Current concepts in acromioclavicular joint (AC) instability - a proposed treatment algorithm for acute and chronic AC-joint surgery

Abstract

Background: There exists a vast number of surgical treatment options for acromioclavicular (AC) joint injuries, and the current literature has yet to determine an equivocally superior treatment. AC joint repair has a long history and dates back to the beginning of the twentieth century.

Main body: Since then, over 150 different techniques have been described, covering open and closed techniques. Low grade injuries such as Type I-II according to the modified Rockwood classification should be treated conservatively, while high-grade injuries (types IV-VI) may be indicated for operative treatment. However, controversy exists if operative treatment is superior to nonoperative treatment, especially in grade III injuries, as functional impairment due to scapular dyskinesia or chronic pain remains concerning following non-operative treatment. Patients with a stable AC joint without overriding of the clavicle and without significant scapular dysfunction (Type IIIA) may benefit from non-interventional approaches, in contrast to patients with overriding of the clavicle and therapy-resistant scapular dysfunction (Type IIIB). If these patients are considered non-responders to a conservative approach, an anatomic AC joint reconstruction using a hybrid technique should be considered. In chronic AC joint injuries, surgery is indicated after failed nonoperative treatment of 3 to 6 months. Anatomic AC joint reconstruction techniques along with biologic augmentation (e.g. Hybrid techniques, suture fixation) should be considered for chronic high-grade instabilities, accounting for the lack of intrinsic healing and scar-forming potential of the ligamentous tissue in the chronic setting. However, complication and clinical failure rates remain high, which may be a result of technical failures or persistent horizontal and rotational instability.

Conclusion: Future research should focus on addressing horizontal and rotational instability, to restore native physiological and biomechanical properties of the AC joint.

Keywords: AC joint; Acromioclavicular joint; Acromioclavicular joint reconstruction; Anatomic acromioclavicular joint reconstruction; Horizontal instability; Vertical instability.

Fig. 1

Preoperative bilateral panoramic view allowing for direct correlation of the CC-distance to the uninjured contralateral AC joint

Fig. 2

Preoperative bilateral panoramic view of a patient with Rockwood IIIB instability (Left side)

Fig. 3

Preoperative modified y-view (Alexander view) allowing for visualization of dynamic horizontal instability (overriding of the lateral clavicle)

Fig. 4

Preoperative modified y-view (Alexander view) of an intact AC joint without overriding of the lateral clavicle

Fig. 5

Computed tomography allowing for adequate visualization of bony imparities such as clavicular bone tunnel position, tunnel width or fractures

Fig. 6

Computed tomography allowing for adequate visualization of bony imparities such as coracoid bone tunnel position, tunnel width or fractures

Fig. 7

Postoperative bilateral panoramic view after stabilization of chronic Rockwood type IIIB AC joint instability using the arthroscopic-assisted hybrid technique

Fig. 8

Postoperative y-view after stabilization of chronic Rockwood type IIIB AC joint instability using the arthroscopic-assisted hybrid technique

Fig. 9

Non-operative or operative treatment based on the author’s therapeutic decision making