Acromio-clavicular joint
Related Subjects:
|Fractured Neck of Femur
|Fractured Shaft Femur
|Supracondylar Femur Fractures
|Femoral fractures and Injuries
|Acromio-clavicular joint
|Shoulder Joint Structure and Form
|Knee Joint Structure and Form
|Wrist Joint Structure and Form
|Types of Joints
|Biceps tendon rupture
|Upper Limb fractures and injuries
|Hand fractures and Injuries
|Lower Limb Fractures and Injuries
ℹ️ About
- 🔗 The Acromioclavicular (AC) Joint sits at the top of the shoulder, where the acromion (part of the scapula) meets the clavicle.
- 🦴 It stabilises the shoulder girdle and allows coordinated motion of the scapula and clavicle → essential for arm elevation and rotation. 💥 Common site of injury in contact sports and falls.
📍 Injury Types (Rockwood Classification)
- 🔹 Type I/II: Sprain or subluxation (partial injury, ligaments stretched or partially torn)
- 🔹 Type III: Superior dislocation with complete ligament rupture → step deformity
- 🔹 Type IV–VI: Posterior or inferior displacement of clavicle (rare, but severe, with mediastinal risk)
⚡ Typical Mechanism
- 🤕 Direct fall onto the lateral shoulder (e.g. fall from bike, sports tackle)
- ⚡ Sometimes fall onto an outstretched hand can transmit force upwards
⚠️ Pitfalls & Complications
- 😣 Persistent pain, cosmetic deformity (“piano key” sign with step-off deformity)
- ⚡ Posterior/inferior dislocations → risk of mediastinal neurovascular compression (subclavian vessels, brachial plexus, trachea, oesophagus) → always consider CT
- 🛑 Chronic instability if not treated properly
🔎 Investigations
- 🩻 Shoulder X-rays (AP, Zanca view) → compare with opposite side
- 🖥️ CT if posterior/inferior dislocation suspected or mediastinal concerns
💊 Management
- 🩹 Type I/II (mild sprain/subluxation): Broad-arm sling, analgesia, early mobilisation with physiotherapy.
- 🩹 Type III: Often conservative, but fixation considered if highly active/manual worker or persistent symptoms.
- 🛑 Posterior/inferior dislocation: Orthopaedic emergency → urgent CT + referral for possible surgical reduction.
- 🏥 Follow-up in fracture clinic for assessment of recovery and stability.
📌 Exam Pearl:
– Step deformity at shoulder tip = classic for AC dislocation.
– Posterior/inferior types are rare but dangerous → always think mediastinal compromise.
– Most AC injuries (Rockwood I–III) are treated conservatively with sling + physio.
📚 References
