Normal Calcaneal-Fifth Metatarsal Angle Size on Radiography
The calcaneal–fifth metatarsal angle is measured on the anteroposterior (AP) foot radiograph and describes the angular relationship between the long axis of the calcaneus and the shaft of the fifth metatarsal. This angle reflects the degree of forefoot abduction or adduction relative to the hindfoot, making it a useful marker of overall foot alignment in the developing child.
Tracking this angle across early childhood helps clinicians assess normal foot development and identify deformities such as metatarsus adductus or skewfoot deformity before they become fixed.
Normal Reference Values
| Orientation | Age | Measurement |
|---|---|---|
| Anteroposterior | Newborn | 3¡ |
| Anteroposterior | 2 y/o | 0¡ |
| Anteroposterior | 4 y/o | -1¡ |
| Anteroposterior | 4-9 y/o | -10-14¡ |
Clinical Significance
In newborns, a small positive angle (approximately 3°) reflects the relatively adducted forefoot position normal at birth. Through early childhood, the angle progressively decreases and becomes negative, indicating increasing forefoot abduction relative to the hindfoot as the foot matures. By ages 4–9, values of −10° to −14° are considered normal.
Deviation from age-expected norms is clinically important. A persistently positive or excessively positive angle beyond infancy may suggest metatarsus adductus, while an abnormally negative value may indicate forefoot abduction seen in skewfoot or planovalgus deformity. Isolated interpretation without clinical examination can be misleading, as positioning artifacts on the AP radiograph significantly affect angle measurements.
- Metatarsus adductus (positive angle persisting beyond expected range)
- Skewfoot deformity (excessively negative angle)
- Clubfoot (talipes equinovarus) — adducted forefoot component
- Congenital vertical talus — forefoot abduction pattern
- Positional foot deformity vs. structural deformity differentiation
Reference: Vanderwilde R, Staheli LT, Chew DE et al. Measurements on radiographs of the foot in normal infants and children. J Bone Joint Surg Am. 1988;70(3):407–15.
Imaging Notes
The calcaneal–fifth metatarsal angle is assessed on a weight-bearing or simulated weight-bearing AP foot radiograph. The angle is formed between a line drawn along the long axis of the calcaneus and a line along the central shaft of the fifth metatarsal; a positive value indicates metatarsal adduction and a negative value indicates abduction relative to the calcaneus. Consistent foot positioning — with the foot flat and the beam centered over the midfoot — is essential for reproducible measurements, as even slight rotation substantially alters the angle.
In non-ambulatory infants, a simulated weight-bearing or stressed AP projection is used. Comparing bilateral views is recommended, as asymmetry between feet may be as diagnostically important as deviation from published norms.