At what age do the cranial sutures (cranial bone joints) typically close?

Cranial Suture Closure Timeline

Cranial sutures close at different times throughout development, with the metopic suture closing earliest (between 3-9 months of age) and the sagittal, coronal, and lambdoid sutures typically remaining open until adulthood.

Normal Timeline of Cranial Suture Closure

Infant Sutures

• Metopic suture: Begins closing as early as 3 months of age, with complete fusion in 100% of individuals by 9 months 1
• Frontoethmoidal suture: Begins closing between 0-2 months, with complete closure by 4 years 2
• Frontosphenoidal suture: Begins closing at 6-8 months, with complete closure by 12 years 2
• Sphenoparietal suture: Begins closing at 6-8 months, with complete closure by 4 years 2

Synchondroses (Cartilaginous Joints)

• Sphenoethmoidal synchondrosis: Begins closing at 3-5 months, with complete fusion by 5 years 2
• Posterior intraoccipital synchondrosis: Begins closing at 18-23 months, with complete fusion by 4 years 2
• Anterior intraoccipital synchondrosis: Begins closing at 4 years, with complete fusion by 10 years 2
• Spheno-occipital synchondrosis: Begins closing at 9 years, with complete fusion by 17 years 2

Adult Cranial Vault Sutures

• Sagittal suture: Typically begins closing in early adulthood and obliterates first among the major cranial vault sutures 3
• Coronal suture: Begins closing after the sagittal suture in adulthood 3
• Lambdoid suture: Last of the major cranial vault sutures to close 3

Clinical Implications

Diagnostic Considerations

• Ultrasound is the preferred initial imaging modality for evaluating cranial sutures in infants under 1 year of age, as it avoids radiation exposure 4, 5
• CT imaging should be reserved for cases where craniosynostosis (premature suture closure) is suspected based on clinical findings 4

Craniosynostosis Management

• The diagnosis of cranial malformations and cranial suture anomalies is primarily clinical 4
• Direct X-ray imaging is not indicated as a routine examination for suspected craniosynostosis, as the same information may be obtained by ultrasound imaging 4
• CT or CBCT (Cone Beam CT) should only be used in selected cases when necessary for treatment planning 4

Important Caveats

• Endocranial (inner surface) suture closure typically precedes ectocranial (outer surface) closure and is considered more reliable for age estimation purposes 3
• Normal closure of the metopic suture occurs much earlier than previously described in older literature, with fusion potentially occurring as early as 3 months 1
• Complete closure of the metopic suture at an early age (3-9 months) should not be considered evidence of pathological metopic synostosis without corresponding clinical features 1
• Cranial suture closure patterns can vary based on geographical location and population 3

Clinical Pearls

• When evaluating an infant with abnormal head shape, focus on clinical assessment first before proceeding to imaging 4
• For suspected craniosynostosis, ultrasound should be the first imaging modality in infants under 1 year 4, 5
• The anterior fontanelle typically closes between 9-18 months of age, but this can vary
• Understanding normal suture closure timelines is essential to avoid misdiagnosing normal physiologic closure as pathological craniosynostosis 1