AC joint osteoarthritis
AC-joint degeneration may be symptomatic or incidental.
Clinical features
- superior shoulder pain
- tenderness directly over the AC joint
- pain with cross-body adduction
- pain from pressure such as a shoulder strap or sleeping on the side
Imaging
Standard shoulder radiographs usually demonstrate osteophytes and joint narrowing. Imaging severity does not always correlate with symptoms.
Treatment
- activity modification
- analgesia
- targeted physiotherapy
- diagnostic/therapeutic injection
- distal clavicle excision for persistent, well-localised symptoms after non-operative treatment
Initial treatment includes:
- activity modification
- analgesia
- physiotherapy addressing the wider shoulder
- selective injection for diagnostic and therapeutic purposes
Persistent clearly localised symptoms may be treated with distal-clavicle excision, ensuring adequate but not excessive resection and preservation of stabilising structures.
AC joint injury
Classify by displacement and integrity of AC and coracoclavicular stabilisers.
Lower-grade injuries are usually treated non-operatively with:
- sling for comfort
- early motion
- progressive strengthening
Higher-grade injuries require individualized discussion based on displacement, symptoms, occupation, sport and chronicity.
Chronic instability
Persistent painful instability can be reconstructed using coracoclavicular ligament reconstruction techniques. Treatment must address both vertical and horizontal instability when clinically important.
Chronic symptomatic instability differs from acute injury because ligament healing potential is reduced. Reconstruction may therefore require graft augmentation or other biological strategies rather than simple acute fixation principles.
Distal clavicle fracture
Stability depends on the relationship of the fracture to the coracoclavicular ligaments. Unstable displaced patterns have a higher risk of nonunion and may require fixation with or without ligament augmentation.
AC joint pain
AC-joint pathology commonly presents with pain localised to the superior shoulder, aggravated by cross-body loading and overhead activity.
Examine for:
- focal AC tenderness
- deformity
- cross-body adduction pain
- clavicle mobility
- associated glenohumeral or cuff pathology
Radiographs may show degenerative change, but radiographic OA can be asymptomatic.
Acute AC injury
Mechanism usually involves a direct force to the lateral shoulder.
Assessment includes:
- skin condition and tenting
- neurovascular status
- associated clavicle/scapular injury
- horizontal as well as vertical instability
Classification systems describe increasing injury to AC and coracoclavicular stabilisers and displacement.
Treatment principles
Lower-grade injuries are generally treated non-operatively with early functional rehabilitation.
Higher-grade or substantially displaced injuries require individualised consideration based on:
- displacement
- horizontal instability
- symptoms
- occupation and sport
- chronicity
- skin risk
- patient preference
Surgical techniques aim to restore coracoclavicular and often AC stability while respecting biological healing.
Complications
Potential surgical complications include:
- loss of reduction
- fracture around tunnels or implants
- infection
- hardware irritation
- stiffness
- persistent horizontal instability
- overcorrection
FRCS synthesis
For AC injuries, describe not only the radiographic grade but whether the patient has symptomatic mechanical instability, especially in the horizontal plane, and whether the injury is acute or chronic.