Which arrangement describes the measurement of shoulder abduction with correct stabilization and goniometer placement?

• A. Position: Supine; Stabilize: GHJ - Stabilize the thorax to prevent lateral flexion; Complex - Scapula to prevent upward rotation and elevation of scapula; Fulcrum: close to the anterior aspect of acromion process; Stationary Arm: parallel to midline of anterior aspect of sternum; Moving Arm: anterior midline of the humerus (medial epicondyle)
• B. Position: Supine; Stabilize: GHJ - distal humerus to keep 90 degrees abduction; Fulcrum: over the acromion; Stationary Arm: along the sternum; Moving Arm: along the humerus
• C. Position: Seated; Stabilize: clavicle to prevent downward rotation; Fulcrum: lateral edge of acromion; Stationary Arm: along midline of chest; Moving Arm: along humerus
• D. Position: Supine; Stabilize: scapula to prevent upward rotation; Fulcrum: lateral aspect of the acromion; Stationary Arm: parallel to the floor; Moving Arm: along the humerus

Answer: (A)

Measuring shoulder abduction with a goniometer requires isolating glenohumeral motion by stabilizing the trunk and the scapula and aligning the instrument with the joint’s movement. Using a supine position helps limit extraneous spinal motion, while stabilizing the thorax prevents lateral flexion and the scapula from upwardly rotating or elevating, so the reading reflects mainly the shoulder joint.

Placing the fulcrum close to the anterior aspect of the acromion aligns the axis with the humeral head’s movement during abduction. The stationary arm should run parallel to the midline of the sternum, giving a solid trunk reference, and the moving arm should track along the anterior midline of the humerus, using the medial epicondyle as a landmark. This setup minimizes compensations and yields an accurate measurement of shoulder abduction at the glenohumeral joint.

Other arrangements either stabilize the wrong structures (like the clavicle or distal humerus), place the axis in a less appropriate location (such as the lateral edge of the acromion), or use a stationary arm that doesn’t reference the trunk, all of which can introduce compensations and inaccuracies in the reading.