Non-syndromic craniosynostosis: contemporary concepts in biology, diagnosis, and distraction-based operative strategy

Wooyeol Baek

doi:10.7181/acfs.2026.0127

Arch Craniofac Surg > Volume 27(4); 2026 > Article

Baek: Non-syndromic craniosynostosis: contemporary concepts in biology, diagnosis, and distraction-based operative strategy

Review Article

Archives of Craniofacial Surgery 2026;27(4):163-172.

Published online: August 20, 2026

DOI: https://doi.org/10.7181/acfs.2026.0127

Non-syndromic craniosynostosis: contemporary concepts in biology, diagnosis, and distraction-based operative strategy

Wooyeol Baek^1,²

¹Department of Plastic and Reconstructive Surgery, Yonsei University College of Medicine, Seoul, Korea

²Institute for Human Tissue Restoration, Yonsei University College of Medicine, Seoul, Korea

Correspondence: Wooyeol Baek Department of Plastic and Reconstructive Surgery, Yonsei University College of Medicine, 50-1 Yonsei-ro, Seodaemun-gu, Seoul 03722, Korea E-mail: parande@yuhs.ac

Received August 11, 2026 Revised August 11, 2026 Accepted August 20, 2026

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Non-syndromic craniosynostosis is the most common clinical form of craniosynostosis, but the mature phenotype cannot be accounted for by a purely local model of premature suture fusion. The deformity is the product of interactions among calvarial growth, cranial base geometry, dural and mesenchymal signaling, orbital development, and regional soft-tissue adaptation. This narrative review examines current evidence on epidemiology, developmental biology, diagnosis, imaging, operative timing, and surgical management, with emphasis on systematic reviews, multicenter and population-based data, comparative cohorts, and larger independent series. Contemporary options—conventional cranial vault remodeling, fronto-orbital advancement and remodeling, endoscope-assisted suturectomy with postoperative orthotic therapy, spring-assisted techniques, and distraction osteogenesis—each occupy a legitimate place in selected age groups and phenotypes. This review gives particular attention to distraction because of its potential for individualized, three-dimensional correction: it is the approach in which vector, magnitude, and regional expansion can be adjusted while new bone forms and the surrounding soft-tissue envelope adapts, which is precisely what a three-dimensional deformity demands. Current comparative evidence does not establish superiority for every subtype, but the biologic rationale and available clinical results justify a broader role for distraction in contemporary reconstruction. Osteotomy design and vector geometry should follow the dominant phenotype: transverse expansion when biparietal restriction predominates in sagittal synostosis; multivector correction when orbital, skull-base, or posterior vault distortion is established; and a higher operative threshold in metopic synostosis, where true fronto-orbital narrowing—not suture fusion alone—should drive the decision. Outcomes should be judged by deformity-specific three-dimensional balance, functional safety, treatment burden, and long-term stability, and not by a single cranial index.

Keywords: Craniofacial abnormalities / Craniosynostoses / Infant / Osteogenesis, distraction / Osteotomy / Three-dimensional imaging / Tomography, X-ray computed

INTRODUCTION

Craniosynostosis has traditionally been defined as the premature fusion of one or more cranial sutures, restricting growth perpendicular to the fused suture and redirecting expansion through the remaining growth sites. As a quick frame for recognizing classic head shapes, that model still serves well. It falls short, however, in accounting for the mature deformity. Even a single fused suture may be followed by secondary changes in the cranial base, the orbit, the facial axis, and the soft-tissue envelope, and the resulting phenotype is a whole-vault problem, not an isolated osseous closure. Non-syndromic craniosynostosis may therefore be better understood as a patterned disorder of cranial growth than as a local event confined to one suture.

The distinction is not academic, because patients who carry the same diagnostic label do not necessarily share the same reconstructive target. An infant referred early with relatively isolated sagittal narrowing may be well served by a limited release or a minimally invasive approach. A later-presenting child with established vault disproportion needs more deliberate control of regional cranial geometry. The same principle governs unicoronal synostosis: frontal projection alone cannot certify correction while orbital dystopia, nasal deviation, and cranial base rotation persist. Throughout this review, operative planning is therefore related to the dominant three-dimensional deformity, rather than simply to the fused suture. Distraction is particularly well suited to this way of thinking, because the osteotomy pattern and the direction, magnitude, and rate of correction can be adapted to the deformity and to the age-dependent response of the skull and soft tissues.

LITERATURE SEARCH AND SELECTION

For this narrative review, a targeted search of PubMed/MEDLINE was performed through August 2026, supplemented by screening of reference lists and citation tracking of recent reviews and comparative studies. The search combined terms for craniosynostosis, non-syndromic, sagittal, metopic, unicoronal, lambdoid, cranial vault remodeling, fronto-orbital advancement, endoscopic, helmet, spring-assisted, distraction osteogenesis, imaging, morphometry, and long-term outcome. The review was restricted to English-language peer-reviewed studies, with priority given to clinical guidelines, systematic reviews and meta-analyses, population-based or multicenter datasets, comparative cohorts, larger institutional series, and studies reporting three-dimensional or long-term outcomes. Seminal technical studies were retained when they remained directly relevant to contemporary practice, and evidence from syndromic craniosynostosis was not used to support subtype-specific recommendations for isolated disease unless the underlying principle was explicitly transferable. Because this is a narrative review, formal risk-of-bias grading and quantitative meta-analysis were not applied; differences in age at surgery, phenotype severity, treatment protocols, and center-specific selection were weighed when interpreting cross-technique comparisons [1-4].

EPIDEMIOLOGY AND PHENOTYPIC SPECTRUM

Population-based estimates vary with geography and ascertainment method, but craniosynostosis affects roughly 4 to 6 per 10,000 live births, and the majority of cases are non-syndromic [5,6]. Sagittal synostosis is generally the most frequent subtype. In several population datasets the proportion of metopic synostosis has increased over time; whether this reflects a true rise in prevalence, changes in referral and diagnostic recognition, or a combination remains unsettled [5,7]. Unicoronal synostosis is less common than sagittal or metopic disease, and true lambdoid synostosis is distinctly uncommon [5,8].

Phenotypic classification still matters, because each subtype represents a different three-dimensional disturbance of cranial growth. Sagittal synostosis produces scaphocephaly, with biparietal narrowing and variable frontal and occipital bossing. Metopic synostosis spans a spectrum from an isolated midline ridge to true trigonocephaly with bifrontal narrowing and hypotelorism. Unicoronal synostosis gives rise to anterior plagiocephaly— ipsilateral frontal retrusion, orbital elevation, nasalroot deviation, and varying degrees of facial and cranial base torsion. Lambdoid synostosis produces an asymmetric posterior-vault pattern that must be separated from deformational plagiocephaly. Representative phenotypes are summarized in Table 1 and shown as three-dimensional computed tomography reconstructions in Fig. 1.

BIOLOGY, MECHANICS, AND GENETICS

The cranial suture is a regulated growth interface, not a passive joint. Osteogenic fronts, dura, periosteum, neural crest- and mesoderm-derived mesenchyme, and local mechanical loading cooperate to keep the suture patent during rapid brain growth. Premature fusion therefore changes both the local growth boundary and the distribution of mechanical strain across the developing skull. This wider mechanical effect helps explain how an apparently isolated synostosis can produce a wholevault phenotype and, in selected subtypes, secondary changes in cranial-base and orbital geometry. It also supplies the biologic rationale for distraction: gradual mechanical loading at an osteotomy site recreates key features of a native growth interface while generating new bone within an expanding soft-tissue envelope.

Non-syndromic disease is also genetically heterogeneous. Familial clustering is well documented, although recurrence risk varies by suture and by family history [6]. In midline craniosynostosis, rare loss-of-function variants in SMAD6 interact with a common BMP2-associated risk allele, providing a wellcharacterized example of incomplete penetrance and two-locus inheritance [9]. Findings of this kind have eroded the older assumption that non-syndromic disease is biologically simple. Genetic testing may therefore be reserved mainly for selected counseling contexts—a positive or otherwise suggestive family history, multi-suture or atypical presentations, and cases where a subtle syndromic diagnosis remains possible—and it does not yet replace phenotype-driven operative planning.

CLINICAL ASSESSMENT AND IMAGING STRATEGY

Diagnosis begins on the examining table, with inspection and palpation. I look at global head shape, vertex contour, frontal and occipital bossing, supraorbital projection, orbital level, nasal deviation, ear position, mastoid prominence, fontanelle status, and any palpable suture ridge. In many infants, a careful clinical examination settles the diagnosis without cross-sectional imaging. The real question is therefore not whether imaging can prove suture fusion, but whether enough diagnostic uncer-tainty or morphologic complexity remains to justify its cost and radiation exposure.

When detailed bone anatomy, skull base asymmetry, or osteotomy planning is needed, three-dimensional computed tomography is the most informative modality; modern low-dose protocols have cut radiation exposure substantially while preserving diagnostic performance [10]. Magnetic resonance imaging evaluates the brain, cerebrospinal fluid spaces, venous anatomy, and selected bony contours without ionizing radiation, and black-bone sequences are especially useful when cortical bone detail at computed tomography level is not required [11]. Three-dimensional surface photography, for its part, has become a useful tool for longitudinal follow-up because it permits repeated measurements with no radiation at all.

Two diagnostic distinctions deserve particular emphasis. First, a fused or ridged metopic suture does not by itself establish surgically significant trigonocephaly. Frontal narrowing, orbital configuration, and hypotelorism must be evaluated together as a geometric phenotype, and recent three-dimensional morphometric work has strengthened the value of objective shape analysis in separating benign metopic ridging from trigonocephaly [12]. Second, posterior plagiocephaly should not automatically be attributed to lambdoid synostosis. True lambdoid fusion is associated with posterior vault distortion and mastoid prominence, a pattern that differs from positional molding and can usually be recognized on careful examination [13]. Table 2 summarizes the practical roles of current imaging modalities.

TIMING OF INTERVENTION

Timing and technique are inseparable. Early referral widens the range of minimally invasive options, because calvarial elasticity, dural expansion, and rapid brain growth can be harnessed to guide postoperative remodeling. As age increases and the threedimensional deformity becomes established, direct reshaping or vector-controlled expansion gains priority. Age should not be treated as an isolated cutoff; it should be interpreted together with suture type, severity, skull-base and orbital involvement, calvarial thickness, and the anticipated burden of adjunctive orthotic or device treatment [1-4,14].

CONTEMPORARY OPERATIVE ALTERNATIVES

Open cranial vault remodeling continues to serve as an established strategy, particularly for older infants or children whose deformity demands immediate direct reshaping (Table 3). Fronto-orbital advancement and remodeling occupies the same position for anterior deformities such as metopic and unicoronal synostosis, offering direct correction of the forehead and the supraorbital bandeau. These operations achieve one-stage skeletal repositioning without prolonged postoperative helmet therapy. The price is a wider exposure and, compared with endoscope-assisted approaches, greater blood loss, higher transfusion requirements, and longer operative time. Long-term series also remind us that residual contour deformity, supraorbital retrusion, temporal hollowing, or revision can follow even a technically successful fronto-orbital advancement [1-4,15,16].

Endoscope-assisted suturectomy followed by cranial orthotic therapy is a well-established alternative for the right young infant. A 31-center propensity-matched study and subsequent systematic reviews have consistently shown lower transfusion exposure, shorter operative time, and shorter hospitalization than open reconstruction, and available morphometric studies suggest that acceptable long-term shape correction can be achieved in selected sagittal and metopic cases [2-4,14,17,18]. The approach has real constraints: a narrow age-dependent treatment window, prolonged orthotic treatment that tests family adherence, and less direct intraoperative control of regional vectors. For non-sagittal sutures, moreover, the comparative evidence base is smaller and more heterogeneous [4].

Spring-assisted cranioplasty, used predominantly for sagittal synostosis, combines a limited-access osteotomy with gradual expansion. Comparative and long-term series report favorable perioperative morbidity and durable correction, and multicenter three-dimensional analyses suggest broadly satisfactory long-term head-shape outcomes across spring-assisted and other minimally invasive techniques [19-22]. The drawbacks are the implanted hardware, a planned second procedure for spring removal, and a vector that cannot be changed once the construct is chosen. For early sagittal synostosis, where the de-formity and the desired expansion are relatively predictable, these limitations are usually acceptable. They become more restrictive when correction must be distributed asymmetrically or across several cranial regions, and it is in precisely those situations that multi-device distraction offers more direct control of vector, magnitude, and regional balance.

RATIONALE FOR DISTRACTION

Distraction osteogenesis occupies a central place in this review because it converts skeletal movement into a gradual, controllable process: vector, magnitude, and regional volume can be directed while regenerate bone forms within an expanding softtissue envelope. That property matters most when treatment requires redistributing a cranial or orbital deformity, not merely releasing a fused suture. In sagittal synostosis, distraction combined with strategic osteotomy design corrects scaphocephalic vault disproportion [23]. In unicoronal synostosis, comparative studies have reported lower perioperative morbidity than conventional fronto-orbital advancement, together with favorable orbital, skull-base, and long-term aesthetic outcomes in selected patients [24-30]. Most of these studies are retrospective and center-specific and do not establish universal superiority over open, endoscopic, or spring-assisted procedures. Even so, distraction offers one practical advantage that a fixed reconstruction cannot reproduce: the correction can be divided among several vectors and modified mid-treatment while bone and soft tissues adapt gradually. For these reasons, I favor a distraction-centered, phenotype-driven strategy whenever the deformity demands this degree of control, while retaining open, endoscopic, and spring-assisted techniques for patients in whom their specific advantages fit the age and phenotype better.

DISTRACTION-BASED OPERATIVE STRATEGY BY SUBTYPE

Sagittal synostosis

In a growing infant with sagittal synostosis, the reconstructive priority is restoration of transverse width and overall vault proportion; normalizing the cephalic index is a secondary concern (Table 4). For infants seen within the early treatment window, endoscope-assisted strip craniectomy with helmet therapy and spring-assisted cranioplasty are well-supported alternatives with lower perioperative burden than wide open remodeling, and current comparative evidence does not show consistent long-term morphometric superiority of any single minimally invasive strategy [2-4,14,19-22]. With distraction, parasagittal or biparietal devices provide direct control of lateral expansion. I find this especially useful when biparietal restriction is pronounced, when different regions require unequal expansion, or when the correction should be adjustable during the distraction period. Wide strip suturectomy is not obligatory, and I add it only when release is needed for effective bilateral expansion; distractor placement and osteotomy geometry are selected according to the dominant three-dimensional restriction [23,31].

Anteroposterior shortening is not a primary objective. Once transverse width is restored, residual elongation often moderates with subsequent growth, and I therefore reserve deliberate anteroposterior reduction for conspicuous persistent elongation— and, in my present operative philosophy, limit it to ≤1 cm to preserve longitudinal growth potential. In older infants or in patients with marked biparietal constriction, a more extensive osteotomy with multivector distraction permits direct control of transverse width and regional contour. The choice must be weighed against conventional remodeling, which provides immediate reshaping, and against early minimally invasive approaches, which reduce blood loss and hospitalization but depend more heavily on subsequent growth or external orthosis [2-4,14,19-23,31-33].

The operative goal is a broader, more proportionate cranial vault, not a mathematically shortened skull. The cephalic index is a useful screen, but it cannot stand alone: a satisfactory index can coexist with frontal narrowing, posterior deformity, or contour irregularity. Long-term assessment should therefore combine global ratios with regional shape and patient-specific morphology.

Metopic synostosis

Metopic synostosis is the hardest of the four to manage decisively, because the boundary among physiologic closure, benign ridging, and operative trigonocephaly is not binary. An isolated ridge without meaningful fronto-orbital narrowing should not be treated as trigonocephaly. Conversely, true metopic synostosis may involve a triangular frontal contour, reduced bifrontal width, temporal narrowing, hypotelorism, and orbital restriction. Objective three-dimensional criteria can reduce diagnostic variation, particularly in borderline phenotypes [12].

When surgery is indicated, the goal is to restore frontal width and the upper facial frame; simply excising the ridge is not enough. For moderate-to-severe trigonocephaly, conventional fronto-orbital advancement and remodeling is the most established open option, while endoscope-assisted strip craniectomy followed by helmet therapy can achieve favorable correction with lower perioperative morbidity in appropriately selected young infants [1,4,17,18]. Bilateral supraorbital osteotomy with fronto-orbital distraction offers a third path, progressively widening the supraorbital bar and bifrontal segment while the periorbital soft tissues adapt gradually. Direct comparative evidence for metopic distraction is still limited, and it cannot yet be regarded as an evidence-proven replacement for fronto-orbital remodeling. Its potential advantage is titration: frontal width and orbital geometry can be adjusted during correction instead of committing to a single acute advancement. Defining its role will require further comparative data and more objective threedimensional outcome measures.

Unicoronal synostosis

Unicoronal synostosis most clearly exposes the limits of a suture-centered model. Visible forehead flattening is only one component of a larger rotational deformity that may include harlequin orbital configuration, vertical orbital dystopia, nasal deviation, anterior cranial fossa rotation, temporal contour imbalance, and secondary facial compensation. Fronto-orbital advancement and remodeling is an effective and widely used strategy for direct anterior correction, and recent pooled data indicate that both unilateral and bilateral approaches can be effective, with different trade-offs in operative exposure and contour irregularity [15,16]. Endoscopic suturectomy with orthotic therapy is another option in very young infants, although the comparative evidence for non-sagittal sutures is less extensive than for sagittal disease [1,4]. Long-term open series have shown that supraorbital retrusion, temporal hollowing, and contour drift may emerge with growth in a subset of patients [15].

Endoscope-assisted fronto-orbital distraction has a defined but narrow indication: very early infancy, before a fixed threedimensional rotational deformity is established, when calvarial elasticity, dural expansion, and scalp compliance remain favorable [28]. Once anterior plagiocephaly has progressed to estab-lished orbital dystopia and cranial-axis rotation, focal anterior correction is likely to fall short. Circumferential osteotomy with balanced multivector distraction can then address frontal projection, orbital level, cranial-axis alignment, and posterior vault geometry within a single correction plan. Comparative cohorts have reported shorter operative time and hospitalization than conventional fronto-orbital advancement in selected patients, preservation of vascularized bone with the rotationalflap technique, differential effects on orbital morphology, improvement in anterior cranial base symmetry, and favorable long-term periorbital symmetry and temporal contour [24-30]. The available studies are predominantly retrospective. Nonetheless, unicoronal synostosis illustrates why correcting the entire rotational deformity may be preferable to treating the forehead as an isolated segment. Fronto-orbital advancement and remodeling and early endoscopic techniques remain valid alternatives, but distraction adds a means of controlling the whole-vault vector when that is required [1,4,15,16]. Representative postoperative reconstructions are shown in Fig. 2.

Lambdoid synostosis

Lambdoid synostosis is rare, yet it demands diagnostic vigilance because positional posterior plagiocephaly is common. Features that favor true lambdoid synostosis include ipsilateral mastoid prominence, posterior-inferior ear displacement, a trapezoidal rather than parallelogram posterior head shape, and more complex skull base asymmetry [13].

When true lambdoid synostosis is confirmed and reconstruction is indicated, open posterior cranial vault remodeling and endoscope-assisted suturectomy with postoperative orthotic therapy are both contemporary options. Small comparative series suggest that both can improve posterior vault asymmetry, although residual cranial base asymmetry may persist, and more recent open-remodeling data show stable improvement in cranial vault asymmetry while confirming incomplete normalization of skull base twist [1,4,34,35]. I choose among distraction configurations according to the extent of the deformity. If the abnormality is confined to the posterior vault, posterior cranial-vault distraction with paired occipital distractors provides gradual expansion and direct control of posterior volume. When anterior compensatory deformity or skull base torsion is substantial, circumferential osteotomy with balanced multivector distraction extends the correction to the cranial axis as a whole. Because lambdoid synostosis is uncommon and comparative cohorts remain small, no technique can currently be considered superior on statistical grounds. The principal advantage of distraction here is its scalability, from regional posterior expansion to a broader rotational correction when the phenotype calls for it.

OUTCOMES AND UNRESOLVED QUESTIONS

Outcome assessment has moved beyond the binary question of whether the head shape has “improved.” In sagittal disease, the cephalic index is still useful, but it needs supplementation with regional contour and volume distribution, especially because the reconstructive priority in a growing infant is transverse expansion, not index normalization. For anterior synostoses, orbital level, frontotemporal contour, cranial-axis congruence, and facial symmetry have become increasingly important outcome domains. Three-dimensional photogrammetry and standardized photographic analysis offer radiation-free longitudinal metrics and may allow more meaningful comparisons across operative techniques, including comparisons among distraction configurations.

Several questions remain genuinely open. Neurodevelopmental differences have been reported at the population level in children with single-suture craniosynostosis, but causal relationships among the underlying developmental condition, intracranial pressure, timing of surgery, operative technique, and later cognition are difficult to separate. The field also lacks universally accepted morphometric thresholds for intervention, particularly in mild metopic disease. Cross-technique comparisons are further confounded by age at referral, phenotype severity, institutional preference, helmet protocols, device design, and nonuniform follow-up. Multicenter studies and systematic reviews increasingly demonstrate that perioperative morbidity can differ substantially among approaches even when short- or intermediate-term shape outcomes are broadly comparable [2-4,14,18-22]. Future comparative work should therefore integrate deformity-specific three-dimensional outcomes, reoperation, neurodevelopment, patient- and parent-reported outcomes, and total treatment burden, rather than leaning on a single cranial index.

Further progress will depend less on introducing yet another fixed operation than on improving how correction is matched to the individual deformity. Distraction helps here because the osteotomy pattern and the corrective vectors can be selected separately and adjusted while the skeleton and soft tissues adapt. The next step is to combine this flexibility with radiationsparing imaging, automated surface morphometry, virtual planning, patient-specific vector design, and improved device strategies. This does not imply that distraction is appropriate for every patient. The more relevant goal is to make three-dimensional, growth-compatible correction measurable and reproducible, whatever the specific operative technique.

CONCLUSION

Non-syndromic craniosynostosis should not be treated with a single operation applied uniformly to a suture diagnosis. Endoscope-assisted surgery with orthotic therapy and spring-assisted cranioplasty are effective in selected young infants, while open cranial vault remodeling or fronto-orbital advancement remains appropriate when immediate direct reshaping is required. Distraction adds a different kind of control: osteotomy geometry, vector direction, magnitude, and regional balance can be planned around the three-dimensional deformity, with gradual bone formation and soft-tissue adaptation during correction. The current evidence is mainly retrospective and center-specific, and it does not show that distraction is superior for every subtype. However, the available clinical data and biologic rationale support its use when correction must extend across several cranial regions or when postoperative vector adjustment is advantageous. Distraction may therefore be regarded as an important component of phenotype-specific reconstruction, rather than a universal replacement for established procedures. Future multicenter studies should compare deformity-specific morphometric and functional outcomes, reoperation, treatment burden, and long-term stability to craniofacial maturity; those data will determine whether the theoretical and technical advantages of distraction translate into better long-term outcomes.

Notes

Conflict of interest

No potential conflict of interest relevant to this article was reported.

Funding

None.

Ethical approval

Ethical approval was not required for this narrative review.

Patient consent

Patient images included in the figures were de-identified, and informed consent for their use and publication was obtained from the patients.

Fig. 1.

Representative three-dimensional computed tomography phenotypes of common non-syndromic craniosynostosis. (A) Sagittal synostosis, vertex view, showing scaphocephalic elongation and biparietal narrowing with fusion of the sagittal suture. (B) Metopic synostosis, frontal view, showing a prominent midline metopic ridge and bifrontal narrowing consistent with trigonocephaly. (C) Unicoronal synostosis, showing ipsilateral frontal retrusion, harlequin orbital configuration, and anterior cranial base rotation. (D) Lambdoid synostosis, showing asymmetric posterior vault distortion and occipitomastoid disproportion.

Fig. 2.

Representative postoperative three-dimensional computed tomography reconstructions after distraction-based correction. (A) Sagittal synostosis after parasagittal or biparietal distraction, showing transverse expansion of the vault while preserving longitudinal growth potential. (B) Unicoronal synostosis after circumferential osteotomy with balanced multivector fronto-orbital distraction, showing correction of frontal projection, orbital level, and cranial-axis alignment. (C) Lambdoid synostosis after distraction-based reconstruction, showing improved posterior- vault symmetry and overall craniofacial balance. CI, cranial index; CVAI, cranial vault asymmetry index.

Table 1.

Hallmark phenotypes and diagnostic clues in common non-syndromic craniosynostosis subtypes

Subtype	Hallmark head shape	Key morphologic clues	Common diagnostic pitfall
Sagittal	Scaphocephaly	Biparietal narrowing, frontal and occipital bossing, and elongated anteroposterior dimension	Mild elongation may be dismissed as familial variation
Metopic	Trigonocephaly	Bifrontal narrowing, hypotelorism, midline ridge, and temporal hollowing	Isolated metopic ridging may be overinterpreted as trigonocephaly
Unicoronal	Anterior plagiocephaly	Ipsilateral frontal retrusion, harlequin orbit, nasal deviation, and cranial-axis rotation	Forehead flattening may be overemphasized while orbital and skull base torsion are missed
Lambdoid	Trapezoidal posterior plagiocephaly	Ipsilateral mastoid prominence, posterior-inferior ear displacement, and skull base asymmetry	The deformity may be confused with positional parallelogram molding

Table 2.

Contemporary imaging tools and practical indications

Modality	Best use	Radiation exposure	Limitations
Low-dose three-dimensional computed tomography	Reference modality for complex osseous geometry and distraction planning [10]	Reduced but present	Requires optimized pediatric protocols
Magnetic resonance imaging, including black-bone techniques	Brain, cerebrospinal fluid spaces, venous anatomy, and radiation-free assessment of selected bony contours [11]	None	Cortical bone detail is inferior to that of computed tomography
Three-dimensional surface photography	Longitudinal morphometry and follow-up	None	Does not visualize sutures or intracranial structures

Table 3.

Contemporary operative alternatives for non-syndromic craniosynostosis

Technique	Typical candidates/role	Principal strengths	Limitations and evidence considerations
Open cranial vault remodeling	Established or later-presenting vault deformity; direct reshaping when broad exposure is required	Immediate one-stage contour correction; no prolonged orthotic therapy	Greater blood loss, transfusion, operative time, and exposure than endoscopic approaches; long-term contour drift may occur [1-4,14]
Fronto-orbital advancement/remodeling	Metopic and unicoronal synostosis with anterior and orbital deformity	Direct correction of forehead and supraorbital bandeau; extensive accumulated clinical experience	Open-surgery morbidity; temporal hollowing, supraorbital retrusion, contour irregularity, or revision can occur with growth [1,15-17]
Endoscope-assisted suturectomy+orthotic therapy	Very young infants with selected single-suture disease	Low blood loss and transfusion exposure; shorter operative time and hospitalization	Age-dependent window; prolonged helmet therapy and family adherence; less direct vector control; non-sagittal evidence more limited [2-4,14,17,18,34]
Spring-assisted cranioplasty	Predominantly sagittal synostosis in young infants	Limited-access surgery with gradual expansion; favorable perioperative and long-term outcomes	Implanted device and planned removal; less freely customizable vector pattern; evidence concentrated in sagittal synostosis [19-22]
Distraction osteogenesis	Sagittal, unicoronal, lambdoid, or complex three-dimensional deformity in which the magnitude and direction of correction must be actively controlled	Greatest flexibility for patient-specific vector and magnitude control; gradual three-dimensional correction with regenerate bone formation and soft-tissue accommodation; adaptable from regional to multivector whole-vault reconstruction	Device activation and care, implanted hardware, and planned removal remain practical burdens; comparative evidence is still largely retrospective and center-specific, but its modifiable geometry makes distraction the most extensible platform for phenotype-driven reconstruction [23-31]

Table 4.

Distraction-based operative strategy by non-syndromic subtype

Subtype	Preferred distraction approach	Primary geometric target	Evidence/context references
Sagittal	Parasagittal or biparietal distraction as the primary vector; strip suturectomy added only when release is required for effective bilateral expansion; anteroposterior shortening limited to ≤ 1 cm only when severe residual elongation persists; distractor design and osteotomy configuration individualized to the deformity	Transverse bilateral expansion prioritized over cephalic index normalization, with preservation of growth potential	[2-4,14,19-23,31-33]
Metopic	Bilateral supraorbital osteotomy with fronto-orbital distraction	Bifrontal widening and supraorbital bar lateralization	[1,12,17,18]
Unicoronal	Endoscope-assisted fronto-orbital distraction reserved for very early infancy; circumferential osteotomy with balanced multivector distraction used for established three-dimensional deformity	Simultaneous correction of orbital dystopia, cranial-axis torsion, frontal projection, and posterior vault balance	[1,4,15,16,24-30]
Lambdoid	Posterior cranial-vault distraction with paired occipital distractors when the deformity is confined posteriorly; circumferential osteotomy with balanced multivector distraction when anterior involvement or skull base torsion coexists	Posterior-vault symmetry, with correction of anterior compensatory changes and cranial-axis rotation when present	[1,4,13,34,35]

REFERENCES

1. Mathijssen IMJ, Working Group Guideline Craniosynostosis. Updated guideline on treatment and management of craniosynostosis. J Craniofac Surg 2021;32:371-450.

2. Thompson DR, Zurakowski D, Haberkern CM, Stricker PA, Meier PM, Bannister C, et al. Endoscopic versus open repair for craniosynostosis in infants using propensity score matching to compare outcomes: a multicenter study from the Pediatric Craniofacial Collaborative Group. Anesth Analg 2018;126:968-75.

3. Goyal A, Lu VM, Yolcu YU, Elminawy M, Daniels DJ. Endoscopic versus open approach in craniosynostosis repair: a systematic review and meta-analysis of perioperative outcomes. Childs Nerv Syst 2018;34:1627-37.

4. Yan H, Abel TJ, Alotaibi NM, Anderson M, Niazi TN, Weil AG, et al. A systematic review of endoscopic versus open treatment of craniosynostosis. Part 2: the nonsagittal single sutures. J Neurosurg Pediatr 2018;22:361-8.

5. Shlobin NA, Baticulon RE, Ortega CA, Du L, Bonfield CM, Wray A, et al. Global epidemiology of craniosynostosis: a systematic review and meta-analysis. World Neurosurg 2022;164:413-23.

6. Greenwood J, Flodman P, Osann K, Boyadjiev SA, Kimonis V. Familial incidence and associated symptoms in a population of individuals with nonsyndromic craniosynostosis. Genet Med 2014;16:302-10.

7. Schraw JM, Woodhouse JP, Langlois PH, Canfield MA, Scheuerle AE, Agopian AJ, et al. Risk factors and time trends for isolated craniosynostosis. Birth Defects Res 2021;113:43-54.

8. Tarnow P, Kolby L, Maltese G, Softeland MB, Lewen A, Nilsson P, et al. Incidence of non-syndromic and syndromic craniosynostosis in Sweden. J Craniofac Surg 2022;33:1517-20.

9. Timberlake AT, Choi J, Zaidi S, Lu Q, Nelson-Williams C, Brooks ED, et al. Two locus inheritance of non-syndromic midline craniosynostosis via rare SMAD6 and common BMP2 alleles. Elife 2016;5:e20125.

10. Montoya JC, Eckel LJ, DeLone DR, Kotsenas AL, Diehn FE, Yu L, et al. Low-dose CT for craniosynostosis: preserving diagnostic benefit with substantial radiation dose reduction. AJNR Am J Neuroradiol 2017;38:672-7.

11. Kuusela L, Hukki A, Brandstack N, Autti T, Leikola J, Saarikko A. Use of black-bone MRI in the diagnosis of the patients with posterior plagiocephaly. Childs Nerv Syst 2018;34:1383-9.

12. Bloch K, Geoffroy M, Taverne M, van de Lande L, O’Sullivan E, Liang C, et al. New diagnostic criteria for metopic ridges and trigonocephaly: a 3D geometric approach. Orphanet J Rare Dis 2024;19:204.

13. Linz C, Collmann H, Meyer-Marcotty P, Bohm H, Krauss J, Muller-Richter UD, et al. Occipital plagiocephaly: unilateral lambdoid synostosis versus positional plagiocephaly. Arch Dis Child 2015;100:152-7.

14. Palavani LB, Costa M, Banderali I, Zattar Ribeiro PV, Nogueira BV, Belfort Santos M, et al. Endoscopic versus open treatment for sagittal craniosynostosis: a systematic review and metaanalysis. Neurosurg Rev 2025;48:262.

15. Taylor JA, Paliga JT, Wes AM, Tahiri Y, Goldstein JA, Whitaker LA, et al. A critical evaluation of long-term aesthetic outcomes of fronto-orbital advancement and cranial vault remodeling in nonsyndromic unicoronal craniosynostosis. Plast Reconstr Surg 2015;135:220-31.

16. Sibar S, Uygur HS, Kuzucu P. Unilateral versus bilateral frontoorbital advancement in non-syndromic unicoronal craniosynostosis: a systematic review and pooled data analysis. Ann Plast Surg 2026;97:166-75.

17. Ha AY, Skolnick GB, Chi D, Nguyen DC, Naidoo SD, Smyth MD, et al. School-aged anthropometric outcomes after endoscopic or open repair of metopic synostosis. Pediatrics 2020;146:e20200238.

18. Schulz M, Liebe-Puschel L, Seelbach K, Paulikat L, Fehlhaber F, Schwarz K, et al. Quantitative and qualitative comparison of morphometric outcomes after endoscopic and conventional correction of sagittal and metopic craniosynostosis versus control groups. Neurosurg Focus 2021;50:E2.

19. Prezelski K, Blondin Fernandez MS, Matsumoto K, David LR, Runyan CM, Patel KB, et al. Assessment of minimally invasive surgical techniques for sagittal craniosynostosis: a multicenter time series study. Plast Reconstr Surg 2025;155:684-92.

20. Runyan CM, Gabrick KS, Park JG, Massary D, Hemal K, Owens ES, et al. Long-term outcomes of spring-assisted surgery for sagittal craniosynostosis. Plast Reconstr Surg 2020;146:833-41.

21. Skolnick GB, Yu JL, Patel KB, David LR, Couture DE, Smyth MD, et al. Comparison of 2 sagittal craniosynostosis repair techniques: spring-assisted surgery versus endoscope-assisted craniectomy with helmet molding therapy. Cleft Palate Craniofac J 2021;58:678-86.

22. Saenz A, Dunaway D, James G, Ong J, Silva D, Borghi A, et al. Spring-assisted cranioplasty for sagittal synostosis: long-term clinical and patient-reported outcomes : ten-year outcomes of spring-assisted cranioplasty for isolated sagittal synostosis: a single-institution cohort study. Childs Nerv Syst 2026;42:250.

23. Lee MC, Shim KW, Yun IS, Park EK, Kim YO. Correction of sagittal craniosynostosis using distraction osteogenesis based on strategic categorization. Plast Reconstr Surg 2017;139:157-69.

24. Tahiri Y, Swanson JW, Taylor JA. Distraction osteogenesis versus conventional fronto-orbital advancement for the treatment of unilateral coronal synostosis: a comparison of perioperative morbidity and short-term outcomes. J Craniofac Surg 2015;26:1904-8.

25. Brandel MG, Dalle Ore CL, Reid CM, Zhu W, Lance S, Meltzer H, et al. Distraction osteogenesis for unicoronal craniosynostosis: rotational flap technique and case series. Plast Reconstr Surg 2018;142:904e-908e.

26. McKee RM, Carbullido MK, Ewing E, Kamel GN, Ryan J, Zaldana-Flynn MV, et al. Orbital volumetric analysis in patients with unicoronal craniosynostosis: a comparison between distraction osteogenesis and fronto-orbital advancement. Ann Plast Surg 2021;86:S367-73.

27. Mellgren J, Saljo K, Tarnow P, Maltese G, Bhatti-Softeland M, Olsson R, et al. Improved facial and skull-base symmetry following osteotomy and distraction of unilateral coronal synostosis. Plast Reconstr Surg 2024;153:447-56.

28. Wu M, Wagner CS, Villavisanis DF, Ng JJ, Massenburg BB, Romeo DJ, et al. Endoscopic-assisted versus open fronto-orbital distraction for unicoronal craniosynostosis: morphometric and technique considerations. Childs Nerv Syst 2024;41:59.

29. Villavisanis DF, Blum JD, Cho DY, Carlson AR, Heuer GG, Swanson JW, et al. Long-term aesthetic and photogrammetric outcomes in non-syndromic unicoronal synostosis: comparison of fronto-orbital distraction osteogenesis and fronto-orbital advancement and remodeling. Childs Nerv Syst 2023;39:1283-96.

30. Wu M, Massenburg BB, Villavisanis DF, Chang AE, Romeo DJ, Ng JJ, et al. The evolution of unicoronal synostosis correction: long-term aesthetics of fronto-orbital distraction versus advancement. Plast Reconstr Surg 2025;156:105-16.

31. Baek W, Kim YJ, Kim M, Kim YO. Retrospective evaluation of different designs of distraction osteogenesis in brachycephalic craniosynostosis. J Craniomaxillofac Surg 2025;53:983-8.

32. Vogel TW, Woo AS, Kane AA, Patel KB, Naidoo SD, Smyth MD. A comparison of costs associated with endoscope-assisted craniectomy versus open cranial vault repair for infants with sagittal synostosis. J Neurosurg Pediatr 2014;13:324-31.

33. Persad A, Aronyk K, Beaudoin W, Mehta V. Long-term 3D CT follow-up after endoscopic sagittal craniosynostosis repair. J Neurosurg Pediatr 2019;25:291-7.

34. Zubovic E, Woo AS, Skolnick GB, Naidoo SD, Smyth MD, Patel KB. Cranial base and posterior cranial vault asymmetry after open and endoscopic repair of isolated lambdoid craniosynostosis. J Craniofac Surg 2015;26:1568-73.

35. Nguyen AN, Purnell CA, Mercan E, Lee A, Birgfeld CB, Susarla SM, et al. Cranial shape changes in nonsyndromic unilateral lambdoid synostosis after open posterior vault remodeling. Plast Reconstr Surg 2023;152:155-65.