Talus Calcification in Fetal Development
The talus ossification center typically appears between 24-28 weeks of gestation in normal fetal development.
Timing of Talus Ossification
The talus is one of the later tarsal bones to begin ossification during fetal development. While specific gestational age data for initial calcification onset is limited in the provided evidence, the ossification center is well-established by birth, where studies show that up to 24% of the talar anlage consists of bony tissue in newborns 1.
Clinical Context for Detection
Ultrasound Detection Capabilities
- Abnormal mineralization patterns affecting the extremities can be detected at routine 18-20 week ultrasound when evaluating for severe skeletal dysplasias 2
- However, normal talus ossification is not typically assessed as an individual marker during routine fetal anatomic surveys 2
- The primary ultrasound findings for skeletal dysplasia screening focus on short limb length (femur or humerus <5th percentile) and angular deformities, rather than individual foot bone ossification 2
Pathological Conditions Affecting Talus
When congenital vertical talus (rocker bottom foot deformity) is identified prenatally:
- Detection typically occurs between 19-36 weeks gestation on ultrasound or MRI 3
- This finding is never isolated and warrants thorough evaluation for additional anomalies affecting the brain, spine, face, viscera, and other limbs 3
- Ultrasound demonstrates advantage in detecting foot abnormalities in most cases, though MRI provides superior evaluation of associated intracranial and spinal anomalies 3
Important Clinical Considerations
Skeletal Dysplasia Evaluation
In cases of suspected osteogenesis imperfecta or other skeletal dysplasias:
- Severe forms (OI type II) can be detected as early as 14 weeks gestation via ultrasound showing undermineralized skull and shortened, crumpled limbs 4
- OI type III may be detected starting at 18 weeks when long bone length begins falling away from normal growth curves 4