What is the normal capsular pattern for the acromioclavicular joint?

• A. Flexion equals extension
• B. No true capsular pattern; possible loss of horizontal adduction and pain (and sometimes slight loss of end range) with each motion
• C. No true capsular pattern; possible loss of horizontal adduction and pain with each motion
• D. No true capsular pattern; possible loss of horizontal adduction and pain (and sometimes slight loss of end range) with each motion

Answer: (D)

The acromioclavicular joint does not have a true capsular pattern. Its capsule is thin and the joint is mainly a small, gliding articulation that contributes to shoulder girdle movement rather than a fixed, direction-limited pattern. Because of this, stiffness isn’t tied to a single sequence of restricted motions.

In practice, what you often see with AC joint irritation or pathology is pain with horizontal adduction (cross-body movement) and some pain with other motions, and there may be slight loss of range at end range, but there isn’t a consistent, uniform pattern across all directions. This combination—no true capsular pattern with possible loss of horizontal adduction and pain (and sometimes slight end-range loss)—best describes the AC joint’s behavior, which is why that option is the correct one.