What is the normal range of the coracoclavicular distance?
Its normal average range is between 11-13 mm, but there is a wide range of individual variance, thus making the comparison with the normal side important. An increase in the distance >50% compared to the normal side is indicative of a complete acromioclavicular dislocation, although complete dislocations can happen with smaller increases such as 25%.
What is the normal range of the acromioclavicular distance?
Its normal average range is between 1-3 mm. As the distance is narrowed with aging, joint space of 0.5 mm can be considered normal in elderly patients. The distance is considered to be suggestive of acromioclavicular ligament lesion if it is >7 mm in men and >6 mm in women.
What is the piano key sign?
The sign is present if the clavicle pops up after being released from a downwards pressure. This indicates an acromioclavicular joint injury.
Annotated images of the coracoclavicular (CC) distance and acromioclavicular (AC) distance. Both distances are widened.
- CC distance: 17.01 mm
- AC distance: 10.30 mm
An acromioclavicular joint injury with a CC distance of <25 mm is classified as a Rockwood type III.