Normal Djian-Annonier's Angle Size on Radiography
Djian-Annonier's angle is a radiographic measurement used to evaluate the longitudinal arch of the foot on a lateral weight-bearing projection. It is formed by two lines drawn along the plantar surface of the foot, intersecting at the lowest point of the medial arch. Accurate measurement of this angle is clinically important for diagnosing and classifying foot deformities such as pes planus and pes cavus.
Normal Reference Values
| Orientation | Measurement |
|---|---|
| Lateral | 120-130¡ |
Clinical Significance
The normal Djian-Annonier's angle ranges from 120° to 130° on a lateral radiograph. Deviation from this range indicates abnormal arch morphology with direct implications for patient symptoms and surgical planning.
An angle greater than 130° suggests a flattened medial longitudinal arch, consistent with pes planus (flatfoot). Conversely, an angle less than 120° indicates an excessively high arch, consistent with pes cavus. Both conditions can lead to pain, gait disturbance, and secondary degenerative changes in the foot and ankle.
- Pes planus (flatfoot) — angle >130°; associated with posterior tibial tendon dysfunction
- Pes cavus (high arch) — angle <120°; may be idiopathic or neurogenic (e.g., Charcot-Marie-Tooth disease)
- Post-traumatic deformity — altered angle following calcaneal or midfoot fractures
- Iatrogenic change — pre- and post-operative assessment of arch reconstruction procedures
- Congenital foot deformities — used alongside other angular measurements for comprehensive evaluation
A key pitfall is failure to obtain a true lateral weight-bearing projection; non-weight-bearing views may underestimate flatfoot deformity and falsely normalize the angle.
Reference: Bouysset M. Pathologie osto-articulaire du pied et de la cheville, Approche médico-chirurgicale. Springer Verlag France. (2004).
Imaging Notes
Djian-Annonier's angle is measured exclusively on a lateral radiograph of the foot, ideally obtained in a full weight-bearing (standing) position to reflect the true functional arch morphology. The angle is constructed by drawing one line from the most inferior point of the calcaneus to the lowest point of the medial arch (navicular or cuneiform region), and a second line from that midpoint to the most inferior aspect of the first metatarsal head. The intersection of these two lines forms the Djian-Annonier's angle.
Strict positioning is essential: the foot must be in a true lateral projection without rotation. Bilateral comparative views are recommended when asymmetry is suspected. This measurement is frequently used alongside other arch indices (e.g., Meary's angle, calcaneal pitch) to provide a comprehensive biomechanical profile of the foot.