An acromioclavicular (AC) joint separation, often called a separated shoulder, is an injury to the ligaments connecting the collarbone (clavicle) to a part of the shoulder blade (acromion). This joint, located at the highest point of the shoulder, plays a role in shoulder movement and stability. The injury typically occurs from a direct, forceful impact to the shoulder, such as a fall or a tackle during sports.
The severity of an AC joint separation is categorized using a grading system, most commonly ranging from Grade I to Grade III for non-surgical cases. A Grade I injury involves a simple sprain or mild stretch of the AC ligament, resulting in minimal displacement. Grade II injuries involve a complete tear of the AC ligament, leading to a partial separation. Grade III separation is the most severe type usually managed without surgery, involving a complete tear of both the AC and coracoclavicular ligaments, causing a noticeable displacement or “bump” at the shoulder. The rehabilitation timeline is directly influenced by this grading, with milder sprains resolving in a few weeks and Grade III injuries requiring a recovery period of up to 12 weeks or longer.
Initial Recovery: Immobilization and Early Movement
The immediate goal following an AC joint separation is to manage pain and protect the integrity of the injured ligaments, which typically lasts for the first one to two weeks, depending on the injury grade. A sling or immobilizer is commonly used to support the arm’s weight and prevent excessive movement that could stress the healing joint. Patients are encouraged to discontinue sling use as soon as pain allows, often within the first week, as it is primarily worn for comfort.
Pain and swelling are managed using a modified RICE protocol: Rest, Ice, Compression, and Elevation. Applying ice to the injury site for 15-20 minutes several times a day helps reduce inflammation and discomfort, particularly in the first few days. While the joint needs protection, movement in the elbow, wrist, and hand should be maintained to prevent stiffness and promote circulation.
Gentle, non-AC focused exercises are introduced early to prevent muscle atrophy and stiffness. Pendulum swings are an excellent starting point, performed by leaning forward and letting the injured arm hang down, using the body’s momentum to swing the arm in small, controlled circles. This passive motion improves blood flow without stressing the AC joint. Scapular squeezes, performed by gently retracting the shoulder blades, can also be initiated early to activate the muscles that stabilize the shoulder girdle.
Restoring Mobility: The Intermediate Phase
Once acute pain subsides and the joint is stable (typically two to six weeks post-injury), the focus shifts to regaining a full, pain-free range of motion (ROM). This phase involves transitioning to active movements, where the muscles move the joint without external help. Initial exercises often involve using the uninjured arm or a cane to assist the injured arm through its range of motion, such as forward elevation or external rotation.
Active range of motion exercises begin cautiously, ensuring no sharp pain or pinching is felt at the AC joint. Movements like wall walks and finger ladders are effective ways to gradually restore overhead mobility in a controlled manner. Gentle stretching, such as a doorway pectoral stretch, helps address tightness that develops from guarding the shoulder or prolonged sling use.
It is important to focus on maintaining proper posture throughout this phase, as slumping can negatively affect the alignment of the shoulder blade and place unnecessary strain on the healing joint. Gentle internal and external rotation exercises, performed with the elbow tucked to the side, are introduced to restore the rotator cuff’s ability to control movement. Movements that involve bringing the arm across the chest (horizontal adduction) or reaching behind the back should be avoided initially, as these can provoke symptoms by compressing the AC joint.
Building Strength: The Advanced Phase and Return to Activity
The advanced phase, generally beginning after six weeks, concentrates on strengthening the muscles surrounding the shoulder joint to provide dynamic stability and prepare the joint for functional loads. The primary muscle groups targeted are the rotator cuff and the scapular stabilizers, including the rhomboids and trapezius. Strengthening exercises often start with isometric holds, where the muscle is contracted without joint movement, and progress to using light resistance bands or tubing.
Exercises like scapular rows and external rotation with a resistance band are fundamental for strengthening the back and shoulder muscles that control the shoulder blade’s position. As strength improves, light free weights are introduced, and exercises like prone T’s and Y’s are used to specifically target the middle and lower trapezius. Closed-chain exercises, such as wall push-ups, are also incorporated early, as they place less direct stress on the AC joint compared to open-chain movements.
Progression involves advancing from light resistance to heavier loads and incorporating more challenging exercises, such as light overhead pressing and a push-up progression. The criteria for returning to full activity, including sports, are performance-based, not strictly time-based. The individual must demonstrate a full, pain-free range of motion and strength symmetry, ideally reaching 90-100% of the strength of the uninjured side. Functional and sport-specific training, such as practicing throwing motions or lifting mechanics, is the final step before a full return to play is cleared.