- What is Acromioclavicular (AC) Joint Pain?
- This is a common source of shoulder pain because it is susceptible to both acute trauma and repeated microtrauma. May manifest as an independent diagnosis after trauma to the shoulder or as a component of a more complex shoulder dysfunction (i.e. Impingement syndromes and Rotator Cuff Disease)
- What is the cause?
- Acute causes:
- Fall directly onto shoulder during sports
- Falling from certain height (i.e. bicycle)
- Repeated strain from throwing injuries or working with arm raised across the body
- Signs and Symptoms:
- Complaints of pain when reaching across the chest
- Unable to sleep on affected shoulder
- Complaints of grinding sensation in joint, especially when first awakening
- Enlargement or swelling of joint
- Numbness at AC joint
- Tenderness to palpation
- Pain increased with downward traction or passive adduction
- Joint instability with ligament disruption
- Type I: Pain with abduction and swelling
- Type II: moderate to severe pain and restricted movement
- Type III: dislocations can result in pronounced deformities
- Pain referral pattern:
- Pain is localized to the Acromioclavicular joint
- Diagnostic tool to rule in/out:
- Physical Examination
- Observation
- Palpation
- Range of Motion
- Special tests: Chin adduction test
- Plain radiographs
- MRI
- Presentation of the disease:
- Type I:
- Partial injury to joint capsule
- Paired with an incomplete tear of AC ligaments and joint capsule
- Type II:
- Moderate injury
- Partial tear of Coracoclavicular ligament with rupture of the capsule and Acromioclavicular ligament
- Subluxation
- Type III:
- Severe injury
- Complete rupture of acromioclavicular ligament and coracoclavicular ligament
- Leads to displacement of clavicle, becoming unstable
- Dislocation occurs at this point to clavicle