Measurement Snapshot
ReferenceTraditional reference: 60 degrees
Common Adult RangeCommon adult active range: 50 to 60 degrees
Primary MusclesLatissimus dorsi, teres major, posterior deltoid, long head of triceps
Shoulder extension measures posterior arm travel and is useful for tracking mobility after trauma, impingement-related stiffness, and capsular restriction workflows.
Standardized Setup
- Patient Position
- Use prone lying when available, or standing with a neutral trunk when table positioning is not practical.
- Stabilization
- Stabilize the scapula and shoulder girdle to prevent trunk rotation, forward lean, or anterior tilting of the shoulder.
- Landmarks
- Use the lateral acromion region as the axis, the lateral trunk as the stationary reference, and the lateral humerus toward the lateral epicondyle as the moving reference.
Step-by-Step Protocol
- Begin with the arm at the side and the elbow fully extended.
- Calibrate the device at the neutral vertical start position.
- Move the arm posteriorly without allowing trunk lean or elbow flexion.
- Record the end-range value and note whether the movement was active or passive.
Common Measurement Errors
- Leaning the trunk forward to create the appearance of more shoulder extension.
- Letting the elbow bend during the posterior lift.
- Failing to stabilize the scapula when anterior shoulder tilt begins.
Cobb Angle Pro Workflow
- Choose Shoulder Extension from the ROM guide list.
- Mount the phone laterally on the humerus or hold the camera parallel to the movement plane.
- Capture the posterior end range and save the context note with patient position and side.
References
- Reese NB, Bandy WD. Joint Range of Motion and Muscle Length Testing. 3rd ed. Saunders; 2016.
- American Academy of Orthopaedic Surgeons. Joint Motion: Method of Measuring and Recording. Chicago: AAOS; 1965.