Comparison of Coracoclavicular Fixation With Versus Without Acromioclavicular Stabilization for Repair of Acute Acromioclavicular Joint Dislocations: A Randomized Controlled Clinical Trial, Double-blind Test

THEORETICAL FRAME The upper extremity is completely attached by the axial skeleton, especially through the clavicle and the acromioclavicular articulation (AC)(1). The previously mentioned articulation is a diarthrodial joint. The stability of this articulation is caused by coracoclavicular ligaments in the vertical plane and the acromioclavicular ligaments in the horizontal plane(2). The AC luxation is a common pathology in youth and athletes who participate in contact sports which has a 9,2 per 1000 incidence between inhabitants every year represented between 30% to 50% from shoulder injuries in young athlete, it is most common in men than women with a ratio of 8:1(3). It's main injury mechanism is direct trauma while the shoulder is adducted and less frequently is the indirect mechanism of dropping the arm in an extended motion(4). In the year 1963, Tossy et al(5) for the first time described and classified some of the patterns of luxation AC, which was then extended to 6 AC luxation degrees and published by Rockwood in the year 1984 becoming the first most accepted and used till this day(6). There have many techniques of conservative treatment and surgery management as a treatment for all time of laxation AC (Rockwood grades I-VI) written as time passed by, although literature suggests and supports the conservative treatment for grades I and II and the surgical management for grades IV-V-VI, the optimal treatment for grade III injuries is still controversial(7). In regards to these type of injuries, taking into account the importance of medial stability an agreement was taken by the committee of the upper extremity of the International Society of Arthroscopy, Knee Surgery and Orthopedic Sports Medicine (ISAKOS), which suggests that a subdivision of the III grade of Rockwood in IIIA when the AC articulation is stable and the IIIB when the AC articulation is unstable(8), helping to differentiate and identify the patients with grade III Rockwood in a better manner who will be benefited from a surgical treatment.

To evaluate the correct AC luxation ligaments, the radiological evaluation must include a projection of bilateral, axillary Zanca and Alexander (also known as Basmania). This last projection has increased its relevance in the past couple of years since it can help us to differentiate whether there's a presence or an absence of medial instability in the case of Rockwood III AC luxation(9). Till this day there are no actual standardized measurements that guide the correct manner of treating it with a good variability, Zumstein et al(10) proposed 2 new quantitative parameters to evaluate the vertical and horizontal instability and based on the Alexander view. To evaluate the vertical stability the use of the vertical distance between the center of the acromion and the midpoint of the lateral clavicle (AC-DC) and to evaluate the horizontal stability he used the distance of the center of the glenoid and lateral clavicle (GC-PC). Both parameters were shown to be trusted sources with excellent validity, which helped guide the treatment for some AC luxation, especially for Rockwood grade II and III injuries.

Despite the numerous described surgical techniques, currently more than 160, do not show evidence of superiority of one in specific and there is no agreement whether it is necessary to stabilize only the AC articulation in the vertical, horizontal or both planes(11). In this case more attention is focused on the complex AC ligament standing out the superior AC band as its main horizontal stabilizer(12), which does have an injury and in the process of insufficiently healing and repairing it can contribute up to 50% of horizontal instability in the AC articulation(13). Many studies demonstrate that the horizontal instability can have an important clinical relevance associated with the worst functional postsurgical results(14-16) which during the past couple of years has increased the interest of conducting many surgical techniques to better the horizontal stability and so the functional results after surgery(17). Al though there have been many advances in surgical techniques during the time, the percentage of complications are still considerable, with up to 14% of inoperable complications, 21% reduction loss and 10% remains in revision surgery(4). With the result of minimizing complications and obtaining better functional results arises the idea of conducting the randomized clinical trial.

INVESTIGATION QUESTIONING

"In patients with an acute and unstable acromioclavicular luxation, the coracoclavicular fixation with stabilized acromioclavicular has a clinical impact to decrease of complications and better its functionality?"