For elbow flexion and extension assessment, which setup provides the correct alignment of fulcrum and arms?

• A. Position: Supine; Stabilize: Humerus to prevent shoulder flexion and pad under distal humerus prevents extension; Fulcrum: lateral epicondyle of the humerus; Stationary Arm: lateral midline of the humerus using center of acromion process for reference; Moving Arm: lateral midline of the radius, using radial head and radial styloid process for reference
• B. Position: Supine; Stabilize: wrist; Fulcrum: olecranon; Stationary Arm: along ulna; Moving Arm: along radius
• C. Position: Prone; Stabilize: elbow; Fulcrum: medial epicondyle; Stationary Arm: along humerus; Moving Arm: along radius
• D. Position: Sitting; Stabilize: shoulder girdle; Fulcrum: lateral epicondyle; Stationary Arm: along humerus; Moving Arm: along ulna

Answer: (A)

In elbow ROM measurement, the goniometer’s axis must line up with the elbow’s actual hinge axis, while the arms track the long bones to isolate elbow motion. The setup that places the fulcrum at the lateral epicondyle of the humerus aligns precisely with the elbow joint axis. Stabilizing the humerus prevents compensatory shoulder movement, and padding under the distal humerus helps maintain proper alignment and prevents unintended extension when starting the measurement.

The stationary arm should run along the midline of the humerus toward the acromion, giving a stable reference tied to the proximal segment. The moving arm should trace the midline of the forearm along the radius, using the radial head or radial styloid as reference landmarks. This alignment ensures the angle read reflects true elbow flexion and extension, not motions at the shoulder or forearm that could skew the result.

Other common setups misplace the axis or reference lines—using the olecranon or medial epicondyle as the fulcrum, or aligning the arms with the ulna instead of the humerus and radius. Those choices can shift the axis away from the elbow joint or fail to isolate elbow movement, leading to inaccurate measurements.