AC Joint Injuries: Understanding, Diagnosis, and Repair

How Do You Repair An AC Joint Injury?

Repairing an AC joint injury involves a spectrum of treatments, ranging from conservative non-surgical management for lower-grade sprains to surgical reconstruction for more severe dislocations, all followed by a structured rehabilitation program to restore function and strength.

Understanding the AC Joint and Its Injuries

The acromioclavicular (AC) joint is located at the top of the shoulder, where the collarbone (clavicle) meets the highest part of the shoulder blade (acromion). This critical joint is stabilized by several ligaments: the acromioclavicular (AC) ligaments, which connect the clavicle directly to the acromion, and the stronger coracoclavicular (CC) ligaments (conoid and trapezoid), which connect the clavicle to the coracoid process of the scapula.

AC joint injuries, often referred to as shoulder separations, typically result from a direct blow to the top or side of the shoulder, such as a fall onto the shoulder or a direct impact in contact sports. These injuries are classified into six types (I-VI) based on the severity of ligamentous damage and the degree of clavicular displacement:

• Type I: A mild sprain of the AC ligaments, with no displacement of the clavicle.
• Type II: A tear of the AC ligaments, with partial displacement of the clavicle, but the CC ligaments remain intact.
• Type III: Complete tears of both the AC and CC ligaments, resulting in noticeable upward displacement of the clavicle.
• Type IV: Similar to Type III, but the clavicle is displaced posteriorly (backward) into or through the trapezius muscle.
• Type V: A severe Type III injury with significant upward displacement of the clavicle (often 100-300% of normal).
• Type VI: A rare injury where the clavicle is displaced inferiorly (downward) beneath the coracoid process.

Diagnosing an AC Joint Injury

Accurate diagnosis is crucial for determining the appropriate treatment path.

• Clinical Examination: A healthcare professional will assess the shoulder for pain, swelling, bruising, and deformity. They will palpate the AC joint and perform specific maneuvers to elicit pain and assess stability.
• Imaging Studies:
  • X-rays: Standard shoulder X-rays, often including specific AC joint views (e.g., Zanca view) and sometimes weighted views (though less common now), are used to assess the degree of clavicular displacement and rule out fractures.
  • MRI (Magnetic Resonance Imaging): May be used to evaluate the extent of soft tissue damage, including ligaments, and to rule out other associated injuries.
  • CT Scan: Can provide detailed bone imaging, useful for assessing complex fractures or precise clavicular displacement in higher-grade injuries.

Non-Surgical Management (Conservative Treatment)

Conservative treatment is the primary approach for most AC joint injuries, particularly Type I, II, and often Type III injuries. The goals are to manage pain, protect the healing ligaments, and restore full shoulder function.

• Pain and Inflammation Management:
  • RICE Protocol: Rest, Ice, Compression (though less common for AC joint), and Elevation.
  • Non-Steroidal Anti-Inflammatory Drugs (NSAIDs): To reduce pain and inflammation.
  • Sling Immobilization: A sling is typically used for comfort and to protect the joint, usually for 1-3 weeks depending on the injury grade. Prolonged immobilization is generally avoided to prevent stiffness.
• Phased Rehabilitation:
  • Acute Phase (Days 1-7+): Focus on pain control, protecting the joint, and maintaining passive range of motion (ROM) of the elbow, wrist, and hand. Gentle pendulum exercises may be initiated.
  • Sub-Acute Phase (Week 2-4+): As pain subsides, the focus shifts to restoring full, pain-free shoulder ROM. This includes passive, active-assisted, and then active range of motion exercises. Scapular mobility exercises are also introduced.
  • Strengthening Phase (Week 4-12+): Gradual introduction of strengthening exercises for the rotator cuff, deltoid, and periscapular muscles (e.g., trapezius, rhomboids, serratus anterior). Initial exercises may be isometric, progressing to isotonic with light resistance. Focus on proper form and controlled movements.
  • Return to Activity Phase (Week 12+): Progressive return to functional and sport-specific activities. This phase involves higher-level strengthening, plyometrics, and simulated sport movements. Full return to contact sports typically requires complete pain resolution, full strength, and confidence in the shoulder.

Surgical Intervention for AC Joint Injuries

Surgical repair is generally reserved for higher-grade injuries (Type IV, V, VI) due to significant instability, severe cosmetic deformity, or for select Type III injuries that fail conservative management or occur in individuals with high overhead demands (e.g., athletes, manual laborers).

• Indications for Surgery:
  • Type IV, V, VI Injuries: These involve severe displacement and often require surgical stabilization to restore function and prevent long-term complications.
  • Failed Conservative Treatment: For some Type III injuries that remain symptomatic with persistent pain, weakness, or instability despite a dedicated conservative rehabilitation program.
  • Cosmetic Concerns: In some cases, the prominent deformity of a Type III injury may lead to a surgical decision.
  • Specific Occupational/Athletic Demands: Individuals requiring maximal overhead function may benefit from surgical stabilization of a Type III injury.
• Surgical Goals: The primary goals are to reduce the clavicle back into its anatomical position, stabilize the AC joint, and allow for healing of the torn ligaments.
• Common Surgical Techniques:
  • Coracoclavicular (CC) Ligament Reconstruction/Repair: This is the most common approach. It involves using strong sutures, synthetic grafts (e.g., TightRope, DogBone), or biological grafts (autograft from the patient or allograft from a donor) to reconstruct the torn CC ligaments, providing stability while the body's natural healing occurs.
  • AC Joint Fixation: Less common for acute injuries, but methods like using a hook plate (which is later removed) or screws across the AC joint were historically used to temporarily stabilize the joint.
  • Distal Clavicle Excision (Mumford Procedure): This is typically performed for chronic AC joint pain or arthritis, often years after an initial injury, where a small portion of the end of the clavicle is removed to prevent bone-on-bone impingement. It is not a primary repair for acute instability.
• Post-Surgical Rehabilitation: This is critical for successful outcomes and follows a structured protocol, often more conservative initially than non-surgical rehab, with strict limitations on weight-bearing and range of motion to protect the repair. It progresses through similar phases of pain control, ROM restoration, progressive strengthening, and return to activity, but typically on a longer timeline.

Rehabilitation Principles Post-Injury or Surgery

Regardless of whether the AC joint injury is treated conservatively or surgically, a structured and progressive rehabilitation program is paramount for optimal recovery. This is typically guided by a physical therapist.

• Phased Progression: Rehabilitation is meticulously phased to ensure proper healing and avoid re-injury.
  • Protection Phase: Focus on pain/swelling control, protecting the healing tissues (sling use), and maintaining general mobility of the arm.
  • Early Motion Phase: Gradual restoration of passive and active-assisted range of motion, starting with gentle pendulum exercises and progressing as tolerated.
  • Strengthening Phase: Introduction of isometric, then isotonic, exercises for the rotator cuff, deltoid, and scapular stabilizers. Emphasis on proper form and controlled movements.
  • Functional/Sport-Specific Phase: Incorporating exercises that mimic daily activities or sport-specific movements, gradually increasing intensity and complexity.
• Key Components of Rehab:
  • Pain and Edema Management: Modalities like ice, heat, and gentle massage.
  • Range of Motion (ROM) Exercises: To prevent stiffness and restore full mobility.
  • Scapular Stability Training: Strengthening muscles that control the shoulder blade (e.g., serratus anterior, trapezius, rhomboids) to provide a stable base for arm movement.
  • Rotator Cuff Strengthening: Crucial for dynamic shoulder stability and preventing impingement.
  • Proprioception and Neuromuscular Control: Exercises to improve the joint's sense of position and movement, enhancing stability.
  • Progressive Loading: Gradually increasing the resistance and demands on the shoulder as healing progresses.
• Patient Education: Understanding the injury, the healing process, and adherence to the rehabilitation protocol are critical for successful outcomes.

Prognosis and Long-Term Considerations

The prognosis for AC joint injuries is generally good, especially for lower-grade sprains.

• Type I and II injuries: Most individuals recover full function with conservative treatment within a few weeks to months. Some may experience a persistent "bump" at the AC joint or occasional mild discomfort, but this usually doesn't limit function.
• Type III injuries: Outcomes vary. Many achieve good functional results with conservative management, even with the persistent deformity. However, a subset may experience chronic pain, fatigue, or instability, potentially leading to a delayed surgical intervention.
• Higher-grade injuries (Type IV, V, VI): Surgical repair often leads to good functional outcomes, but the recovery period is longer, and a diligent rehabilitation program is essential.
• Potential Complications: Chronic pain, residual instability, early onset of AC joint arthritis (due to altered biomechanics or persistent instability), and cosmetic deformity are possible long-term issues.

Prevention Strategies

While not all AC joint injuries can be prevented, especially those from traumatic falls, certain strategies can reduce risk:

• Proper Falling Techniques: Athletes in sports like cycling, skiing, or martial arts can learn techniques to distribute impact away from the direct shoulder.
• Shoulder Strength and Stability: Maintaining strong rotator cuff and periscapular muscles can enhance overall shoulder stability and potentially absorb some impact.
• Protective Gear: In contact sports, appropriate padding and protective gear can help mitigate direct blows to the shoulder.