Great. Thank you very much, all of you, for being here, and thanks for the opportunity to present as part of this session. I'm honored to be a member of the forum as well. So I'm going to talk about AC joint injuries. Let's see if I can present. So these are my disclosures, none of which are directly relevant to this talk. As an overview, I'm going to talk a little bit about the anatomy of the AC joint, how we classify these injuries, what we do to diagnose and manage them, and then a little bit about outcomes and return to play. So I wanted to start with a brief case. This is a 26-year-old right-hand dominant male who presented about a month after falling onto his right upper extremity while skiing. He had immediate pain, had difficulty with shoulder range of motion, and was complaining of frequent clicking about the AC joint. On exam, his shoulder range of motion was somewhat limited because of pain. He did have prominence of the distal clavicle. As you can see in the picture here, this is not this particular patient, but this is exactly what it looked like. He had tenderness over the AC joint, and he had obvious horizontal instability of the AC joint. So these are his x-rays in clinic that day. He had elevation of the distal clavicle, otherwise the x-rays were normal. So we'll get back to the case at the end of the presentation. A little bit about anatomy. There are two main ligaments that stabilize the AC joint. These are the acromioclavicular and coracoclavicular ligaments. So the AC ligaments are comprised of the superior, inferior, anterior, and posterior components. These are thickenings of the joint capsule, and this is the major stabilizer against horizontal translation and posterior rotational forces that are generated by scapular protraction. So the CC ligaments are comprised of the conoid and trapezoid ligaments that confer vertical stability. These work as restraints against scapular internal rotation. And this is a study that we did that's in press looking at AC and CC ligament anatomy. So the conoid ligament arises from the posterior coracoid precipice. It inserts on the conoid tubercle, which is on the posterior inferior aspect of the clavicle. It inserts about 45 millimeters from the lateral edge of the clavicle, and it's responsible for 60% of the restraint to anterior and superior clavicular displacement and rotation. The trapezoid ligament originates from the anterosuperior aspect of the coracoid. It runs anterior to the conoid ligament and inserts on the trapezoid line, which is also on the inferior aspect of the clavicle. It inserts about 25 millimeters from the lateral edge of the clavicle and provides resistance to AC joint compression. This is just a picture of the inferior surface of the clavicle showing the insertion point for the conoid and trapezoid ligaments. And so we concluded in this study that the quantitative and qualitative descriptions of the CC ligaments have been well defined, but the quantitative data on the capsuloligamentous anatomy of the AC ligaments are limited. So there are high complication and failure rates that we've seen from many different AC joint reconstruction techniques, and the anatomy of the AC and CC ligaments really needs to be better understood to improve our patient outcomes. A little bit about classification of these injuries. They can range from minor sprains and subluxation to complete dislocation. It's often associated with other injuries to the shoulder joint. AC joint injuries were first classified in 1963 by Tosi and then further classified by Rockwood in 1984, which is the system that we're most familiar with. This is just a picture demonstrating the six types of the Rockwood classification for AC joint injuries. So type 1 is a sprain of the AC ligament. Type 2 is a tear of the AC ligament. In type 3, we have disruption of the AC and CC ligaments with displacement of the distal clavicle from about 25% to 100%. Type 4 is posterior displacement of the distal clavicle. Type 5 is about 100% to 300% displacement superiorly. And then type 6, which is quite rare, is displacement inferiorly below the coracoid. A little bit of an expansion on type 3 AC joint injuries. So they can be further classified into 3A or 3B. This was discussed or described by the Issacoss shoulder committee in a consensus statement. So 3A is horizontally stable and 3B is horizontally unstable. This is a very important distinction and can influence our treatment. So type 3 is characterized by overriding the distal part of the clavicle on AP radiographs with the cross-arm adduction view. These patients often have substantial scapular dyskinesia that does not respond to physical therapy. And in turn, these patients may benefit from early operative fixation. These patients with AC joint injuries, about 15% to 18% of them can have associated shoulder pathology, most commonly slap tears or rotator cuff injuries. And bearing that in mind, we may want to consider ordering an MRI in these patients, especially if we're considering moving forward with surgery for the AC joint injury. AC joint injuries comprise about 12% of shoulder injuries overall, much more common in males and tend to occur in the first three decades of life. They usually result from a direct blow to the shoulder while the arm is in an adducted position and commonly occur in sports such as bicycling, skiing, hockey, football, etc. So in terms of diagnosis, these patients present with pain that's accentuated with abduction and cross-body adduction. They may have tenting of the skin by displacement of the distal clavicle. Patients with Type 4 injuries may have pain at the SC joint as well. And then patients can have pain in the neck or trapezius when they have a Type 5 or 6 injury. On exam there are a lot of different tests that we can perform. I've included a few of them here. So the cross-arm adduction test, we can do Pacino's test which is evaluating tenderness by applying pressure at the posterior AC joint. And then very commonly we're doing O'Brien's test, which I skipped over. So pain that's referred to the AC joint is most consistent with an AC joint injury. And pain referred to the anterior glenohumeral joint is more consistent with labral or biceps injury. Additionally, we can do the AC-resisted extension test. And very importantly, we want to evaluate for horizontal instability, which is to evaluate for A to P translation of the clavicle. We can use one hand to shift the clavicle and the other hand to maintain position of the acromion. So this is a video just demonstrating, evaluating for horizontal instability. And that video is courtesy of my partner, Dr. Mike O'Brien. In terms of imaging, we'll obtain the standard glenohumeral joint x-rays. If we want to get further, more specific for the AC joint, we can do the Zenka view. We saw this a lot, of course, on our OITE. And then horizontal instability, it's actually kind of difficult to diagnose it based on standard radiographs. So we can consider obtaining an Alexander view, which is when the arm is in an adducted horizontal stress position, or supine dynamic lateral view, which can give some additional information. So this is demonstrating the Alexander view and what the corresponding x-ray looks like. And on the subsequent slide, we see the supine dynamic axillary lateral. This is not done very commonly, but it's just something to think about in terms of additional radiographic evidence for horizontal instability. In terms of management, types 1 and 2 are managed non-operatively with a sling, anti-inflammatory medications, physical therapy, et cetera. We want patients to avoid contact sports and heavy lifting until they're pain-free and they have symmetric range of motion and strength relative to the contralateral upper extremity. With type 3, management is controversial. We see this a lot in our literature. In order to maximize function, some surgeons advocate surgery for acute type 3 AC joint injuries in young, active patients. But we have to keep in mind that optimal treatment for an athlete who plays overhead sports or has high demand may be quite different from someone who's not as active and maybe a little bit older. So the current literature really shows that there's no difference between operative and non-operative management. So bearing that in mind, the recommendation is to start with non-operative management and then consider surgical management in patients who have significant AC joint deformity, who have tenting of the skin, who have persistent pain despite non-operative management, and those patients who have higher functional demands. For types 4 through 6, these are treated operatively. There are many, many techniques that are described, can include open reduction, direct repair of the AC joint capsule, rigid internal fixation of the AC joint with a hook plate, et cetera. And there are definitely potential complications and residual pain that could be attributed to the implants. In terms of outcomes, this is a 2018 study. They saw that with post-op ACS scores, there was a pretty significant increase with free tendon graft. That is commonly what we use for AC joint injuries or AC joint reconstruction, rather. All treatment modalities improved patient outcomes. And then hook plates and K wires had the highest rate of complications. They concluded that there were comparable subjective outcomes after surgical treatment With all modalities, there was relatively low unplanned re-operation rate. And then with modified weaver done, there was the highest unplanned re-operation rate. A little bit about return to play. So the rate of return to pre-injury level of sport ranged from about 60% to 100%. The rate of return to sport after type 3 and type 5 was greater than 85%. In terms of specific criteria used, strict time-based cutoffs ranged from 6 weeks to 6 months. There was an earlier return to non-contact sports and delayed for those patients playing contact sports. So they concluded that there was an almost perfect rate of return to sport after surgical management of AC joint injuries. Most were able to return to their pre-injury level of sport. And the rates of return to sport were comparable across different types of injuries and surgical procedures. And of course, as we see with many of the treatments we do, there's lack of universal guidelines for post-op rehab and return to sport. So just concluding quickly with our case is a 26-year-old right-hand dominant male with a type 3 AC separation. He had some improvement with range of motion and physical therapy. He was complaining though of persistent pain and clicking. And he elected to proceed with AC joint reconstruction using allograft. So these are a couple of intraoperative videos. In this first video, I'm just passing the graft around the coracoid. I also had a strong piece of suture tape that I passed along with that. And then in this video on the right-hand side is passing the graft around the posterior aspect of the clavicle. So I actually tied the graft over the clavicle and the suture tape on top of the graft, which you'll see in subsequent slides. Let me just go here. These are a couple of still images showing the two limbs of the graft around the clavicle. And in the picture on the right, the tape is in my left hand. This is what the final construct looked like. So after tying the graft and tying the tape over the graft, of course, when we tied the graft, we were holding the clavicle reduced. And then the long limb of the graft was brought over the AC joint along with the two limbs of the tape. And that was incorporated with the AC joint capsule and the surrounding soft tissue to stabilize the AC joint from A to P stability. These are his post-op x-rays. If you look really closely, you can see the teeny tiny drill holes that we put in the clavicle. That was just to pass the tape. So in summary, the AC joint is very important to assist in arm movement. Injuries to the AC joint are often caused by a direct blow to the shoulder and contact sports. The Rockwood classification system is very helpful to us to determine the extent of the injuries and subsequent treatment. And there are a lot of different techniques that can be used for operative treatment. So thank you so much for your attention. I'd be happy to answer questions during the discussion.

AC joint injuries

Rockwood classification system

diagnostic techniques

management options

AC joint reconstruction