Acromioclavicular (AC) Joint Injury

1. Anatomy

1.1 Overview of the Acromioclavicular Joint Complex

The acromioclavicular (AC) joint represents a critical articulation within the shoulder girdle, serving as the sole bony connection between the axial skeleton (via the clavicle) and the upper extremity (via the scapula). Understanding the intricate anatomy of this joint and its surrounding structures is fundamental to comprehending injury patterns, classification systems, and treatment rationale.

The AC joint functions as a diarthrodial synovial articulation positioned at the lateral terminus of the clavicle where it meets the medial aspect of the acromion process. Despite its relatively small size, this joint plays an outsized role in upper extremity mechanics, shoulder stability, and force transmission during activities of daily living and athletic performance.

1.2 Osseous Anatomy

1.2.1 Distal Clavicle

The clavicle is the first bone to ossify in the human body (occurring during the fifth week of fetal development) and is unique in being the only long bone to ossify via intramembranous ossification. The distal clavicle comprises approximately the lateral one-third of the bone and exhibits distinct morphological features:

Morphological Characteristics:

• Shape transformation: The clavicle transitions from a tubular cross-section medially to a flattened configuration distally
• Articular surface: The distal articular facet is typically oval or elliptical, measuring approximately 9-12 mm in the anteroposterior dimension and 18-22 mm in the superoinferior dimension
• Orientation: The articular surface is oriented obliquely, facing laterally and slightly inferiorly at an angle of approximately 10-15 degrees from the coronal plane
• Curvature: The distal clavicle curves anteriorly as it approaches the AC joint, contributing to the S-shaped contour of the entire clavicle

Surface Features:

• Superior surface: Provides attachment for the deltoid muscle anteriorly and the trapezius muscle posteriorly
• Inferior surface: Contains the conoid tubercle (a prominent bony projection) and the trapezoid line (a ridge extending anterolaterally from the conoid tubercle)
• Anterior border: Relatively smooth, providing attachment for the anterior deltoid fibers
• Posterior border: Roughened for trapezius muscle attachment

Conoid Tubercle:

• Location: Inferior surface of the clavicle, approximately 45-50 mm from the distal end (range: 25-65 mm)
• Morphology: Conical projection, typically 5-10 mm in height
• Clinical significance: Serves as the attachment site for the conoid ligament; damage during injury or surgical reconstruction can affect ligament healing

Trapezoid Line:

• Location: Extends anterolaterally from the conoid tubercle toward the distal clavicle
• Length: Approximately 25-30 mm
• Width: 8-12 mm
• Clinical significance: Attachment site for the trapezoid ligament; must be preserved during surgical approaches

1.2.2 Acromion Process

The acromion is the lateral extension of the scapular spine, forming the roof of the subacromial space and the lateral wall of the AC joint:

Morphological Classification (Bigliani Classification):

• Type I (Flat): Flat undersurface; present in approximately 12-17% of population
• Type II (Curved): Convex curvature; most common type (43-56% of population)
• Type III (Hooked): Anterior-inferior hook; associated with rotator cuff pathology (29-40% of population)
• Type IV (Upturned): Convex on the undersurface; least common variant

Articular Surface:

• The medial aspect of the acromion contains a small, concave or flat articular facet for articulation with the distal clavicle
• The articular surface orientation is variable, ranging from nearly vertical to angled medially up to 50 degrees
• Surface area: Typically 4-9 cm², slightly smaller than the clavicular articular surface

Ossification Centers:

• The acromion develops from multiple ossification centers (typically 2-4)
• Primary ossification occurs between ages 15-18
• Fusion is typically complete by age 25
• Os acromiale: Failure of fusion results in this anatomical variant, present in 1-15% of population, which may predispose to AC joint pathology or complicate surgical planning

1.2.3 Joint Configuration and Articulation

The articular surfaces of both bones are covered with fibrocartilage rather than hyaline cartilage, distinguishing the AC joint from most other synovial joints. This fibrocartilaginous covering may represent an adaptation to the complex loading patterns experienced by the joint.

Joint Space Characteristics:

• Width: Normally 1-3 mm in adults (up to 6 mm in children)
• Joint space > 6 mm in adults suggests AC joint pathology
• Asymmetry > 50% compared to the contralateral side is suggestive of injury

Articular Surface Variations: Several anatomical variations exist in the relationship between the articular surfaces:

• Underriding clavicle: The clavicular surface is positioned inferior to the acromial surface (approximately 50% of individuals)
• Overriding clavicle: The clavicular surface is positioned superior to the acromial surface (approximately 27% of individuals)
• Congruent: The surfaces are level with each other (approximately 23% of individuals)

1.3 Intra-Articular Structures

1.3.1 Meniscoid Disc (Intra-Articular Fibrocartilaginous Disc)

A fibrocartilaginous disc is present within the AC joint, though its morphology varies considerably:

Types of Disc:

• Complete disc: Fully divides the joint cavity into two compartments (rare in adults)
• Partial disc (Meniscoid): Partially extends into the joint space from the superior capsule (most common)
• Remnant/Absent: Minimal or no discernible disc structure (common in older adults due to degeneration)

Age-Related Changes:

• At birth: A complete disc is typically present
• By age 2-3: The disc begins to show degenerative changes
• By age 40: The disc is often fragmented, absent, or minimally present
• Clinical studies have shown that only 10-15% of adults possess a complete or partial disc

Functional Significance:

• Theorized to distribute compressive loads across the joint
• May function as a shock absorber
• Potential pain generator when torn or degenerated
• Its progressive degeneration may contribute to the high prevalence of AC joint osteoarthritis in older adults

1.3.2 Synovial Membrane and Joint Capsule

Synovial Membrane:

• Lines the inner surface of the fibrous joint capsule
• Does not cover the articular cartilage surfaces
• Produces synovial fluid for joint lubrication and cartilage nutrition
• Contains type A synoviocytes (macrophage-like) and type B synoviocytes (fibroblast-like)

Joint Capsule:

• Thin, fibrous capsule surrounding the joint
• Blends with the AC ligaments superiorly and inferiorly
• Relatively lax to allow the complex motions of the AC joint
• Capsular thickness: Approximately 1-2 mm

1.4 Ligamentous Anatomy

The stability of the AC joint is maintained by two distinct ligament groups: the acromioclavicular ligaments (intrinsic stabilizers) and the coracoclavicular ligaments (extrinsic stabilizers). The relative contribution of each ligament group to joint stability has been extensively studied and is critical to understanding injury classification and treatment.

1.4.1 Acromioclavicular Ligaments

The AC ligaments form a capsular thickening around the joint and are divided into four distinct components:

Superior Acromioclavicular Ligament:

• Location: Forms the superior aspect of the joint capsule
• Dimensions: Approximately 10-15 mm in width, 6-8 mm in anteroposterior dimension
• Thickness: 2-4 mm (thickest of the AC ligaments)
• Fiber orientation: Primarily horizontal, running from the superior clavicle to the superior acromion
• Reinforcement: Strengthened by fibers from the deltoid and trapezius aponeuroses, which contribute significantly to its strength
• Function: Primary restraint to posterior translation of the clavicle; contributes to horizontal stability
• Biomechanical contribution: Provides approximately 56% of resistance to posterior clavicular translation

Inferior Acromioclavicular Ligament:

• Location: Forms the inferior aspect of the joint capsule
• Dimensions: Similar to superior ligament but thinner (1-2 mm)
• Function: Contributes to vertical and horizontal stability
• Clinical significance: Often torn in conjunction with superior ligament in higher-grade injuries

Anterior Acromioclavicular Ligament:

• Location: Forms the anterior aspect of the joint capsule
• Fiber orientation: Runs horizontally from the anterior clavicle to the anterior acromion
• Function: Limits posterior translation of the clavicle

Posterior Acromioclavicular Ligament:

• Location: Forms the posterior aspect of the joint capsule
• Fiber orientation: Runs horizontally from the posterior clavicle to the posterior acromion
• Function: Primary restraint to anterior translation and axial rotation
• Biomechanical contribution: Provides approximately 25% of resistance to anterior translation

Biomechanical Properties of AC Ligaments:

• Ultimate tensile strength: Approximately 500-700 N
• Primary function: Provide horizontal (anteroposterior) stability
• Secondary function: Contribute to rotational stability
• The superior AC ligament is the strongest component, followed by the posterior ligament

1.4.2 Coracoclavicular Ligaments

The coracoclavicular (CC) ligament complex represents the primary vertical stabilizer of the AC joint. It consists of two distinct ligaments—the conoid and trapezoid—that connect the coracoid process of the scapula to the inferior surface of the distal clavicle.

Conoid Ligament:

• Shape: Cone-shaped or triangular
• Origin: Superior and posterior aspect of the base of the coracoid process
• Insertion: Conoid tubercle on the posterior-inferior surface of the clavicle
• Orientation: Runs nearly vertically with slight anterior angulation
• Dimensions:
  • "Length: 20-25 mm (average 22 mm)"
  • "Width at insertion: 8-12 mm"
  • "Thickness: 3-5 mm"
• Fiber structure: Dense, organized collagen fibers
• Function:
  • Primary restraint to superior clavicular translation
  • Limits anterior-posterior translation
  • Controls scapular rotation relative to the clavicle
• Biomechanical properties:
  • "Ultimate tensile strength: 390-725 N (average 500 N)"
  • "Stiffness: Approximately 48-54 N/mm"
  • "Strain to failure: Approximately 13-18%"

Trapezoid Ligament:

• Shape: Quadrilateral or trapezoidal
• Origin: Superior aspect of the coracoid process, anterior to the conoid attachment
• Insertion: Trapezoid line on the anterior-inferior surface of the clavicle
• Orientation: Runs obliquely from posteromedial (coracoid) to anterolateral (clavicle)
• Dimensions:
  • "Length: 15-20 mm (shorter than conoid)"
  • "Width: 15-25 mm (wider than conoid)"
  • "Thickness: 6-10 mm"
• Function:
  • Limits axial compression of the AC joint
  • Resists superior clavicular translation (secondary)
  • Controls horizontal displacement
• Biomechanical properties:
  • "Ultimate tensile strength: 440-840 N (average 640 N)"
  • "Stiffness: Approximately 46-60 N/mm"
  • Generally stronger than the conoid ligament despite its shorter length

Inter-Ligamentous Space:

• A bursa (coracoclavicular bursa) often exists between the conoid and trapezoid ligaments
• This space may contain fat or loose connective tissue
• Distance between ligaments: Approximately 10-15 mm

Combined CC Ligament Properties:

• Total ultimate load to failure: Approximately 725-1,600 N
• The CC ligaments provide 40-60% of the restraint to superior displacement of the clavicle
• Sequence of failure: The conoid typically fails before the trapezoid in superior displacement injuries

Anatomical Variations:

• Bifid conoid ligament: Present in approximately 10% of individuals
• Accessory coracoclavicular ligaments have been described
• The coracoclavicular distance (normal: 11-13 mm) is a critical radiographic parameter

1.4.3 Coracoacromial Ligament

While not directly involved in AC joint stability, the coracoacromial (CA) ligament is anatomically adjacent and clinically relevant:

• Course: Extends from the anterolateral coracoid to the anteromedial acromion
• Function: Forms the roof of the coracoacromial arch; restrains superior humeral head migration
• Clinical relevance: May be used as autograft tissue in CC ligament reconstruction (Weaver-Dunn procedure)
• Dimensions: Approximately 30-40 mm in length, 10-15 mm in width

1.5 Muscular Anatomy

The muscles surrounding the AC joint contribute both to its dynamic stability and to the forces that may cause deformity following injury.

1.5.1 Deltoid Muscle

Anatomy:

• Origin: Anterior third from the lateral third of the clavicle; middle third from the acromion; posterior third from the spine of the scapula
• Insertion: Deltoid tuberosity of the humerus
• Innervation: Axillary nerve (C5, C6)
• Blood supply: Thoracoacromial artery (deltoid branch), posterior circumflex humeral artery

Relationship to AC Joint:

• The anterior deltoid fibers originate from the superior surface of the distal clavicle and cross the AC joint
• These fibers blend with the superior AC ligament, providing dynamic reinforcement
• Contraction of the deltoid exerts an inferior force on the distal clavicle
• Following AC joint injury, deltoid-trapezius delamination is a key surgical finding

Clinical Significance:

• Deltoid detachment from the clavicle occurs in higher-grade injuries
• Repair or protection of the deltoid origin is essential during surgical treatment
• Postoperative deltoid rehabilitation is crucial for outcome

1.5.2 Trapezius Muscle

Anatomy:

• Origin:
  • "Upper fibers: External occipital protuberance, medial third of the superior nuchal line, ligamentum nuchae"
  • Middle fibers

4. Clinical Presentation

4.1 History Taking

4.1.1 Mechanism of Injury

Direct Trauma (Most Common - 85%)

The classic mechanism involves a direct blow to the superior aspect of the shoulder with the arm in an adducted position. This drives the acromion inferiorly while the clavicle remains relatively stable, placing stress on the AC joint ligaments.

Indirect Trauma (15%)

Fall onto an outstretched hand (FOOSH) transmits force through the upper limb to the AC joint. This mechanism typically produces lower-grade injuries.

4.1.2 Key History Questions

SOCRATES Pain Assessment:

Functional Impact Assessment:

Patient Demographics and Goals:

Understanding patient-specific factors is essential for treatment planning:

4.1.3 Timeline of Symptom Progression

Acute Phase (0-72 hours):

Subacute Phase (1-6 weeks):

• Pain becomes more localized to AC joint
• Swelling subsides
• Deformity becomes more defined as swelling resolves
• Range of motion improves
• Cross-body adduction remains painful
• Lying on affected side uncomfortable

Chronic Phase (> 6 weeks):

4.2 Physical Examination

4.2.1 Inspection

Systematic Approach:

Always examine the patient in a seated or standing position with adequate exposure of both shoulders for comparison.

Grading Deformity by Inspection:

4.2.2 Palpation

Systematic Palpation Sequence:

Piano Key Sign:

Grading the Piano Key Sign:

4.2.3 Range of Motion Assessment

Active Range of Motion:

Passive Range of Motion:

Usually preserved or near-normal, as the glenohumeral joint is not directly affected. Pain may occur at end range due to stress on the AC joint.

4.2.4 Neurovascular Examination

Mandatory Assessment (RED FLAG Screening):

Brachial Plexus Quick Screen:

4.3 Symptoms by Injury Grade

4.3.1 Type I Injury

4.3.2 Type II Injury

4.3.3 Type III Injury

4.3.4 Type IV Injury

4.3.5 Type V Injury

4.3.6 Type VI Injury

4.4 Associated Injuries

Injuries to Evaluate in All AC Joint Injuries:

---

5. Differential Diagnosis

5.1 Primary Differential Diagnoses

5.1.1 Traumatic Differentials

10. Management

10.1 Management Philosophy

The management of AC joint injuries follows a structured approach based on injury severity (Rockwood Classification), patient factors, and functional demands. The fundamental principle is to restore anatomic alignment and function while minimizing intervention-related morbidity.

Core Management Principles:

1. Accurate Classification: Proper radiographic assessment including stress views when indicated
2. Patient-Centered Decision Making: Consider occupation, athletic demands, dominant arm, and patient preferences
3. Timing Considerations: Acute repairs generally yield better outcomes than delayed reconstruction
4. Rehabilitation Focus: Structured physiotherapy is essential regardless of operative or non-operative management

10.2 Management Decision Algorithm

┌─────────────────────────────────────────────────────────────────────────────┐
│                    AC JOINT INJURY MANAGEMENT ALGORITHM                      │
└─────────────────────────────────────────────────────────────────────────────┘
                                      │
                                      ▼
              ┌───────────────────────────────────────────┐
              │         INITIAL ASSESSMENT                 │
              │  • History & Mechanism                     │
              │  • Physical Examination                    │
              │  • Radiographic Evaluation                 │
              │  • Neurovascular Status                    │
              └───────────────────────────────────────────┘
                                      │
                                      ▼
              ┌───────────────────────────────────────────┐
              │         CHECK FOR RED FLAGS                │
              │  • Skin tenting/blanching                  │
              │  • Neurovascular deficit                   │
              │  • Open wound                              │
              │  • Posterior/Inferior displacement         │
              └───────────────────────────────────────────┘
                                      │
                    ┌─────────────────┴─────────────────┐
                    │                                   │
                    ▼                                   ▼
        ┌───────────────────┐               ┌───────────────────┐
        │   RED FLAGS       │               │   NO RED FLAGS    │
        │   PRESENT         │               │                   │
        └───────────────────┘               └───────────────────┘
                    │                                   │
                    ▼                                   ▼
        ┌───────────────────┐               ┌───────────────────┐
        │ URGENT REFERRAL   │               │ ROCKWOOD          │
        │ • Orthopaedics    │               │ CLASSIFICATION    │
        │ • Reduction if    │               │                   │
        │   Type IV/VI      │               │                   │
        │ • Wound care if   │               │                   │
        │   open injury     │               │                   │
        └───────────────────┘               └───────────────────┘
                                                    │
                    ┌───────────────────────────────┼───────────────────────────────┐
                    │                               │                               │
                    ▼                               ▼                               ▼
        ┌───────────────────┐       ┌───────────────────────┐       ┌───────────────────┐
        │   TYPE I - II     │       │   TYPE III            │       │   TYPE IV - VI    │
        │                   │       │                       │       │                   │
        │ CONSERVATIVE      │       │ INDIVIDUALIZED        │       │ SURGICAL          │
        │ MANAGEMENT        │       │ APPROACH              │       │ MANAGEMENT        │
        └───────────────────┘       └───────────────────────┘       └───────────────────┘
                    │                               │                               │
                    ▼                               ▼                               ▼
        ┌───────────────────┐       ┌───────────────────────┐       ┌───────────────────┐
        │ • Sling 1-2 weeks │       │ ASSESS PATIENT        │       │ • Pre-op workup   │
        │ • Ice/Analgesia   │       │ FACTORS:              │       │ • Acute repair    │
        │ • Early ROM       │       │ • Age                 │       │   preferred       │
        │ • Strengthening   │       │ • Occupation          │       │   (less than 3 weeks)      │
        │   at 2-4 weeks    │       │ • Athletic level      │       │ • Anatomic vs     │
        │ • Return to sport │       │ • Dominant arm        │       │   non-anatomic    │
        │   4-6 weeks       │       │ • Cosmetic concerns   │       │   techniques      │
        └───────────────────┘       └───────────────────────────────────────────────────┘
                                                    │
                            ┌───────────────────────┴───────────────────────┐
                            │                                               │
                            ▼                                               ▼
                ┌───────────────────────┐                   ┌───────────────────────┐
                │ LOW DEMAND PATIENT    │                   │ HIGH DEMAND PATIENT   │
                │ • Older age           │                   │ • Young, active       │
                │ • Sedentary lifestyle │                   │ • Manual laborer      │
                │ • Non-dominant arm    │                   │ • Overhead athlete    │
                │ • Minimal symptoms    │                   │ • Dominant arm        │
                └───────────────────────┘                   └───────────────────────┘
                            │                                               │
                            ▼                                               ▼
                ┌───────────────────────┐                   ┌───────────────────────┐
                │ CONSERVATIVE          │                   │ SURGICAL              │
                │ TRIAL                 │                   │ STABILIZATION         │
                │ • 3-6 months rehab    │                   │ • Within 2-3 weeks    │
                │ • Re-evaluate if      │                   │ • Various techniques  │
                │   persistent symptoms │                   │   available           │
                └───────────────────────┘                   └───────────────────────┘
                            │                                               │
                            ▼                                               ▼
                ┌───────────────────────┐                   ┌───────────────────────┐
                │ OUTCOME               │                   │ POST-OPERATIVE        │
                │ • 80-90% satisfactory │                   │ REHABILITATION        │
                │ • Some residual       │                   │ • Sling 4-6 weeks     │
                │   deformity acceptable│                   │ • Supervised PT       │
                │ • Chronic symptoms    │                   │ • Return to sport     │
                │   → Consider delayed  │                   │   4-6 months          │
                │   reconstruction      │                   │                       │
                └───────────────────────┘                   └───────────────────────┘

10.3 Non-Operative Management

10.3.1 Indications for Conservative Treatment

10.3.2 Conservative Treatment Protocol

Phase 1: Acute Phase (Days 0-14)

Phase 2: Early Rehabilitation (Weeks 2-4)

Phase 3: Strengthening (Weeks 4-8)

Phase 4: Return to Activity (Weeks 8-12+)

10.3.3 Bracing and Support Options

Clinical Pearl: The Kenny Howard sling and similar reduction harnesses have fallen out of favor due to:

• High skin complication rates (pressure ulcers)
• Poor patient compliance
• No demonstrated superiority over simple sling
• Failure to maintain reduction long-term

10.4 Operative Management

10.4.1 Surgical Indications

Absolute Surgical Indications:

• Type IV injury (posterior clavicle displacement)
• Type V injury (> 100% CC distance increase)
• Type VI injury (inferior displacement)
• Open AC joint injury
• Skin tenting with impending necrosis
• Neurovascular compromise

Relative Surgical Indications:

• Type III injury in:
  • Overhead athletes (throwing sports, swimming, volleyball)
  • Manual laborers with heavy lifting requirements
  • Young, active patients with high functional demands
  • Dominant arm involvement in laborers
• Failed conservative treatment with persistent symptoms
• Chronic symptomatic instability

10.4.2 Timing of Surgery

Key Evidence: Multiple studies demonstrate superior outcomes with acute repair (less than 3 weeks) compared to delayed reconstruction. The tissue quality deteriorates significantly after 3 weeks, necessitating augmentation or reconstruction rather than primary repair.

10.4.3 Surgical Techniques Overview

┌─────────────────────────────────────────────────────────────────────────────┐
│                    SURGICAL TECHNIQUE CLASSIFICATION                         │
└─────────────────────────────────────────────────────────────────────────────┘
                                      │
          ┌───────────────────────────┼───────────────────────────┐
          │                           │                           │
          ▼                           ▼                           ▼
┌───────────────────┐     ┌───────────────────┐     ┌───────────────────┐
│ ANATOMIC          │     │ NON-ANATOMIC      │     │ HYBRID/COMBINED   │
│ RECONSTRUCTION    │     │ TECHNIQUES        │     │ APPROACHES        │
└───────────────────┘     └───────────────────┘     └───────────────────┘
          │                           │                           │
          ▼                           ▼                           ▼
┌───────────────────┐     ┌───────────────────┐     ┌───────────────────┐
│ • CC Ligament     │     │ • Hook Plate      │     │ • Augmented       │
│   Reconstruction  │     │ • Bosworth Screw  │     │   Repairs         │
│   - Autograft     │     │ • AC Suture/Wire  │     │ • Double-Bundle   │
│   - Allograft     │     │ • Tight-Rope/     │     │   + AC Repair     │
│ • Anatomic AC     │     │   Endobutton      │     │ • Biologic +      │
│   Ligament Repair │     │   (some variants) │     │   Synthetic       │
└───────────────────┘     └───────────────────┘     └───────────────────┘

10.4.4 Detailed Surgical Techniques

A. Hook Plate Fixation

B. Coracoclavicular (CC) Stabilization Techniques

C. Anatomic CC Ligament Reconstruction

13. Clinical Cases

Case 1: Type I AC Joint Injury in a Recreational Athlete

Presentation: A 28-year-old male recreational cyclist presents to the emergency department after falling off his bicycle onto his outstretched left arm. He reports immediate pain over the top of his left shoulder. He denies any numbness, tingling, or weakness in the arm.

Examination:

• Tenderness localized to the AC joint
• No visible deformity or step-off
• Mild swelling over the AC joint
• Full range of motion with pain at extremes
• Cross-body adduction test positive for pain
• Neurovascularly intact distally

Investigations:

• AP and Zanca views: Normal alignment, no widening of AC or CC interval
• No fractures identified

Diagnosis: Rockwood Type I AC joint injury (sprain without ligament disruption)

Management:

• Broad arm sling for comfort (1-2 weeks)
• Ice application 20 minutes every 2-3 hours for 72 hours
• NSAIDs (Ibuprofen 400mg TDS with food) for 5-7 days
• Early pendulum exercises within pain limits
• Return to cycling in 2-3 weeks as symptoms allow

Outcome: Patient returned to full activity at 3 weeks with complete resolution of symptoms. No long-term sequelae at 6-month follow-up.

Teaching Points:

• Type I injuries have excellent prognosis with conservative management
• Early mobilization prevents stiffness
• Patients can be reassured about full recovery

---

Case 2: Type III AC Joint Injury - Shared Decision-Making

Presentation: A 35-year-old male professional rugby player sustains a direct blow to his right shoulder during a tackle. He felt immediate pain and noticed a "bump" over his shoulder. He is concerned about returning to professional sport.

Examination:

• Obvious step deformity at AC joint
• Piano key sign positive (reducible with direct pressure)
• Cross-body adduction severely painful
• Full passive range of motion with guarding
• Neurovascularly intact

Investigations:

• Zanca view: 100% superior displacement of clavicle
• CC distance: 15mm (contralateral 10mm) - 50% increase
• Weighted views: Further widening to 18mm
• No associated fractures

Diagnosis: Rockwood Type III AC joint injury

Management Discussion: Given the patient's occupation as a professional contact athlete, a detailed shared decision-making conversation was conducted:

Option 1: Conservative Management

• 6-week rehabilitation protocol
• Potential for residual cosmetic deformity
• Some studies suggest equivalent functional outcomes
• Risk of chronic instability requiring delayed surgery

Option 2: Early Surgical Reconstruction

• Anatomic CC reconstruction with tendon graft
• Better biomechanical restoration
• Earlier return to contact sport with confidence
• Surgical risks: infection, hardware failure, recurrence

Decision: After multidisciplinary discussion including the team physician, the patient elected for early surgical stabilization given his high-demand athletic requirements.

Surgical Procedure:

• Arthroscopic-assisted anatomic CC reconstruction
• Semitendinosus allograft passed through coracoid and clavicular tunnels
• Supplemental TightRope fixation
• AC joint capsule repair

Post-operative Course:

• Sling immobilization for 6 weeks
• Physiotherapy commenced at 2 weeks (pendulum exercises)
• Progressive strengthening from 6 weeks
• Contact training at 4 months
• Return to professional rugby at 5 months

Outcome: At 12 months, patient had full strength, no instability, and had played a full professional season without issue.

Teaching Points:

• Type III injuries require individualized management
• Occupation, athletic demands, and patient preferences guide treatment
• Early surgery may benefit high-demand athletes
• Shared decision-making is essential

---

Case 3: Type V AC Joint Injury with Urgent Surgical Intervention

Presentation: A 22-year-old female collegiate volleyball player presents after a fall onto her right shoulder during a diving save. She reports severe pain and inability to lift her arm. She noticed immediate deformity at her shoulder.

Examination:

• Marked prominence of distal clavicle (> 300% displacement estimated)
• Skin tenting present over clavicle (no blanching)
• Unable to actively abduct shoulder beyond 30 degrees
• Significant tenderness over AC joint and coracoid
• Cross-body adduction impossible due to pain
• Neurovascularly intact

Red Flags Identified:

• Skin tenting warranting urgent assessment
• Severe displacement suggesting Type V injury

Investigations:

• Zanca view: Complete superior displacement of clavicle
• CC distance: 28mm (contralateral 9mm) - 300% increase
• CT scan: Confirmed severe displacement, no associated fractures
• MRI (if needed): Complete disruption of AC and CC ligaments, deltotrapezial fascia torn

Diagnosis: Rockwood Type V AC joint injury

Management: Given the severity of injury with skin tenting and complete disruption of the deltotrapezial fascia, urgent surgical intervention was recommended.

Surgical Procedure:

• Open anatomic CC ligament reconstruction
• Semitendinosus autograft (ipsilateral)
• Coracoid and clavicular tunnel technique
• AC joint capsule reconstruction
• Deltotrapezial fascia repair

Post-operative Protocol:

• Strict sling immobilization for 6 weeks
• No active shoulder movement for 4 weeks
• Passive ROM commenced at 4 weeks
• Active ROM at 6 weeks
• Strengthening at 10 weeks
• Return to sport at 6 months

Outcome: At 12-month follow-up, the patient demonstrated near-symmetric strength, full range of motion, and returned to collegiate volleyball. Constant-Murley score was 95/100.

Teaching Points:

• Type V injuries are surgical emergencies when skin tenting is present
• Complete deltotrapezial disruption prevents healing with conservative treatment
• Anatomic reconstruction provides best outcomes in young athletes
• Thorough rehabilitation is essential for return to overhead sports

---

Case 4: Type IV Posterior Dislocation - Rare but Critical

Presentation: A 45-year-old male construction worker presents after being struck on the posterior shoulder by a falling beam. He reports severe pain and inability to use his right arm. He noticed his shoulder appeared "pushed backward."

Examination:

• Clavicle palpable posteriorly, buttonholed through trapezius
• No anterior step deformity typically seen in Type III-V
• Significant pain with any shoulder movement
• Palpable posterior prominence
• Trachea midline, no respiratory distress
• Neurovascularly intact (specifically tested for brachial plexus injury)

Red Flags Identified:

• Posterior displacement of clavicle (Type IV pattern)
• Risk of brachial plexus or vascular injury

Investigations:

• AP radiograph: Clavicle appears shortened
• Axillary lateral view: Confirmed posterior displacement of clavicle relative to acromion
• CT scan with 3D reconstruction: Clavicle buttonholed through trapezius posteriorly
• CT angiography: No vascular injury identified

Diagnosis: Rockwood Type IV AC joint injury (posterior displacement through trapezius)

Management: Type IV injuries are universally treated surgically due to buttonholing of the clavicle through muscle, which prevents closed reduction.

Surgical Procedure:

• Open reduction of clavicle from trapezius
• AC joint capsule repair
• CC ligament reconstruction with synthetic loop (TightRope)
• Trapezius muscle repair

Post-operative Course:

• Sling for 6 weeks
• Physiotherapy from week 2
• Return to light duties at 3 months
• Return to construction work at 5 months

Outcome: At 18 months, the patient had returned to full construction duties. He had a Constant-Murley score of 88/100 with mild residual discomfort during heavy lifting.

Teaching Points:

• Type IV injuries are easily missed on AP radiographs alone
• Axillary lateral or CT scan essential for diagnosis
• Posterior displacement cannot heal with conservative management
• Surgical reduction and reconstruction required for all Type IV injuries

---

Case 5: Chronic Type III Injury with Failed Conservative Management

Presentation: A 42-year-old female office worker presents 4 months after a fall at home. She was initially diagnosed with a Type III AC joint injury and managed conservatively. She reports persistent pain with overhead activities, difficulty carrying her handbag on the affected side, and dissatisfaction with the cosmetic appearance of her shoulder.

Examination:

• Obvious chronic deformity at AC joint
• Piano key sign positive
• Painful arc between 120-180 degrees
• Cross-body adduction painful
• Shoulder abduction strength 4/5
• No neurovascular deficit

Investigations:

• Zanca view: Persistent Type III displacement
• CC distance: 16mm (contralateral 10mm)
• MRI: No rotator cuff tear, chronic AC and CC ligament injury
• No signs of distal clavicle osteolysis

Diagnosis: Chronic Type III AC joint injury with functional impairment despite conservative treatment

Functional Assessment:

• Constant-Murley Score: 62/100
• DASH Score: 45/100
• Unable to perform overhead filing at work
• Significant impact on quality of life

Management Decision: Given functional impairment persisting beyond 3 months of adequate conservative treatment, surgical reconstruction was offered. The patient was counseled about:

• Delayed reconstruction outcomes (slightly inferior to acute)
• Need for graft reconstruction (not hook plate alone)
• Longer rehabilitation compared to acute surgery

Surgical Procedure:

• Anatomic CC ligament reconstruction with gracilis allograft
• Modified Weaver-Dunn technique with graft augmentation
• Distal clavicle resection (6mm) for associated arthritis

Post-operative Course:

• Sling for 6 weeks
• Physiotherapy commenced at 3 weeks
• Return to office work at 8 weeks
• Full duties at 4 months

Outcome: At 12-month follow-up:

• Constant-Murley Score: 89/100
• DASH Score: 12/100
• Returned to all daily activities
• Satisfied with cosmetic result

Teaching Points:

• Conservative management fails in 20-30% of Type III injuries
• Delayed reconstruction is viable but outcomes may be slightly inferior
• Chronic injuries often require graft reconstruction, not simple fixation
• Distal clavicle resection may be needed for associated arthritis
• Patient selection and shared decision-making remain essential

---

14. Discharge Advice

For Patients Managed Conservatively

Immediate Post-Injury Care (First 72 Hours)

Rest and Immobilization:

• Wear your sling at all times except when performing gentle exercises as advised
• Sleep in a semi-reclined position or on your unaffected side
• Avoid lifting anything heavier than a cup of tea with the affected arm

Ice Application:

• Apply ice pack wrapped in a thin towel to your shoulder
• 20 minutes on, at least 2 hours off
• Repeat 3-4 times daily for the first 3 days
• Never apply ice directly to skin (risk of ice burn)

Pain Management:

• Take prescribed painkillers regularly for the first 48-72 hours
• Do not wait until pain is severe before taking medication
• If prescribed anti-inflammatory medications, take with food to protect your stomach

Activity Modifications (Weeks 1-6)

What You CAN Do:

• Gentle pendulum exercises as taught by physiotherapy
• Use your hand for light activities below shoulder level
• Typing and computer work (with elbow supported)
• Walking and light cardio (stationary bike without arm involvement)

What You Should AVOID:

• Lifting objects heavier than 1-2 kg with the affected arm
• Reaching overhead or behind your back
• Carrying bags on the affected shoulder
• Contact sports or activities with fall risk
• Driving (until you can safely perform emergency maneuvers)

Signs to Watch For (Return to ED or Call Doctor)

Seek IMMEDIATE Medical Attention If You Experience:

• Increasing numbness or tingling in your arm, hand, or fingers
• Weakness in your arm that is getting worse
• Skin over the injury becoming white, blue, or breaking down
• Signs of infection: increasing redness, warmth, swelling, or discharge
• Fever above 38°C
• Chest pain or difficulty breathing

Contact Your Doctor or Clinic If:

• Pain is not improving after 1-2 weeks despite medication
• You notice increasing deformity at the joint
• You are unable to perform prescribed exercises due to pain
• Swelling is not reducing after 1 week

Follow-Up Arrangements

Typical Follow-Up Schedule:

• Physiotherapy: Usually starts 1-2 weeks after injury
• Orthopaedic clinic: 2-4 weeks for review (Type II-III injuries)
• Imaging: Repeat X-rays may be taken at follow-up

What to Bring to Follow-Up:

• Your sling
• List of current medications
• Any questions or concerns written down
• Diary of symptoms and progress

---

For Patients After Surgery

Wound Care

General Instructions:

• Keep the dressing clean and dry for 48-72 hours
• After this, you may shower with the wound covered with waterproof dressing
• Do not soak in a bath, pool, or hot tub for 2-3 weeks
• Do not apply creams, lotions, or ointments to the wound unless advised

Dressing Changes:

• Your first dressing change is usually at 7-10 days
• If the dressing becomes soaked through or falls off, contact the hospital for advice
• Once healed, massage the scar with vitamin E cream to prevent adhesions (usually after 3-4 weeks)

Signs of Surgical Complications

Seek URGENT Medical Attention If:

• Wound becoming increasingly red, swollen, or painful
• Discharge of pus or foul-smelling fluid from the wound
• Wound opening or stitches coming apart
• Fever above 38°C
• Numbness or tingling that is new or worsening
• Fingers becoming cold, blue, or white
• Unable to move fingers

Sling Wear

Duration:

• Typically 4-6 weeks depending on the procedure
• Your surgeon will give specific instructions

Proper Sling Application:

• Ensure elbow is at 90 degrees
• Wrist should be supported
• Strap should be comfortable across opposite shoulder
• Remove only for washing and exercises as instructed

Rehabilitation Milestones

Return to Activities

Driving:

• Not permitted while wearing sling
• Typically allowed 6-8 weeks after surgery
• Must be able to perform emergency maneuvers safely
• Check with your insurance company

Work:

• Sedentary/office work: 2-4 weeks
• Light manual work: 6-8 weeks
• Heavy manual work: 3-6 months
• Contact sports: 4-6 months minimum

Sports:

• Swimming (freestyle): 3 months
• Golf: 3-4 months
• Tennis: 4-5 months
• Contact sports (rugby, football): 5-6 months
• Overhead sports (volleyball, baseball): 5-6 months

---

Frequently Asked Questions

Q: Will I have a permanent bump on my shoulder? A: Type I and II injuries usually heal without visible deformity. Type III-VI injuries may have some residual prominence even after surgery. Most patients find this acceptable and it does not affect function.

Q: When can I sleep normally again? A: Most patients find they can sleep on their back comfortably by 2-3 weeks. Sleeping on the affected side usually becomes comfortable by 6-8 weeks. A pillow under the elbow often helps.

**Q: Will I need the metalwork