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Definition
By: Gregory R. Waryasz, MD
The acromioclavicular joint of the musculoskeletal system is characterized by connecting the upper extremity to the clavicle.
It is part of the upper extremity and consists of bone, skeletal muscle, cartilage, synovial tissue, and tendon.
Its unique structural is that it is a plane type of joint is covered by a capsule. The average coracoclavicular distance is 1.1 to 1.3 cm.
The bones are the clavicle and acromion process of the scapula. The articular surfaces are covered with fibrocartilage.
There is an articular disc located between the articulation surfaces.
The ligaments are the acromioclavicular ligament (anterior, posterior, superior, and inferior) and the coracoclavicular ligament. The coracoclavicular ligament is made up of the trapezoid and the conoid.
The blood supply is from the thoracoacromial and the suprascapular arteries.
The innervation is from the lateral pectoral and axillary nerves. There is also innervation by the lateral supraclavicular nerve.
The acromioclavicular joint’s components as well as all other bones, muscles, and ligaments of the body are derived of mesodermal origin in the embryo.
The function of the acromioclavicular joint is to help with motion of the scapulothoracic joint. There is some mobility through the intraarticular disc.
Common diseases of the acromiooclavicular joint include arthritis, fractures, and dislocation/separtation.
Fractures can occur in the clavicle that can result in a change to the biomechanics of the acromioclavicular joint.
Arthritis is a condition of joint space narrowing leading to pain.
Dislocation/separation is an injury to the ligaments resulting in displacement of the clavicle. This is due to a trauma.
Commonly used diagnostic procedures include clinical history, physical exam, x-ray, CT, and MRI.
It is usually treated with rest, NSAIDs, physical therapy, and possibly surgery. Dislocation/separation and fractures may not respond to nonoperative treatments and may require surgery. Arthritis can be treated with NSAIDs and physical therapy, but may require surgery to remove part of the distal clavicle.
References
Davis MF, Davis PF, Ross DS. Expert Guide to Sports Medicine. ACP Series, 2005.
Elstrom J, Virkus W, Pankovich (eds), Handbook of Fractures (3rd edition), McGraw Hill, New York, NY, 2006.
Koval K, Zuckerman J (eds), Handbook of Fractures (3rd edition), Lippincott Williams & Wilkins, Philadelphia, PA, 2006.
Lieberman J (ed), AAOS Comprehensive Orthopaedic Review, American Academy of Orthopaedic Surgeons, 2008.
Moore K, Dalley A (eds), Clinically Oriented Anatomy (5th edition), Lippincott Williams & Wilkins, Philadelphia, PA, 2006.
Wheeless’ Textbook of Orthopaedics: Acromioclavicular Joint (http://www.wheelessonline.com/ortho/acromioclavicular_joint)