MANUAL MINORS
An injury to the acromioclavicular (AC) joint, commonly referred to as AC joint dislocation or tear, occurs when the ligaments stabilising the joint are stretched or torn, leading to a separation between the clavicle and the acromion of the scapula.
This injury often results from direct falls onto the shoulder, as seen in contact sports or cycling accidents. AC joint tears are classified into different grades based on the severity of the ligament damage and the displacement of the bones.
Diagnosis
Diagnosis is based on a history of direct trauma to the shoulder, with symptoms such as localised pain at the top of the shoulder, swelling, and, in severe cases, visible deformity (elevation of the clavicle, known as “piano key sign”).
The physical examination includes palpation of the AC joint, which reproduces the pain. Anteroposterior and axillary shoulder X-rays help classify the injury based on the degree of separation or displacement.
Classification of AC Joint Injury
Grade I: Sprain of AC ligaments without visible displacement.
Grade II: Rupture of the AC ligament with minimal displacement of the clavicle.
Grade III: Rupture of both AC and coracoclavicular ligaments, with complete displacement of the clavicle.
Grades IV-VI: More severe displacements, with possible damage to surrounding tissues and displacement towards adjacent structures.
Differential Diagnosis
Pathology | Characteristics |
|---|---|
Clavicle fracture | Pain at the top of the shoulder, palpable deformity over the clavicle |
Rotator cuff tear | Shoulder weakness and pain, especially when lifting the arm |
Glenohumeral dislocation | Deformity and displacement of the humeral head out of the glenoid cavity |
Bicipital tendinitis | Pain in the front of the shoulder without visible deformity |
Shoulder contusion | Shoulder pain after trauma, without visible deformity or bone displacement |
Emergency Management
Initial emergency management includes immobilising the affected arm with a sling to relieve pain, administering analgesics and non-steroidal anti-inflammatory drugs (NSAIDs), and applying ice to reduce inflammation.
For lower-grade injuries (Grades I and II), rest and outpatient follow-up are recommended. For Grade III or higher injuries, particularly with significant deformity or neurovascular damage, referral to an orthopaedic surgeon is required.
Definitive Treatment
Treatment depends on the severity of the injury:
Grades I and II: Conservative management with rest, ice, analgesics, and progressive physiotherapy to restore range of motion and strengthen shoulder muscles. Recovery typically takes 4 to 6 weeks.
Grade III: May be treated conservatively or surgically, depending on the patient’s age, activity level, and the presence of instability or persistent pain.
Grades IV-VI: Usually require surgery to reduce the clavicle and stabilise the joint using plates or screws. Postoperative rehabilitation is essential to restore full shoulder function and prevent stiffness or weakness.
Physiotherapy is crucial at all injury levels to regain shoulder mobility and strength.
Comments