I'm Joe Galvin from Madigan Army Medical Center, and today I'll be talking about arthroscopic suprascapular nerve decompression. My disclosure is on the AOS website. So let's start with the case. This is JL. He's a 44-year-old right-hand dominant active-duty military male with a chief complaint of left shoulder pain and weakness. He injured his shoulder six months ago, lifting a heavy box. His main complaint is significant external rotation weakness with his arm at the side. His subjective shoulder value is 25% of a normal shoulder. He has 6 out of 10 pain and positive night pain. On exam, on the left, you can see he has significant wasting of these infraspinatus with prominence of the infraspinatus fossa. He has full painful shoulder range of motion, but significant weakness with external rotation with his arm at the side. This also reproduces his symptoms of shoulder pain. He also has a positive O'Brien's test. Radiographs demonstrate no glenohumeral arthritis. An MRI of the shoulder without contrast demonstrates a large multiloculated suprascapular fossa cyst, which extends into the spinal glenoid notch. As you can see here on the axial images, the extension in the spinal glenoid notch. Electrodiagnostic studies show evidence of suprascapular nerve compression. My plan was an arthroscopic cyst decompression, biceps tenodesis, slap repair, and arthroscopic suprascapular nerve decompression. One of the best articles out there on suprascapular neuropathy is by Robert Boykin and Dr. Warner in JBJS 2010, reviewing the anatomy all the way through the treatment with a really comprehensive review. The suprascapular nerve branches off the upper trunk of the brachial plexus, passes under the transverse scapular ligament, just medial to the core base of the coracoid, and then passes through the floor. The supraspinatus fossa and then around the spinal glenoid notch to innervate both the supraspinatus and the infraspinatus as it passes below the spinal glenoid notch. There's variable anatomy in the suprascapular notch. You can even have an ossified transverse scapular ligament, and that can be a point of compression of the nerve. The best in that anatomic study is also by Dr. Warner and Christian Gerber, along with Mascalet, where they looked at the anatomic relationship of the suprascapular nerve and cadavers and found that the average distance from the origin of the biceps tendon to the motor branches of the supraspinatus was three centimeters, and from the posterior glenoid rim, it was two centimeters. Typically, there's one to two motor branches to the supraspinatus and three to four to the infraspinatus. Here on the right, you can see a depiction of the scapula with the suprascapular nerve passing under the transverse scapular ligament, and then around the spinal glenoid notch to innervate the infraspinatus. Laurent Lafosse popularized the arthroscopic technique, and Dr. Warner showed us, along with Dr. Higgins, good results can be obtained from arthroscopic suprascapular nerve decompression in properly selected patients. He also showed us that in a cadaveric model, if you had a massive supra and infra tear, the nerve retracted immediately, and with repairing that, you could restore the normal course of the suprascapular nerve. Then clinically, in arthroscopy, they showed, Dr. Warner did, that you could reverse suprascapular neuropathy as measured by follow-up EMG nerve conduction velocity studies by repairing the massive rotator cuff tear. However, more recently, Christian Gerber and his group did a level two randomized control trial comparing arthroscopic rotator cuff repair for supra-infra tears versus rotator cuff repair with nerve decompression, and they found no difference. They also found that in the patients who also had a suprascapular nerve decompression, three of nine had worsening in their EMG findings, and so they stopped the study early, seeing that it was not indicated. My indications for surgery are extrinsic suprascapular nerve compression with progressive pain and weakness. This is most commonly due to a cyst, but you can also have compression at the transverse scapular ligament, or in the variably present cases of a spinal glenoid notch ligament, it can be compressed there as well. A relative indication for release is persistent superior shoulder pain, which improves with a diagnostic image-guided suprascapular notch injection. These are typically patients who have had all other diagnoses excluded and have the classic pain distribution that gets completely better with a suprascapular notch injection. Next, I'm going to move to our arthroscopic technique. This is a video of that patient I presented with a large spinal glenoid notch cyst. He's positioned in the beach chair. You can see our superior portals, both medially and laterally, that we're going to use for our decompression. This patient had a large slap tear, so I performed a biceps tenotomy. By squeezing the biceps, muscle belly tensions the interarticular tendon, allows easier transection, and then an open subpectoral biceps tenodesis. Next, I established a trans cuff portal medial to the rotator cable with a five millimeter cannula. Then we'll place the arthroscope in the anterior portal and work through that trans cuff portal. Next, we'll perform a posterior superior capsulotomy. This is a technique that I learned by watching a video by Peter Millett. We're at the posterior superior glenoid, just superior to the labrum. There, you can see the cyst in between the labrum and rotator cuff. You can, under direct visualization, see that cyst and decompress it safely. We'll open up our visualization a little bit better. Then we'll come in with a liberator. Again, under direct visualization, I could see the cyst and safely decompress it. We knew from the MRI that this was a multi-loculated cyst. Because the liberator is very sharp, we'll remove that and put in a blunt switching stick, which is inserted here, and break up those loculations while protecting the suprascapular nerve, which is more posteriorly and medially. There, you can see. Next, we will repair the slap tear. I used my trans rotator cuff portal to place that anchor and repair it. Next, we'll go subacromial. This is a model showing the scope placed in the lateral viewing portal. You can see that yellow pipe cleaner is the nerve. Then we'll pass our scope, trocar through our more medial incision, posterior to the clavicle. Then through that more lateral divisor-type portal, we'll cut the transverse scapula ligament. Here, we are viewing laterally. The radiofrequency device is in the anterolateral working portal. There's my scope trocar retracting medially. To the left is the base of the coracoid, and there is the suprascapular notch. We'll sweep medially, and that scope trocar is in the more medial incision, posterior to the clavicle. There's the nerve passing under the transverse scapular ligament, which is right here. In this case, I actually took a picture and inadvertently turned off my video. I have another case I'll show you. There's the transverse scapular ligament, and then we'll cut it just like this. The next case is a more classic view of how you do this. We're viewing posteriorly. There's the CA ligament. You can see it very nicely. The radiofrequency is in the lateral portal. Now, we'll place our arthroscope in the lateral viewing portal, and we want to follow the posterior border of the CA ligament, which is right here. We'll establish an anterolateral working portal, and here is the posterior border of the CA ligament. Then, with the radiofrequency device, I'm feeling the base of the coracoid. I know the CA ligament is traversing right down here to the base of the coracoid. I feel that, and I know my CC ligaments are going to be directly posteriorly here. I'm going to open up this subacromial bursa. This is the technique described by Ronald Foss that I got to see him do very nicely. This is the tunnel. Here's the anterior border of the supraspinatus, and here's the CC ligaments. That is the tunnel that you want to exploit. We see CC ligaments over here. I can palpably feel them and see them, and then the anterior border of the supraspinatus. You want to work directly in that tunnel. There you can see. Here is the muscular portion of the supraspinatus. We're clearing up some of the bursa. There's the tunnel that I want to go into. If I back up and show you some perspective, here is the posterior rotator cuff, and you can see where we're at. We'll zoom back in. One trick to help exploit that tunnel is make your more lateral visors portal and come in and retract the supraspinatus posteriorly. This allows you to gain a foothold and then move more medially. There I've sweeped medially, and I've found the nerve. Now I'm going to establish my more medial portal and come in with the blunt trocar and use that again to retract it medially. Here is the switching stick retracting the supraspinatus posteriorly, and the more medial trocar retracting medially. There's the transverse scapular ligament. I'm going to place my blunt retractor medially. There's the nerve, and then I'll remove the switching stick, which was retracting the supraspinatus posteriorly, and I'll insert my cutting device. I'm finding the superior border of the ligament, and then we'll clear off the inferior border of the ligament, and then we'll cut it. There we have the ligament, and there's the nerve free. We can degrade this medial aspect to ensure it does not impinge on the nerve. That's the technique. All of these things are things I learned from Dr. Warner and Dr. LaFosse, who are truly the experts. Thank you for allowing me the opportunity to present, and thank you very much.

Joe Galvin

Madigan Army Medical Center

arthroscopic suprascapular nerve decompression

shoulder injury

suprascapular fossa cyst