Abstract
The acromioclavicular joint is vulnerable to injury from both acute trauma and repeated microtrauma. Acute injuries are frequently the result of falling directly onto the shoulder when playing sports or riding a bicycle. Repeated strain from throwing or working with the arm raised across the body may also result in trauma to the joint. After trauma, the joint may become acutely inflamed; if the condition becomes chronic, arthritis of the acromioclavicular joint may develop. Cysts of the acromioclavicular joint can become quite large and contribute to functional disability and pain. Rarely, infection of the acromioclavicular joint may occur. Patients suffering from acromioclavicular joint dysfunction frequently complain of pain when reaching across the chest. Often, patients are unable to sleep on the affected shoulder and may complain of a grinding sensation in the joint, especially on first awakening. Physical examination may reveal enlargement or swelling of the joint, with tenderness to palpation. Downward traction or passive adduction of the affected shoulder may cause increased pain. Physical examination of the abnormal acromioclavicular joint will reveal positive provocative tests including the acromioclavicular adduction stress test, the chin adduction test, and the Paxino test. If the ligaments of the acromioclavicular joint are disrupted, these maneuvers may reveal actual joint instability.
Keywords
acromioclavicular joint, acromioclavicular ligament, shoulder pain, chin adduction text, Paxino test, acromioclavicular joint injection, ultrasound guided injection
ICD-10 CODE M25.519
The Clinical Syndrome
The acromioclavicular joint is vulnerable to injury from both acute trauma and repeated microtrauma. Acute injuries are frequently the result of falling directly onto the shoulder when playing sports or riding a bicycle. Repeated strain from throwing or working with the arm raised across the body may also result in trauma to the joint. After trauma, the joint may become acutely inflamed; if the condition becomes chronic, arthritis of the acromioclavicular joint may develop. Cysts of the acromioclavicular joint can become quite large and contribute to functional disability and pain ( Fig. 26.1 ). Rarely, infection of the acromioclavicular joint may occur.
Signs and Symptoms
Patients suffering from acromioclavicular joint dysfunction frequently complain of pain when reaching across the chest ( Fig. 26.2 ). Often, patients are unable to sleep on the affected shoulder and may complain of a grinding sensation in the joint, especially on first awakening. Physical examination may reveal enlargement or swelling of the joint, with tenderness to palpation. Downward traction or passive adduction of the affected shoulder may cause increased pain. Physical examination of the abnormal acromioclavicular joint will reveal positive provocative tests including the acromioclavicular adduction stress test, the chin adduction test, and the Paxino test ( Fig. 26.3 ). If the ligaments of the acromioclavicular joint are disrupted, these maneuvers may reveal actual joint instability.
Testing
Plain radiographs of the joint may reveal narrowing or sclerosis, consistent with osteoarthritis or actual separation or dislocation of the joint ( Fig. 26.4 ). Magnetic resonance imaging (MRI) is indicated if disruption of the ligaments is suspected and to clarify the extent of ligamentous injury or to help rule out infection ( Fig. 26.5 ). Ultrasound evaluation of the joint is useful to further delineate acromioclavicular joint pathology ( Fig. 26.6 ). The injection technique described later serves as both a diagnostic and a therapeutic maneuver. In selected patients, arthroscopy of the joint may provide additional diagnostic information. If polyarthritis is present, screening laboratory tests consisting of a complete blood count, erythrocyte sedimentation rate, and antinuclear antibody testing should be performed.
