PROCEDURE
THE FIRST STEP IN A RIGHT REVERSE TOTAL SHOULDER ARTHROPLASTY
So, we're going to do a right reversal shoulder arthroplasty and for the exposure, my main references would be the tip of the coracoid, which is somewhere around here, and the posterior corner of the acromion, which is somewhere over there. And I divide these mentally in thirds, and typically the incision is just slightly lateral to the coracoid, approximately one-third medial and two-thirds lateral for the distance.
Incision. And then the first thing we do is go through the subcutaneous tissues, identify the deltoid fascia, and once we get there, we're going to use a Gelpi retractor distally, a second Gelpi retractor proximally, and I'll take a pickup. In order to get proximal and medial, we're going to have to elevate medial skin flap here.
We'll get initiated with electrocautery and then we place a rake, pulling up on the skin and constantly reposition this retractor in order to keep gaining access to the deltopectoral interval because it's going to be medial in reference to the location of my skin infection. So, typically, one can identify, reasonably well, the location of the interval by identifying this fat, what people called Mohrenheim's triangle. And then we're going to use fine scissors and a Cushing in order to develop this plane between that fat triangle and the deltoid. Now, here we can see deltoid, pecotoralis will be there, and the cephalic vein will be somewhere down here.
My preference is to preserve the cephalic vein and mobilize it medially with the pectoralis. And we're going to get these little bleeders over here. And the challenge sometimes would be to create a little pocket between the vein and the coracoid process. And then we're going to place a Hohmann retractor that is going to go over the tip of the coracoid. And that will allow us to reposition this Gelpi, so that we can now mobilize the space again between the deltoid. So, you can see here the cephalic vein, this is the deloid muscle, the pectoralis is down here, and there are a few branches that are deeper that I'm going to coagulate in order to continue our dissection distally.
Take fine scissors again. And now that we have vein identified, it's like a roadmap for the deltopectoral interval. We'll develop all that plane from this distal to proximal. And of course, as we mobilize the vein medially, there's to be a few branches that are going to drain from the deltoid to the cephalic vein. And so we're going to start to dissect this in electrocautery so that we can coagulate those branches as we all distally.
DISSECTION
And then again, we can reposition our Gelpi retractors to open up that space even further and continue the dissection. Now, we can see the beautifully, the cephalic vein pectoralis major, deltoid. I'll take fine scissors again and then we'll finalize by taking our dissection all the way to the lowest portion of the deltopectoral approach.
And now we have created a plane between the pectoralis and the deltoid. There is a very natural pocket, where we can place the second Hohmann retractor just distal to the humeral shaft. And now before we can change positions, we're going to remove the Gelpi's carefully, not to puncture the cephalic vein.
THE MAYO STAND
And then we're going to place a knee retractor. We'll retract the pectoralis, which is in the cephalic vein. Now, we're going to place the arm in a Mayo stand, and we're going to place the arm in some abduction, and the benefit is that it will now allow us to place the subdeltoid space under tension and avoid injury to any rotator cuff. Now, this patient has a massive posterior superior cuff tear, so the exposure may be more difficult because of the migration, but we can see how we're opening the space between the deltoid and the rotator cuff, trying to pierce through the bursa.
And then once we have that space completely recreated, I can actually feel in this patient the humeral head on the posterior aspect of the acromion is fine. But because of her disease, we're going to mobilize her deltoid laterally. So now we have the deltoid out of the way. And we have the pectoralis here. So, I'm going to drop down the Mayo stand just a little bit.
And, most of us will do our biceps tenodesis if the biceps is still there. So one way to identify it is to look for the muscle and the tendon of the pectoralis and then feel underneath. You can see how that is a cord that is moving.
FISHING THE TENDON OUT
I'm going to open up that sheath and then use fine scissors to try to fish the tendon out. So, that's the biceps tendon. Now, we're going to place a suture that we will double loop around the tendon, and then we're going to divide the tendon so you can see how the biceps tendon is under. And now we're going to identify proximally the location of the biceps tendon, which, as you can see in this patient, is slightly subluxed. But it will give us a very good idea of how to aim for the interval region.
FINDING THE CONJOINED TENDON
The next step is to have your assistant pull with the retractor laterally and then identify the conjoined tendon. The conjoined tendon has always a muscular edge and the mistake is to try to expose by cutting here. I'm just going to lift and then use electrocautery to find the plane between the remaining, if there is any, subscapularis and the conjoined tendon, as you can see here. Again, in patients with anterior cuff tears involving the subscapularis, that may be a more difficult plane to identify.
SUBSCAPULARIES TENOTOMY
And now we have the whole shoulder well exposed, and we're going to try to approach the shoulder through a subscapularis tenotomy. So here you can see the tendon of the long head of the biceps, and by palpation, one can feel the interval. So we will take the Mayo stand out and have our assistant hold the arm. And that's the top of the subscapularis tendon.
We're going to divide the superior aspect of the subscapularis tendon just in line to where the interval was and then we'll use fine scissors. Because the humeral head is a sphere, the mistake is to perform your tenotomy as a straight line. It has to be a slightly curved line.
We're going to be placing a second Hohmann retractor on the lower part of the skin incision. And then we will continue our tenotomy, and again, realizing that this is a sphere, so we want to leave a tendon stump on this side. Again, in this particular patient, as you can see the letter tuberosity is almost bare, so she does have the upper two-thirds of the subscapularis.
So we're now grabbing together the capsule of the shoulder and whatever remaining subscapularis is, which is not a lot. And then we use a point to have these two sutures controlling the subscapularis. Now, I want to get the patient's arm, and we're going to aim for the location of the inferior capsule. If I can have a RayTec?
LATISSIMUS DORSI
So what I try to do is understand what's the location of the latissimus dorsi. So we want to stay proximal to latissimus dorsi, but that still leaves the whole inferior capsule, so I'm going to remove this Hohmann and reapply it subperiosteally so that the latissimus dorsi is inferior.
Now, the key is to move the elbow of the patient up to the ceiling. So, we will slowly release the inferior capsule, in a controlled way, where we're rotating the arm and keeping the latissimus dorsi intact. And you can see where parts of the equator of the humeral head, so we have the whole medial aspect of the humerus skeletonized.
And again, we've had our assistant pull out and we use a large Darrach, use the part that is curved on the lower part of a humeral head and dislocate the joint. Typically, this location is much easier in patients that have a rotator cuff. It's important not to over-rotate so that the brachial plexus is not at risk. It is more extension than rotation, the maneuver.
HUMERAL SHAFT
Now, here is a humeral shaft and what we want to do is open the canal in line with the center of the humeral head, in reference to the canal. And I always like to use a thin instrument to make sure that we can understand the alignment of our reamers. You can see how that way we can replicate exactly that line of reaming. And then we use reamers for our so-called short stem.
And then, depending on the system that a surgeon uses, the preparation of the canal may be slightly different. But in this particular case, with this system, we want to get some cortical fit. So the idea is to get this line, which is a combined length of the shaft on the humeral head all the way to the top of the humeral head. And that would be enough reaming depth. You can see an arrow that is going to match the arrow on this part of the cutting edge.
You can see them both together. So if they are aligned, then this is our rotation rod for our assistant to use, then with a thumb, this can be depressed so that we get our version in.
ADDUCTION AND THE ROTATION ROD
The next thing I'm going to do is hold the arm right there, and place it into adduction. So what I'm trying to do is get this rotation rod, which is at 30 degrees, parallel to the forearm. And then with a C-guide, I'm going to try to understand what is the height of the human head cut. And it's a little bit higher. I'm aiming at the connection between the footprint of a rotator cuff where it used to be and the articular cartilage. Double-check my version one more time and then place a couple of pins.
We're going to go ahead and do our humeral cut. We have a very nice resection place now. So for broaching, we're going to do two sizes smaller than what we reamed, and the key is to place it in enough valgus. And in this particular patient, with some osteopenia, then we use a protector so that when we place our retractor on the metaphysis of the humerus, it just doesn't cross the bone.
RETRACTORS
So then we take those retractors out. We want to switch this retractor to the other side, and we're going to bring the Mayo stand again. And we're going to place this retractor posteroinferiorly. So it's going to go just to posterior to the glenoid rim, and we'll take the retractor out and, very gently, move the retractor with the hand of the patient so that we can see that the hand rest.
We can see the glenoid peeping there. We place a knee retractor in the front in that interval between the subscapularis and the conjoined tendon and then we'll proceed with our inferior and anterior capsular release. So, again, in this patient, the cuff is compromised, but this would be the typical location of the superior glenohumeral ligament and the coracohumeral ligament.
You can see very well the continuity of the anterior with the inferior capsule. So, we will go ahead and divide. And this is the plane that one wants to identify where the muscle fibers of the subscap are protected and left intact. But if the capsule is divided, now with just a knife, and go just lateral to the labrum and divide the anterior capsule, so that now, whatever subscapularis is remaining is mobilized and has nice excursion.
But there is a still anterior capsule here that will increase the holding power of the suture when we do a repair and then we'll protect the subscap and capsule underneath this retractor in the back.
REMOVING THE LABRUM
Our next step is to remove the labrum and any hypertrophic capsule that the patient may have and something important in this patient is to remember that many times when they have a massive cuff tear without arthropathy, the glenoid is very, very nonsclerotic, and as such, it's very easy to overeem.
We're going to identify the lowest part of the glenoid. You can see the lowest part of the glenoid. And if we pull the soft tissues down, underneath is the axillary nerve so one has to be mindful of that, but you can really see here the inferior pillar, which is actually posterior inferior. So, with this particular system, the size of the base plate is 28 millimeters, and you can use this guide in patients that have no abnormal bone loss to get the right superior inclination, which is typically 10 to 12 degrees.
MAKING SURE YOU HAVE THE RIGHT ORIENTATION
And then, before I commit, I want to make sure that they have the right orientation. So we want to go completely past the second cortex of the glenoid. Now we'll take the reamer and be mindful of the lack of subchondral sclerosis. So what we don't want to do is activate the reamer on the bone. We want to make sure that it goes all the way down.
And then, before we activate the trigger, make sure it's actually off the bone. And then this hand is the hand that will control the direction of the reamer. You can open the base plate.
So now, we can see how all this is cancellous bone. This is cortical bone. So I think we're in good shape to remove this pin and measure. So now, we're going to measure the length of the screw, which is measured with this scale and what you want to do is go inside the hole and then pull back until the hook of a measurement device anchors. And I'm seeing that we're in 24, typically at four millimeters, so it's going to be at 28, so it can be opened. And we can see how, as a consequence of the reaming, there is still some inferior bone and hypertrophic labrum.
GLENOSPHERE
So we'll get a pickup, and then we will remove this inferior tissue over here just to make sure that we can see our glenosphere completely on the base plate. Now, for reverse arthroplasty, clocking on the base plate is important to make sure that this screw is going to be in the right location. We actually want to under rotate the component, just a little bit.
And then, once we get to a position where the threads of the compression screw are reaching the base plate, we will switch to a hand screwdriver to control compression because this is very powerful, and it can actually fracture the glenoid. So what you want to do is get adequate contact and compression.
GETTING ADEQUATE CONTACT AND COMPRESSION
So, now with a single screw, we'll use a straight guide for the superior screw so that we're more parallel and then we'll use the angled for the inferior screw. That's straight. We're going to do a shorter screw here, especially since it’s is not very large.
A 20 screw. And then we'll see the angled guide. And then with this inferior screw, we want to diverge just a little bit, so I'm going to raise a little bit my hand and get potentially a longer screw. I'm at 32, so I'm going to use a 28. We'll take the first screw, which is the superior one – the one we placed more straight. And we will take the second screw, on the hand screwdriver. For glenosphere selection, I'm going to check how much bone do we have exposed inferiorly.
This is an eccentric component and has a mark. And as we have already marked the location of the eccentricity inferiorly. If one wanted to, you can also mark it with a marking pen, so here it is so I can better visualize it. My goal is to move the humerus posteroinferiorly.
As such, I'm going to place the component not exactly as straight up and down like this, but slightly more anterior. So that the eccentricity is posteroinferiorly and then we'll drive the more Morse taper. We can confirm with this tool, which is a screw-in tool, that we have adequate coverage of the glenosphere and, just in case, I'm going to impact again.
FINAL STEP BEFORE GLENOSPHERE IMPLANTATION
This will be the final step before glenosphere implantation. Get the deltoid out of the way and then very gently remove this retractor also so that the teeth do not scratch the glenosphere too much. Next, we'll move the Mayo stand out, and then we'll get the ball hook to translate the humerus anteriorly, and then we'll take the tool to remove the plate protector. And we'll try to start with the thinnest possible humeral bearing, realizing that, in patients that have cuff arthropathy, sometimes have to use a thicker bearing than expected.
So this is the trial bearing that has four millimeters on the metal side and four on the polyethylene. This is an unconstrained implant. And then we're gonna take all retractors out, and we're going to do a trial reduction. And typically, I don't do a full reduction. I just feel what the soft tissue tension is. And to me, that feels like a perfectly tensioned shoulder arthroplasty. One could relocate and then check for a range of motion, and we'll do that for the recording for this case. But technically, we don’t do that.
Here you can see very well how the joint is very well located. If I go into adduction, there is still some space between the tip of the coracoid, the conjoined tendon, and the lesser tuberosity. I have unrestricted external rotation in extension so that should minimize polyethylene wear. And if we take the retractor out, we can confirm we have full elevation and very nice internal rotation.
DISLOCATING THE BONE HOOK
So, for me, it's a very well-balanced reverse arthroplasty. Let me see a bone hook. We'll try to dislocate with a bone hook, if we can. There is another tool to dislocate and then, because it has osteopenia, we're going to actually assemble the component on the back table. So we can open the size ten humeral component and the size four metal and four plastic for a 36.
So we're going to place it in the ten holder and then we place the metal and the plastic. It's important to align properly the four polyethylene tubs, and then we're going to take our clean salt to rotate the component. I can confirm my rotation of the component that this is all completely fitted. And then, again, we support the component with a clean instrument and avoid touching the coating with our fingers by holding the component from the superior aspect.
Then it's important to make sure that we're going to match the version by looking at how parallel the back of the component is. You want to go completely concentric with our inserter until the component is sitting in bone, which it is, superior you can see there.
Then, to relocate, it is basically a translation laterally as the humerus is driven posteriorly. You can see the conjoined tendon on the coracoid. This is the lesser tuberosity, and there is no impingement there. Internal rotation goes under a little bit. Unrestricted external rotation. And then we take this retractor out. We can see how we have very good elevation and internal rotation.
REPAIRING ANTERIOR SOFT TISSUES
And, even though the subscapularis is not very healthy, this is still there. So I'm gonna try to do some repair of these anterior soft tissues, to some extent have anterior resistance to translation that might increase the stability. But again, this patient's subscapularis is compromised, and she will not likely have much power for internal rotation just with the subscapularis.
You can see how even with the implant that does lateralize on the glenoid, on the humeral side, it is typically possible to do a subscapularis repair.
CONCLUSION
One of the final steps with these devices is to place a suture between the edge of the conjoined tendon and the biceps, making sure that one doesn't go too deep with a needle to cause any injury to the musculocutaneous nerve. Correct tension of my suture. And that will secure the tendon of the long head of the biceps so that there is no deformity and potential less cramping.
And now for the closure, we probably don't need to do much in the deltopectoral interval, because, as you can see, it kind of falls into place by itself.
Watch the full surgery here: https://watch.giblib.com/video/3980
