Current Concepts in the Management of Acromioclavicular (AC) Joint Dislocations

High-Yield Summary

• Acromioclavicular (AC) joint dislocations primarily affect young, active adults and are classified by the Rockwood system, which guides treatment decisions.
• Type I and II injuries are managed non-operatively with excellent outcomes; types IV to VI require surgical intervention due to significant displacement and soft tissue disruption.
• Type III injuries remain controversial; patient-specific factors such as activity level, occupationand chronicity influence operative versus non-operative management.
• Surgical techniques focus on anatomical reconstruction of the coracoclavicular (CC) ligaments and AC capsule to restore both vertical and horizontal stability.
• Recent evidence favors anatomic ligament reconstruction with suspensory fixation devices over traditional hook plates or non-anatomic methods, improving functional outcomes and reducing complications.

Clinical Fundamentals

Relevant Anatomy

The AC joint is a diarthrodial joint stabilized by the AC ligaments (superior, inferior, anterior, posterior) and the coracoclavicular ligaments (conoid and trapezoid). The AC ligaments primarily resist horizontal translation, while the CC ligaments provide vertical stability. The deltotrapezial fascia contributes to dynamic stabilization and must be preserved or repaired during surgery.

Biomechanics

Vertical displacement results from CC ligament disruption, while horizontal instability arises from AC ligament injury. Both planes of stability are critical for shoulder girdle function, particularly in overhead and contact activities. Failure to restore horizontal stability correlates with persistent symptoms and poor functional outcomes.

Epidemiology

AC joint dislocations account for approximately 9% of shoulder injuries, predominantly affecting males aged 20-40 years. Mechanisms typically involve a direct blow to the lateral shoulder or fall onto an outstretched hand.

Classification & Diagnosis

Diagnostic Pearls

• Obtain bilateral AP and axillary lateral radiographs for accurate displacement assessment.
• Stress views are generally not recommended due to pain and variability.
• Assess horizontal instability clinically and with axillary views, especially in type III injuries.
• MRI is reserved for chronic cases or when concomitant rotator cuff pathology is suspected.

Decision-Making Algorithm

Non-Operative Management

Indicated for Rockwood types I and II due to intact or minimally disrupted CC ligaments and preserved joint stability. Type III injuries may be managed non-operatively in low-demand patients or those with contraindications to surgery. Treatment includes sling immobilization, early passive range of motionand progressive strengthening.

Operative Management

Indicated for types IV, Vand VI due to gross displacement and soft tissue disruption. Surgery is also considered for type III injuries in high-demand athletes, laborersor patients with persistent pain and instability after conservative treatment.

Surgical Approach and Implant Selection

• Anatomic CC ligament reconstruction using suspensory fixation devices (e.g., TightRope, Dog Bone) is preferred for restoring vertical stability.
• Augmentation of the AC capsule and deltotrapezial fascia repair is essential to address horizontal stability.
• Hook plates are reserved for salvage or specific fracture-dislocation patterns due to higher complication rates.
• Biological grafts (autograft or allograft) may be used in chronic cases or revision surgery to enhance ligamentous healing.

Surgical Mastery & Pearls

Step-by-Step Conceptual Overview

1. Patient Positioning: Beach chair or supine with a bump under the scapula to optimize exposure.
2. Incision and Exposure: Longitudinal incision centered over the distal clavicle and AC joint; careful dissection to preserve the deltotrapezial fascia.
3. Joint Assessment: Debride the AC joint and assess ligament remnants; excise distal clavicle if indicated (typically <1 cm).
4. Coracoid Preparation: Identify the coracoid base; avoid neurovascular injury by staying medial and inferior to the conjoint tendon.
5. Tunnel Drilling: Create clavicular and coracoid tunnels for suspensory fixation devices; use fluoroscopy to confirm position and avoid fractures.
6. Fixation: Pass suspensory device and tension to restore clavicle position; confirm reduction clinically and radiographically.
7. AC Capsule Repair: Reconstruct or augment the AC ligaments to restore horizontal stability.
8. Fascial Closure: Meticulous repair of the deltotrapezial fascia to prevent postoperative deformity and hardware irritation.

Intraoperative Red Flags

• Excessive tunnel diameter or malposition increases fracture risk.
• Over-tensioning the construct can cause clavicle fracture or hardware failure.
• Failure to address horizontal instability leads to persistent symptoms.
• Inadequate fascial repair predisposes to hardware prominence and wound complications.

Evidence-Based Synthesis

Recent randomized controlled trials and meta-analyses have clarified management paradigms. Non-operative treatment yields excellent outcomes for types I and II, with low complication rates. For type III injuries, studies reveal no clear superiority of surgery over conservative care in the general population; however, subgroup analyses favor surgery in athletes and laborers for earlier return to function and improved cosmetic results.

Surgical innovation has shifted from rigid fixation (hook plates) to anatomic ligament reconstruction using suspensory devices and biological grafts. High-quality trials demonstrate improved functional scores, lower complication ratesand reduced need for hardware removal with suspensory fixation. However, debate persists regarding the optimal graft choice and the necessity of AC capsule reconstruction, with emerging evidence supporting combined ligamentous repair for superior horizontal stability.

Long-term data remain limitedand ongoing studies aim to define best practices for chronic and revision cases. The balance between early mobilization and protection of repair integrity continues to evolve based on biomechanical and clinical findings.

Master Class Pro-Tip

Mastery in AC joint reconstruction hinges on restoring both vertical and horizontal stability through anatomic ligament reconstruction combined with meticulous soft tissue repair. Prioritize precise tunnel placement under fluoroscopic guidance to minimize fracture risk. Never underestimate the importance of deltotrapezial fascia repair-this step is critical to prevent postoperative deformity and hardware irritation, often overlooked by less experienced surgeons. Finally, tailor your approach to the individual patient’s functional demands and chronicity of injury, integrating evidence with clinical judgment to optimize outcomes.

Last Updated on September 2, 2026 by OrthoNet AI