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Orthopaedic Emergencies
Published in Anthony FT Brown, Michael D Cadogan, Emergency Medicine, 2020
Anthony FT Brown, Michael D Cadogan
A fall on to the shoulder that tears the acromioclavicular ligament results in subluxation. Dislocation occurs if the strong coracoclavicular ligaments are torn as well, with the clavicle losing all connection with the scapula.
A to Z Entries
Published in Clare E. Milner, Functional Anatomy for Sport and Exercise, 2019
The acromioclavicular joint is also considered part of the shoulder girdle, since the acromion process is part of the scapula. Several ligaments connect the clavicle to the scapula. At this joint, the acromioclavicular ligament is a thickening of the joint capsule, equivalent to the glenohumeral ligament at the glenohumeral joint. In addition, coracoclavicular ligaments, between the coracoid process and the clavicle assist in keeping the clavicle in place. These ligaments attach to the clavicle medial to the acromioclavicular joint and connect to the coracoid process inferiorly. There are two distinct coracoclavicular ligaments, the trapezoid and conoid, named according to their shape (trapezoidal and cone-shaped). The conoid is the more medial of the two. The important role of these ligaments becomes apparent after an acromioclavicular joint separation. This injury is a dislocation of the acromioclavicular joint which typically occurs as a result of a fall directly onto the shoulder. The severity of the injury is determined by the degree of separation of the clavicle from the acromion process. If only the acromioclavicular joint is torn, there is no apparent separation of the joint because the coracoclavicular ligaments keep the clavicle in place. In a more severe injury, the coracoclavicular ligaments are also torn, and the clavicle is now free to move superiorly and become separated from the acromion. In this case, the lateral end of the clavicle can be identified clearly under the skin as a bump on the superior aspect of the shoulder.
The shoulder
Published in David Silver, Silver's Joint and Soft Tissue Injection, 2018
This is a small plane joint or synostosis where the lateral end of the clavicle articulates with the acromion process of the scapula. The capsular ligament is strengthened by the acromioclavicular ligament. There is a very small joint space that will admit 0.2–0.5 ml of injection fluid. Acromioclavicular pain is often overlooked as the cause of pain and a meticulous clinical examination will avoid this pitfall.
Acromioclavicular joint injuries at a Colorado ski resort
Published in The Physician and Sportsmedicine, 2023
Naomi Kelley, Lauren Pierpoint, Jack Spittler, Morteza Khodaee
Acromioclavicular joint (ACJ) injuries (also known as separations or dislocations) are very common, accounting for up to forty percent of all shoulder injuries [1–4]. The AC joint is a diarthrodial joint where the clavicle can rotate and translate anteriorly, posteriorly and inferiorly in relation to its articulation with the acromion. The joint is composed of a meniscus-type structure of hyaline cartilage, surrounded by synovium [2]. Stability of the ACJ is provided horizontally by the acromioclavicular ligament, and vertically by the coracoacromial ligament. Although not directly attached to the acromion, two coracoclavicular ligaments (conoid and trapezoid ligaments) provide further vertical stability to the joint [5]. Overall, the anatomy of the ACJ provides resistance against significant forces.