Arthroscopy of The Ac Joint: Two and Three Portal Approaches

Arthroscopy of The Ac Joint: Two and Three Portal Approaches

James P. Tasto

Amar Arora

Pain derived from the AC joint is a prevalent complaint and can be the result of various specific disorders. Since first being described by Mumford and Gurd in 1941, methods for excision of the distal clavicle have evolved to incorporate both open and arthroscopic techniques. After attempts of nonsurgical pain management have been unsuccessful, surgical resection of the joint can be employed to address AC joint pathology and effectively relieve pain. Current arthroscopic techniques have evolved over the past 20 to 25 years and can lead to reproducible favorable outcomes. However, if not done correctly, arthroscopic AC joint resection can lead to increased morbidity over traditional open procedures. It is therefore important to have a good understanding of the anatomy prior to undertaking surgical correction of AC joint pathology.


The AC joint is a diarthrodial joint with fibrocartilaginous articular surfaces, allowing for dynamic movement. A fibrocartilaginous meniscal homolog is usually present. In the sagittal view, the joint slopes superior lateral to inferior medial, whereas in the coronal plane, it slopes anterior lateral to posterior medial. The AC joint lies directly over the supraspinatus muscle and musculotendinous junction. The AC and coracoclavicular ligaments contribute to the stability of the AC joint and are the chief restraints to motion. The conoid ligament primarily restricts anterior and superior displacement of the clavicle. The trapezoid ligament is the chief constraint against compression of the distal clavicle into the acromion. The AC joint has been shown to allow for up to 3 mm of laxity with stress and allow for 5° to 8° of rotation. There appears to be little motion between the clavicle and the scapula. Synchronous motion is usually obtained as the clavicle rotates upward allowing the scapula to rotate downward. Preservation of the AC ligaments that make up the posterior superior capsule is critical when performing surgery. If performed correctly with recognition and protection of distinct anatomical structures, arthroscopic resection appears to be an improvement over traditional open procedures as it results in enhanced ligament preservation, reduced infection rate, improved cosmesis, and accelerated rehabilitation.



It is important to determine the contribution of the AC joint in a patient who presents with shoulder pain. Obtaining a detailed history is an essential component used to design an appropriate treatment plan. It is necessary to ascertain a history of joint separation, a posttraumatic event, generalized osteoarthritis, and/or conditions isolated to sports-specific
injuries such as osteolysis in weight lifters. Ascertaining a history of instability or previous separation of the AC joint is paramount and cannot be overemphasized.

Physical Exam

It is imperative to clinically evaluate the AC joint. Differentiation between classical impingement, subcoracoid impingement, early frozen shoulder, and AC joint pathology is critical. Most patients may initially complain of global shoulder pain. Patients may present with tenderness to direct palpation of the AC joint and may have swelling as well as a clinical deformity in the region. Physical tests have been used to identify AC pathology and include the following: (1) Pain may be elicited by passive and active horizontal adduction and internal rotation; (2) a positive O’Brien’s test with the arm adducted and forward elevated to 90° producing greater pain localized to the AC joint with a thumbs down position when compared with a thumbs up position; (3) AC joint tenderness with attempts at AP translation; (4) localized pain at the AC joint during conventional impingement testing. In addition, patients often respond positively to an injection of lidocaine with or without additional steroid into the AC joint. Proper injection technique into the joint should take into account the normal superolateral to inferomedial sagittal inclination and is commonly limited to approximately 1 to 2 cc of fluid.


X-ray analysis is critical before any type of shoulder surgery to define acromial morphology, the presence of any AC joint involvement, presence or absence of an os acromiale, any calcification in the area, and to help rule out a diagnosis of neoplasia. A radiographic shoulder series should include an anteroposterior view taken in the scapular plane with humeral internal and external rotation, an outlet, and an axillary view. In addition, the following studies can be helpful: (1) 15° cephalic coned-down view with a comparative view of the contralateral AC joint, (2) 30° tangential glenoid view, (3) a bone scan, and (4) magnetic resonance imaging, which can be used to evaluate the pathology of the rotator cuff, detect AC synovitis and localize osteophytes. A bone scan may be helpful if a history of osteolysis is suspected.

Differential Diagnosis

  • The most common cause of symptomatic AC joint pain remains degenerative AC arthritis in the setting of rotator cuff disease. In this particular setting, pain can be caused by the AC joint itself, from the degenerative tear of the rotator cuff, or from impingement of inferior osteophytes from the acromion or the AC joint compressing the rotator cuff.

  • Posttraumatic arthritis of the AC joint is also a very common diagnosis. In this setting, a careful history usually reveals an episode of AC joint separation. With this diagnosis, a careful physical examination is mandatory to evaluate the presence or absence of AC joint instability.

  • Osteolysis of the clavicle is a less common cause of AC joint pathology but should be thought of with a history of trauma, active weight lifting, or with certain metabolic disorders especially hyperparathyroidism. Radiographs may show massive bony resorption of the distal clavicle and bone scans usually show increased activity in that same area.

  • Other causes of AC joint pathology include symptomatic meniscal derangement, rheumatoid arthritis, infection, gout, and polymyalgia rheumatica.

Decision-Making Algorithms/Indications for Resection

Jul 22, 2016 | Posted by in ORTHOPEDIC | Comments Off on Arthroscopy of The Ac Joint: Two and Three Portal Approaches
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