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AC-joint separation (acromioclavicular joint)

Definition of

Traumatic complete or incomplete rupture of the ACG (acromioclavicular joint) with subluxation or dislocation and overstretching and rupture of ligaments:

1. Acromioclavicular ligament: causes horizontal instability
2. Coracoclavicular ligaments: causes vertical instability
3. Lig. trapezoideum, lig. conoideum: depending on the severity, vertical or horizontal instability occurs

Incidence 3-4/100,000 / a, third most common injury to the shoulder joint, 2.5-6% of all dislocations, men more frequently affected. Formerly classified into 3 grades according to Tossy, today into 6 grades according to Rockwood:

1. (=Tossy 1): Strain to partial rupture of the capsular/ligamentous apparatus. No acromioclavicular joint instability, slight pressure pain, slight pain on movement. X-ray without clear dislocation
2. (=Tossy 2): Partial rupture of the capsular/ligamentous apparatus(rupture of the acromioclavicular ligaments) with subluxation of the acromioclavicular joint and tearing of the coracoclavicular ligaments. Painful movement and slight subluxation of the peripheral clavicle. X-ray: widened joint space and elevation of the lateral clavicle by 1/2 shaft width
3. (=Tossy 3): Rupture of the entire capsular/ligamentous apparatus(rupture of the acromioclavicular ligaments and the coracoclavicular ligaments) with complete dislocation of the acromioclavicular joint in the vertical plane to the cranial (acromioclavicular joint disruption), step formation. X-ray: stepping up by one shaft width (corresponds to Tossy III).
4. Dislocation of the distal end of the claviclein the horizontal plane due to partial detachment of the deltoid fascia, tearing of the deltoid insertion, therefore dislocation (luxation) dorsally, through and possibly into the trapezius. Very rarely also ventral(dislocation/luxation) due to tearing of the trapezius (irrelevant for classification). X-ray: dorsal translation in the axial image.
5. Extreme clavicle elevation with extensive detachment of the muscle insertions at the lateral end of the claviclewith horizontal and vertical instability
6. Dislocation of the lateral end of the clavicle caudally under the coracoid or under the acromion. Frequent concomitant injuries: rib fractures, clavicle fracture, lesions of the brachial plexus

If the coracoclavicular ligaments are severed, the result is no dislocation of the ACG , but only a subluxation . For a dislocation must also to occur, the capsule and the acromioclavicular ligaments (inferius and superius) be severed and parts of the must deltoid and trapezius insertions also be detached. Then the defect in the coracoclavicular ligaments is not necessary for the dislocation ; it only has an aggravating effect. The ACG tear appears visually like a cranially that has been displaced clavicle , but in fact the scapula has sunk relative to the clavicle . The elevation of the clavicle is relative, not absolute.

ICD M43

Cause

1. Trauma: usually a fall on the shoulder with an adducted arm, more rarely also on an abducted arm that transfers the force to the shoulder joint
2. iterated microtraumas

Diagnosis

1. Sono: enlarged joint space
2. X-ray in 3 planes, possibly for lateral comparison as a shoulder total with 5-10 kg weight in the hand

Symptoms

1. Hematoma, swelling
2. Adducted recovery posture
3. Continuous pain, tenderness, pain on movement, more or less significant painful restriction of movement. The pain localises at the acromion and projects towards the deltoid.
4. prominent distal clavicle end
5. Depending on the degree: Highlight: piano key phenomenon (painful, non-permanent reduction of the distal end of the clavicle possible, it jumps up again like a piano key). The test is often not tolerated by the patient. If the clavicle is fixed and the arm and shoulder blade are raised, this can be tolerated.
6. The least painful of all shoulder joint movements are rotations of the loosely hanging arm.
7. Bei älteren, unbehandelten Sprengungen ist die Schmerzhaftigkeit deutlich reduziert, jedoch ist häufig
8. A disturbance of the kinetics of the scapula and arm is noticeable during frontal abduction and lateral abduction between about 135° and 150° (disturbed scapula-thoracic rhythm).

Complications

1. remaining instability,
2. Tendency to subluxate
3. Increased risk of osteoarthritis

Therapy

1. Analgesics (e.g. ibuprofen)
2. Grade 1 (Tossy), usually also 2: conservative, according to current studies, conservative treatment is also more favourable for grade 3, from 4 usually surgery (various methods, none optimal)