Normal Calcaneus–2nd Metatarsal Angle Size on Radiography
The calcaneus–2nd metatarsal angle is a angular measurement taken on anteroposterior (AP) foot radiographs that quantifies the relationship between the long axis of the calcaneus and the shaft of the second metatarsal. It serves as a reliable indicator of overall foot alignment, reflecting both hindfoot and midfoot contributions to the medial longitudinal arch. Accurate measurement is essential when evaluating pes planus, pes cavus, and postoperative outcomes following reconstructive foot surgery.
Normal Reference Values
| Orientation | Measurement |
|---|---|
| Anteroposterior | 12-18¡ |
Clinical Significance
A normal calcaneus–2nd metatarsal angle of 12–18° on the AP view reflects well-balanced foot architecture. Values outside this range suggest malalignment that may be symptomatic or predispose patients to accelerated joint degeneration, pain, and functional disability.
An increased angle (greater than 18°) is associated with forefoot abduction and conditions such as adult-acquired flatfoot deformity (posterior tibial tendon dysfunction), whereas a decreased angle may accompany adductus or cavovarus deformities. Clinicians should correlate this measurement with weight-bearing lateral views and clinical examination, as isolated angular values can be misleading without full context.
- Pes planovalgus (flatfoot deformity)
- Posterior tibial tendon dysfunction (PTTD)
- Metatarsus adductus
- Cavovarus foot deformity
- Post-traumatic hindfoot malalignment
Reference: Banks AS. McGlamry's Comprehensive Textbook of Foot and Ankle Surgery, 3e. Philadelphia: Lippincott Williams & Wilkins, c2001. (2001).
Imaging Notes
Measurement is performed on a weight-bearing anteroposterior radiograph of the foot, which is the standard projection for assessing transverse-plane foot alignment. The angle is formed by drawing a line along the longitudinal axis of the calcaneus and a second line along the central shaft of the second metatarsal; the intersection of these lines yields the calcaneus–2nd metatarsal angle. Non-weight-bearing studies may underestimate deformity and should be avoided when clinically feasible.
Proper patient positioning—foot flat on the cassette, beam angled 15° posteriorly—is critical for reproducibility. Technologist positioning errors and rotational artifacts are the most common sources of measurement variability; bilateral comparative views are recommended when subtle asymmetry is present.