Normal Humeral Angle Size on Radiography
The humeral angle is a geometric measurement assessed on the lateral elbow radiograph, reflecting the angular relationship of the distal humeral shaft relative to the articular surface. Accurate measurement is essential in evaluating distal humeral morphology and detecting subtle fractures or post-traumatic deformity. It serves as a reliable reference in both acute trauma workup and post-surgical follow-up.
Normal Reference Values
| Orientation | Measurement |
|---|---|
| Lateral | 72-95¡ |
Clinical Significance
A humeral angle falling outside the normal range of 72–95° on lateral projection should raise concern for distal humeral fracture, physeal injury, or malunion following prior trauma. In the pediatric population, subtle angulation changes are particularly significant and may indicate a supracondylar fracture variant that could be overlooked without careful angular assessment.
Angulation exceeding the upper limit may suggest anterior or posterior displacement of the distal humeral articular segment, while values below the lower threshold may indicate pathological remodeling or growth disturbance. Comparison with the contralateral elbow is often valuable when findings are borderline.
- Supracondylar fracture (especially in children)
- Lateral condyle fracture
- Distal humeral malunion or nonunion
- Post-traumatic cubitus varus or valgus deformity
- Physeal growth arrest
Reference: Yochum TR, Rowe LJ. Essentials of Skeletal Radiology. (2005).
Imaging Notes
The humeral angle is measured on a true lateral radiograph of the elbow. Proper positioning requires the elbow flexed to 90° with the forearm in neutral rotation, ensuring the medial and lateral condyles are superimposed. Rotational malpositioning is the most common source of measurement error and can artificially alter the apparent angle.
To perform the measurement, draw a line along the long axis of the distal humeral shaft and a second line along the anterior cortex or articular surface; the angle subtended between these lines is recorded. Consistent technique and adherence to positioning standards are critical for reproducible, clinically actionable values.