All right. This is Dr. William Ciccone. I want to thank the Arthroscopy Association for giving me the opportunity to present on this topic of arthroscopic subacromial decompression. My disclosures are present on the Academy website. I wanted to talk a little bit about an outline for this talk. I wanted to start with talking about the etiology of subacromial impingement. We'll talk a bit about the anatomy and then some arthroscopic techniques for the treatment of subacromial impingement, and then discuss outcomes associated with those techniques, how to maybe better diagnose the impingement syndrome, and then talk a little bit about the critical shoulder angle. Subacromial impingement has been described from both intrinsic and extrinsic mechanisms. The extrinsic theory is the more classic theory, which states that the subacromial impingement occurs from a direct compression of the rotator cuff between the humeral head and the acromion. This has been classically treated with acromionectomy in the past, which resulted in deltoid detachment and poor outcomes. The anterior inferior acromioplasty described by Neer maintained a deltoid attachment, and this same technique was then modified by Elman to arthroscopic. The intrinsic theory, however, states that impingement is not related to the acromial morphology. It's more related to rotator cuff weakness and degeneration, leading to superior humeral migration and acromial spurring. So in this theory, subacromial decompression does not play a role. Subacromial anatomy is important to understand for those patients who require surgery. It's first to understand that the subacromial space is a real space that's present in the anterior third of the acromion, and to understand that the bursa is an anterior structure along the acromion. An adequate decompression, therefore, requires removal of the anterior edge of the acromion and the undersurface of the anterior acromial process, as described by Neer. Subacromial vessels are difficult or important to know where those are present, especially for surgical intervention. In the anterior bursa, there's the acromial branch of the thoracoacromial artery, which is present in the video there on the right. It's located on the superior aspect of the CA ligament, so general resection of the CA ligament will help you not cut into this artery and get a red out during the procedure. Posteriorly, there's the posterior medial acromial artery, which is present along the posterior acromion, which can be involved with posterior rotator cuff releases, as well as posterior exposures of the rotator cuff in the subacromial space. And at the AC joint, the posterior fat pad can also cause a significant amount of bleeding. Another structure involved in subacromial decompression is a coracoracromial ligament. And there's been questions of, can this stay intact after decompression? In this anatomic study performed, it was noted the insertion of the coracoracromial ligament was along the inferior portion of the acromion, and superiorly, it blends with the deltoid insertion. So the superior fibers can stay intact with an anterior inferior acromioplasty, and an acromioplasty with the burr from posterior, as in the cutting block technique, would be more reliable to save this insertion. The treatment for patients with subacromial space syndrome or subacromial impingement has classically been physical therapy to work with rotator cuff strengthening and scapular stabilization exercises. Subacromial injections can be both diagnostic and therapeutic. Posterior capillary stretching can allow for better alignment of the glenohumeral joint. And then acromioplasty, surgical intervention, should those conservative management fails. Preoperative planning, as in any surgery, is important, even those with simple decompressions. The acromial shape is important to know on the outlet radiograph. The thickness of the acromion, and is it curved or not, to know how much acromion you need to resect at the time of surgery. And whether or not there's any AC joint problems or an osacromion is important to know as well. Positioning, this can be done in the beach chair position. Make sure that there's enough scapular exposure posteriorly with padding of the low back. This allows easy conversion to open surgery if you needed to. It gives good anesthesia access, but you have to worry about cerebral perfusion pressure in those older patients. Lateral cubitus positioning is also an option. Using a bean bag, you want to roll the patient about 20 degrees posterior to better align the shoulder with the floor. You want to do appropriate padding and watch for neck position when using this positioning. To enter the subacromial space, I found it easiest to use my standard posterior viewing portal and angle the trocar superiorly through the subacromial space underneath the acromion, and then out the anterior portal. You can then slide the sheath over this obturator into the subacromial space and then create your lateral portal, which will allow you to triangulate better within that space more rapidly. The lateral portal is created just in the posterior line of the clavicle, just two centimeters lateral to the acromion. The goals of subacromial decompression are a complete bursectomy and then create a smooth surface on the underside of the acromion for the rotator cuff tendons. You want to try to create what's called a type 1 acromion. There's been two techniques described for arthroscopic acromioplasty. One is with the scope posterior and the burr lateral as described by Elman. The second is with the scope lateral and the burr posterior, the so-called cutting block technique. Using both of these techniques allow for orthogonal viewing of the acromial resection, noting that you have a smooth surface in both views. This first technique is of a right shoulder with the scope posterior and the burr lateral. Resecting the bursa, you can see the full thickness rotator cuff pathology. Start with the bursal resection and then using electrocautery, you want to expose the inferior side of the acromion. You want to make sure that you have a good idea where the edges of the acromion are. In this patient, there's a small osacromion or a preacromial fragment that you can see moving off the anterior edge there. We want to make sure we have good exposure of the lateral side of the acromion. Then we can insert the burr from the lateral portal. Going from lateral to lateral, going from lateral to medial, will smooth the undersurface of the acromion. In this case, as due to the osacromial fragment, we're going to be a little bit more aggressive in thinning that anterior fragment as it will tend to move with forward flexion of the deltoid. This is done in a progressive fashion, working underneath the acromion. To where a smooth surface is created. Again, anteriorly, we're going to address that preacromial fragment a little bit more, leading to a nice smooth surface for the rotator cuff. The second arthroscopic technique is the so-called cutting block technique. This is performed with the scope lateral and the burr posterior. You're using the posterior edge of the acromion to create the resection line to create the type 1 acromion. However, preoperative planning is important because if you have a curved acromion, you can resect too much of the acromion using this line. On the radiograph on the lower corner, you can see how much acromion could potentially be resected. You have to use a modified cutting block line in these patients to make sure you don't over resect the acromion. Preoperative planning is important. Here's an example of the cutting block technique. This is a left shoulder with the scope lateral and the burr posterior. We've already cleared the acromion. Now we'll use the burr to smooth out the inferior portion of the acromion. This is done with sweeping the burr from medial to lateral. The scope thing can then be changed back to the posterior portal to view it from a different angle. Here's the scope from posterior showing a adequate resection of the anterior chromium. The outcomes of subacromial decompression are variable. In this study, this is a perspective randomized controlled trial that looked at subacromial decompression versus patients who just had supervised exercises and those in a placebo group. With a follow-up of 30 months, 60 percent of the patients improved with surgery. Sixty-one percent, however, also improved with exercise. But with further follow-up, 50 percent of the exercise group also underwent surgery because of persistent pain, and 22 percent in the placebo group also had surgery. In another outcome study, again, another randomized controlled trial, 87 patients underwent either surgery, either open or arthroscopic, or non-operative care. At a minimum 10-year follow-up, surgical groups had better clinical outcomes than the physical therapy-only group. However, other studies have not shown these results. In these three randomized controlled trials, there was no clinical difference in patients with and without acromioplasty. To further add to the confusion, it's unclear exactly what helps these patients. In this study, this is a double-blind randomized clinical trial. The inclusion criteria were three months of lateral shoulder pain and inability to lie down on the affected shoulder, pain with abduction, extension, and internal rotation, a positive NeuroHockens impingement signs, and a positive lidocaine impingement test, and conservative treatment for six weeks. These patients were divided into two groups. One with underwent arthroscopic bursal debridement only, and the second one that had arthroscopic bursal debridement plus acromioplasty. At a 12-year follow-up, there were no significant differences, and there was no advantage noted of acromioplasty over bursectomy. Perhaps we're not choosing the right patients for these surgeries. What devices do we have to help further decide which patients will do better with surgery and which do not need surgery? One of them classically described as a subacromial injection or the impingement test. However, even with this test, Dr. Kirkley in 2002 in a randomized trial, indicated that the impingement test was a poor predictor of surgical outcome. In a study in 2004, a positive test was associated with 88 percent successful surgical results, and a negative test with only 60 percent successful results. What criteria, either clinically or by physical examination may help determine those patients which might do better with subacromial decompression. This is a study that looked at patients with pain with overhead activity, a positive Hawkins test, temporary pain relief with injection, and radiological evidence of mechanical impingement that being greater tuberosity sclerosis and cysts. They had one-year follow-up. Patients with all four criteria had significantly better outcomes than those who did not. But perhaps we're not treating the right pathology. We know that acromial morphology has long been related to rotator cuff disease. However, while Muir and others have talked about the inferior portion of the acromion, it may be the lateral extension of the acromion that is more associated with pathology. The critical shoulder angle is a measurement of the lateral acromial overhang. It's a line drawn from the inferior lateral acromion to inferior lateral glenoid to the superior lateral glenoid, then aligned from the inferior glenoid point to the most lateral acromial extension. This difference in bony alignment can lead to different biomechanics potentially leading to different disease pathologies. With a lower critical shoulder angle or CSA, the middle deltoid wraps more around the greater tuberosity, causing greater glenohumeral compression with motion, which could lead to glenohumeral arthritis. A higher CSA leads to a larger humeral ascension force, meaning that there's less wrap around the glenoids or more direct pull of the deltoid. Because of this increased force, it leads to more supraspinatus force to balance this deltoid pull leading to rotator cuff pathology. This hypothesis was tested in this study that looked at patients with different CSA angles. They had three groups, one with no arthritis and no rotator cuff pathology. They had another group with no arthritis and a full thickness rotator cuff tear, and a third group with arthritis and no cuff tear. You can see the CSA angles on the right there. However, when you combine the data, you find that those with a CSA of greater than 35, 84 percent were those in the rotator cuff tear group. With the CSA less than 30, 93 percent were in the osteoarthritis group. It was then proposed when patients with rotator cuff tears, perhaps a lateral acromioplasty may decrease the force across the rotator cuff and help assist in rotator cuff healing. In this clinical study, 49 patients underwent scope rotator cuff repair and lateral acromioplasty. They had a mean CSA preoperatively of 37.5 degrees, postoperatively of 33.9 degrees. Following the procedure, they all had CSA less than 33 degrees. Those patients had increased abduction strength, and there was no deltoid compromise in this study. This was further confirmed in a cataveric study that looked at 5-millimeter and 10-millimeter lateral acromioplasty resections and with mechanical testing had no significant difference in deltoid pull-off between these two groups. The indications for subacromial decompression are controversial. In a level 5 publication, it was suggested that pain with overhead activities and night pain for over six months, a persistently positive Hawkins test, a poor response to at least six weeks of physical therapy, radiological evidence for impingement, including greater tuberosity, sclerosis, and cysts, and no rotator cuff tear would be reasonable indications for surgical intervention. Steroid injections were not unreasonable to help, but multiple injections should be avoided due to the effects on bone quality and potentially the rotator cuff. The goals of decompression are to perform a complete persectomy, create a smooth service, and avoid any over-resection of the acromion, which can be done with appropriate preoperative planning. It's unclear when or if decompression is actually necessary and one can consider lateral acromioplasty if there's an elevated critical shoulder angle. Thank you for your attention.

subacromial impingement

acromioplasty techniques

rotator cuff

critical shoulder angle

surgical intervention