metaphyseal-diaphyseal angle
Also written as: MDA — metaphyseal-diaphyseal angle
A radiographic measurement used to assess tibia vara, calculated as the angle between the metaphyseal and diaphyseal axes of the proximal tibia.
Full Definition
The metaphyseal-diaphyseal angle (MDA) is a crucial radiographic measurement in the evaluation of tibia vara, particularly in Blount disease. The angle is measured on an anteroposterior radiograph by drawing lines along the metaphyseal beaking of the proximal tibia and the long axis of the tibial diaphysis. Normal values are typically less than 11 degrees, while values greater than 16 degrees are considered abnormal and suggestive of Blount disease. The MDA is part of the Langenskiöld classification system and helps distinguish between physiologic bowing and pathologic tibia vara, influencing treatment decisions.
Usage
Usage note: Always hyphenated when used as a compound modifier.
In Context
- "The metaphyseal-diaphyseal angle measured 18 degrees, confirming the diagnosis of infantile Blount disease." — Radiology report
- "Serial measurements of the metaphyseal-diaphyseal angle showed progressive worsening despite bracing." — Follow-up assessment