Purpose
Observation of the relationship between the humerus and scapula in the zero position.
Diagnosis of unstable shoulder or shoulder dislocation.
The zero position, as proposed by Saha, is a limb position where the muscles around the shoulder joint converge and relax along the axis that aligns the scapular spine with the humerus, without any rotation. It is the position where the joint is most stable. The limb is elevated to 150-165 degrees from a relaxed position and moved 30-45 degrees anteriorly.
Prior confirmation
Remove any obstructing objects.
Positioning
Erect, sitting (or supine) position.
Face away from the cassette and align the coronal plane with the cassette.
Align the glenohumeral joint with the center of the cassette.
Elevate the relaxed upper limb to approximately 150 degrees and move it forward by about 30 degrees. Take care to avoid curving the body axis.
Place the R/L marker.
CR, distance, field size
CR : Perpendicular incidence towards the glenohumeral joint.
Distance : 100cm.
Field size : Narrow down to include the proximal 1/3 of the humerus and the inferior angle of the scapula.
Exposure condition
70kV / 16mAs
Grid ( + )
Suspend respiration
Image, check-point
Normal
The axis of the humerus and the scapular spine are aligned in a straight line.
The acromion, acromioclavicular joint, and coracoid process are observable.
The R/L marker is visible.
There is no motion blur due to body movement.
Videos
Related materials
