.

For a field in which surgical decisions can hinge on millimetre-scale judgments of bone position, the value of a large, standardised morphometric dataset is difficult to overstate. By demonstrating that the four zygomatic sutures have distinct projected profiles, that their orientations span a remarkable range from nearly horizontal to steeply inclined, and that individual bilateral symmetry is variable even when population averages appear balanced, the study gives anatomists, radiologists and surgeons a firmer quantitative foundation for understanding the midface. The next step, as the authors make clear, is to test whether these normal values can discriminate between restored and malpositioned bones in real fracture cohorts, transforming a descriptive anatomical atlas into a practical instrument for reconstructive care.

Subject of Research: Computed tomography-based morphometry of the four zygomatic sutures in adults

Article Title: Computed tomography-derived projected morphometry of four zygomatic sutures: distinct geometric profiles and bilateral agreement

Article References: Altıntaş, H. M., Köksal, A., Cingöz, G., Eberliköse, H., & Demir, B. T. (2026). Computed tomography-derived projected morphometry of four zygomatic sutures: distinct geometric profiles and bilateral agreement. BMC Medical Imaging. https://doi.org/10.1186/s12880-026-02896-x

Image Credits: AI Generated

DOI: 10.1186/s12880-026-02896-x

Keywords: computed tomography, zygomatic sutures, morphometry, craniofacial anatomy, zygomaticomaxillary complex, facial asymmetry, maxillofacial surgery, maximum intensity projection, bilateral agreement, Frankfort horizontal plane, facial trauma, BMC Medical Imaging

The zygomaticomaxillary complex, or ZMC, is the bony buttress that anchors the middle third of the face, articulating with the frontal, temporal, sphenoid, and maxillary bones. It is far more than a cosmetic structure. It serves as the insertion site for the masseter muscle, protects the temporal muscle and coronoid process, separates the orbit from the temporal fossa and maxillary sinus, and absorbs forces directed toward the eye and brain during trauma. Fractures of this region are the second most common facial fractures after nasal fractures, accounting for more than 40 percent of midface trauma cases reported in Washington, 44.3 percent in Belgium, and roughly 30 to 40 percent of midface fractures in Indonesia.

The standard surgical treatment is open reduction and internal fixation, known as ORIF, in which the fractured bone is directly visualized, repositioned, and secured with miniplates. The rationale is to achieve maximum reduction and stability to prevent micromovement of the bone fragments. If fixation is inadequate, even tiny shifts in the position of the malar bone can produce visible asymmetry and serious functional complications, including orbital dystopia, enophthalmos, and diplopia. Yet despite the stakes, there has never been a settled consensus on how many fixation points are needed, and previous studies have pointed in conflicting directions.

Some evidence favored more hardware. A systematic review by Jazayeri and colleagues reported that three-point fixation was superior to two-point fixation in terms of orbital dystopia symmetry and malar bone symmetry. Degala and colleagues, working with CT scans, found that two-point fixation was sufficient for malar symmetry with a more minimal surgical approach, while Shokri and colleagues went further, arguing that a single fixation point at the zygomaticomaxillary buttress was adequately stable in non-comminuted fractures. Each additional surgical approach, however, carries a price: more scarring, more risk of nerve injury and paresthesia, longer operating times, and more extensive stripping of periosteum.

To resolve the question, researchers at Universitas Gadjah Mada and Prof. Dr. Margono Soekarjo Regional General Hospital conducted a retrospective analysis of patients treated between 2020 and 2024. From 144 patients with unilateral ZMC fractures, 60 met strict inclusion criteria: non-comminuted fractures, adequate Waters-view radiographs, complete medical records, ages between 11 and 60, and the presence of molar teeth for occlusion. Patients were excluded if their radiographs were of inadequate quality or if they had additional mandibular fractures that could affect occlusion. The final cohort was divided into three groups of 20 patients each: one-point, two-point, and three-point fixation.

The methodological centerpiece was a symmetry analysis performed on Waters radiographs taken three days after surgery, a time point chosen because it marks the beginning of primary healing and the end of the inflammatory phase. The images were standardized to a fixed pixel size and analyzed in ImageJ software. Anatomical landmarks, including the anterior nasal spine, the crista galli, and the lowest point of the orbital rim on both sides of the face, were connected to form right triangles on the fractured and non-fractured sides. Horizontal, vertical, and diagonal line lengths were then compared using a modified version of Kim’s symmetry index, in which the squared differences between the two sides are summed and square-rooted. A smaller index means a more symmetrical result. The team added a second layer of statistical rigor with Bland-Altman analysis, which assesses agreement between paired measurements by calculating 95 percent limits of agreement.

The results were striking. The smallest mean symmetry index, 0.42 plus or minus 0.16, was found in the two-point fixation group, followed closely by the three-point group at 0.45 plus or minus 0.18. The one-point group lagged well behind at 0.79 plus or minus 0.22. Tukey post-hoc testing showed no statistically significant difference between the two-point and three-point groups, with a p value of 0.8, but both differed significantly from the one-point group, with p values below 0.001 and large effect sizes. The Bland-Altman analysis told the same story: the two-point group had the narrowest 95 percent limits of agreement, spanning roughly 1.37 to minus 1.11, compared with wider limits in the three-point and especially the one-point group. All three groups nonetheless fell within the range considered symmetrical overall.

The patient population reflected the epidemiology of facial trauma in a developing country. The cohort was predominantly male, mostly aged 11 to 30, and road traffic accidents were the dominant cause, with closed fractures predominating, a pattern the authors attribute to the high-risk activity profiles of young men and the prevalence of motorcycles as a primary mode of transportation in Indonesia. The intraoral vestibular approach was the most common surgical route in all groups, valued for being effective, minimally invasive, and cosmetically favorable. Two-point fixation was most often placed at the zygomaticomaxillary and frontozygomatic regions, while three-point fixation added the infraorbital rim. Notably, paresthesia was the only complication observed, present preoperatively in all groups and decreasing by postoperative day three, with the largest decrease, 35 percent, seen in the two-point group.

The authors are careful about what their findings do and do not prove. The measurements capture the accuracy of reduction in the immediate postoperative period, not long-term stability, and masticatory forces from the masseter and temporalis muscles can cause secondary malposition over time. No diplopia, dystopia, or malocclusion was found, but the short follow-up cannot exclude delayed complications. The team also acknowledges technical limitations: a single radiologist performed the assessments, and the reported gaps of 0.01 to 0.06 millimeters fall below the approximate 0.2 to 0.4 millimeter spatial resolution of conventional radiography, meaning some measured differences may be smaller than the imaging can reliably resolve. Radiological asymmetry below two millimeters, other work suggests, is generally not visible clinically.

Even with those caveats, the clinical message is pragmatic and potentially practice-changing. Theoretically, more fixation points should mean better stability, but each additional plate demands wider surgical access, more periosteal stripping, greater risk of nerve injury, and longer anesthesia time. This study indicates that if adequate reduction and stability can be achieved with two plates, adding a third offers no measurable symmetry benefit in early radiographic assessment while increasing surgical burden. The authors conclude that the number of fixation points should be tailored to each case, considering displaced fragments, the number of fracture locations, and the stability achieved after reduction, and they call for longer follow-up studies to confirm that the early symmetry advantage of two-point fixation translates into durable, complication-free outcomes.

Subject of Research: Radiographic comparison of one-, two-, and three-point fixation for postoperative malar symmetry in zygomaticomaxillary complex fracture repair

Article Title: Optimal postoperative symmetry after two-point fixation with open reduction in internal fixation of complex zygomaticomaxillary fractures: a radiographic analysis

Article References: Nastiti, K. A., Rahajoe, P. S., & Istadi, D. (2025). Optimal postoperative symmetry after two-point fixation with open reduction in internal fixation of complex zygomaticomaxillary fractures: a radiographic analysis. BMC Plastic and Reconstructive Surgery, 1(1), Article 10. https://doi.org/10.1186/s44452-025-00010-8

Image Credits: AI Generated

DOI: 10.1186/s44452-025-00010-8

Keywords: zygomaticomaxillary complex fracture, open reduction internal fixation, fixation points, facial symmetry, Waters radiograph, symmetry index, Bland-Altman analysis, maxillofacial surgery, malar bone, facial trauma, miniplate fixation, retrospective study