In the shoulder posterior glide joint mobilization, what is described as the loose-packed position?

• A. Wedge under scapula; GHJ 20 degree scaption, slight ER
• B. Arm abducted 90 degrees
• C. Arm by side
• D. Arm overhead with 0 degrees ER

Answer: (A)

The key idea is recognizing what the joint is doing in a mobilization. A loose-packed (open-packed) position is when the joint capsule is most lax and the articular surfaces are not pressed firmly together, which allows the therapist to glide one surface on the other with minimal compressive forces. For a posterior glide of the glenohumeral joint, this setup is achieved with the arm in the scapular plane (scaption) in a modest amount of abduction, with a small amount of external rotation. Stabilizing the scapula, such as with a wedge placed under it, helps keep the scapulothoracic mechanics from interfering, so the glenohumeral joint can be treated in its most permissive state.

Positioning the arm at about 20 degrees of scaption with slight external rotation places the humeral head in a relatively lax capsule position and aligns the joint surfaces to allow a posterior glide to be applied efficiently and safely. In contrast, positions like an arm by the side or overhead, or a large abduction, tend to tighten the capsule, alter joint alignment, and reduce the available glide, making them less suitable for achieving the desired posterior glide.