A normal Atlantodental Interval (ADI) in adults varies slightly between sexes, generally considered to be less than 3 mm in men and less than 2.5 mm in women.
Understanding the Atlantodental Interval (ADI)
The Atlantodental Interval (ADI) is a crucial measurement used in medical imaging to assess the relationship between the atlas (C1 vertebra) and the axis (C2 vertebra) in the cervical spine. Specifically, it measures the distance between the posterior aspect of the anterior arch of the atlas and the anterior aspect of the dens (odontoid process) of the axis. This measurement is vital for evaluating the stability and alignment of the atlanto-axial joint, which is a pivotal joint enabling head rotation.
Normal ADI Values
The conventional normal values for ADI differ for adult males and females:
| Sex | Normal ADI (Conventionally Held) |
|---|---|
| Men | Less than 3 mm |
| Women | Less than 2.5 mm |
These values are key indicators for clinicians when assessing the integrity of the craniocervical junction. Deviations from these normal ranges can suggest potential issues such as atlanto-axial instability, which might be caused by trauma, inflammatory conditions like rheumatoid arthritis, or congenital anomalies. Accurate measurement of the ADI helps healthcare professionals determine the appropriate course of management, from conservative treatment to surgical intervention, to prevent neurological complications.
