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About Shoulder AC Joint Separations
Injuries to the acromioclavicular (AC) joint are common. In a shoulder separation, the junction of the clavicle and the scapula is disrupted and is often the result of trauma to the shoulder.
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Types of AC Joint Separations
Type I: Partial tear of the acromioclavicular ligament without real change in position of the distal clavicle in relation to the acromion.
Type II: Rupture of the acromioclavicular ligament with a partial tear of the coracoclavicular ligaments. The distal end of the clavicle is displaced in relation to the acromion less than the full width of the clavicle itself.
Type III: Rupture of the AC ligament and the coracoclavicular ligaments, with displacement of the distal clavicle more than its full width.
Type IV: Posterior displacement of the distal clavicle through the muscle aponeuroses of the trapezius. Deltoid and trapezius muscles are detached from the distal clavicle.
Type V: The distal clavicle is severely displaced upward toward the base of the neck, covered only by skin and subcutaneous tissue with a complete rupture of the deltoid-trapezius musculature.
Type VI: Inferior dislocation of the clavicle under either the acromion or the coracoid process. Coracoclavicular ligaments and muscles are intact or disrupted.
Causes of AC Joint Separation
Type II: Rupture of the acromioclavicular ligament with a partial tear of the coracoclavicular ligaments. The distal end of the clavicle is displaced in relation to the acromion less than the full width of the clavicle itself.
Type III: Rupture of the AC ligament and the coracoclavicular ligaments, with displacement of the distal clavicle more than its full width.
Type IV: Posterior displacement of the distal clavicle through the muscle aponeuroses of the trapezius. Deltoid and trapezius muscles are detached from the distal clavicle.
Type V: The distal clavicle is severely displaced upward toward the base of the neck, covered only by skin and subcutaneous tissue with a complete rupture of the deltoid-trapezius musculature.
Type VI: Inferior dislocation of the clavicle under either the acromion or the coracoid process. Coracoclavicular ligaments and muscles are intact or disrupted.
Causes of AC Joint Separation
The AC joint can become separated most typically by falling or by being hit on the shoulder blade or outstretched arm. Other causes include:
- Biochemical or hormone imbalances
- Changes in the immune system
- Diabetes
- Immobilization
- Previous surgery
- Biochemical or hormone imbalances
- Changes in the immune system
- Diabetes
- Immobilization
- Previous surgery
Signs & Symptoms of AC Joint Separation
AC joint separation symptoms can include shoulder instability and pain, especially when making overhead movements or during sleep. There may also be a bump or bulge above the shoulder.
AC joint separation symptoms can include shoulder instability and pain, especially when making overhead movements or during sleep. There may also be a bump or bulge above the shoulder.
Diagnosis of an AC Joint Separation
A careful history and physical examination is required to make the diagnosis of AC joint separation and must be confirmed with X-rays.
A careful history and physical examination is required to make the diagnosis of AC joint separation and must be confirmed with X-rays.
Treatment for AC Joint Separation
Although most of the injuries are treated without surgical repair, surgical intervention is often preferred for throwing athletes with severe dislocations. The management for acute dislocations of the acromioclavicular joint is controversial. Most of orthopaedists have agreed that Type I and II injuries require a conservative treatment; however, the debate in the case of Type II injury concerns which type of non-surgical treatment to employ - either symptomatic only or bandaging in order to attempt an external reduction of the AC joint dislocation. Type III injuries may be managed either with surgery or non-operatively. The trend in management of Type III dislocations in young active people is suggested by results of a questionnaire sent by Cox to the chairmen of all orthopaedic residency training programs in North America and to a group of orthopaedic surgeons active in sports medicine. Eighty-six per cent of physicians involved in care of collegiate and professional athletes and seventy-two per cent of the chairmen preferred non-surgical treatment. Among the physicians that were choosing a conservative treatment, 33% and 28% respectively (team physicians and chairmen) were using manual reduction of the dislocation and maintenance of that reduction by an acromioclavicular immobilizer. However, the questionnaire failed to ask whether the athlete was male or female, a thrower or not, or whether the dominant arm was injured. In our experience, throwers and other overhead athletes playing tennis, volleyball, and squash are significantly weakened by the Type III joint dislocation for up to a year after injury. In these athletes, and with patients concerned about the cosmetic appearance of the dislocation, we recommend prompt repair and rapid return to training. To learn more about AC Joint Reconstruction surgery, click here.
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